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International Conference on Computer Sciences and Convergence Information Technology (ICCIT)

作者： Aijun Sang Xin Zhao Hexin Chen Silin Mang School of Communication Engineering Jilin University Changchun China

Three-dimensional vector matrix discrete cosine transform coding (3DVMDCT) deals with each component of color image in a unified model, fully eliminates the correlation between them and gets an obvious advantage. But its block-size of image segmentation is fixed and does not fully take into account that there are different statistical properties in different regions. In this paper, we take gradient as the image measure activity (IAM), propose a new method-variable matrix-size three-dimensional vector matrix image segmentation (VMS-3DVMDCT), and implement the corresponding multi-dimensional vector matrix discrete cosine transform coding, experimental results show that, compared with the fixed block partition, the proposed algorithm improves PSNR at most 1dB, and the quality of the reconstructed image is improved in subject evaluation, much better than JPEG.

关键词： PSNR Discrete cosine transforms Image coding Color transform coding Image segmentation Image reconstruction

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Improved transform coding (imaging coding)

Improved transform coding (imaging coding)

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： K. Mensa-Ababio Canopus Electronics Company Kobe Japan

A novel method for coding of images using the discrete cosine transform is presented. It is based on a modification of the idea of reducing subthreshold coefficients to zero during transform coding. A simple analysis shows that if the subthreshold coefficients are represented by reduced magnitudes other than zero, then the net error that results in a reconstructed pixel is less than if the coefficients have zero value. Based on this reasoning, the subthreshold coefficients are grouped according to their magnitudes, and only the average value of the coefficients in each group is selected in place of all the members of that group during coding. During image reconstruction, the average value of each group is used to generate all the members of that group. By selecting only one coefficient to represent many, the compression ratio is greatly improved.< >

关键词： transform coding Image reconstruction Image coding Discrete cosine transforms Degradation Image enhancement

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An adaptive interframe transform coding system for images

An adaptive interframe transform coding system for images

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： M. Gotze G. Ocylok Institut für Elektrische Nachrichtechnik RWTH Aachen Aachen Germany

An adaptive interframe coding system for monochrome pictures is described, which uses the three-dimensional discrete cosine transform. Based on three-dimensional classification the coder is matched according to the amount of detail and the predominant direction of the structure within a transform block. The distinction between temporally changed and unchanged blocks enables coding of still blocks with an alternative algorithm. This algorithm increases the reconstruction quality for still pictures, making possible a transmission of graphs with good resolution. Simulation results are presented for a moving picture at a rate of 0.4 bit per element and still grey and black-and-white pictures with increasing quality.

关键词： transform coding Discrete transforms Discrete cosine transforms Probability density function Adaptive systems Image reconstruction Data compression Delay effects Matrix decomposition Tensile stress

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Comparative study of transform coding for super high definition images

Comparative study of transform coding for super high definit...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： J. Suzuki M. Nomura S. Ono NTT Transmission Systems Laboratories Yokosuka Japan

The characteristics of super-high-definition images with resolutions of up to 4096*2880 pixels are examined by autocorrelation measurement, and these values are compared with an image having spatial resolution comparable to existing TV. In order to obtain the basic characteristics of such images and coding performance, a simulation system including a digital camera with 4096*4096 pixels and a frame memory and monitor system with 2048*2048 pixels is set up. Two different DCT (discrete cosine transform) coding schemes, DCT with adaptive bit allocation and DCT with variable-length coding, are applied to evaluate the performance of transform coding on super-high-definition images.< >

关键词： transform coding Discrete cosine transforms Pixel Image coding Spatial resolution Image resolution Autocorrelation TV Digital cameras Monitoring

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A mixture of local PCA learning algorithm for adaptive transform coding

A mixture of local PCA learning algorithm for adaptive trans...

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International Conference on Neural Information Processing

作者： B.-L. Zhang Q. Huang T.D. Gedeon Department of Information Engineering School of Computer Science and Engineering University of New South Wales Sydney Australia Department of Electrical Engineering South China University of Technology Guangzhou China

Karhunen-Loeve transform (KLT) is the optimal linear transform for coding images under the assumption of stationarity. For images composed of regions with widely varied local statistics, R.D. Dony and S. Haykin (1995) proposed a transform coding method called optimally integrated adaptive learning (OIAL), in which a number of localized KLTs are adapted to regions with roughly the same statistics. The new transform coding method is shown to be superior to the traditional KLT. However, the performance of OIAL depends on an estimate of the global principal components of the data, which is not only computationally expensive bat also impractical in some cases. Another problem of OIAL is that the mean vector in each region is not taken into account, which is required to define a local PCA. The authors propose an improvement over the OIAL which replaces the winner-take-all (WTA) based clustering with an optimal soft-competition learning algorithm called "neural gas". The mean vector in each region is also incorporated. Experiments show a better performance than OIAL.

