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Сжатие видео - DCT


Английские материалы
Авторы Название статьи Описание Рейтинг
Przemysіaw Czerepinґski, Colin Davies, Nishan Canagarajah, and David Bull Matching Pursuits Video Coding: Dictionaries and Fast Implementation
Abstract—Matching pursuits over a basis of separable Gabor functions has been demonstrated to outperform DCT methods for displaced frame difference coding for video compression. Unfortunately, apart from very low bit-rate applications, the algorithm involves an extremely high computational load. This paper contains original contribution to the issues of dictionary selection and fast implementation for matching pursuits video coding. First, it is shown that the PSNR performance of existing matching pursuits codecs can be improved and the implementation cost reduced by a better selection of dictionary functions. Secondly, dictionary factorization is put forward to further reduce implementation costs. A reduction of the computational load by a factor of 20 is achieved compared to implementations reported to date. For a majority of test conditions, this reduction is supplemented by an improvement in reconstruction quality. Finally, a pruned full-search algorithm is introduced, which offers significant quality gains compared to the better-known heuristic fast-search algorithm, while keeping the computational cost low.
RAR  771 кбайт
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Yun-Chin Li, Tong-Hai Wu, and Yung-Chang Chen, A Scene Adaptive Hybrid Video Coding Scheme Based on the LOT
Abstract—Conventional standard video coding schemes based on independent coding of nonoverlapping image blocks produce undesirable effects (blocking effect and color bleeding, etc.) at low bit rate. In this paper, a hybrid coding scheme evolving from the standard MPEG codec that combines lapped orthogonal transform (LOT) and overlapped block motion compensation and quantization approaches based on human visual system sensitivity is proposed to remove the artifacts. The LOT is applied to compress the resulting prediction errors of the overlapped motion compensation. The LOT coefficients are quantized by a dynamic intra/inter scene adaptive quantizer that is designed according to the human visual system and scene analysis to optimize the decoded image quality. This technique involves automatically deriving the most favorable quantizer matrix from the motion and scene analysis of image sequences and scaling the resulting matrix furthermore by considering the buffer status. If scene change is detected from the motion information, the proposed adaptive quantization can also help solve the difficulty of the buffer controller and maintain the picture quality as constant as possible. Performance of the proposed hybrid coding scheme with scene adaptive quantizer is demonstrated by computer simulations using standard test sequences and compared to that of the conventional MPEG-2 coding schemes. Subjective and objective tests show that image quality is improved considerably and the required bit rate is much less than that of the conventional method. Particularly, the image quality can be kept almost consistent, and the undesirable artifacts are reduced considerably. To reduce the amount of bit rate, coarse quantization of DCT coefficients and/or discarding of some unimportant coefficients are introduced in the technique. However, it causes serious a blocking effect in the coded image sequence at low bit rate especially. The blocking effect mainly results from the quantization errors occurring at lower frequencies and the confinement of the DCT basis within a block.
RAR  301 кбайт
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Yao Zhao and Baozong Yuan A New Affine Transformation: Its Theory and Application to Image Coding
Abstract—The fractal image coding technique has attracted a degree of interest for its low bit rate. But the reconstructed image is of medium quality. This problem has prevented the fractal technique from being practically used. In order to improve the compression fidelity, a new affine transformation is proposed in this paper. Meanwhile, its contractivity requirement is analyzed, and the optimal parameters are derived using the least square method. The new affine transformation has been practically used in image coding. Experiments show that the PSNR can reach 28.7dB at a compression ratio (CR) of 16.4 for the 256 . 256 . 8 “Lena” image. Comparison with other fractal coding schemes shows that the new affine transformation can improve the reconstructed image quality efficiently.
RAR  251 кбайт
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I-Ming Pao and Ming-Ting Sun Approximation of Calculations for Forward Discrete Cosine Transform
Abstract—This paper presents new schemes to reduce the computation of the discrete cosine transform (DCT) with negligible peak-signal-to-noise ratio (PSNR) degradation. The methods can be used in the software implementation of current video standard encoders, for example, H.26x and MPEG. We investigated the relationship between the quantization parameters and the position of the last nonzero DCT coefficient after quantization. That information is used to adaptively make the decision of calculating all 8 . 8 DCT coefficients or only part of the coefficients. To further reduce the computation, instead of using the exact DCT coefficients, we propose a method to approximate the DCT coefficients which leads to significant computation savings. The results show that for practical situations, significant computation reductions can be achieved while causing negligible PSNR degradation. The proposed method also results in computation savings
RAR  124 кбайт
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Hong Ren Wu and Zhihong Man Comments on “Fast Algorithms and Implementation of 2-D Discrete Cosine Transform”
Abstract— This letter shows that using the Loeffler’s onedimensional (1-D) 8-point discrete cosine transform (DCT) algorithm [4] in Cho and Lee’s two-dimensional (2-D) 8 . 8-point DCT algorithm in the above paper1 will result in an optimal algorithm in the sense of multiplicative complexity theory.
RAR  29 кбайт
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Jiangtao Xi and Joe F. Chicharo Computing Running Discrete Cosine/Sine Transforms Based on the Adaptive LMS Algorithm
Abstract— Least mean square (LMS)-based computation of block-based discrete orthogonal transforms has been extensively studied in literature [1]–[5]. This paper establishes the relationship between the running discrete cosine transform II (DCT-II), discrete sine transform II (DST-II), and the adaptive LMS algorithm. From this analysis a new parallel structure for computing the running DCT-II and DST-II is proposed.
RAR  244 кбайт
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Ryszard Stasiґnski, and Janusz Konrad, A New Class of Fast Shape-Adaptive Orthogonal Transforms and Their Application to Region-Based Image Compression
Abstract—Region-based approaches to image and video compression have been very actively explored in the last few years. It is widely expected that they will result in rate/quality gains and expanded functionalities. In such approaches, one of the essential problems is the representation of luminance and color in arbitrarily shaped regions. For rectangular blocks extracted from natural images, the discrete cosine transform (DCT) has been found to perform close to the eigentransform. Although for arbitrarily shaped regions orthogonalization-based procedures have been shown to perform very well, their computational complexity and memory requirements are prohibitive for today’s technology. Therefore, other approaches are presently investigated, and particular attention is paid to low implementation complexity. In this paper, we propose a new class of orthogonal transforms that self-adapt to arbitrary shapes. The new algorithms are derived from flow graphs of standard fast transform algorithms by a suitable modification of certain butterfly operators. First, we show how to derive a shape-adaptive transform from the discrete Walsh–Hadamard transform (DWHT) flow graph. Then, we discuss modifications needed to arrive at a DCT-based shapeadaptive transform. We give implementation details of this transform, and compare its computational complexity with several well-known approaches. We also evaluate the energy compaction performance of the new transform for both synthetic and natural data. We conclude that the proposed DCT-based shape-adaptive transform gives a very beneficial compaction/complexity ratio compared to other well-known approaches. The complexity of the new method does not exceed the complexity of two nonadaptive DCT’s on a circumscribing rectangle, and therefore, unlike other tested methods with comparable energy compaction, it is suitable for large regions. This property should prove very valuable in the future when true region-based image/video compression methods are developed.
RAR  907 кбайт
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Tin-Chak Johnson Pang, Chiu-Sing Oliver Choy, Cheong-Fat Chan, and Wai-Kuen Cham A Self-Timed ICT Chip for Image Coding
Abstract— This paper describes an asynchronous onedimensional order-8 integer cosine transform chip, which can calculate either forward or inverse transforms. The chip’s performance is maximized with a fast computation algorithm and the self-timed circuit technique. The basic self-timed block is a microcoded programmable processor. Eight of these processors are used and achieve a data rate of up to 50 MHz in 0.7-.m CMOS technology. If the delay in the handshake circuit can be minimized, the design suggests that asynchronous techniques are a feasible alternative to synchronous designs.
RAR  307 кбайт
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G. Sudhir, Ming L. Liou, Fellow, and John C. M. Lee Average Optimal Vector Transform for VQ-Based Image and Video Compression
Abstract—We present an average sense optimal vector transform (AOVT) for vector quantization (VQ)-based coding of square block vectors. We introduce new notions of average intervector correlations and exploit the new structure of the intervector correlation matrix in deriving our AOVT. We present the results of applying our AOVT to many real images and demonstrate the superiority of the AOVT in terms of better preservation of the intravector correlation in the transform domain. We also present coding results on a variety of images to demonstrate the fact that the above-mentioned advantage of AOVT translates into coding gains since the performance of VQ increases if the transform domain vectors have more intravector dependencies.
RAR  471 кбайт
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Jae-Beom Lee, and Alexandros Eleftheriadis 2-D Transform-Domain Resolution Translation

RAR  191 кбайт
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M. Bi, Sim-Heng Ong, and Yew-Hock Ang A Hybrid Shape-Adaptive Orthogonal Transform for Coding of Image Segments
Abstract—Improvements in compression performance can be achieved if the image transform is able to adapt to the shape of the objects present. We propose a new hybrid shape-adaptive orthogonal transform which is based on -channel subband decomposition and shape-adaptive DCT techniques. The signal extension method for the region-based dyadic wavelet transform is applied to region-based image coding using -channel filter banks. Simulation results show that the proposed method outperforms shape-adaptive DCT coding.
RAR  181 кбайт
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Nam Ik Cho, and Sanjit K. Mitra, Fellow Warped Discrete Cosine Transform and Its Application in Image Compression
Abstract—This paper introduces the concept of warped discrete cosine transform (WDCT) and an image-compression algorithm based on the WDCT. The proposed WDCT is a cascade connection of a conventional DCT and all-pass filters whose parameters can be adjusted to provide frequency warping. Because only the first-order all-pass filters are considered in this paper, the WDCT can be implemented by Laguerre network connected with the DCT. For the more efficient software implementation, we propose truncated and approximated FIR filter banks which can be used instead of the Laguerre network. As a result, the input–output relationship of the WDCT can be represented by a single matrix-vector multiplication, like the DCT. In the proposed image-compression scheme, the frequency response of the all-pass filter is controlled by a fixed set of parameters from which a specified warping parameter is used for a specified frequency range. Also, for each parameter, the corresponding WDCT matrices are computed a priori. For each image block, the best parameter is chosen from the set and the index is sent to the decoder as side information along with the result of corresponding WDCT matrix computation. At the decoder, an inverse WDCT is performed to reconstruct the image. The WDCT based compression outperforms the DCT based compression, for high bit rate applications and for images with high-frequency components. It results in 1.1–3.1-dB PSNR gain over conventional DCT at 1.5 bpp for natural images, and provides more gain for compound images with texts.
RAR  320 кбайт
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Ulrich Benzler, Student Spatial Scalable Video Coding Using a Combined Subband-DCT Approach
Abstract—A combined subband-DCT approach for spatial scalable video coding is presented. The high-resolution input signal is decomposed into four spatial subband signals. The low-frequency subband is used as the low-resolution signal and is separately coded in the base-layer bitstream, and the high-frequency subband signals are coded in the enhancement-layer bitstream. The low-resolution signal is reconstructed from the base-layer bitstream and the high-resolution signal is reconstructed using both the base- and the enhancement-layer bitstream. Similar to MPEG, DCT-based hybrid coding techniques are applied for the coding of the subband signals, but an improved motion-compensated prediction is used for the low-resolution signal. Additionally, SNR scalability is introduced to allow a flexible bit allocation for the base and the enhancement layer. Experimental results at a bit rate of 6 Mbit/s show that the reference coder MPEG-4 spatial scalable profile (SSP) leads to a loss of more than 2.2-dB peak signal-to-noise ratio (PSNR) compared with nonscalable MPEG-2 coding at the same bit rate, whereas the proposed combined subband-DCT scheme is able to achieve a decrease of less than 0.4 dB in PSNR.
RAR  136 кбайт
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Thuyen Le and Manfred Glesner Flexible Architectures for DCT of Variable-Length Targeting Shape-Adaptive Transform
Abstract—Shape-adaptive block-based texture coding schemes such as the shape-adaptive discrete cosine transform (SA-DCT) raise the need for an architecture which performs efficiently the transform of variable length . For an implementation requiring standard DCT and SA-DCT, it is advantageous to have a VLSI architecture which can be configured to compute both schemes. Existing fast algorithms usually consider only the standard DCT of fixed-size length and lack regular structure leading to complex routing. This paper discusses two different architectures satisfying the given requirement in terms of scalability, modularity, and regularity. The first proposed architecture represents a time-recursive fully modular, but nonefficient, structure regarding the number of operation counts. The second proposed feedforward architecture overcomes problems of numerical instability found in time-recursive structure. Both architectures are modeled in VHDL and synthesized using an 0.7- m two metal-layers CMOS technology for comparison. The design in VHDL is kept generic so that new SA-DCT cores can be easily generated to produce application tailored circuits.
RAR  221 кбайт
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Gopal Lakhani Distribution-Based Restoration of DCT Coefficients
Abstract—Although it is established that distribution of discrete cosine transform coefficients can be modeled, it is not known how this knowledge can best be applied to improve the JPEG compression algorithms.We studied this problem by making modifications to both the JPEG baseline encoder and decoder separately. Experimental results show that modifications to the decoder alone do not reduce any compression losses. However, if the encoder is also modified, the losses can be reduced, but only marginally.
RAR  81 кбайт
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Tian-Sheuan Chang, Chin-Sheng Kung, and Chein-Wei Jen A Simple Processor Core Design for DCT/IDCT
Abstract—This paper presents a cost-effective processor core design that features the simplest hardware and is suitable for discrete cosine transform/indiscrete cosine transform (DCT/IDCT) operations in H.263 and digital camera. This design combines the techniques of fast direct two-dimensional DCT algorithm, the bit-level adder-based distributed arithmetic, and common subexpression sharing to reduce the hardware cost and enhance the computing speed. The resulting architecture is very simple and regular such that it can be easily scaled for higher throughput rate requirements. The DCT design has been implemented by 0.6 m SPDM CMOS technology and only costs 1493 gate count, or 0.78 mm2. The proposed design can meet real-time DCT/IDCT requirements of H.263 codec system for QCIF image frame size at 10 frames/s with 4:2:0 color format. Moreover, the proposed design still possesses additional computing power for other operations when operating at 33 Mhz.
RAR  332 кбайт
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Junehwa Song and Boon-Lock Yeo A Fast Algorithm for DCT-Domain Inverse Motion Compensation Based on Shared Information in a Macroblock
Abstract—The ability to construct intracoded frame from motion-compensated intercoded frames directly in the compressed domain is important for efficient video manipulation and composition. In the context of motion-compensated discrete cosine transform (DCT)-based coding of video as in MPEG video, this problem of DCT-domain inverse motion compensation has been studied and, subsequently, improved faster algorithms were proposed. These schemes, however, treat each 8 8 block as a fundamental unit, and do not take into account the fact that in MPEG, a macroblock consists of several such blocks. In this paper, we show how shared information within a macroblock, such as a motion vector and common blocks, can be exploited to yield substantial speedup in computation. Compared to previous brute-force approaches, our algorithms yield about 44% improvement. Our technique is independent of the underlying computational or processor model, and thus can be implemented on top of any optimized solution. We demonstrate an improvement by about 19%, and 13.5% in the worst case, on top of the optimized solutions presented in existing literature.
RAR  285 кбайт
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Hoon Paek, Rin-Chul Kim, and Sang-Uk Lee A DCT-Based Spatially Adaptive Post-Processing Technique to Reduce the Blocking Artifacts in Transform Coded Images
Abstract—In this letter, we propose a discrete cosine transform (DCT)-based post-processing technique to alleviate the blocking artifacts in transform coded images. In our approach, the highfrequency components, mainly caused by the edge components, are examined through two steps. First, two adjacent homogeneous blocks from block boundary are found, where the homogeneous block is defined as the block in which no adjacent pixels' difference is larger than the difference of the block boundary. Second, the local frequency characteristics in the homogeneous block are examined through DCT. Then, we derive the relation between the DCT coefficients of two homogeneous blocks of different sizes. By considering the information about the original edge and the relation, we can detect the high-frequency components, mainly caused by the blocking artifact. The performance of the proposed technique is evaluated on both still and moving images. The simulation results indicate that the proposed technique reduces the blocking artifacts effectively and preserves the original edges faithfully, and its performance is very robust to the degree of degradation in decoded images.
RAR  193 кбайт
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I-Ming Pao and Ming-Ting Sun Modeling DCT Coefficients for Fast Video Encoding
Abstract—Digital video coding standards such as H.263 and MPEG are becoming more and more important for multimedia applications. Due to the huge amount of computations required, there are significant efforts to speed up the processing of video encoders. Previously, the efforts were mainly focused on the fast motion-estimation algorithm. However, as the motion-estimation algorithm becomes optimized, to speed up the video encoders further we also need to optimize other functions such as discrete cosine transform (DCT) and inverse DCT (IDCT). In this paper, we propose a theoretical model for DCT coefficients. Based on the model, we develop an adaptive algorithm to reduce the computations of DCT, IDCT, quantization, and inverse quantization. We also present a fast DCT algorithm to speed up the calculations of DCT further when the quantization step size is large.We show, by simulations, that significant improvement in the processing speed can be achieved with negligible video-quality degradation. We also implement the algorithm in a real-time PC-based platform to show that it is effective and practical.
RAR  207кбайт
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Changhoon Yim and Michael A. Isnardi An Efficient Method for DCT-Domain Image Resizing with Mixed Field/Frame-Mode Macroblocks
Abstract— This paper deals with discrete cosine transform (DCT)-domain image resizing as compressed domain processing. Previous DCT-domain image resizing methods assume that all macroblocks are in the frame mode. In this paper, we propose an efficient method for DCT-domain image resizing with mixed field/frame-mode macroblocks. This method is developed from the investigation of the DCT-domain image resizing operation through a decomposition of matrix operations, from which we define new downsampling matrices for frame- and field-mode macroblocks. This leads to new frame- and field-mode resizing transformation matrices for DCT-domain image resizing. The proposed DCT-domain image resizing method can be used when there are mixed field/frame-mode macroblocks.
RAR  1225кбайт
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Peter Kauff and Klaas SchЁuЁur Shape-Adaptive DCT with Block-Based DC Separation and DC Correction
Abstract—This paper refers to a shape-adaptive DCT algorithm (SA-DCT) originally proposed by Sikora and Makai in 1995. The SA-DCT has been developed in the framework of the ongoing MPEG-4 standardization phase of ISO/IEC, and has recently been included in the video verification model of MPEG-4. In this context, the focus of the present paper is to emphasize a systematic performance limitation of conventional SA-DCT, and to propose an extended version (.DC-SA-DCT) which avoids this restriction in general. This modification considerably improves the efficiency of SA-DCT, and can easily be implemented in existing SA-DCT tools.
RAR  187кбайт
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Chung-Yen Lu and Kuei-Ann Wen On the Design of Selective Coefficient DCT Module
Abstract—In this transactions letter, an innovative selective coefficient discrete cosine transform (SCDCT) architecture is proposed which is designed for selective coefficient computation and straightforward row–column computation. Having these features, the selective coefficient DCT core will fit for various area/speed requirements. It can save the transposition delay to simplify the computation flow of two-dimensional (2-D) DCT and, in view of circuit implementation, SCDCT is multiply-free and thus area/speed efficient.
RAR  130кбайт
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Ut-Va Koc, and K. J. Ray Liu Interpolation-Free Subpixel Motion Estimation Techniques in DCT Domain
Abstract—Currently existing subpixel motion estimation algorithms require interpolation of interpixel values which undesirably increases the overall complexity and data flow and deteriorates estimation accuracy. In this paper, we develop discrete cosine transform (DCT)-based techniques to estimate subpel motion at different desired subpel levels of accuracy in the DCT domain without interpolation. We show that subpixel motion information is preserved in the DCT of a shifted signal under some condition in the form of pseudophases, and we establish subpel sinusoidal orthogonal principles to extract this information. The proposed subpixel techniques are flexible and scalable in terms of estimation accuracy with very low computational complexity O(N2) compared to O(N4) for the full-search block-matching approach and its subpixel versions. Above all, motion estimation in the DCT domain instead of the spatial domain simplifies the conventional hybrid DCT-based video coder, especially the heavily loaded feedback loop in the conventional design, resulting in a fully DCT-based high-throughput video codec. In addition, the computation of pseudophases is local, and thus a highly parallel architecture is feasible for the DCT-based algorithms. Finally, simulation on video sequences of different characteristics shows comparable performance of the proposed algorithms to block-matching approaches.
RAR  1270кбайт
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Bo Shen, Ishwar K. Sethi, and Vasudev Bhaskaran DCT Convolution and Its Application in Compressed Domain
Abstract—Conventional processing of JPEG or MPEG compressed image or video data involves first decompressing the data and applying the desired processing function, and then the processed data are recompressed for the purposes of transmission or storage. We propose an alternate processing pipeline which involves direct manipulation of the JPEG or MPEG compressed domain representation to achieve the desired spatial domain processing. For direct manipulation in the compressed domain, we develop a discrete cosine transform (DCT)-domain convolution theorem which besides exploiting the sparseness of the DCT-domain representation also exploits the orthogonality and symmetry in the DCT-domain representation. These properties lead to efficient compressed domain-based processing methods unlike their spatial domain counterparts, where such properties are not available. This theorem can be used in a variety of image and video editing functions when the image and video data are available only as a JPEG or MPEG bitstream. We illustrate the use of the DCT-domain convolution theorem in a typical video editing application such as video bluescreen editing.
RAR  329кбайт
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Neri Merhav and Renato Kresch Approximate Convolution Using DCT Coefficient Multipliers
Abstract—We develop a method for designing discrete cosine transform (DCT) coefficient multipliers in order to approximate the operation of two-dimensional (2-D) convolution of an image with a given kernel. The method is easy to implement on compressed formats of DCT-based compression methods (JPEG, MPEG, H.261) by using decoding quantization tables that are different from the encoding quantization tables.
RAR  420кбайт
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Sung Bum Pan and Rae-Hong Park Unified Systolic Arrays for Computation of the DCT/DST/DHT
Abstract—In this paper, we propose unified systolic arrays for computation of the one-dimensional (1-D) and two-dimensional (2-D) discrete cosine transform/discrete sine transform/discrete Hartley transform (DCT/DST/DHT). By decomposing the transforms into even- and oddnumbered frequency samples, the proposed architecture computes the 1-D DCT/DST/DHT. Compared to the conventional methods, the proposed systolic arrays exhibit advantages in terms of the number of PE’s and latency. We generalize the proposed structure for computation of the 2-D DCT/DST/DHT. The unified systolic arrays can be employed for computation of the inverse DCT/DST/DHT (IDCT/IDST/IDHT).
RAR  224кбайт
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Peter Kauff, Bґela Makai, Stefan Rauthenberg, Ulrich GЁolz, Jan L. P. De Lameillieure, and Thomas Sikora Functional Coding of Video Using a Shape-Adaptive DCT Algorithm and an Object-Based Motion Prediction Toolbox
Abstract—This paper presents an object-based layered video coding scheme which achieves very high compression efficiency along with the provision for advanced content-based functionalities, e.g., content-based scalability or content-based access and manipulation of video data. In a first step, a video sequence is segmented into several arbitrarily shaped “object layers.” To achieve the desired contentbased functionalities, a baseline shape-adaptive discrete cosine transform (DCT) coding algorithm is introduced which can be seen as an extension of conventional block-based DCT coding schemes (e.g., H.261, H.263, MPEG-1, or MPEG-2) toward coding of arbitrarily shaped image content. In order to increase compression efficiency, the baseline object-based layered approach can be extended with an object-based motion prediction toolbox. Using this toolbox, the coding scheme can potentially select specific prediction techniques for every object layer to be coded. To illustrate the concept, an extension of the baseline shape-adaptive DCT algorithm with a technique for global background motion estimation and compensation is described which significantly improves the compression efficiency of suitable video sequences compared to standard MPEG coding schemes.
RAR  1493кбайт
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Neri Merhav, and Vasudev Bhaskaran Fast Algorithms for DCT-Domain Image Down- Sampling and for Inverse Motion Compensation
Abstract—Straightforward techniques for spatial domain processing of compressed video via decompression and recompression are computationally expensive. We describe an alternative approach wherein the compressed stream is processed in the compressed, discrete cosine transform (DCT) domain without explicit decompression and spatial domain processing, so that the output compressed stream, corresponding to the output image, conforms to the standard syntax of 8 . 8 blocks. We propose computation schemes for down-sampling and for inverse motion compensation that are applicable to any DCT-based compression method. Worst-case estimates of computation savings vary between 37% and 50% depending on the task. For typically sparse DCT blocks, the reduction in computations is more dramatic. A by-product of the proposed approach is improvement in arithmetic precision.
RAR  345кбайт
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Yung-Pin Lee, Thou-Ho Chen, Liang-Gee Chen, Mei-Juan Chen, and Chung-Wei Ku A Cost-Effective Architecture for 8*8 Two-Dimensional DCT/IDCT Using Direct Method
Abstract— In this paper, we develop a novel 8 . 8 twodimensional (2-D) discrete cosine transform/inverse discrete cosine transform (DCT/IDCT) architecture based on the direct 2-D approach and the rotation technique. The computational complexity is reduced by taking advantage of the special attribute of complex number. Both the parallel and the folded architectures are proposed. Unlike other approaches, the proposed architecture is regular and economically allowable for VLSI implementation. Compared to the row-column method, less internal wordlength is needed in order to meet the error requirement of IDCT, and the throughput of the proposed architecture can achieve two times that of the row-column method with 30% hardware increased.
RAR  368кбайт
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