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Postprocessing of decoded color images by adaptive linear filtering

SIGNAL PROCESSING-image COMMUNICATION 2003年第2期18卷 91-101页

作者： Bayazit, U Isik Univ Dept Elect Engn TR-80670 Istanbul Turkey

This paper presents an image adaptive linear filtering method for the reconstruction of the RGB (red, blue, green) color coordinates of a pixel from the lossy compressed luminance/chrominance color coordinates. In the absence of quantization noise, the RGB coordinates of a pixel can be perfectly reconstructed by employing a standard, fixed filter whose support includes only the luminance/chrominance coordinates at the spatial location of the pixel. However, in the presence of quantization noise, a filter with a larger support, that also spatially extends over the luminance/chrominance coordinate planes, is capable of exploiting the statistical dependence among the luminance/chrominance coordinate planes, and thereby yields more accurate reconstruction than the standard, fixed filter. We propose the optimal (in the minimum mean squared error sense) determination of the coefficients of this adaptive linear filter at the image encoder by solving a system of regression equations. When transmitted as side information to the image decoder, the filter coefficients need not incur significant overhead if they are quantized and compressed intelligently. Our simulation results demonstrate that the distortion of the decompressed color coordinate planes can be reduced by several tenths of a dB with negligible overhead rate by the application of our image adaptive linear filtering method. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： color image coding color image processing adaptive linear filter

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JPEG 2000: Retrospective and new developments

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PROCEEDINGS OF THE IEEE 2005年第1期93卷 32-41页

作者： Lee, DT Yahoo Inc Sunnyvale CA 94089 USA

JPEG 2000 is a new image coding system that delivers superior compression performance and provides many advanced features in scalability, flexibility, and system functionalities that outperform all previous standards. It brings exciting possibilities to many imaging applications such as the Internet, wireless, security, and digital cinema. This paper gives an overview of this triumph in innovations and teamwork. It gives brief introductions to the four new parts that are under development by the JPEG committee. It attempts to summarize the lessons learned from the JPEG 2000 development experience and draw some conclusions on the success factors of this important standard.

关键词： color image coding data compression image communication Internet imaging Joint Photographic Experts Group (JPEG) JPEG 2000 motion JPEG 2000 source coding subband coding wavelet transform

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Low bit-rate multi stage vector quantization based on energy clustered training set

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MULTIMEDIA TOOLS AND APPLICATIONS 2014年第3期70卷 2293-2308页

作者： Krishnamoorthy, R. Punidha, R. Anna Univ Technol Dept CSE Comp Vis Lab Tiruchirappalli 620024 Tamil Nadu India

In this paper, a new multi stage vector quantization with energy clustered training set is proposed for color image coding. The input image is applied with orthogonal polynomials based transformation and the energy clustered transformed training vectors are obtained with reduced dimension. The stage-by-stage codebook for vector quantization is constructed from the proposed transformed training vectors so as to reduce computational complexity. This method also generates a single codebook for all the three color components, utilizing the inter-correlation property of individual color planes and interactions among the color planes due to the proposed transformation. As a result, the color image encoding time is only slightly higher than that of gray scale image coding time and in contrast to the existing color image coding techniques, whose time is thrice greater than that of gray scale image coding. The experimental results reveal that only 35 % and 10 % of transform coefficients are sufficient for smaller and larger blocks respectively, for the reconstruction of images with good quality. The proposed multi stage vector quantization technique is faster when compared to existing techniques and yields better trade-off between image quality and block size for encoding.

关键词： color image coding Energy clustered training set Multi stage vector quantization Orthogonal polynomials transform

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The impact of tree structures on the performance of zerotree-based wavelet video codecs

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SIGNAL PROCESSING-image COMMUNICATION 2010年第3期25卷 179-195页

作者： Moinuddin, Athar Ali Khan, Ekram Ghanbari, Mohammed Aligarh Muslim Univ Dept Elect Engn Aligarh 202002 UP India Univ Essex Sch Comp Sci & Elect Engn Colchester CO4 3SQ Essex England