关键词： Principal component analysis transform coding Karhunen-Loeve transforms Image coding Discrete cosine transforms Signal processing algorithms Power engineering and energy Statistics Covariance matrix Artificial neural networks

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Vector transform and Image coding

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 1991年第4期1卷 297-307页

作者： Li, Weiping Lehigh Univ Dept Comp Sci & Elect Engn Bethlehem PA 18015 USA

A vector transform is introduced. Application of the vector transform to image coding is discussed, and a scheme of implementing the vector transform is presented.

关键词： Image coding Phase change materials transform coding Discrete transforms Pulse modulation Pixel Discrete cosine transforms Decorrelation Digital TV Videoconference

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Sum-difference stereo transform coding

Sum-difference stereo transform coding

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： J.D. Johnston A.J. Ferreira AT and T Bell Laboratories Inc. USA

An audio filterbank coder using both monophonic and stereophonic redundancy and irrelevancy is described. This coder, with a transform filterbank, uses both signal-processing gains and perceptual gains to provide transparent or nearly transparent coding of CD and R-DAT audio signals at 192 kb/s/stereo pair, and high-quality coding at 128 kb/s/stereo pair. Methods of using the interchannel redundancies and psychoacoustic characteristics are described.< >

关键词： transform coding Frequency Filter bank Psychoacoustic models Psychology Bit rate Testing Low-frequency noise Entropy coding Loudspeakers

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An efficient direct 2-D transform coding IP design for MPEG-4 AVC/H.264

An efficient direct 2-D transform coding IP design for MPEG-...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： Kuan-Hung Chen Jiun-In Guo Jinn-Shyan Wang Department of Electrical Engineering National Chung Cheng University Chiayi Taiwan Department of Computer Science and Information Engineering National Chung Cheng University Chiayi Taiwan

ISBN: (纸本)0780388348

This paper proposes an efficient direct 2D transform coding IP design for MPEG-4 AVC/H.264. The proposed direct 2D transform coding design eliminates the data transposition registers to greatly increase the data processing rate and reduce the hardware cost. When comparing the proposed design with the existing designs, the proposed design has over 90% higher hardware efficiency through the measure of DTUA (data throughput per unit area) for computing the multi-transform in MPEG-4 AVC/H.264. By using a 0.18-/spl mu/m CMOS technology, the optimum operating clock frequency of the proposed multi-transform design is 100 MHz, which achieves 800 Mpixels/sec data throughput rate with an area cost of 6482 gates. Moreover, the proposed design balances the I/O data rate and processing rate through an interlaced I/O schedule.

关键词： transform coding MPEG 4 Standard Automatic voltage control Hardware Throughput CMOS technology Registers Data processing Costs Area measurement

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Closed-form quality measures for compressed medical images: statistical preliminaries for transform coding

Closed-form quality measures for compressed medical images: ...

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Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

作者： Dunling Li M. Loew Department of Electrical and Computer Engineering George Washington University Washington D.C. DC USA

As digital imaging technology advances, the amount of image data we generate increases and the need for compressed images becomes apparent. Because lossy compression will yield higher compression ratios than lossless methods, objective assessment metrics of reconstructed image quality are needed. In medical applications, model observers, especially the channelized Hotelling observer, have been successfully used to predict human observer performance and to evaluate image quality for detection tasks on various backgrounds. To use model observers, however, requires knowledge of noise statistics. This paper finds closed-form expressions for the noise induced by transform coding, one of the most commonly used methods for image compression. Knowledge of the noise enables us to study the effect of image compression on the clinical utility of medical images that have been reconstructed after being compressed using transform coding. In this paper, by analyzing image compression procedures, we propose a block-based transform coding representation in 1-D form, identify the quantization noise as the sole distortion source in transform coding, and derive the compression noise statistics. We show that the probability density function (pdf) of the compression noise is defined as a function of the transform matrix and its corresponding quantization matrix in the transform coding algorithm. We prove that the compression noise is a normal distribution when the dimension of the transform (the block size) is typical. We also provide the pdf of JPEG compression noise as a function of the quantization table and the DCT transform bases. This work provides the theoretical foundation for using the model observers in closed mathematical form, and can be applied to other image compression application areas that require the statistics of compression noise as well.

关键词： Image coding Biomedical imaging transform coding Quantization Image reconstruction Image quality Statistics Digital images Image generation Medical services

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INTRA PREDICTIVE transform coding BASED ON PREDICTIVE GRAPH transform

INTRA PREDICTIVE TRANSFORM CODING BASED ON PREDICTIVE GRAPH ...

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IEEE International Conference on Image Processing

作者： Yongzhe Wang Antonio Ortega Gene Cheung Signal and Image Processing Institute University of Southern California Los Angeles California USA National Institute of Informatics (NII) Tokyo Japan

ISBN: (纸本)9781479923427

In this paper, we propose a new intra-frame coding approach using the predictive graph transform (PGT). The predicted block together with the reference pixels are modeled as a normal distributed random vector with respect to a graph whose edges represent the correlations between pixels. This model is more flexible than the Gaussian Markov random field (GMRF) model in the sense that it enables us to adapt the graph both before and after the collection of the statistics. The optimal prediction and the transform of the prediction residual are then derived jointly. