Language：Japanese   Publishing type：Research paper (scientific journal)  

This article reviews redundant transforms for sparse representation of images. The term “sparse representation” here denotes a way of signal representation by a linear combination of a small number of vectors, sequences or functions. This representation is used for signal modeling and finds a lot of applications such as signal estimation, restoration and feature extraction. In order to obtain a good sparse representation, it is essential to choose a signal transform appropriately. In this article, redundancy is firstly explained as an effective property of transforms for sparse representation. Then, some problem settings of sparse representation are introduced and their solvers are overviewed. Next, redundant transforms are shown to be successfully applied to image restoration problems. Furthermore, desired properties of transforms for image processing are summarized, and then dictionary learning methods are introduced as a design technique of redundant transforms. Finally, trends of related works are summarized as concluding remarks.

DOI： 10.11370/isj.53.290

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

This paper proposes a directional design method of 2-D nonseparable linear-phase paraunitary filter banks. The proposed method is based on a lattice structure consisting of the 2-D separable DCT block and nonseparable support extension processes. Because of the nonseparability, the bases are allowed to be directional with the critically fixed subsampling, overlapping, orthogonal, symmetric, real-valued, and compact support properties. First, a novel vanishing moment (VM) condition is introduced as a suitable directional constraint, where the moment is referred to as the trend VM. The condition forces wavelet filters, i.e., high-pass and bandpass filters, to annihilate trend-surface components. Second, some theoretical properties of TVMs are discussed for general 2-D paraunitary systems, and then, the properties are applied to the lattice parameters. In order to verify the significance, several design examples are shown, the trend-surface annihilation properties are numerically confirmed, and the denoising capability is evaluated for images through shrinkage. It is shown that our proposed transforms yield perceptually preferable results.

DOI： 10.1109/TIP.2011.2182055

Web of Science

PubMed

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

This paper proposes a boundary operation technique of 2-D nonseparable linear-phase paraunitary filter banks (NS-LPPUFBs) for size limitation. The proposed technique is based on a lattice structure consisting of the 2-D separable block discrete cosine transform and nonseparable support-extension processes. The bases are allowed to be anisotropic with the fixed critically subsampling, overlapping, orthogonal, symmetric, real-valued, and compact-support properties. First, the blockwise implementation is developed so that the basis images can be locally controlled. The local control of basis images is shown to maintain orthogonality. This property leads a basis termination (BT) technique as a boundary operation. The technique overcomes the drawback of NS-LPPUFBs that the popular symmetric extension method is invalid. Through some experimental results of diagonal texture coding, the significance of the BT is verified.

DOI： 10.1109/TIP.2011.2181527

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PubMed

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

A lattice structure of multidimensional (MD) linear-phase paraunitary filter banks (LPPUFB's) is proposed, which makes it possible to design such systems in a systematic manner. Our proposed structure can produce MD-LPPUFB's whose filters all have the region of support N(M Xi), where M and Xi are the decimation and positive integer diagonal matrices, respectively, and N(N) denotes the set of integer vectors in the fundamental parallelepiped of a matrix N, It is shown that if N(M) is reflection invariant with respect to some center, then the reflection invariance of N(M Xi) is guaranteed. This fact is important in constructing MD linear-phase filter banks because the reflection invariance is necessary for any linear-phase filter. Since our proposed system structurally restricts both the paraunitary and linear-phase properties, an unconstrained optimization process can be used to design MD-LPPUFB's. Our proposed structure is developed for both an even and an odd number of channels and includes the conventional 1-D system as a special case. It is also shown to be minimal, and the no-DC-leakage condition is presented. Some design examples will show the significance of our proposed structure for both the rectangular and nonrectangular decimation cases.

DOI： 10.1109/78.747776

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

The overlap-add method (OLA) and overlap-save method (OLS) are well known as efficient schemes for high-order FIR filtering, In this correspondence, new sampling rate conversion methods are proposed by extending the OLA and OLS and eliminating the redundancy caused by the conversion, First, for finite-duration sequences, a rate conversion with the DFT-domain approach is discussed, Then, using the result, the extended OLA and OLS are proposed for infinite-duration sequences. Last, the computational complexities of our proposed methods are shown.

DOI： 10.1109/78.622960

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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DOI： 10.1063/5.0232852

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/itc-cscc62988.2024.10628276

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/itc-cscc62988.2024.10628402

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

The application of data science technologies in geotechnical and earthquake engineering is a hot topic. This study aimed to identify the macroscopic dynamic properties of the soil from the previous records of seismic motions observed at the ground surface utilizing the dynamic mode decomposition (DMD). The key to our ingenuity was to replace the soil layer composition and dynamic properties with a single-degree-of-freedom (SDOF) vibration model based on the ground surface observation records. In the validation process, first, a comparison was made between the proposed method and the analytical solution for an SDOF vibration system; second, a comparison was made with a one-dimensional equivalent linear multiple reflection theory analysis considering the nonlinear soil profile. The proposed method effectively approximated complex ground profiles to an equivalent SDOF vibration system and constructed shear strain-dependent models of the macroscopic pseudo-shear modulus and damping constant from the observed ground surface seismic motions. This study was based on numerical experiments and limited conditions of small seismic amplitudes for which equivalent linear approximations could be made. Based on the results obtained in this paper, we aim to extend the model to wide-area forecasting by improving it to a practical model that covers strong nonlinearities.

DOI： 10.1080/17499518.2023.2184479

Scopus

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

In channelized alluvial rivers, alternating sandbars are formed by alternating scouring and sedimentation in the downstream direction. The conditions for the occurrence of sandbars are obtained in the stability analysis as when the ratio of channel width to depth, $\beta$, exceeds a critical value due to innate instability of bottom. However, neither the mechanism nor the conditions for the occurrence of sandbars are well understood because it is difficult to quantify bars before or early in the occurrence of that using conventional measurement methods. We conducted experiments in a laboratory flume with slope as a variable to obtain dense data on the geometry of the water surface, bottom surface, and flow depth. We then performed a wavenumber analysis of the measured data to verify the validity of the results estimated by the stability analysis. We calculated the temporal variation of the correlation coefficients between the depth--water surface $r_{wl}$ and depth--bottom $r_{bl}$ along the development stage of the sandbar since flow state could be estimated from the relationship between the flow depth and the water surface/bottom surface. The temporal variation of the correlation suggests that the development process of sandbars can be divided into three phases, and the flow state is different for each phase. We also found that the occurrence time of sandbars would be defined based on the intersection of the temporal variation of $r_{wl}$ and $r_{bl}$. Furthermore, we show that the formation process of the sandbar is independent of Fr.

DOI： 10.1063/5.0128760

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

Hydraulic quantities governing the generation of bedforms (formed spontaneously on the bottoms of rivers) have been investigated through geomorphological methods, laboratory experiments, stability analyses, numerical analyses, and other research methods. Recently, numerical analysis has been conducted using fine spatial grids to accurately describe morphodynamics. However, numerical analysis cannot always describe the real phenomena, because it is based on assumptions. One effective way to verify physical assumptions is to compare numerical analysis with actual measurements of equivalent resolution. Measurement data with high resolution enable the construction of a duplicate of the measurement target on a computer called a “digital twin.” To construct a digital twin of the process of bedforms generation and development, geometries of the water surface and the bed surface must be simultaneously measured. We developed and verified a measurement method for the construction of a digital twin during the generation and development of bedforms. The measurement system uses two cameras and a line laser to simultaneously measure the water surface and bed surface. Accurate refraction correction at the water surface is possible by acquiring the shape of the water surface, allowing the bottom shape to be determined by geometric processing. The method provides sub-millimeter-accurate measurements of the water surface and bottom with a spatial resolution of 0.95 cm longitudinally and 0.038 cm transversely in a 12 m × 0.45 m flume and takes only 1 min per measurement. This method can provide measurement results that contribute to the understanding of the generation and development of bedforms.

DOI： 10.1063/5.0085574

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publisher：IEEE  

This work proposes convolutional-sparse-coded dynamic mode decomposition<br />
(CSC-DMD) by unifying extended dynamic mode decomposition (EDMD) and<br />
convolutional sparse coding. EDMD is a data driven analysis method for<br />
describing a nonlinear dynamical system with a linear time-evolution equation.<br />
Compared with existing EDMD methods, CSC-DMD has an advantage of reflecting<br />
spatial structure of the target. As an example, the proposed method is applied<br />
to river bed shape estimation from the water surface observation. The<br />
estimation problem is reduced to sparsity-aware restoration with a hard<br />
constraint, which is given by the CSC-DMD prediction, where the algorithm is<br />
derived by the primal-dual splitting method. A time series set of water surface<br />
and bed shape measured through an experimental river setup is used to train and<br />
test the system. From the result, the significance of the proposed method is<br />
verified.

DOI： 10.1109/ICASSP.2019.8683848

arXiv

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Other Link： https://dblp.uni-trier.de/db/conf/icassp/icassp2019.html#KanekoMYHOOY19

Language：English  

J-GLOBAL

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

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Other Link： https://dblp.uni-trier.de/rec/conf/apsipa/2021

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/icas49788.2021.9551113

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Authorship：Last author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Human Motion Recognition (HMR) using radar has been expected to be applied to human monitoring. Radar-based HMR can be realized by extracting features by deep learning from radar motion-sensing data. In this paper, three 2-D domains (Time-Doppler, Time-Range, and Range-Doppler) are analyzed as the motion data. The motion classification results using Convolutional Neural Network (CNN) shows that multiple domains improve classification accuracy. In addition, we show the motion analysis results with high range resolution including DOA, and show that further accuracy improvement can be expected.

DOI： 10.23919/ISAP47053.2021.9391487

Scopus

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/ICASSP39728.2021.9414533

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Other Link： https://dblp.uni-trier.de/db/conf/icassp/icassp2021.html#AraiMYHO21

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BACKGROUND: Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) is a life-threatening cutaneous adverse drug reaction (cADR). Distinguishing SJS/TEN from nonsevere cADRs is difficult, especially in the early stages of the disease. OBJECTIVE: To overcome this limitation, we developed a computer-aided diagnosis system for the early diagnosis of SJS/TEN, powered by a deep convolutional neural network (DCNN). METHODS: We trained a DCNN using a dataset of 26,661 individual lesion images obtained from 123 patients with a diagnosis of SJS/TEN or nonsevere cADRs. The DCNN's accuracy of classification was compared with that of 10 board-certified dermatologists and 24 trainee dermatologists. RESULTS: The DCNN achieved 84.6% sensitivity (95% confidence interval [CI], 80.6-88.6), whereas the sensitivities of the board-certified dermatologists and trainee dermatologists were 31.3 % (95% CI, 20.9-41.8; P < .0001) and 27.8% (95% CI, 22.6-32.5; P < .0001), respectively. The negative predictive value was 94.6% (95% CI, 93.2-96.0) for the DCNN, 68.1% (95% CI, 66.1-70.0; P < .0001) for the board-certified dermatologists, and 67.4% (95% CI, 66.1-68.7; P < .0001) for the trainee dermatologists. The area under the receiver operating characteristic curve of the DCNN for a SJS/TEN diagnosis was 0.873, which was significantly higher than that for all board-certified dermatologists and trainee dermatologists. CONCLUSIONS: We developed a DCNN to classify SJS/TEN and nonsevere cADRs based on individual lesion images of erythema. The DCNN performed significantly better than did dermatologists in classifying SJS/TEN from skin images.

DOI： 10.1016/j.jaip.2021.09.014

PubMed

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Authorship：Last author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Other Link： https://dblp.uni-trier.de/db/journals/corr/corr2009.html#abs-2009-00831

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER HEIDELBERG  

In mammals, audition is triggered by travelling waves that are evoked by acoustic stimuli in the cochlear partition, a structure containing sensory hair cells and a basilar membrane. When the cochlea is stimulated by a pure tone of low frequency, a static offset occurs in the vibration in the apical turn. In the high-frequency region at the cochlear base, multi-tone stimuli induce a quadratic distortion product in the vibrations that suggests the presence of an offset. However, vibrations below 100 Hz, including a static offset, have not been directly measured there. We therefore constructed an interferometer for detecting motion at low frequencies including 0 Hz. We applied the interferometer to record vibrations from the cochlear base of guinea pigs in response to pure tones. When the animals were exposed to sound at an intensity of 70 dB or higher, we recorded a static offset of the sinusoidally vibrating cochlear partition by more than 1 nm towards the scala vestibuli. The offset's magnitude grew monotonically as the stimuli intensified. When stimulus frequency was varied, the response peaked around the best frequency, the frequency that maximised the vibration amplitude at threshold sound pressure. These characteristics are consistent with those found in the low-frequency region and are therefore likely common across the cochlea. The offset diminished markedly when the somatic motility of mechanosensitive outer hair cells, the force-generating machinery that amplifies the sinusoidal vibrations, was pharmacologically blocked. Therefore, the partition offset appears to be linked to the electromotile contraction of outer hair cells.

DOI： 10.1007/s00424-020-02373-6

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

<p> Recently, the need for the robust design and the resilience design methods under accidental loading of soil structures has been the subject of many discussions. Herein, we are developing a dynamic reliability analysis base on mode decomposition for evaluating the failure mode of the soil structure. This analysis features quantifying uncertainties related to the accuracy of the parameter settings. This paper describes the deformation calculation procedure for the case of a simple embankment on a liquefiable sand layer. We conducted a dynamic effective stress analysis to evaluate the liquefaction phenomenon in the sand layer. This study aimed to derive an alternative numerical analysis model that considers the space and time required for calculating the aforementioned deformed embankment.</p>

DOI： 10.2208/jscejge.76.2_142

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J-GLOBAL

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejam.76.2_i_25

J-GLOBAL

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Automatic operating system for vehicle has been widely studied. Especially, automotive millimeter-wave (MMW) radar has been attracting attentions. Synthetic Aperture Radar (SAR) processing by using MMW radar can obtain high-resolution 2-D images. In general, SAR processing is used in straight orbits. However, in the case of automobiles, it is necessary to consider not only straight tracks but also curved tracks. In this paper, we show that the performance of automotive MMW-SAR processing on curved tracks by experimental results.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

Array radar needs enough array length to realize high angular resolution. However, it takes cost to increase elements physically. Recently, Minimum Redundancy Multiple- Input Multiple-Output (MR-MIMO) was proposed to increase the number of virtual elements efficiently. Further improvements by using Khatri-Rao (KR) transformation in the case of incoherent waves were also proposed. In this paper, we show experimental results on indoor human tracking with millimeter-wave MR- MIMO radar to verify the improvements of resolution and tracking performance in comparison with the results by a conventional MIMO radar.