In this paper we analyze the impact of tree structures on the performance of zerotree-based wavelet video codecs. Since zerotree approach is based on aggregation of insignificant coefficients in trees, therefore design of a tree structure is the key issue for a better performance. We have considered six different tree structures with characteristics varying from a simple to relatively complex and composite tree structures to code the luminance-chrominance components of a video sequence. Their performances are compared in terms of average number of bits generated per bitplane, number of coded bitplanes for a given bit budget, rate-distortion performance, memory requirements and computational complexity. We observe that in general more complex and longer trees do not necessarily improve the coding efficiency. However, the tree structures encapsulating more elements per tree are memory efficient. Therefore, the rate-distortion performance, memory requirements and computational complexities need to be traded-off while selecting a particular tree structure. It is also observed that the additional improvement due to optional entropy coding is also tree structure dependent. Further, the simulation results show that by designing an efficient tree structure, depending on the picture content, the performance of a video coder can be improved by up to 2.0 dB, while reducing the computational complexity by 45-60% as well as the memory requirements by almost 29-35%. Compared to the standard JPEG2000 (for intra-frame), tree-based coders are found to be efficient in terms of coding and complexity, particularly at lower bit rates. (C) 2010 Elsevier B.V. All rights reserved.

关键词： Zerotree coding SPIHT color image coding Wavelet video Tree structure

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An enhanced one-dimensional SPIHT algorithm and its implementation for TV systems

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DISPLAYS 2015年 40卷 68-77页

作者： Kim, Sunwoong Lee, Donghyeon Kim, Hyun Truong, Nguyen Xuan Kim, Jin-Sung Seoul Natl Univ Dept Elect & Comp Engn Seoul 151744 South Korea Sun Moon Univ Dept Elect Engn Asan 336708 South Korea

In general, to achieve high compression efficiency, a 2D image or a 2D block is used as the compression unit. However, 2D compression requires a large memory size and long latency when input data are received in a raster scan order that is common in existing TV systems. To address this problem, a 1D compression algorithm that uses a 1D block as the compression unit is proposed. 1D set partitioning in hierarchical trees (SPIHT) is an effective compression algorithm that fits the encoded bit length to the target bit length precisely. However, the 1D SPIHT can have low compression efficiency because 1D discrete wavelet transform (DWT) cannot make use of the redundancy in the vertical direction. This paper proposes two schemes for improving compression efficiency in the 1D SPIHT. First, a hybrid coding scheme that uses different coding algorithms for the low and high frequency bands is proposed. For the low-pass band, a differential pulse code modulation-variable length coding (DPCM-VLC) is adopted, whereas a 1D SPIHT is used for the high-pass band. Second, a scheme that determines the target bit length of each block by using spatial correlation with a minimal increase in complexity is proposed. Experimental results show that the proposed algorithm improves the average peak signal to noise ratio (PSNR) by 2.97 dB compared with the conventional 1D SPIHT algorithm. With the hardware implementation, the throughputs of both encoder and decoder designs are 6.15 Gbps, and gate counts of encoder and decoder designs are 42.8 K and 57.7 K, respectively. (C) 2015 Elsevier B.V. All rights reserved.

关键词： color image coding Discrete wavelet transform (DWT) Set partitioning in hierarchical trees (SPIHT) Differential pulse code modulation (DPCM) Golomb-Rice coding Bit allocation

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Segment-based coding of color images

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Science in China(Series F) 2009年第6期52卷 914-925页

作者： ZHANG YuDong WU LeNan School of Information Science & Engineering Southeast University Nanjing 210096 China

Based on the idea of second generation image coding, a novel scheme for coding still images is pre- *** first, an image was partitioned with a pulse-coupled neural network; and then an improved chain code and the 2D discrete cosine transform was adopted to encode the shape and the color of its edges *** code its smooth and texture regions, an improved zero-trees strategy based on the 2nd generation wavelet was *** that, the zero-tree chart was selected to rearrange quantified *** finally some regulations were given according to psychology of various *** under noiseless channels demonstrate that the proposed method performs better than those of the current one, such as JPEG, CMP, EZW and JPEG2000.

关键词： image segmentation color image coding lifting scheme wavelet pulse-coupled neural networks structure coding

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What is wrong and right with MSE?

What is wrong and right with MSE?

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8th IASTED International Conference on Signal and image Processing

作者： Guo, Linfeng Meng, Yan BrainMedia LLC New York NY 10016 USA Stevens Inst Technol Dept Elect & Comp Engn Hoboken NJ 07030 USA

ISBN: (纸本)9780889865839

Mean squared error (MSE), or its equivalence, peak signal-to-noise ratio (PSNR), has been widely used as the quality metric in image compression for long time. Meanwhile, numerous evidences testified the loose correlation between MSE (or PSNR) and the subjective quality assessment result of the same distorted image. If MSE is such an unreliable quality metric, why do encoders based on it work well in most cases? But if it works well in image compression, why can't people count on it in objective quality assessment? These questions are investigated in this paper under the framework of JPEG baseline compression on color images. We concluded that MSE generally works well in comparing two images compressed by the same encoder, since they normally share the same distortion structure. When comparing compressed images from different encoders or artificially distorted images. MSE will perform very poor, since there are significant discrepancies between the essence of MSE and contrast sensitivities of human visual system.

关键词： quality assessment JPEG color image coding

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Low Memory Strip-Based image Compression for color images

Low Memory Strip-Based Image Compression for Color Images

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International Conference on Intelligent Human-Machine Systems and Cybernetics

作者： Chew, Li Wern Ang, Li-Minn Seng, Kab Phooi Univ Nottingham Selangor 43500 Malaysia

ISBN: (纸本)9780769537528

In this paper, a low memory strip-based image compression for color images using the set-partitioning in hierarchical trees (SPIHT) coding is presented. The proposed coding scheme applies a lower scale of discrete wavelet decomposition and uses a new spatial orientation tree structure to achieve a low memory strip-based coding implementation. It also incorporates a modified SPIHT algorithm which uses a degree-0 to degree-2 zerotree coding methodology to increase the compression efficiency. The main advantage of the proposed work is the significant reduction in both the memory requirements as well as the complexity of the image coder for practical software and hardware implementation. Simulation results on color images also show that the proposed coding scheme gives a better compression performance compared to the traditional SPIHT coding at most bit-rates.

关键词： color image coding low memory image compression SPIHT strip-based image compression

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An optimization based approach to color image compression using a Rate-Distortion model

An optimization based approach to color image compression us...

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6th International Conference on Modelling, Simulation, and Optimization

作者： Gershikov, Evgeny Porat, Moshe Technion Israel Inst Technol Dept Elect Engn IL-32000 Haifa Israel

ISBN: (纸本)9780889865914

In this work a new model for color image compression is introduced. The model predicts the expected distortion in compressed images as a function of the compression rate, known as a Rate-Distortion curve. Based on the model, we present anon-linear optimization problem, from which the optimal color components and rate allocation are derived. We extend the problem to consider down-sampling of the color components. We show that the rate-distortion model in conjunction with the probability distribution of subband coefficients can be used to develop an efficient algorithm for coding color images. We demonstrate this approach for the Discrete Cosine Transform (DCT) and the Laplacian distribution as the probability model. We measure the distortion using Mean Square Error (MSE) and Weighted Mean Square Error (WMSE). Simulation results are presented and discussed to support the efficiency of the new algorithm.

关键词： Mathematical Modelling color image coding Rate-Distortion model probability model Discrete Cosine Transform Laplacian distribution

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Linear filtering of image subbands for low complexity postprocessing of decoded color images

Linear filtering of image subbands for low complexity postpr...

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Conference on image and Video Communications and Processing 2005

作者： Bayazit, U Isik Univ Buyukdere Caddesi TR-34398 Istanbul Turkey

ISBN: (纸本)0819456586

In [1], image adaptive linear minimum mean squared error (LMMSE) filtering was proposed as an enhancement layer color image coding technique that exploited the statistical dependencies among the luminance/chrominance or Karhunen Loeve Transform (KLT) coordinate planes of a lossy compressed color image to enhance the red, blue, green (RGB) color coordinate planes of that image. In the current work, we propose the independent design and application of LMMSE filters on the subbands of a color image as a low complexity solution. Towards this end, only the coordinates of the neighbors of the filtered subband coefficient, that are sufficiently correlated with the corresponding coordinate of the filtered subband coefficient, are included in the support of the filter for each subband. Additionally, each subband LMMSE filter is selectively applied only on the high variance regions of the subband. Simulation results show that, at the expense of an insignificant increase in the overhead rate for the transmission of the coefficients of the filters and with about the same enhancement gain advantage, subband LMMSE filtering offers a substantial complexity advantage over fullband LMMSE filtering.

关键词： postprocessing linear filtering color image coding enhancement layer subband wavelet transform

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