Scopus

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/ICIP.2019.8803737

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Other Link： https://dblp.uni-trier.de/db/conf/icip/icip2019.html#FujiiYMOCONH19

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DOI： 10.1364/BOE.10.003317

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DOI： 10.1109/iWEM.2018.8536598

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DOI： 10.1109/ICASSP.2018.8462343

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE Computer Society  

This work generalizes an existing framework of nonseparable oversampled lapped transforms (NSOLTs) to effectively represent complex-valued images. The original NSOLTs are lattice-structure-based redundant transforms, which satisfy the linear-phase, compact-supported and real-valued property. The lattice structure is able to constitute a Parseval tight frame with rational redundancy and to generate a dictionary with directional atomic images. In this study, a generalized structure of NSOLTs is proposed to cover complex-valued atomic images. The novel transform is referred to as a complex NSOLT (CNSOLT). The effectiveness of the structure is verified by evaluating the sparse approximation performance using the iterative hard thresholding (IHT) algorithm for a millimeter wave radar image.

DOI： 10.1109/ICIP.2017.8296776

Scopus

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Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1109/APSIPA.2017.8282330

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OPTICAL SOC AMER  

Because conventional laser Doppler vibrometry or Doppler optical coherence tomography require mechanical scanning probes that cannot simultaneously measure the wide-range dynamics of bio-tissues, a multifrequency-swept optical coherence microscopy with wide-field heterodyne detection technique was developed. A 1024 x 1024 x 2000 voxel volume was acquired with an axial resolution of similar to 1.8 mu m and an acquisition speed of 2 s. Vibration measurements at 10 kHz were performed over a wide field of view. Wide-field tomographic vibration measurements of a mouse tympanic membrane are demonstrated to illustrate the applicability of this method to live animals.(C) 2017 Optical Society of America

DOI： 10.1364/BOE.8.000608

Web of Science

PubMed

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Language：English   Publishing type：Research paper (international conference proceedings)  

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DOI： 10.1017/ATSIP.2016.3

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this study, an acceleration technique for nonseparable oversampled lapped transforms (NSOLT) is proposed. NSOLT is a non-separable transform which simultaneously satisfies the oversampled, overlapped, symmetric, tight-frame, real-valued and compact-supported property. From the non-separability, NSOLT is valid for sparsely representing edges and textures with oblique directions as a linear generative model. In this paper, a fast convolution technique for NSOLT is proposed by using fast Fourier transform (FFT) and frequency-domain multirate processing. The analysis and synthesis processing for 2-D and 3-D data is evaluated through GPGPU implementation, and the processing speed of the proposed structure is compared with the conventional lattice-based one to show the effectiveness.

DOI： 10.1109/APSIPA.2016.7820816

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Recently, single image super-resolution (SISR) is very important research field to reconstruct a high-resolution (HR) image from a low resolution (LR) image. However, existing image super-resolution approaches require a lot of computations or consider parameters for various situations. This paper proposes an efficient and simple image super-resolution technique using multiple directional lapped orthogonal transforms (M-DirLOTs). It captures high-frequency informations, e.g. edges and slant textures, of images efficiently, and reduce the computational cost. Simultaneously, this model avoids any a priori hypotheses on the LR picture. The proposed method overcomes some disadvantages of existing methods. Experimental results show that the proposed method is able to significantly improve the super resolution performance.

DOI： 10.1109/ICIP.2016.7532595

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes an efficient design method of nonseparable oversampled lapped transform (NSOLT). NSOLT is a multidimensional redundant transform which satisfies the nonseparable, symmetric, real-valued, overlapped, compact-supported and perfect reconstruction property. A typical example-based design approach, which consists of sparse coding and parameter optimization, is applicable to NSOLT. In the previous implementation, however, the parameter optimization stage dominated the computation. The main reason is that the quasi-Newton method with numerical gradient of the objective function was adopted. To reduce the computational cost, the analytical gradient is derived and introduced. For further acceleration, the quasi-Newton method is replaced by stochastic gradient descent. Through some experiments, the significance of the proposed method is verified.

DOI： 10.1109/ICIP.2016.7533034

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Redundant-transform-based image fusion approaches require a lot of memory and computations. This paper proposes an effective and efficient multi-focus image fusion technique in dual domain using a redundant transform. The proposed scheme captures high-frequency informations, e.g. edges and slant textures, of images efficiently, and reduce the computational cost. The proposed scheme extracts the high-frequency information of images with multiple directional lapped orthogonal transforms (M-DirLOTs) through the following procedure: (1) reconstruct the detail image using high-pass sub-bands, (2) execute a fusion operation in spatial domain through joint measurement and (3) improve the performance by mathematical morphology processing. The proposed method overcomes some disadvantages of traditional transform-based and spatial-based fusion techniques. Experimental results show that the proposed method is able to significantly improve the fusion performance.

DOI： 10.1109/ICASSP.2016.7471974

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This letter proposes an image fusion method which adopts a union of multiple directional lapped orthogonal transforms (DirLOTs). DirLOTs are used to generate symmetric orthogonal discrete wavelet transforms and then to construct a union of unitary transforms as a redundant dictionary with a multiple directional property. The multiple DirLOTs can overcome a disadvantage of separable wavelets to represent images which contain slant textures and edges. We analyse the characteristic of local luminance contrast, and propose a fusion rule based on interscale relation of wavelet coefficients. Relying on the above, a novel image fusion method is proposed. Some experimental results show that the proposed method is able to significantly improve the fusion performance from those with the conventional discrete wavelet transforms.

DOI： 10.1587/transfun.E98.A.2360

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Maruzen Co., Ltd.  

This paper proposes a Poisson denoising method with a union of directional lapped orthogonal transforms (DirLOTs). DirLOTs are 2-D non-separable lapped orthogonal transforms with directional characteristics under the fixed-critically-subsampling, overlapping, orthonormal, symmetric, real-valued and compact-support property. In this work, Dir- LOTs are used to generate symmetric orthogonal discrete wavelet transforms and then a redundant dictionary as a union of unitary transforms. The multiple directional property is suitable for representing natural images which contain diagonal textures and edges. Multiple DirLOTs can overcome a disadvantage of separable wavelets in representing diagonal components. In addition to this feature, multiple DirLOTs make transformbased denoising performance better through the redundant representation. Experimental results show that the combination of the variance stabilizing transformation (VST), Steinïs unbiased risk estimator-linear expansion of threshold (SURE-LET) approach and multiple DirLOTs is able to significantly improve the denoising performance.

DOI： 10.1587/transfun.E98.A.1820

Scopus

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：European Signal Processing Conference, EUSIPCO  

This paper presents a new method for selecting key frames from a given video sequence. It is characterized by the fact that the entire process works in a wavelet transform domain. At first, shot boundaries are detected to define initial key frames. Secondly, specified but any number of key frames are selected by clustering feature vectors. Its effectiveness is evaluated in terms of precision rates and processing speeds. The proposed method offers more satisfactory results and works faster than the other existing methods.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：European Signal Processing Conference, EUSIPCO  

A coefficient-parameter embedding method is presented for invertible deinterlacing with variable coefficients in the application to Motion-JPEG2000 (MJP2). Invertible deinterlacing, which the authors have developed before, can be used as a preprocess of frame-based video codec, such as MJP2, for interlaced videos. When the conventional field-interleaving is used instead, comb-tooth artifacts appear around edges of moving objects. On the other hand, the invertible deinterlacing technique allows us to suppress the comb-tooth artifacts and also to recover an original picture on demand. As previous works, the authors have developed a variable coefficient scheme with a motion detector, which realizes adaptability to local characteristics of given pictures. When applying this deinterlacing technique to an image codec, however, it is required to send coefficient parameters to receivers for original picture recovery. This work proposes a parameter-embedding technique and constructs a standard stream which consists both of picture data and parameters. The parameters are embedded into the first LH subband of the wavelet domain through the ROI (region of interest) function of JPEG2000, while maintaining the capability of comb-tooth suppression and quality recovery.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes 3-D OCT data denoising with nonseparable oversampled lapped transform (NSOLT), and examines the effectiveness through experiments. NSOLT is a lattice-based redundant transform which simultaneously satisfies the symmetric, real-valued and compact-support property. It is possible to apply a dictionary learning technique to the design by preparing examples. NSOLT is capable of having rational redundancy by controlling the number of channels and decimation ratio. In this study, a denoising technique is proposed by combining learned NSOLT dictionary and iterative hard thresholding (IHT), and the performance of the proposed method is evaluated for 3-D OCT data. It is verified through robust median estimator of noise variance and structural similarity index measure (SSIM) that the proposed technique yields effective denoising performance with moderate redundancy.

DOI： 10.1109/APSIPA.2015.7415402

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：European Signal Processing Conference, EUSIPCO  

In this work, we propose a design method for oversampled FIR DFT filter banks which have the paraunitary property, where the number of channel M is the multiple of decimation ratio D and the filter length is the multiple of M. Our proposed method is based on Householder factorization, which can keep the perfect reconstruction condition and the paraunitary property of filter banks in optimization process. In addition, we examine the linear phase property for oversampled DFT filter banks, and the design method of oversampled linear phase DFT filter banks. In order to show the effectiveness of our method, we give some design examples.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：European Signal Processing Conference, EUSIPCO  

In this work, a new design method of M channel linear- phase paraunitary filter banks (LPPUFB) is proposed for odd M with a cascade structure.The conventional cascade structure has a problem that one of the filters is restricted to be of length M.In the proposed method, all filters are permitted to be of the same length as each other and longer than M.The significance of our proposed method is verified by showing some design exam pies.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This work proposes a novel design method of a two-dimensional (2-D) Non-Separable Oversampled Lapped Transform (NSOLT) for a given image by introducing a typical two stage procedure of dictionary learning. NSOLT is a lattice-structure-based transform and yields a redundant dictionary of which atoms satisfy the nonseparable, symmetric, real-valued, overlapping and compact-support property. In addition, the Parseval tight frame constraint can structurally be imposed, while the redundancy R is flexibly controlled by the ratio of the number of channels P and the downsampling ratio M. Compared with the other dictionary learning approaches, the proposed method is moderately structured so that it is capable of multiscale construction as well as atom termination at image boundary. The significance of the proposed method is verified by showing an example of learned dictionary and sparse approximation results.

DOI： 10.1109/ICASSP.2014.6854075

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes a Poisson denoising with a union of directional lapped orthogonal transforms (DirLOTs). DirLOTs are 2-D non-separable lapped orthogonal transforms with directional characteristics. Its bases overcome a disadvantage of the separable wavelet image denoising for the diagonal textures and edges. Based on this feature, multiple DirLOTs are used to improve the performance by introducing redundant representation with multiple directions. Experimental results show the combination of the variance stabilizing transformation (VST), Stein's unbiased risk estimator-linear expansion of thresholds (SURE-LET) approach and multiple DirLOTs is able to significantly improve the denoising performance, and verify the feasibility of the proposed method.

DOI： 10.1109/ICASSP.2014.6853792

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes a Poisson denoising with a union of directional lapped orthogonal transforms (DirLOTs). DirLOTs are 2-D non-separable lapped orthogonal transforms with directional characteristics. Its bases overcome a disadvantage of the separable wavelet image denoising for the diagonal textures and edges. Based on this feature, multiple DirLOTs are used to improve the performance by introducing redundant representation with multiple directions. Experimental results show the combination of the variance stabilizing transformation (VST), Stein's unbiased risk estimator-linear expansion of thresholds (SURE-LET) approach and multiple DirLOTs is able to significantly improve the denoising performance, and verify the feasibility of the proposed method.

DOI： 10.1587/transfun.E98.A.1820

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes an embedded implementation architecture of 2-D Non-separable Oversampled Lapped Transform (NSOLT). NSOLT yields a frame for image representation which satisfies the symmetry and overlapping property. Since the redundancy can be set to an arbitrary rational value, high performance image processing can be realized while saving memory consumption. This work mainly concerns the implementation issue. In general, non-separable systems require more computational resources than separable ones. However, NSOLT can be implemented by a separable manner thanks to the order factorable property. Based on the fact, a transposition-based architecture is proposed, and the significance is verified through the estimation of required hardware resources and its processing speed. The hardware module performances are evaluated for Xilinx XC7Z020-1CLG484 (Zynq).

DOI： 10.1109/APSIPA.2014.7041733

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

A directional lapped orthogonal transform (DirLOT) is an orthonormal transform of which basis is allowed to be anisotropic with the symmetric, real-valued and compact-support property. Due to its directional property, DirLOT is superior to the existing separable transforms such as DCT and DWT in expressing diagonal edges and textures. The goal of this paper is to enhance the ability of DirLOT further. To achieve this goal, we propose a novel image restoration technique using multiple DirLOTs. This paper generalizes an image denoising technique in [1], and expands the application of multiple DirLOTs by introducing linear degradation operator P. The idea is to use multiple DirLOTs to construct a redundant dictionary. More precisely, the redundant dictionary is constructed as a union of symmetric orthonormal discrete wavelet transforms generated by DirLOTs. To select atoms fitting a target image from the dictionary, we formulate an image restoration problem as an l(1)-regularized least square problem, which can efficiently be solved by the iterative-shrinkage/thresholding algorithm (ISTA). The proposed technique is beneficial in expressing multiple directions of edges/textures. Simulation results show that the proposed technique significantly outperforms the non-subsampled Haar wavelet transform for deblurring, super-resolution, and inpainting.

DOI： 10.1587/transfun.E96.A.1954

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A color-tone similarity index (CSIM) between two color images is presented. CSIM is defined by a statistical analysis of cumulative histograms in a hue-oriented color space. It characterizes the color distributions, while the existing structural similarity index reflects the spatial structure involved with grayscale images. The behaviors of CSIM are checked by the comparisons of color code chips. Through an image quality assessment on TID2008, the correlation between CSIM and the mean opinion score was proved to be statistically significant.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electronics, Information and Communication, Engineers, IEICE  

This work proposes an exponential computation with lowcomputational complexity and applies this technique to the expectation-maximization (EM) algorithm for Gaussian mixture model (GMM). For certain machine-learning techniques, such as the EM algorithm for the GMM, fast and low-cost implementations are preferred over high precision ones. Since the exponential function is frequently used in machinelearning algorithms, this work proposes reducing computational complexity by transforming the function into powers of two and introducing a lookup table. Moreover, to improve efficiency the look-up table is scaled. To verify the validity of the proposed technique, this work obtains simulation results for the EM algorithm used for parameter estimation and evaluates the performances of the results in terms of the mean absolute error and computational time. This work compares our proposed method against the Taylor expansion and the exp() function in a standard C library, and shows that the computational time of the EM algorithm is reduced while maintaining comparable precision in the estimation results. Copyright © 2013 The Institute of Electronics.

DOI： 10.1587/transfun.E96.A.935

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This paper proposes lattice structures for two-dimensional (2-D) non-separable (NS) oversampled (OS) lapped transforms. The proposed systems consist of the 2-D separable discrete cosine transform and NS support extension processes, and allow us to simply realize rational redundancy as well as the overlapping, paraunitary (PU), symmetric, real-valued and compact support property. The lattice structures have two aspects. One is an extention of OS linear-phase (LP) perfect reconstruction (PR) filter banks (FBs) to the 2-D NS case. The other is a generalization of 2-D NS LPPR FBs to the OS case. The significance is verified by showing some design examples and image restoration results with the iterative shrink-age/thresholding algorithm (ISTA).

DOI： 10.1109/ICASSP.2013.6638742

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This work proposes to apply a two-dimensional (2-D) non-separable oversampled lapped transform (NSOLT) to image restoration. NSOLT is a lattice-structure-based redundant transform which satisfies the symmetric, real-valued and compact-support property. The lattice structure is able to constitute a Parseval frame with rational redundancy and produce a dictionary with directional atoms. In this study, the performance for deblurring, super-resolution and inpainting is evaluated. The iterative-shrinkage/thresholding algorithm (ISTA) is adopted to show the significance of NSOLT in the image restoration applications. It is verified that the six-level NSOLT with redundancy less than two yields superior or comparable restoration performance to the two-level non-subsampled Haar transform of redundancy seven in both of PSNR and SSIM.

DOI： 10.1109/ICIP.2013.6738217

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes a boundary operation technique of 2-D non-separable oversampled lapped transforms (NSOLT). The proposed technique is based on a lattice structure consisting of the 2-D separable block discrete cosine transform (DCT) and non-separable redundant support-extension processes. The atoms are allowed to be anisotropic with the oversampled, overlapping, symmetric, real-valued, and compact-support property. First, the blockwise implementation is developed so that the atoms can be locally controlled. The local control of atoms is shown to maintain perfect reconstruction. This property leads an atom termination (AT) technique as a boundary operation. The technique overcomes the drawback of NSOLT that the popular symmetric extension method is invalid. Through some experimental results, the significance of AT is verified.

DOI： 10.1109/APSIPA.2013.6694258

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

A simple image compression scheme is presented for various types of images, which include color/grayscale images, color-quantized images, and bilevel Images such as document and digital halftone images. It is a bitplane coding composed of a new context modeling and adaptive binary arithmetic coding. A target bit to be encoded is conditioned by the estimates of the neighboring pixels including non-causal locations. Several functionalities are also integrated. They are arbitrary shaped ROI transmission, selective tile partitioning, accuracy scalability, and others. The proposed bitplane codec is competitive with JPEG-LS in lossless compression of 8-bit grayscale and 24-bit color images. The proposed codec is close to JBIG2 in bilevel image compression. It outperforms the existing standards in compression of 8-bit color-quantized images.

DOI： 10.1587/transfun.E95.A.938

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Reversible color component transforms derived by the LU factorization are briefly described. It is possible to obtain an reversible implementation to a given component transform, even if the original transform is irreversible. Some examples are presented and their performances are compared in image compression.

DOI： 10.1587/transfun.E95.A.824

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This work proposes to apply directional lapped orthogonal transforms to image restoration. A DirLOT is an orthonormal transform of which basis is allowed to be anisotropic with the symmetric, real-valued and compact-support property. In this work, DirLOTs are used to generate symmetric orthonormal discrete wavelet transforms and then a redundant dictionary as a union of unitary transforms. The multiple directional property is suitable for representing natural images which contain diagonal edges and textures. The performances of deblurring, super-resolution and inpainting are evaluated for several images with the iterative-shrinkage/thresholding algorithm. It is verified that the proposed dictionary yields comparable or superior restoration performance to the non-subsampled Haar transform.

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Other Link： http://dblp.uni-trier.de/db/conf/apsipa/apsipa2012.html#conf/apsipa/MuramatsuAY12

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

A color-tone similarity index (CSIM) between two color images is presented and another index, picture similarity index (PSIM), is also given for a comprehensive similarity comparison between color images. CSIM is defined by a statistical analysis of cumulative histograms in a hue-oriented color space. It characterizes the color distributions, while the existing structural similarity index reflects the spatial structure involved with grayscale images. The behaviors of CSIM are checked by the comparisons of color code chips. Experimental results are given. The proposed indexes combined with SSIM are hopeful to provide a tool for color image quality analysis (IQA).

DOI： 10.1109/ICIP.2013.6738081

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

A novel image denoising technique is proposed by using directional lapped orthogonal transforms (DirLOTs). DirLOTs satisfy orthogonality and the bases are allowed to be anisotropic with the fixed-critically-subsampling, overlapping, symmetric, real-valued and compact-support property. In this work, DirLOTs are used to construct directional symmetric orthonormal discrete wavelet transforms and then the bases are adopted to generate a redundant dictionary with several directions. The multiple directional property is suitable for representing natural images which contain diagonal edges and textures. The proposed dictionary is applied to solve the basis pursuit denoising problem. The denoising performance is evaluated for several images through the heuristic shrinkage and block-coordinate-relaxation algorithm. It is verified that the proposed technique is simple but yields perceptually preferable results.

DOI： 10.1109/ICASSP.2012.6288076

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes to adopt a union of directional lapped orthogonal transforms (DirLOTs) to the SURE-LET image denoising. DirLOTs are 2-D non-separable transforms and can have directional characteristics under the fixed-critically-subsampling, overlapping, orthogonal, symmetric, real-valued and compact-support property. As a previous work, the author showed that a DirLOT overcomes a disadvantage of separable wavelet image denoising for diagonal textures and edges. Since there remains a problem that the approach is applicable only to a single geometric direction, this work further investigates to improve the performance by introducing redundant representation with multiple directions. Through some experimental results, it is verified that the proposed technique shows better performance than the traditional single wavelet approach for natural images with rich amount of geometrical structures.

DOI： 10.1109/PCS.2012.6213334

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We propose an effective technique for optically detecting images of the inner hole-surface of a hole (hereafter, referred to as the hole-surface) using the polarization property of a 3D television (TV) monitor. The polarized light emitted by the TV monitor illuminates the hole-surfaces present in the test target placed on the screen of the monitor. When the polarizer placed in front of a camera lens is adjusted such that the camera captures a dark image for the transmitted light, only the highlighted hole-surfaces are visible in the captured image.

DOI： 10.1117/12.999726

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

A color-tone similarity index (CSIM) between two color images is presented and another index, picture similarity index (PSIM), is also given for a comprehensive similarity comparison between color images. CSIM is defined by a statistical analysis of cumulative histograms in a hue-oriented color space. It characterizes the color distributions, while the existing structural similarity index reflects the spatial structure involved with grayscale images. The behaviors of CSIM are checked by the comparisons of color code chips. Experimental results are given. The proposed indexes combined with SSIM are hopeful to provide a tool for color image quality analysis (IQA).

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Other Link： http://dblp.uni-trier.de/db/conf/apsipa/apsipa2012.html#conf/apsipa/KikuchiHHYMS12

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TRANS TECH PUBLICATIONS LTD  

A non-traditional processing cycle for sheet-metal working based on the computerized image processing techniques is proposed. This novel system enables the effective fabrication cycle that realizes automatic inspection, quick delivery, and cost reduction.

DOI： 10.4028/www.scientific.net/AMM.152-154.331

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Language：Japanese   Publisher：一般社団法人 映像情報メディア学会  

本研究では,デジタルカメラを用いた高精度且つ低コストな板金検査システムを提案する.提案検査システムは単一のデジタルカメラにより板金の画像を取得し,設計データと比較することで板金の加工誤差を検出する.デジタルカメラにより取得した画像はレンズ歪を有するため,高精度検査システムの実現にはレンズ歪の推定及び補正が必要となる.また,台座の高さや板金の厚みによるズレも考慮する必要がある.本研究では半径歪モデルと位相限定相関法を組み合わせた歪推定,局所的射影変換を用いた歪補正及び高さ・厚み補正の方法を提案する.実験により提案検査システムの検査精度を評価し,精度0.5mmの達成を確認する.

DOI： 10.11485/itetr.36.34.0_23

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

This paper proposes a fast decision algorithm in pattern classification based on Gaussian mixture models (GMM). Statistical pattern classification problems often meet a situation that comparison between probabilities is obvious and involve redundant computations. When GMM is adopted for the probability model, the exponential function should be evaluated. This work firstly reduces the exponential computations to simple and rough interval calculations. The exponential function is realized by scaling and multiplication with powers of two so that the decision is efficiently realized. For finer decision, a refinement process is also proposed. In order to verify the significance, experimental results on TI DM6437 EVM board and TED TB-3S-3400DSP-IMG board are shown through the application to a color extraction problem. It is verified that the classification was almost completed without any refinement process and the refinement process can proceed the residual decisions.

DOI： 10.1007/s11265-009-0439-z

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We propose and demonstrate a novel processing cycle for sheet-metal working based on the computerized image processing techniques. The interconnected test system based on the cross network communication enables the effective fabrication cycle that realizes automatic inspection, quick delivery, and cost reduction.

DOI： 10.1117/12.906564

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC AND ENGINEERING ACAD AND SOC  

We present image edge detection using the total variation functional and morphological methods. First, we derive the total variation functional from first principles and vector gradient method. The total variation functional is then minimized using the Euler-Lagrange optimization method. The steady state equation which results from the minimization of the total variation functional is then used as an anisotrpic filter on images. While the total variation method has proven to be a better edge detector than the Marr-Hildreth method, it also segments the image into regions delineated by strong edges. To achieve results similar to the Marr-Hildreth method, we apply morphological considerations. We develop new operations based on erosion, dilation, opening and closing to achieve morphological edge detection of total variation filtered images.

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Language：Japanese   Publisher：The Institute of Image Information and Television Engineers  

This report proposes an adaptive basis switching technique of two-dimensional (2-D) non-separable (NS) GenLOT for picture coding. The conventional DCT and DWTs are separable and have disadvantage in representing diagonal edges and textures of a given picture. In order to overcome the problem, the authors proposed 2-D NS GenLOT as a previous work. In this work, the adaptive local basis control of overlap and direction is investigated and the significance is verified.

DOI： 10.11485/iteac.2011.0_3-6-1

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DOI： 10.11485/itetr.34.34.0_31

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

We have developed a new computer-aided diagnostic system for differentiating oral borderline malignancies in hematoxylin-eosin stained microscopic images. Epithelial dysplasia and carcinoma in-situ (CIS) of oral mucosa are two different borderline grades similar to each other, and it is difficult to distinguish between them. A new image processing and analysis method has been applied to a variety of histopathological features and shows the possibility for differentiating the oral cancer borderline grades automatically. The method is based on comparing the drop-shape similarity level in a particular manually selected pair of neighboring rete ridges. It was found that the considered similarity level in dysplasia was higher than those in epithelial CIS, of which pathological diagnoses were conventionally made by pathologists. The developed image processing method showed a good promise for the computer-aided pathological assessment of oral borderline malignancy differentiation in clinical practice.

DOI： 10.1587/transfun.E93.A.1544

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

The error diffusion filter in this paper is optimized with respect to the ideal blue noise pattern corresponding to a single tone level. The filter coefficients are optimized by the minimization of the squared error norm between the Fourier power spectra of the resulting halftone and the blue noise pattern. During the process of optimization, the binary pattern power spectrum matching algorithm is applied with the aid of a new blue noise model. The number of the optimum filters is equal to that of different tones. The visual fidelity of the bilevel halftones generated by the error diffusion filters is evaluated in terms of a weighted signal-to-noise ratio, Fourier power spectra, and others. Experimental results have demonstrated that the proposed filter set generates satisfactory bilevel halftones of grayscale images.

DOI： 10.1587/transfun.E93.A.1465

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society for Oral Pathology  

DOI： 10.3353/omp.14.89

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Other Link： http://search.jamas.or.jp/link/ui/2010293190

Language：English   Publishing type：Research paper (international conference proceedings)  

This work contributes to investigate theoretical properties of the trend vanishing moment (TVM) which the authors have defined in a previous work and applied to the directional design of 2-D nonsep-arable GenLOTs. The TVM condition can be regarded as a natural extention of 1-D VM to 2-D one and alternative of the conventional directional vanishing moment (DVM). Firstly, the definition of TVM is given to clarify what it is, and then the mathematical meaning is discussed. While the conventional DVM condition requires for the moments to vanish along lines in the frequency domain and restricts the direction to a rational factor, the TVM condition imposes the moments only point-wisely and the direction can be steered flexibly. Some significant properties of TVMs are also shown and a simulation result of zonal coding for an artifical picture is given to verify the trend surface annihilation property. © 2010 IEEE.

DOI： 10.1109/PCS.2010.5702440

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A scaled transform is defined for a given irreversible linear transformation based on the LU factorization of a nonsingular matrix so that the transformation may be computed in a lifting form and hence may be reversible. Round-off errors in the lifting computation and the computational complexity are analyzed. Some reversible component transforms are presented and experimented to give some remarks to image compression applications. Discussions are developed with coding gain and actual bit rates. © 2010 IEEE.

DOI： 10.1109/PCS.2010.5702475

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This work proposes a low complexity computation of EM algorithm for Gaussian mixture model(GMM) and accelerates the parameter estimation. In previous works, the authors revealed that the computational complexity of GMM-based classification can be reduced by using an interval calculation technique[1], [2]. This work applies the idea to EM algorithm for GMM parameter estimation. From experiments, it is confirmed that the computational speed of the proposal achieves more than twice that of the standard method with &apos;exp( )&apos; function. The relative errors are less than 0.6% and 0.053% when the number of bits for table addressing are 4 and 8, respectively.

DOI： 10.1109/ISCAS.2010.5537044

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

A novel design method of 2-D non-separable linear-phase paraunitary filter banks (LPPUFBs) is proposed. The trend vanishing moment (TVM) condition is newly derived for the lattice structure. The TVM condition can be regarded as a natural extension of 1-D VM to 2-D one and alternative of the conventional directional vanishing moments(DVMs). The structure is based on the 2-D DCT and can be regarded as an extension of GenLOT to the 2-D non-separable case. Because of the non-separability, the bases are allowed to be anisotropic and directional in addition to the fixed-subsampling, overlapping, orthogonal, real-valued, symmetric and compact-support property. As a previous work, the authors have shown that the block-wise implementation is appealing for the image processing application since the technique serves boundary operation for size-limitation, seamless basis alteration and compatibility with the block DCT. This work further contributes to yield the TVM condition so that piece-wise smooth images with smooth contours are compactly approximated. The condition is imposed directly on the design parameters and, therefore, the desirable properties of the lattice structure are maintained. From an experimental result of coding, it is shown that the TVM condition gives smooth reconstruction of a diagonal texture image.

DOI： 10.1109/ICIP.2010.5654186

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Language：Japanese   Publisher：The Institute of Image Information and Television Engineers  

DOI： 10.11485/itetr.34.34.0_5

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DOI： 10.11485/itetr.34.34.0_47

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In this paper, a design method of two-dimensional (2D) orthogonal symmetric wavelets is proposed by using a lattice structure for multi-dimensional (M-D) linear-phase paraunitary filter banks (LPPUFB), which the authors have proposed as a previous work and then modified by Lu Gan et al. The derivation process for the constraints on the second-order vanishing moments is shown and some design examples obtained through optimization with the constraints are exemplified. In order to verity the significance of the constraints, some experimental results are shown for Lena and Barbara image.

DOI： 10.1587/transfun.E92.A.788

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

A simple lossy-to-lossless bit-plane coding of still images is presented to integrate several functionality extensions including selective the partitioning, progressive transmission, ROI transmission, accuracy scalability, and others. The mean squared error between the original image and a decoded image at any progression level is known prior to encoding/decoding. The proposed bit-plane codec is competitive with JPEG-LS and JPEG 2000 in the lossless compression of 8-bit grayscale and 24-bit color images. The codec outperforms the existing standards in 8-bit color-quantized image compression.

DOI： 10.1109/PCS.2009.5167351

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This paper introduces block-wise implementation of 2-D nonseparable linear-phase paraunitary filter banks (LPPUFB) and shows a directional design approach. As a previous work, the authors have proposed a lattice structure of non-separable LPPUFBs which guarantees both of the linear-phase and orthogonal property. This paper shows that the structure serves variability of basis images without any violation to the orthogonality. Consequently, a boundary operation for size-limitation is yielded and compatibility with the 2-D separable block-DCT becomes possible since the lattice structure is based on the block-DCT. The main advantage of non-separable systems is its directional capability, and it is allowed to produce a directional non-separable GenLOT. Although the adaptive control of basis images is under investigation, experimental results of texture coding show prospective significance of the directional GenLOT.

DOI： 10.1109/ICIP.2009.5413823

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Language：Japanese   Publishing type：Research paper (scientific journal)  

The use of a novel motion compensated spatio-temporal nonseparable filter (MCSTF) is proposed for scalable video coding. This filter is an alternative to the present motion-compensated temporal filtering (MCTF), a fundamental component for scalable video coding in the next generation. MCTF improve the coding efficiency and provide the temporal scalability. We classify MCSTF as a non-separable sub-sampling version of MCTF, and it provides interlaced pictures as intermediate video sequence by using a spatio-temporal split process. Furthermore, its 1/3-transform structure, which excludes the lifting-update-step, significantly suppresses the PSNR fluctuation that occurs when the existing MCTF technique is used. Our proposed system suppresses PSNR fluctuation with a higher average PSNR than the existing MCTF. Two types of sub-sampling lattices were investigated: the vertical-temporal (VT) quincunx and the face-centered orthorhombic (FCO) ones. Experimental results with entropy coded scalar quantization show the signifaicance of our proposed technique.

DOI： 10.3169/itej.63.1604

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes a novel design method of two-dimensional (2-D) non-separable linear-phase paraunitary filter banks (LPPUFB). The two-degree vanishing moment constraint is derived for the lattice structure. In the 2 x 2-decomposition case, the authors have already derived the constraint and designed non-separable symmetric orthonormal wavelets with two-degree vanishing moments. This work extends the discussion to more general 2m(y) x 2m(x)-decomposition case and yields a method to impose the condition to the lattice structure. The constraint is imposed directly on design parameters so that both of the linear-phase and paraunitary property are structurally guaranteed. It is shown that the two-degree vanishing moment constraint reduces the number of parameters to be freely chosen and gives a smooth lowpass filter. Several design examples are shown to verify the significance of the novel constraint on the lattice structure.

DOI： 10.1109/ISPACS.2009.5383856

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this paper a set of the optimum error diffusion filters is presented for the bilevel halftoning of grayscale images and the visual fidelity of the bilevel halftones generated by the error diffusion filters is investigated. The error diffusion filter is optimized with respect to the ideal blue noise mask (BNM) corresponding to a single tone level. The number of the optimum filters is hence equal to that of different tones. The filter coefficients are optimized by the minimization of the squared error norm between the frequency response of the filter and the Fourier spectrum of the BNM. During the process of optimization, the binary pattern power spectrum manipulation algorithm (BIPPSMA) is applied. Visual fidelity of the bilevel halftones generated by the error diffusion filters is investigated in terms of a weighted signal-to-noise ratio (WSNR) and Fourier power spectra. Experimental results have demonstrated that the proposed filter set generates satisfactory bilevel halftones of grayscale images.

DOI： 10.1109/ISPACS.2009.5383823

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This work proposes a fast decision algorithm in pattern classification based on Gaussian mixture models (GMM). Statistical pattern classification problems often meet a situation that comparison between probabilities is obvious and involve redundant computations. When GMM is adopted for the probability model, the exponential function should be evaluated. This work firstly reduces the exponential computations to simple and rough interval calculations. The exponential function is realized by scaling and multiplication with powers of two so that the decision is efficiently realized. For finer decision, a refinement process is also proposed. In order to verify the significance, experimental results on TI DM6437 EVM board are shown through the application to a skin-color extraction problem. It is verified that the classification was almost completed without any refinement process and the refinement process can proceed the residual decisions.

DOI： 10.1109/ICASSP.2009.4959663

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Language：Japanese   Publisher：一般社団法人 映像情報メディア学会  

本研究では,指向性GenLOTにおける境界処理について述べる.JPEGやMPEG-2で採用されている離散コサイン変換(DCT)はブロック歪が発生するという問題がある.JPEG2000では基底画像が重複性を持つ離散ウェーブレット変換(DWT)を採用し,ブロック歪を回避している.これらDCT,DWTは可分離処理のため,画像の斜めエッジに適していない.そこで筆者らは指向性GenLOT/DWTを提案している.この変換は指向性設計が可能で,基底画像が重複性を有するためブロック歪を起こさない.しかしながら,対称拡張による境界処理ができず実際の画像処理への妨げとなっていた.本報告では,ラティス構成のパラメータ制御によって,基底画像の重複性を制御可能であることを示し,指向性GenLOT/DWTにおける境界処理が可能となることを示す.

DOI： 10.11485/itetr.33.34.0_67

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Language：Japanese   Publisher：The Institute of Image Information and Television Engineers  

In the optical soldering inspection systems, the existence or nonexistence of soldering paste and unfirm solder are relatively easy to be detected. However, it is difficult to classify the amount, the shape and the state of the fillet of brazed joints. This study aims at a development of an automatic classification system of solder joints on printed circuit boards and an exploration of effective features for defective soldering detection by means of statistical image analysis of digital images. A number of features are selected from textural features to be tested for the classification into 5 typical classes of solder joints. Experiments have shown that they are effective.

DOI： 10.11485/itetr.33.31.0_5

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This paper presents a method of scalable lossless image compression by means of lossy coding. A progressive decoding capability and a full decoding for the lossless rendition are equipped with the losslessly encoded bit stream. Embedded coding is applied to large-amplitude coefficients in a wavelet transform domain. The other wavelet coefficients are encoded by a context-based entropy coding. The proposed method slightly outperforms JPEG-LS in lossless compression. Its rate-distortion performance with respect to progressive decoding is close to that of JPEG2000. The spatial scalability with respect to resolution is also available.

DOI： 10.1093/ietfec/e91-a.11.3356

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This paper proposes a new type of layered video coding especially for the use of monitoring water level of a river. A sensor node of the system decomposes an input video signal into some kinds of component signals and produces a bit stream functionally separated into three layers. The first layer contains the minimum components effective for detecting the water level. It is transmitted at very low bit rate for regular monitoring. The second layer contains signals for thumb-nail video browsing. The third layer contains additional data for decoding the original video signal. These are transmitted in case of necessity. A video signal is decomposed into several bands with the three dimensional Haar transform. In this paper, optimum bands to be contained into the 1st layer are experimentally investigated considering both of water level detection and data size to be transmitted. As a result, bit rate for transmitting the first layer is reduced by 32.5% at the cost of negligible 3.7% decrease of recognition performance for one of video examples.

DOI： 10.1093/ietfec/e91-a.4.1006

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This paper presents a color demosaicing method applied to the Bayer pattern color filter array (CFA). Reliable estimation of an edge direction, edge-directed asymmetric interpolation, and the use of color samples at immediate neighbors are considered as the key guidelines for smooth and sharp image restoration. Also, special interest is directed to local areas that are rich in high spatial frequency variations. For suppression of false colors likely to occur in those areas, a hue vector representation is introduced so that the spatial correlation between different color components may be exploited in consistent with the local constant-hue principle. Smoothing is repeated in the hue vector field a few times. Experimental results have shown preferable performances in terms of PSNR, CIELAB color difference, hue angle difference, CIE chromaticity and visual appearance, in particular resulting in less false colors.

DOI： 10.1093/ietfec/e91-a.4.978

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

The interpolation of color pixel values prior to digital halftoning is discussed and a new color interpolation scheme is presented by a directional copy of color values in the gradient field of luma. Error diffusion quantization is combined with clustered-dot ordered dithering to prevent from contouring. Experimental results demonstrate that sharp and false color-free interpolation is obtained to produce color bilevel AM halftones with weak rosettes and no contouring artifacts.

DOI： 10.1587/elex.5.170

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Language：Japanese   Publisher：The Institute of Image Information and Television Engineers  

This work proposes a novel design method of 2-D non-separable linear-phase paraunitary filter banks (LPPUFB). Especially the two-degree vanishing moment constraint is derived for the lattice structure. In the 2 × 2-decomposition case, the authors have already derived the constraint and designed non-separable symmetric orthonormal wavelets with vanishing moments of degree two. This work extends the discussion to more general 2m_y × 2m_x-decomposition case and yields a method to impose the condition to the lattice structure. The constraint is imposed directly on design parameters so that both of the linear-phase and paraunitary property are structurally guaranteed. Since the structure adopted in this work is based on the 2-D separable DCT, 2-D separable GenLOT, a popular lattice structure of DCT-based LPPUFB, is regarded as a special case. The main advantage of non-separable systems is the directional capability. This work allows us to obtain directional non-separable LOT with two-degree vanishing moments. Some design examples are shown to verify the significance of the proposed method.

DOI： 10.11485/itetr.32.58.0_9

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Language：Japanese   Publisher：The Institute of Image Information and Television Engineers  

In this work, we evaluate the directional adaptive nonseparable interpolation filter for sub-pixel motion compensation. In the future video coding systems, developing more efficeient interpolation filter for motion compensation is impotant subject to implove coding efficiency. In this work, we develop some nonseparable interpolation filters support different frequency region, and propose a new edge adaptive nonseparable interpolation method altering the filter by edge direction. Simulation for simple edge images and coding experiments for real video are shown.

DOI： 10.11485/itetr.32.58.0_1

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Language：Japanese   Publisher：一般社団法人 映像情報メディア学会  

本研究では,筆者らが既に提案しているラティス構成に基づく多次元直線位相直交フィルタバンクの設計法を用いて,指向性を考慮した二次元直交対称ウェーブレット変換の設計法を検討する.異方性の自己相関関数モデルに対する最適化設計をとおして,2次のバニッシング・モーメントを持つ指向性フィルタバンクの設計を行い,シミュレーションによる性能評価を行う.

DOI： 10.11485/itetr.32.35.0_49

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this paper, theoretical properties of deinterlacer banks are analyzed. Deinterlacer banks are novel filter banks in the sense that a progressive video sequence is separated into two progressive video sequences of a half frame rate and, furthermore, interlaced sequences are produced as intermediate data. Unlike the conventional filter banks, our deinterlacer banks are constructed in a way unique to multidimensional systems by using invertible deinterlacers, which the authors have proposed before. The system is a kind of shift-varying filter banks and it was impossible to derive the optimal bit-allocation control without any equivalent parallel filter banks. This paper derives an equivalent polyphase matrix representation of the whole system and its equivalent parallel structure, and then shows the optimal rate allocation for the deinterlacer banks. Some experimental results justify the effectiveness of the optimal rate allocation through our theoretical analysis.

DOI： 10.1093/ietfec/e90-a.3.642

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes a new type of layered video coding especially for the use of monitoring a river or a water channel. A sensor node of the system decomposes a video signal into some components and produces a bit stream which is functionally separated into three layers. The first layer contains the minimum components effective for detecting water level. The second layer contains signals for thumb-nail video browsing. Each of them is transmitted at very low bit rate for regular monitoring. The third layer contains additional data for decoding the original video signal. It is transmitted in case of necessity. The original video signal is decomposed into band signals as the components by the Haar transform in a sensor node. Experimental results show which band signals should be included into the first layer considering both of water level detection performance and data size to be transmitted.

DOI： 10.1109/ICIP.2007.4379157

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Inst. of Image Information and Television Engineers  

A color demosaicing method has been developed that effectively performs within local areas that are rich in high spatial frequency variations. Such areas are likely to cause strong artifacts after demosaicing because of the inherent difficulty in subsampling. In visually tolerable image restoration, the spatial correlation between different color components is exploited to consistently maintain favorable transitions in the component intensities. Missing primary color values on the Bayer pattern color filter array are estimated using an edge-directed interpolation of primary color difference signals. The local transitions of the primary color differences are then smoothed by spatially adaptive filtering. Experimental results showed objectively-good and visually-preferable performance in terms of PSNR, CIELAB color difference and visual appearance, particularly resulting in less false color.

DOI： 10.3169/itej.61.1209

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this paper, a coefficient-parameter embedding method into Motion-JPEG2000 (MJP2) is proposed for invertible deinterlacing with variable coefficients. Invertible deinterlacing, which the authors have developed before, can be used as a preprocess of frume-based motion picture codec, such as MJP2, for interlaced videos. When the conventional field-interleaving is used instead, comb-tooth artifacts appear around edges of moving objects. On the other hand, the invertible deinterlacing technique allows us to suppress the comb-tooth artifacts and also guaranties recovery of original pictures. As previous works, the authors have developed a variable coefficient scheme with a motion detector, which realizes adaptability to local characteristics of given pictures. However, when this deinterlacing technique is applied to a video codec, coefficient parameters have to be sent to receivers for original picture recovery. This paper proposes a parameter-embedding technique in MJP2 and constructs a standard stream Which consists both of picture data and the parameters. The parameters are embedded into the LH1 component of wavelet transform domain through the ROI (region of interest) function of JPEG2000 without significant loss in the performance of comb-tooth suppression. Some experimental results show the feasibility of our proposed scheme.

DOI： 10.1093/ietisy/e89-d.11.2794

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Institute of Electronics, Information and Communication Engineers  

This paper proposes a novel active contour description for video retrieval. Some feature descriptors for image content retrieval are defined in MPEG-7. An contour shape descriptor is also defined in the standard for descripting contour shape features of objects in still pictures. It has both of scale and rotation invariant properties since it is based on Curvature Scale Space (CSS). In this paper, we extend this descriptor to the temporal direction for video applications and propose a feature descriptor that compactlly describes an object contour shape and its temporal variation. The proposed descriptor is effective in the situation that both of videos and still pictures are assumed to be retrieved because the descriptor maintains the compatibility with the descriptor of still pictures defined in MPEG-7. From several experimental results, the significance of our proposed descriptors will be evaluated.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

A two-step color demosaicing algorithm for Bayer-pattern mosaic images is presented. Missing primary colors are at first estimated by an asymmetric average interpolation, and then sharpness of the initial estimate is improved by an iterative procedure. The intensity variation along an edge is not always uniform along one direction and its opposite with respect to a target pixel to be interpolated. Spatially asymmetric averaging along an edge is hence introduced in this study, where less intensity variation is assumed to be of stronger significance in the sense of stable restoration for details. Also, we restrict ourselves to use short-kernel filters for sharpness recovery. Spatially-adaptive filtering is involved with color demosaicing and an optical system for image acquisition and color filter array (CFA) sampling are subjected to the spatio-temporal aperture effect. Hence it is unavoidable to produce a blurred restoration to some extent. In order to overcome these difficulties and to restore a sharp image, an iterative procedure is introduced. Experimental results have shown a favorable performance in terms of objective measures such as PSNR and CIELAB color difference and subjective visual appearances, especially in sharpness recovery.

DOI： 10.1117/12.650446

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes a method of lossless image coding by the aid of lossy image coding. It aims at an improvement in the compression efficiency. We apply a kind of embedded coding to large coefficients in magnitude in a wavelet transform domain. The other wavelet coefficients are encoded by a context-based entropy coding. The result slightly outperforms the compression efficiency in JPEG-LS.

DOI： 10.1109/ICIP.2006.312814

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this work, a novel motion compensated spatio-temporal filter (MCSTF) is proposed for scalable video coding. MCSTF is an alternative technique of existing motion-compensated temporal filtering (MCTF), a fundamental component for scalable video coding in next generation. MCSTF is a non-separable sub-sampling version of MCTF and provides interlaced pictures as intermediate video sequence by using a spatio-temporal split process. Furthermore, the 1/3-transform structure, which excludes the lifting-update-step, significantly suppresses the PSNR fluctuation which occurs in the existing MCTF technique. Our proposed system has an advantage of suppressing PSNR fluctuation with almost the same average PSNR as that of existing MCTF. In this paper, two types of sub-sampling lattices are investigated: the vertical-temporal (VT) quincunx and face-centered orthorhombic (FCO) lattices. Some experimental results with entropy coded scalar quantization show the significance of our proposed technique.

DOI： 10.1109/ICIP.2006.312870

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

This paper presents an implementation scheme of Motion-JPEG2000 (MJP2) integrated with invertible deinterlacing. In previous work, we developed an invertible deinterlacing technique that suppresses the comb-tooth artifacts which are caused by field interleaving for interlaced scanning videos, and affect the quality of scalable frame-based codecs, such as MJP2. Our technique has two features, where sampling density is preserved and image quality is recovered by an inverse process. When no codec is placed between the deinterlacer and inverse process, the original video is perfectly reconstructed. Otherwise, it is almost completely recovered. We suggest an application scenario of this invertible deinterlacer for enhancing the sophisticated signal-to-noise ratio scalability in the frame-based MJP2 coding. The proposed system suppresses the comb-tooth artifacts at low bitrates, while enabling the quality recovery through its inverse process at high bitrates within the standard bitstream format. The main purpose of this paper is to present a system that yields high quality recovery for an MJP2 codec. We demonstrate that our invertible deinterlacer can be embedded into the discrete wavelet transform employed in MJP2. As a result, the energy gain factor to control rate-distortion characteristics can be compensated for optimal compression. Simulation results show that the recovery of quality is improved by, for example, more than 2.0 dB in peak signal-to-noise ratio by applying our proposed gain compensation when decoding 8-bit grayscale Football sequence at 2.0 bpp.

DOI： 10.1109/TIP.2005.857255

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This paper presents a color demosaicing method by introducing iterative asymmetric average interpolation. Missing primary colors on a Bayer pattern color filter array (CFA) are estimated by an asymmetric average interpolation where less intensity variation is assumed to be of stronger significance, before sharpness of an initial estimate is further improved by an iterative procedure. The iteration is implemented by an observation process followed by a restoration process. The former is modeled by blurring followed by CFA sampling and the latter is completely as same as the color demosaicing method initially applied. Experimental results have shown a favorable performance in terms of PSNR and visual appearance, in particular, in sharpness recovery.

DOI： 10.1093/ietfec/e88-a.8.2108

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Institute of Electronics, Information and Communication Engineers  

In this work, hierarchical deinterlacer banks are proposed as a new tool for spatio-temporal scalable coding. Deinterlacer banks are novel filter banks in the sense that a progressive video sequence is separated into two progressive video sequences of a half rate and interlaced sequences are producted as intermediate data. Unlike the conventional filter banks, the technique is constructed in a way unique to multidimensional systems by using invertible deinterlacers which we have proposed before. In this report, we further investigate spatio-temporal multi-resolution analysis through the deinterlacer banks. We propose hierarchical deinterlacer banks accompanied by the discrete wavelet transform as a spatial transform. The proposed technique provides an interlaced sequence as intermediate data, a half-rate progressive sequence, and a quarter spatial resolution sequence, as well as the original full-resolution full-rate video sequence. It is verified that fine spatio-temporal multi-resolution analysis involved with various formats is given through the multistage process of our proposed deinterlacer banks. Some experimental results show the potential of the proposed filter banks to practical scalable video compression.

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This paper presents a two-step algorithm for detecting video shot boundaries in a wavelet transform domain. It captures gradual shot transitions such as dissolves and fades as well as abrupt shot transitions such as cuts. At the first step, it computes a distance between video intervals to find an isolated interval. Then, at the second step, it computes a distance between frames to specify the exact location of a shot boundary. Its effectiveness is evaluated in terms of recall and precision. © 2005, The Institute of Image Electronics Engineers of Japan. All rights reserved.

DOI： 10.11371/iieej.34.17

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A lossless implementation technique of Motion JPEG2000 (MJP2) integrated with invertible deinterlacing is presented. In previous works, we developed an invertible deinterlacing technique that suppresses the comb-tooth artifacts, which are caused by field interleaving of interlaced videos and affect the quality of scalable intraframe-based coding such as MJP2. We suggested a scenario of applying the technique as a prefilter to intraframe-based coding systems. This system suppresses the comb-tooth artifacts, while guaranteeing recovery of the original quality through the inverse process. In this work, we further propose an exact lossless implementation technique by embedding the deinterlacer into MJP2 and modifying header information for appropriate decoding. We demonstrate that the comb-tooth suppression capability can be kept at low bitrates with the standard MJP2 decoder. The experiments also show that the overhead of our proposed method is less than 0.9% compared with the normal field interleaving. © 2005 IEEE.

DOI： 10.1109/ISCAS.2005.1466088

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

A lossless implementation technique of Motion JPEG2000 (MJP2) integrated with invertible deinterlacing is presented. In previous works, we developed an invertible deinterlacing technique that suppresses the comb-tooth artifacts, which are caused by field interleaving of interlaced videos and affect the quality of scalable intraframe-based coding such as MJP2. We suggested a scenario of applying the technique as a prefilter to intraframe-based coding systems. This system suppresses the comb-tooth artifacts, while guaranteeing recovery of the original quality through the inverse process. In this work, we further propose an exact lossless implementation technique by embedding the deinterlacer into MJP2 and modifying header information for appropriate decoding. We demonstrate that the comb-tooth suppression capability can be kept at low bitrates with the standard MJP2 decoder. The experiments also show that the overhead of our proposed method is less than 0.9% compared with the normal field interleaving.

DOI： 10.1109/ISCAS.2005.1466088

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

In this work, hierarchical motion compensated three-dimensional (3-D) filter banks for spatio-temporal multiresolution analysis are presented as new tools for scalable video format control. For recent developments in scalable video coding, most of them are based on 3-D wavelet transform with motion compensation. To achieve the function of frame-rate and spatial resolution scalabilities, motion compensated temporal filtering (MCTF) through lifting wavelet transform currently attracts many researchers as an effective temporal decomposition tool. As previous works, we proposed single stage deinterlacer banks as novel 3-D filter banks. Unlike other filter banks, our proposed system is constructed in a way unique to multi-dimensional systems by using invertible deinterlacers, which we have proposed before. The single stage deinterlacer banks decompose a progressive video into two subband sequences of a half frame-rate in the progressive scanning manner. Even though the system handles interlaced videos as intermediate data, introducing a multistage decomposition is simply achieved because the output sequences have also the progressive format as like the input. Our proposed hierarchical deinterlacer banks are accompanied by 2-D discrete wavelet transforms (DWT) as spatial transforms. The multistage technique provides interlaced sequences as well as several reduced-rate progressive sequences while maintaining the reconstruction of the original full-resolution full-rate video sequence. We show that fine granular control of spatio-temporal resolution can be achieved through the hierarchical process. Some experimental results show novel functions and the significance of the proposed filter banks.

DOI： 10.1117/12.631544

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

There are growing needs for quick preview of video contents for the purpose of improving accessibility of video archives as well as reducing network traffics. In this paper, a storyboard that contains a user-specified number of keyframes is produced from a given video sequence. It is based on hierarchical cluster analysis of feature vectors that are derived from wavelet coefficients of video frames. Consistent use of extracted feature vectors is the key to avoid a repetition of computationally-intensive parsing of the same video sequence. Experimental results suggest that a significant reduction in computational time is gained by this strategy.

DOI： 10.1117/12.631385

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Inst. of Image Information and Television Engineers  

A lossless implementation technique of Motion JPEG2000 (MJP2) integrated with invertible deinterlacing is presented in this paper. The invertible deinterlacing, which has been previously published, is a technique that suppresses the comb-tooth artifacts caused by field interleaving of interlaced videos and also guarantees the recovery of the original through the inverse process. The comb-tooth artifacts affect the performance of scalable intraframe-based codecs such as MJP2 and, thus we have suggested a scenario for applying this invertible deinterlacing as a prefilter to such a scalable codec since it is possible to suppress flickering due to the artifacts for low and middle bit-rate decoding and to remove the filtering effect for high quality decoding. In this work, we further propose an exact lossless implementation technique by integrating the deinterlacer into MJP2 codecs and modifying the header information for appropriate standard decoding. We demonstrate some simulation results to show that the comb-tooth suppression capability can be kept at low bitrates with standard MJP2 decoders. Furthermore, some experimental results show that the overhead of our proposed method is less than 2.0% compared with normal field interleaving in video sequence 'Football'.

DOI： 10.3169/itej.59.1011

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Other Link： http://dblp.uni-trier.de/db/conf/eusipco/eusipco2004.html#conf/eusipco/IshidaUMKK04

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Other Link： http://dblp.uni-trier.de/db/conf/eusipco/eusipco2004.html#conf/eusipco/HasebeNMK04

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Performance of selective Rake (SRake) receiver is evaluated for direct sequence ultra wideband (DS-UWB) communications considering an independent Rayleigh channel having exponentially decaying power delay profile (PDP). BEP performances are shown. The results obtained are compared with similar results in a channel having flat PDP. Assumption of a flat PDP is found to predict the optimum spreading bandwidth to be lower and sub-optimum operating performance beyond optimum spreading bandwidth to be severely worse than that is achievable in a channel having exponentially decaying PDP by employing an SRake receiver having fixed number of combined paths. Optimum spreading bandwidth for SRake in a channel having exponentially decaying PDP is shown to be much larger than the one in a channel having flat PDP; that is specifically a good-news for UWB communications. Effects of partial band interference are also investigated. Interference is found to be less effective in exponentially decaying PDP.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this paper, a coefficient-parameter reduction method is proposed for invertible deinterlacing with variable coefficients. Invertible deinterlacing, which the authors have developed before, can be used as a preprocess of frame-based motion picture codec, such as Motion-JPEG2000 (MJP2), for interlaced videos. When the conventional field-interleaving is used instead, comb-tooth artifacts appear around edges of moving objects. On the other hand, the invertible deinterlacing technique allows us to suppress the comb-tooth artifacts and also to recover an original picture on demand. As previous works, the authors have developed a variable coefficient scheme with a motion detection filter, which realizes adaptability to local characteristics of given pictures. When applying this deinterlacing technique to an image codec, it is required to send coefficient parameters to receivers for original picture recovery. This work proposes a parameter decimation technique and shows that this reduction approach can be achieved without significant loss of comb-tooth suppression capability and improves the quality at high bit-rate decoding.

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This letter discusses the performance of online SNR estimation including fading parameter estimation for parallel combinatorial SS (PC/SS) systems. The PC/SS systems are partial-code-parallel multicode SS systems, which have high-rate data transmission capability. Nakagami-m distribution is assumed as fading channel model to cover a wide range of fading conditions. The SNR and fading parameter estimation considered in this letter is based on only a statistical ratio of correlator outputs at the receiver. Numerical results show that SNR estimation performance with fading parameter estimation is close to the one in the case of perfect fading parameter information, if the number of transmitting PN codes is less than a half of assigned PN codes.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Institute of Electronics, Information and Communication Engineers  

可変係数型可逆デインタレース処理を提案する．これまでに筆者らは，Motion-JPEG2000のようなフレーム内符号化で問題となるインタレース映像のくし状効果を抑えるために，可逆デインタレース処理を提案した．しかしながら，このデインタレースフィルタは固定係数であり，局所的には必ずしも適しているとはいえなかった．そこで，可逆性を犠牲にすることなく係数を可変とする新たな手法を提案し，画像の局所的性質に適した係数を用いることで画質の更なる改善を行う．シミュレーション結果により評価し，本手法の有効性を確認する．

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Multiple antenna systems are promising architectures for overcoming the effects of multi-path interference an increasing the spectrum efficiency. In order to be able to investigate these systems, in this article, we derive generalized spatial correlation equations of a circular antenna array for two typical angular energy distributions: a Gaussian angle distribution and uniform angular distribution. The generalized spatial correlation equations are investigated carefully by exact and approximate analyses.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Multiple antenna arrays are promising architectures for overcoming the efects of multipath interference and increasing the spectrum efficiency. In order to be able to investigate these systems, in this article, we derive generalized spatial correlation equations of a circular antenna array for two types of angular energy distributions: a Gaussian angle distribution, and uniform angular distribution. The ganaralized spatial correlation equations and BER (:Bit Error Rate) performance is investigated. It has been reported that spatial correlation and BER performance using linear array antenna, but very few attempts have been made at circular array antenna [5][7]. It was found from the result that BER of receiving arrival wave with uniform distribution is better than that with gaussian distribution.

DOI： 10.1109/APCCAS.2004.1412776

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this work, a coefficient-parameter embedding method is proposed for invertible deinterlacing with variable coefficients in the application to Motion-JPEG2000 (MJP2). Invertible deinterlacing, which the authors have developed before, can be used as a preprocess of frame-based motion picture codec, such as MJP2, for interlaced videos. When the conventional field-interleaving is used instead, comb-tooth artifacts appear around edges of moving objects. On the other hand, the invertible deinterlacing technique allows us to suppress the comb-tooth artifacts and also to recover an original picture on demand. As previous works, the authors have developed a variable coefficient scheme with a motion detector, which realizes adaptability to local characteristics of given pictures. When applying this deinterlacing technique to video codec, however, it is required to send coefficient parameters to receivers for original picture recovery. This work proposes a parameter-embedding technique for MJP2 and constructs a standard stream which consists both of picture data and the parameters. We investigate to embed the parameters into the LH1 component of the wavelet domain through the ROI (region of interest) function of JPEG2000 without significant loss in the performance of comb-tooth suppression.

DOI： 10.1109/MWSCAS.2004.1354184

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Perfect reconstruction (PR) deinterlacer banks are proposed as new tools for spatio-temporal scalable video codec. The proposed systems separate a progressive video into two different progressive videos of a half frame rate and are novel from the viewpoint of filter-banks in that interlaced videos are given as intermediate data during, analysis and synthesis process. Unlike the conventional filter banks, Our systems are constructed in a way unique to multidimensional systems by using invertible deinterlacers which we have proposed before. This paper suggests two kinds of interlaced video formats: the vertical-temporal (VT) Quincunx and face-centered-orthorhombic (FCO) format. As a primal application, a spatio-temporal scalable video codec, or field scalable video codec (FSVC). system is experimented. This technique offers a functionality by which decoding a base layer by itself provides both of half-rate progressive and interlaced videos, and adding all enhancement layer improves the spatio-temporal resolution. Some experimental results of the filter banks combined with JPEG2000 show their potential for practical video codec applications.

DOI： 10.1109/ICIP.2004.1421553

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Performance of selective Rake (SRake) receiver is evaluated for direct sequence ultra wideband (DS-UWB) communications considering an independent Rayleigh channel having exponentially decaying power delay profile (PDP). BEP performances are shown. The results obtained are compared with similar results in a channel having flat PDP. Assumption of a flat PDP (as was previously made in DS-SS) is found to predict the optimum spreading bandwidth to be lower and suboptimum operating performance beyond optimum spreading bandwidth to be severely worse than that is achievable in a real channel with an SRake receiver having fixed number of combined paths. Optimum spreading bandwidth for SRake in a channel having exponentially decaying PDP is shown to be much larger than the one in a channel having flat PDP. This is specifically a good-news for UWB communication. Effects of partial band interference have also been considered. Interference is found to be less effective in case of exponentially decaying PDP.

DOI： 10.1109/UWBST.2004.1320968

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this paper, we derive the SEP for time-hopping M-ary PPM (TH-MPPM) UWB communication systems as a function of captured SNR per symbol and simplify the results for TH-BPSK. For TH-MPPM system, we incorporate the effect of modulation index (b) on SEP. The results obtained give us way to evaluate the performance of Rake reception of UWB signals in dense multipath channels from energy capture perspective. We present more general type of results that can be applied for verities of Rake implementations. We present simulation results using IEEE 802.15.3a UWB channel models for various pulse-widths. We evaluate the performances of optimum and ordinary all Rake (ARake) and selective Rake (SRake) receivers in different channel models (CM1 to CM3). We compare relative costs of simplifying various Rake complexities. Conditioned on some parameters, we present an optimum pulse-width for UWB communications while SRake is employed.

DOI： 10.1109/UWBST.2004.1320970

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

A novel class of deinterlacing for intra-frame/field-based motion-picture coding, such as Motion JPEG2000, as well as an inter-frame-based coding without the support of interlaced scanning video, such as MPEG-1, is developed. This technique has two features: sampling-density preservation and invertibility. These features mean that the amount of deinterlaced pictures is not increased, and the original pictures can be perfectly reconstructed. This deinterlacing technique is a kind of sampling-lattice alteration and is regarded as a generalization of conventional field interleaving and field separation. With the help of multidimensional (M-D) multirate theory, it is shown that the design problem of such a system, that is, invertible deinterlacer with sampling-density preservation, can be replaced to finding a 2 x 2 multivariable polynomial matrix with a monomial determinant. This problem resembles the design of two-channel M-D maximally decimated perfect-reconstruction finite-impulse-response (FIR) filterbanks. The inverse system, which is referred to as a reinterlacer, is given as FIR when the dual deinterlacing system is FIR. A practical design procedure is provided by suggesting three constraints considered to be preferable: normalization, regularity, and vertical symmetry. The significance of the procedure is verified by showing some design examples of deinterlacing and reinterlacing filters. Simulation results show that the developed method causes fewer comb-shaped artifacts than conventional field interleaving.

DOI： 10.1109/TSP.2003.815368

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this paper, a lifting implementation of variable-coefficient invertible deinterlacer with embedded motion detector is proposed. As previous works, the authors have developed invertible deinterlacing that suppresses comb-tooth artifacts caused by field interleaving for interlaced scanning video, which affect the quality of intraframe-based codec such as Motion-JPEG2000. To improve the local adaptability for given pictures, its variable-coefficient processing with motion detection has also been proposed so that filters can be changed according to local properties of motion pictures, while maintaining the invertibility. In this paper, it is shown that the variable-coefficient invertible deinterlacing can be realized by a lifting-based simple hardware architecture, and motion detector can also be embedded. Both of the motion detection and deinterlacing filters are shared by a special choice of their coefficients, and by adaptive selection of deinterlacing filters. The significance of our proposed architecture is verified by showing synthesis results from the VHDL models. The proposed implementation with embedded motion detector achieves about 28% reduction of the gate count compared with the corresponding separate implementation.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this paper, we derive spatial correlation functions of linear and circular antenna arrays for three types of angular energy distributions: a Gaussian angle distribution, the angular energy distribution arising from a Gaussian spatial distribution, and uniform angular distribution. The spatial correlation functions are investigated carefully. The spatial correlation is a function of antenna spacing, array geometry and the angular energy distribution. In order to emphasize the research and their applications in diversity reception, as an example, performance of the antenna arrays with MRC in correlated Nakagami fading channels is investigated, in which analytical formulas of average BER for the spatial correlation are obtained.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPIE-INT SOCIETY OPTICAL ENGINEERING  

As an extra option, fine grayscale data that exceed eight bits per pixel are encoded into pseudogray colors in 8-bit sRGB color space to be displayed on an 8-bit sRGB CRT monitor. The characteristics of the pseudogray are investigated in terms of the CIELAB color difference and a*b* coordinates. (C) 2003 Society of Photo-Optical Instrumentation Engineers.

DOI： 10.1117/1.1578492]

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The demand for wireless mobile communications has grown at a very high rate, recently. In order to solve the non-uniform traffic rates, the use of cell splits is unavoidable for balancing the traffic rate and maximizing total system capacity. For cell planning, a DS-CDMA cellular system can be comprise of different cell sizes because of different demands and population density of the service area. In this paper, we develop a general model to study the forward link capacity and outage probability of a DS-CDMA cellular system with mixed cell sizes. The analysis of outage probability is carried out using the log-normal approximation. When a macrocell is split into the three microcells, as an example, we calculate the multi-cross interferences between macrocells and microcells, and the forward link capacities for the microcells and the neighboring macrocells. The maximum allowable capacity plane for macrocell and microcell is also investigated. The numerical results and discussions with previous published results of reverse link are summarized.

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Several lifting implementation techniques for invertible deniterlacing are proposed in this paper. Firstly, the invertible deinterlacing is reviewed, and an efficient implementation is presented. Next, two deinterlacer-embedded lifting architectures of discrete wavelet transforms (DWT) is proposed. Performances are compared among several architectures of deinterlacing with DWT. The performance evaluation includes dual-multiplier and single-multiplier architectures. The number of equivalent gates shows that the deinterlacing-embedded architectures require less resources than the separate implementaion. Our experimental evaluation of the dual-multiplier architecture results in 0.8% increase in the gate count, whereas the separate implementation of deinterlacing and DWT requires 6.1% increase from the normal DWT architecture. For the proposed single-multiplier architecture, the gate count is shown to result in 4.5% increase, while the separate counterpart yields 10.7% increase.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Invertible deinterlacing with variable coefficients is proposed to suppress comb-tooth artifacts caused by field interleaving of interlaced scanning video. A vertical highpass filter is applied to detect moving artifacts around boundaries of moving objects. The coefficients of a deinterlacing filter is varied depending on the motion intensity so that the deinterlacing filter may be matched to the local characteristics of moving pictures. Note that the deinterlacing filter is motion-adaptive and is time/translation-varying, while the deinterlacing is still kept to be invertible. The deinterlacing filter performance and its contribution to intraframe-based video coding are evaluated. In addition, since the processing of motion detection and a part of deinterlacing filtering can be shared, their efficient implementation is derived in the form of lifting popular in wavelets.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：BEIJING UNIV POSTS TELECOMMUNICAT PRESS  

Diversity reception, a key technique derived against multi-path mitigation in wireless communication system, is examined and discussed. Especially, we present an approach to investigate perfect/imperfect channel detection when a simple transmit diversity scheme (STD)[9] are used in the wireless systems, which provide remarkable schemes for diversity transmission over Rayleigh-fading channels using multiple antennas. In order to effectively make use of the transmit diversity techniques, the same approach is extended to process the situation of two transmit antennas and N receive antennas in STD scheme (2 x N STD), in which the effects of perfect/imperfect channel detection and the diversity reception with independent and correlated Rayleigh-fading signals are evaluated and compared.

DOI： 10.1109/ICCT.2003.1209670

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Invertible deinterlacing with variable coefficients is proposed to suppress comb-tooth artifacts caused by field interleaving of interlaced scanning video. A vertical highpass filter is applied to detect moving artifacts around boundaries of moving objects. The coefficients of a deinterlacing filter is varied depending on the motion intensity so that the deinterlacing filter may be matched to the local characteristics of moving pictures. Note that the deinterlacing filter is motion-adaptive and is time/translation-varying, while the deinterlacing is still kept to be invertible. The deinterlacing filter performance and its contribution to intraframe-based video coding are evaluated. In addition, since the processing of motion detection and a part of deinterlacing filtering can be shared, their efficient implementation is derived in the form of lifting popular in wavelets.

DOI： 10.1109/ICME.2003.1221277

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：UNIV ZAGREB, FACULTY MECHANICAL ENGINEERING & NAVAL ARCHITECTURE  

This paper presents a two-step algorithm that automatically detects shot boundaries of a video in a wavelet transform domain. It at first finds isolated intervals in a given video sequence, and then detects a shot boundary within those intervals. Its effectiveness for several different kinds of videos is evaluated in terms of recalls and precisions.

DOI： 10.1109/ISPA.2003.1296902

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this work, discrete-wavelet-transform (DWT) gain compensation of Motion-JPEG2000 (MJP2) for invertible deinterlacer is proposed. As previous works, we have developed invertible deinterlacer that suppresses comb-tooth artifacts caused by field interleaving for interlaced scanning video, which affect the quality of scalable intraframe-based codec such as MJP2. Our technique has two features that the sampling density is preserved and the image quality can be recovered by the inverse process on demand. When no codec is applied in between the deinterlacer and inverse process, the original video is perfectly reconstructed. Otherwise, it is approximately recovered. The purpose of this work is to improve the quality of recovered images when MJP2 codec is inserted. It is shown that our invertible deinterlacer can be embedded into the DWT. As a result, frequency weighting for rate-distortion control can be moderately compensated. Simulation results show that the quality recovery is improved more than 1.5 dB in PSNR by applying the proposed compensation compared with the original weighting at 2.0bpp of decoding rate for 8-bit grayscale pictures.

DOI： 10.1109/ICIP.2003.1246657

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this paper, we derive spatial correlation functions of linear and circular antenna arrays for three types of angular energy distributions: a Gaussian angle distribution, the angular energy distribution arising from a Gaussian spatial distribution, and uniform angular distribution. The spatial correlation functions are investigated carefully. The spatial correlation is a function of antenna spacing, array geometry and the angular energy distribution. In order to emphasize the research and their applications in diversity reception, as an example, performance of the antenna arrays with MRC in correlated Nakagami fading channels is investigated, in which analytical formulas of average BER for the spatial correlation are obtained.

DOI： 10.1109/GLOCOM.2003.1258410

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this paper, an online SNR estimator is proposed for parallel combinatorial SS (PC/SS) systems in Nakagami fading channels. The PC/SS systems are called as partial-code-parallel multicode DS/SS systems, which have the higher-speed data transmission capability comparing with conventional multicode DS/SS systems referred to as all-code-parallel systems. We propose an SNR estimator based on a statistical ratio of correlator outputs at the receiver. The SNR at the correlator output is estimated through a simple polynomial from the statistical ratio. We investigate the SNR estimation accuracy in Nakagami fading channels through computer simulations. In addition, we apply it to the convolutional coded PC/SS systems with iterative demodulation and decoding to evaluate the estimation performance from the viewpoint of error rate. Numerical results show that the PC/SS systems with the proposed SNR estimator have superior estimation performance to conventional DS/SS systems. It is also shown that the bit error rate performance using our SNR estimation method is close to the performance with perfect knowledge of channel state information in Nakagami fading channels and correlated Rayleigh fading channels.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Transmit diversity, a key technique derived against multi-path mitigation in wireless communication system, is examined and discussed. Especially, we present an approach to investigate perfect/imperfect channel detection when the maximal ratio receiver combined scheme (MRRC) and a simple transmit diversity scheme (STD) are used in the wireless systems, which provide remarkable schemes for diversity transmission over Rayleigh-fading channels using multiple antennas. In order to effectively make use of the transmit diversity techniques, the same approach is extended to process the situation of one transmit antennas and N receive antennas in MRRC scheme (1 x N MRRC) and two transmit antennas and N receive antennas in STD scheme (2 x N STD). The effects of perfect/imperfect channel detection and the diversity reception with independent and correlated Rayleigh-fading signals are evaluated and compared carefully.

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Other Link： http://dblp.uni-trier.de/db/conf/eusipco/eusipco2002.html#conf/eusipco/KikuchiMIK02

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In this paper, the co-existence of TDMA and W-CDMA spectrum sharing system (TDMA/W-CDMA overlaid system) with cellular architecture is discussed. In this system, both systems share the same frequency band to improve the spectrum efficiency. Overall rate, bit error ratio (BER) and spectrum efficiency of the system are calculated for the forward link (down-link) in the presence of AWGN channel. Taking into account the path loss and shadow fading loss in this system with cellular architecture, W-CDMA applying interference cancellation (IC) shows a substantial difference in spectrum efficiency, the overlaid system can provide a greater overall rate arid higher spectrum efficiency than a single multiple access-based system such as TDMA system or W-CDMA system. The interference cancellation can significantly improve BER of the spectrum overlaid system.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Upper bounds on the bit error rate (BER) for maximum likelihood (ML) decoding are derived in convolutional coded parallel combinatorial spread spectrum (PC/SS) systems over additive white Gaussian noise (AWGN) channels. PC/SS systems can achieve higher data transmission than conventional multicode SS systems. To make the derivation tractable, we put a uniform interleaver between a convolutional encoder and a PC/SS transmitter. Since the PC/SS transmitter is employed as the "inner encoder," the bounds are obtained in a similar manner of the derivation in serially concatenated codes through a uniform interleaver. Two different error patterns in the PC/SS system are considered in the performance analysis. Numerical results show that the derived BER bounds are sufficiently accurate. It is found that the coded PC/SS systems outperform coded all-code-parallel DS/SS systems under the same data rate conditions if the number of pre-assigned PN codes increases.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

next generation wireless communication is based on a global system of fixed and wireless mobile services that are transportable across different network backbones,network service providers and network geographical boundaries. Although the power control is essential for Direct Sequence Code Division Multiple Access (DS-CDMA) cellular systems to overcome the near-far problem, one of the most important problems for the system is handover management and its effects on the system. This paper presents an approach to investigate the effects of soft handover[1][2] and perfect power control[3][4] on the forward link in a DS-CDMA cellular system. Especially, the relationships between the size of handover zone and the capacity gain are evaluated under the log-normal shadow channel. Then the optimization of maximum forward capacity is very necessary to be done with the maximum size of soft handover zone to the various system characteristics.

DOI： 10.1109/ICCCAS.2002.1180632

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this paper, we propose an approach to solve the power control issue in a DS-CDMA cellular system using genetic algorithms (GAs). The transmitter power control developed in this paper has been proven to be efficient to control co-channel interference, to increase bandwidth utilization and to balance the comprehensive services that are sharing among all the mobiles with attaining a common signal-to-interference ratio (SIR). In this paper, the optimal centralized power control (CPC) vector is characterized and its optimal solution for CPC is presented using GAs, in which first in-first out (FIFO) stacks and non-linear decreasing functions are derived in the investigation for enforcing the convergence rate. Emphasis is put on the balance of services and convergence rate by using GAs.

DOI： 10.1109/WCNC.2002.993486

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

A new class of de-interlacing is developed for intra-frame-based motion picture coding such as Motion-JPEG2000. The proposed technique has two features: the sampling density preservation and the invertibility. Thus, the amount of de-interlaced pictures is not increased and the original pictures can perfectly be reconstructed. This technique is regarded as a generalization of the conventional field interleaving. The significance is verified by showing some design examples and simulation results. The proposed technique is also shown to cause less comb-shape artifacts than the conventional one. The intra-field-based case is also discussed.

DOI： 10.1109/ICASSP.2002.5745353

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

in this article, the co-existence of TDMA and W-CDMA spectrum sharing system (TDMA/W-CDMA overlaid system) with cellular architecture is discussed. In this system, both systems share the same frequency band to improve the spectrum efficiency. Overall rate and spectrum efficiency of the system are calculated for the forward link (down-link) in the presence of AWGN channel. Taking into account the path loss and shadow fading loss in this system with cellular architecture, W-CDMA applying interference cancellation (IC) shows a substantial difference in. spectrum efficiency, the overlaid system can provide a greater overall rate and higher spectrum efficiency than a single multiple access-based system such as TDMA system or W-CDMA system.

DOI： 10.1109/ICCCAS.2002.1180601

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this paper, a simple and accurate on-line SNR estimator is proposed for parallel combinatorial SS (PC/SS) systems in Nakagami fading channels. The PC/SS systems are a kind of partial-code-parallel multicode DS/SS systems., Our proposed SNR estimator estimates the SNR at the correlator output by using a statistical ratio of the sum of correlator outputs for pre-assinged PN codes. We investigate the SNR estimation accuracy in Nakagami fading channels through computer simulations. Numerical results show that the the proposed SNR estimator brings superior estimation performance to that in conventional estimator that has proposed by Summers and Wilson [9]. In addition, we apply it to the convolutional coded PC/SS systems with iterative demodulation and decoding to evaluate the estimation performance from the viewpoint of error rate. By using our estimator, the bit error rate performance is close to the performance with perfect knowledge of the SNR information in Nakagami fading channels and correlated Rayleigh fading channels.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Upper bounds on the codeword and bit error probabilities are obtained for maximum-likelihood (ML) decoding of block coded parallel combinatorial spread spectrum (PC/SS) systems in additive white Gaussian noise (AWGN) channels. To make the analysis tractable, we put a uniform inter-leaver between a block encoder and a PC/SS transmitter. An input-output distance enumerating function (IODEF) is introduced to calculate the number of codewords for an overall coded PC/SS system instead of the input-output weight enumerating function (IOWEF). The average bounds on the bit error rate (BER) of block coded PC/SS systems on AWGN channels are shown. It is demonstrated that the performance advantage between PC/SS systems is determined by the number of information bits per active transmitting PN code. A comparison between the coded PC/SS systems and coded conventional multicode DS/SS systems is also discussed.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this paper, a simple and accurate on-line SNR estimator is proposed for parallel combinatorial SS (PC/SS) systems in Nakagami fading channels. The PC/SS systems are a kind of partial-code-parallel multicode DS/SS systems., Our proposed SNR estimator estimates the SNR at the correlator output by using a statistical ratio of the sum of correlator outputs for pre-assinged PN codes. We investigate the SNR estimation accuracy in Nakagami fading channels through computer simulations. Numerical results show that the the proposed SNR estimator brings superior estimation performance to that in conventional estimator that has proposed by Summers and Wilson [9]. In addition, we apply it to the convolutional coded PC/SS systems with iterative demodulation and decoding to evaluate the estimation performance from the viewpoint of error rate. By using our estimator, the bit error rate performance is close to the performance with perfect knowledge of the SNR information in Nakagami fading channels and correlated Rayleigh fading channels.

DOI： 10.1109/GLOCOM.2002.1188395

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This paper proposes iterative demodulation/decoding for parallel combinatorial spread spectrum (PC/SS) systems. A PC/SS system conveys information data by a combination of pre-assigned orthogonal spreading sequences with polarity. In this paper, convolutional coding with a uniform random interleaver is implemented in channel coding, just like as a serial concatenated coding. A 'soft-in/soft-out' PC/SS demodulator based on a posteriori probability algorithm is proposed to perform the iterative demodulation and decoding. Simulation results demonstrate that the proposed iterative demodulation/decoding scheme bring significant improvement in bit error rate performance. This proposed decoding scheme achieves highspeed transmission by two approaches. One is a puncturing operation, and the other is to increase the number of transmitting sequences. In the latter approach, lower error rate performance is achieved comparing with that the punctured convolutional code is used to increase the information bit rate.

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DOI： 10.1109/PIMRC.2001.965285

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

A unified polyphase representation of analysis and synthesis filter banks is introduced in this paper, and then the efficient implementation on digital signal processors (DSP) is investigated. Especially, the number of memory accesses, power consumption, processing accuracy and the required instruction cycles are discussed. Firstly, a unified representation is given, and then two types of procedures, SIMO system-based and MISO system-based procedures, are shown, where SIMO and MISO are abbreviations for single-input/multiple-output and multiple-input/single-output, respectively. These procedures are compared to each other. It is shown that the number of data load in SIMO system-based procedure is a half of that in MISO system-based procedure for two-channel filter banks. The implementation of W-channel filter banks is also discussed.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This paper proposes iterative demodulation/decoding for parallel combinatorial spread spectrum (PC/SS) systems. The PC/SS systems convey the information data by a combination of pre-assigned spreading sequences with the polarity. In this paper, convolutional coding with random interleaver is implemented as channel coding, just like as a serial concatenated concatenated coding. A &apos;soft-in/soft-out&apos; PC/SS demodulator based on a posteriori probability algorithm is proposed to perform the iterative demodulation and decoding. Simulation results demonstrate that the proposed iterative demodulation and decoding bring significant improvement in the bit error rate performance.

DOI： 10.1109/GLOCOM.2001.965531

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE COMPUTER SOC  

In this paper, we proposed a theoretical method in order to estimate the forward link outage probability and user capacity of a cellular system which are based on IS-95 CDMA standard, especially impact of power control strategy and voice activity monitoring on the system under long-term fading. According to the numerical results obtained in this paper, the power control strategy leads to approximately threefold the user capacity contrast to the situation without power control strategy. The power control strategy not only improves the desired signal to interference ratio in the reference user's receiver, but also offers uniform service to the user wherever it is located in the cell.

DOI： 10.1109/ICON.2001.962392

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Institute of Electronics, Information and Communication Engineers  

低階調画像を用いて動きベクトルを推定する場合，動きベクトルの推定精度は，量子化の際のしきい値の値に依存する．本論文では，しきい値を計算するための演算量を低減する二つの方法を提案する．一つは2種類の低階調画像を用いる方法で，他の一つは，マクロブロックを分割し，より細かい単位でしきい値を計算する方法である．これらの二つの方法は組み合わせて使用することも可能である．シミュレーションにより，提案法は，動きベクトルの推定精度を保ち，しきい値決定に要する演算量を低減できることが確認できた．

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In MPEG standard, motion estimation (ME) is used to eliminate the temporal redundancy of video frames. This ME is the most time-consuming task in the encoding of video sequences and is also the one using the most power. Using low-bit images can save power of ME and a conventional architecture fixed to a certain bit width is used for low-bit motion estimator. It is known that there is a trade-off between power and image quality. ME may be used in various situations, and the relation between demands for power or image quality will depend on those circumstances. We therefore developed an architecture for a low-bit motion estimator with adjustable power consumption. In this architecture, we can select the bit width for the input image and adjust the amount of power for ME. To evaluate its effectiveness, we designed the motion estimator by VHDL and used the synthesis results to estimate the performance.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this paper, an algorithm of the median-cut quantization (MCQ) is proposed. MCQ is the technique that reduces multi-valued samples to binary-valued ones by adaptively taking thr median value as the threshold. In this work, the search process of the median value is derived from the quick-sort algorithm. The proposed algorithm searches the median value bit by bit, and samples are quantized during the search process. Firstly the bit-parallel procedure is shown, and then it is modified to the bit-parallel procedure. The extension to the multi-level quantization is also discussed. Since the proposed algorithm is based on bit operations, it is suitable for hardware implementation. Thus, its hardware architecture is also proposed. To verify the significance, for the application to the motion estimation, the performance is estimated from the synthesis result uf the VHDL model.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In MPEG standard, motion estimation (ME) is used to eliminate the temporal redundancy of video frames. This ME is the most time-consuming task in the encoding of video sequences and is also the one using the most power. Using low-bit images can save power of ME and a conventional architecture fixed to a certain bit width is used for low-bit motion estimator. It is known that there is a trade-off between power and image quality ME may be used in various situations, and the relation between demands for power or image quality will depend on those circumstances. We therefore developed an architecture for a low-bit motion estimator with adjustable power consumption. In this architecture, we can select the bit width for the input image and adjust the amount of power for ME. To evaluate its effectiveness, we designed the motion estimator by VHDL and used the synthesis results to estimate the performance.

DOI： 10.1109/ICIP.2000.899309

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS  

Filter banks are usually designed so that the perfect reconstruction condition is satisfied. This condition, however, is not always satisfied in actual applications. In such a case, the filter bank operates as a time-varying system, and checkerboard distortion is produced by the time-varying effect. This paper discusses the checkerboard effect in a two-channel filter bank, including the effect of finite word length implementation and the case in which the perfect reconstruction condition is not satisfied. The general condition for avoiding the checkerboard effect is formulated. A design procedure for a paraunitary QMF bank satisfying that condition, as well as an implementation by the lattice configuration, are shown. It is furthermore shown that the checkerboard effect can be minimized in a finite word length implementation by employing the proposed lattice configuration and adding a correction to the rotation angle. (C) 1999 Scripta Technica, Electron Comm Jpn Pt 3, 82(11): 74-85, 1999.

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Doctoral thesis  

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Other Link： http://dblp.uni-trier.de/db/conf/eusipco/eusipco1998.html#conf/eusipco/MuramatsuYK98

Language：English   Publishing type：Research paper (international conference proceedings)  

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Other Link： http://dblp.uni-trier.de/db/conf/eusipco/eusipco1998.html#conf/eusipco/HaradaMK98

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this paper, a two-dimensional (2-D) binary valued (BV) lapped transform (LT) is proposed. The proposed LT has basis images which take only BV elements and satisfies the axial-symmetric (AS) properly. In one dimension, there is no 2-point LT with the symmetric basis vectors, and the property is achieved only with the non-overlapping basis which the Hadamard transform (HT) has. Hence, in two dimension, there is no 2 x 2-point separable ASLT, and only 2-D I-IT can be the 2 x 2-point separable AS orthogonal transform. By taking nonseparable BV basis images, this paper shows that a 2 x 2-point ASLT can be obtained. Since the proposed LT is similar to HT, it is referred to as the lapped Hadamard transform (LHT). LHT of larger size is shown to be provided with a tree structure. In addition, LHT is shown to be efficiently implemented by a lattice structure.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

The checkerboard effect is caused by the periodic time-variant property of multirate filters which consist of up-samplers and digital filters. Although the conditions for some one-dimensional (1D) multirate systems to avoid the checkerboard effect have been shown, the conditions for Multidimensional (MD) multirate systems have not been considered. In this paper, some theorems about the conditions for MD multirate filters without checkerboard effect are derived. In addition, we also consider MD multirate filter banks without checkerboard effect. Simulation examples show that the checkerboard effect can be avoided by using the proposed conditions.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this letter, a design method of linear-phase paraunitary filter banks is proposed for an odd number of channels. In the proposed method, a non-linear unconstrained optimization process is assumed to be applied to a lattice structure which makes the starting guess of design parameters simple. In order to avoid insignificant local minimum solutions, a recursive initialization procedure is proposed. The significance of our proposed method is verified by some design examples.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Institute of Electronics, Information and Communication Engineers  

In this letter, a design method of linear-phase paraunitary filter banks is proposed for an odd number of channels. In the proposed method, a non-linear unconstrained optimization process is assumed to be applied to a lattice structure which makes the starting guess of design parameters simple. In order to avoid insignificant local minimum solutions, a recursive initialization procedure is proposed. The significance of our proposed method is verified by some design examples.

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Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： 10.1109/ISCAS.1998.694414

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this paper, a 2-D binary-valued (BV) lapped transform (LT) is proposed. The proposed LT has basis images which take only BV elements and satisfies the axial-symmetric (AS) property. In ID, there is no 2-point LT with the symmetric basis vectors. Hence, in 2D, there is no 2 x 2-point separable ASLT. By taking non-separable BV basis images, this paper shows that a 2 x 2-point ASLT can be obtained. For its similarity to the Hadamard transform (HT), this paper refer to it as the lapped Hadamard transform (LHT). The efficient implementation is also given.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Institute of Electronics, Information and Communication Engineers  

フィルタバンクは，多くの場合，完全再構成条件を満たすように設計されるが，実際の使用においては，必ずしもこの条件は満足されない．このとき，フィルタバンクは時変システムとして動作し，この時変性の影響によりチェス盤ひずみが発生する．本論文では，2分割フィルタバンクにおいて，有限語長実現の影響や完全再構成条件を満たさない場合も含めチェス盤ひずみの考察を行い，チェス盤ひずみを回避するための条件を一般的に定式化する．また，その条件を満足するパラユニタリQMFバンクの設計法およびそのラティス構成による実現法を示す．更に，有限語長で実現する際に，このラティス構成を用いることにより回転角に補正角を加えることでチェス盤ひずみを極力抑えることが可能であることを示す．

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS  

This paper describes an efficient structure for generalized lapped orthogonal transforms (GenLOT) for finite-duration sequences, which we expect to be used for subband image coding. When linear convolution is carried out on the finite-duration sequences and filter, the number of points in the output signal increases. Therefore, the linear convolution is not desirable in subband image coding. In order to solve this problem, the convolution is carried out after the finite-duration sequences are symmetrically and periodically extended (symmetric extension method). This method is superior to circular. convolution because the former method causes less distortion at the signal boundaries. In the GenLOT structure proposed in this paper, the symmetric extension can be realized without redundant operations due to signal extension and, furthermore, with fast implementation. This structure is considered to be a generalization of the lapped orthogonal transform (LOT) for finite-duration sequences. In addition, its application to the M-band discrete-time wavelet transform (DTWT) will be described. Finally, it will be shown that an efficient structure for finite-duration sequences can be realized in the M-band DTWT. (C) 1997 Scripta Technica, Inc.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Block delay caused by using fast Fourier transform (FFT), and computational complexity in sampling rate conversion system are considered in this paper. The relationship between the number of block delays and the computational complexity is investigated. The proposed method can avoid the redundant operations of sampling rate conversion completely and moreover provide a good trade-off between the number of block delays and the computational complexity. As a result, it is shown that with the proposed method, the sampling rate conversion can be realized more efficiently under a small number of blocks delays.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：I E E E  

A new implementation method for sampling rate conversion (SRC) is discussed in this work. Since the proposed method performs sampling rate conversion in a block way via FFT and inverse FFT (IFFT), we call the sampling rate conversion in this case the block sampling rate conversion (BSRC). The proposed method can reduce the additional input-output delay resulted from the use of FFT and trade-off it against the computational complexity more easily, compared with other FFT-based approaches.

DOI： 10.1109/ISCAS.1997.612796

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

A lattice structure of multidimensional (MD) linear-phase paraunitary filter banks (LPPUFBs) is proposed, which makes it possible to design such filter banks in a systematic manner. The proposed structure can produce MD-LPPUFBs whose filters all have the region of support N(M Xi), where M and Xi are the decimation and an integer diagonal matrices, respectively, and ni (N) is the set of integer vectors in the fundamental parrallelpiped of N. Since our proposed system structurally restricts both the paraunitary and linear-phase properties, an unconstrained optimization process can be used to design MD-LPPUFBs. Some design examples will show the significance.

DOI： 10.1109/TENCON.1997.647260

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Institute of Electronics, Information and Communication Engineers  

本論文では，サブバンド画像符号化において応用が期待されている一般化重複直交変換（GenLOT: Generalized Lapped Orthogonal Transforms）の有限長信号に対する効果的な構成を提案する．有限長信号とフィルタとの直線畳込みを行うと，出力信号の点数が増加する．この理由から，サブバンド画像符号化において直線畳込みを行うことは望ましくない．そこで，この問題の解決法として，有限長信号を対称かつ周期的に拡張し，畳込みを行う対称拡張法が提案されている．この方法は，信号境界部分でのひずみが少ない点で循環畳込みよりも優れている．今回提案するGenLOTの構成は，信号拡張による冗長な処理を伴わずに対称拡張法を実現するものであり，高速処理が可能な利点ももつ．また，重複直交変換（LOT: Lapped Orthogonal Transforms）の有限長信号に対する構成の一般化としてみなすことができる．本論文では，更に，提案する構成のM帯域の離散時間ウェーブレット（DTWT: Discrete-Time Wavelet Transforms）への拡張についても議論する．結果として，M帯域DTWTにおいても，有限長信号に対する効果的な構成が得られることを示す．

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Other Link： http://dblp.uni-trier.de/db/conf/eusipco/eusipco1996.html#conf/eusipco/KajitaKMYK96

Language：English   Publishing type：Research paper (international conference proceedings)  

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Other Link： http://dblp.uni-trier.de/db/conf/eusipco/eusipco1996.html#conf/eusipco/MuramatsuK96

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this work, a new structure of M-channel linear-phase paraunitary filter banks is proposed, where nl is even. Our proposed structure can be regarded as a modification of the conventional generalized linear-phase lapped orthogonal transforms (GenLOT) based on the discrete cosine transform (DCT). The main purpose of this work is to overcome the limitation of the conventional DCT-based GenLOT, and improve the performance of the fast implementation. II is shown that our proposed fast GenLOT is superior to that of the conventional technique in terms of the coding gain. This work also provides a recursive initialization design procedure so as to avoid insignificant local-minimum solutions in the non-linear optimization processes. In order to verify the significance of our proposed method, several design examples are given. Furthermore, it is shown that the fast implementation can be used to construct ni-band linear-phase orthonormal wavelets with regularity.

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：PUBLISHING HOUSE ELECTRONICS INDUSTRY  

In this work, we investigate the generalized overlap add and overlap-save methods (GenOLA and GenOLS) using discrete sine and cosine transforms (DST's & DCT's). Compared to the GenOLA and GenOLS using discrete Fourier Transform (DFT), the merit of the DST & DCT approach is that the filtering can be implemented by real-valued operations. It is shown that the computational complexity can be minimized when the transform size of DST or DCT is chosen optimally, and a good tradeoff between the computational complexity and system delay can be achieved.

DOI： 10.1109/ICSIGP.1996.566980

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In this paper, we propose two parallel processing methods for multidimensional (MD) sampling lattice alteration. The use of our proposed methods enables us to alter the sampling lattice of a given MD signal sequence in parallel without any redundancy caused by up- and down-sampling, even if the alteration is rational and non-separable. Our proposed methods are provided by extending two conventional block processing techniques for FIR filtering: the overlap-add method and the overlap-save method. In these proposed methods, firstly a given signal sequence is segmented into some blocks, secondly sampling lattice alteration is implemented for each block data individually, and finally the results are fitted together to obtain the output sequence which is identical to the sequence obtained from the direct sampling lattice alteration. Besides, we provide their efficient implementation: the DFT-domain approach, and give some comments on the computational complexity in order to show the effectiveness of our proposed methods.

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SCRIPTA TECHNICA PUBL  

The overlap-add (OLA) and overlap-save (OLS) methods are well known as efficient schemes for higher-order filtering. In those methods, the linear convolution for the infinite-duration data is reduced to the circular convolution for the finite blocks, and the fast-Fourier transform (FFT) is applied to the execution of the circular convolution.
This paper proposes new OLA and OLS methods, which can directly be applied without a redundancy to the rate conversion. First, the conventional theory is extended for the finite-duration data. Then, the result is generalized for the infinite-duration data. Two methods are proposed as the main result in this paper, which are the extended overlap-add and extended overlap-save methods. Finally, the proposed method is compared to the polyphase structure, which is well known as an effective realization method for the rate conversion.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：I E E E  

DOI： 10.1109/ISCAS.1995.521627

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SCRIPTA TECHNICA PUBL  

The decimation and interpolation (contraction and expansion) processings of the image based on the orthogonal transform are simple and useful in the communication and storage of the digital image data. Consequently, their application to the resolution conversion of the image is expected. The conversion factor in this type of resolution conversion can be set as an arbitrary rational number if the size of the matrices in the forward and backward transforms can de set arbitrarily.
On the other hand, the size of the transform matrix in the encoding is specified by the international standard and other specifications and it is not possible to set the conversion factor arbitrarily on the decoding side. When the transform matrix has the size of N, for example, the conversion factor is restricted to be the integer multiple of 1/N.
From such a viewpoint, this paper proposes a method that can realize a resolution conversion with an arbitrary conversion factor even if the transform matrix size in the encoding is already specified. The basic principle of the proposed method is to combine the conventional method and the decimation processing and can be characterized as a more general method than the conventional method.
By a discussion based on the filter bank and multirate system, the effective configuration for the proposed method is shown. It is shown also as a result that the conversion with an arbitrary rational factor can be executed with nearly the same computational complexity as in the conventional method. A simulation is executed using DCT and LOT and the effectiveness of the proposed method is demonstrated while indicating the problems in DCT.

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Institute of Electronics, Information and Communication Engineers  

ディジタル画像データの通信や蓄積の分野において，直交変換に基づく拡大・縮小処理が，その容易さと有効性から，画像の解像度変換への応用に期待されている．この解像度変換法は，もし順変換と逆変換の行列サイズを任意に選択可能ならば，その変換倍率を任意の有理数に選ぶことができる．しかしながら，国際規格等によって，符号化の際の変換サイズは決まっており，復号側において，変換倍率を任意に選ぶことが不可能となる．例えば変換サイズがNの場合，変換倍率は1/Nの整数倍に制限されてしまう．そこで本論文では，符号化の際の変換サイズが固定の場合においても，任意の有理数倍率の解像度変換を可能にする方法について提案する．提案法の基本原理は，従来法と間引き処理を組み合わせた構成であり，より一般的な形として位置づけることができる．また，フィルタバンクとマルチレートシステムに基づく考察により，提案法の効果的な構成を示す．この結果，任意の有理数倍率の変換においても，従来法と同程度の演算量で実行可能となる．また，DCTとLOTを使用したシミュレーションを行い，提案法の有効性を示し，DCTのもつ問題点を指摘する．

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：I E E E  

高次のFIRフィルタによる直線畳込みを効果的に実行する一手法として，重複加算法（OLA）や重複保持法（OLS）がある．これらの方法は，無限長データに対する直線畳込みを，有限なブロックごとの循環畳込みに帰着させ，その循環畳込みの実行に高速フーリエ変換（FFT）を利用できる．本論文ではレート変換においても冗長性なしに直接適用可能な新しいOLAとOLSを提案する．論文中では，まず有限長データのもとで，従来の理論を拡張する．次に，無限長データに対してそれを一般化し，本論文の目的である拡張重複加算法と拡張重複保持法の二つの方法を提案する．最後に，レート変換の効果的な実現技術として知られるポリフェーズ構成と本方法を比較し，提案法の有効性を示す．

DOI： 10.1109/ISCAS.1994.408967

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

It is known that the resolution conversion based on orthogonal transform has a problem that is difference of luminance between the converted image and the original. In this paper, the scale factor of the system employing various orthogonal transforms is generally formulated by considering the DC gain, and the condition of alias free for DC component is indicated. If the condition is satisfied, then the scale factor is determined by only the basis functions.

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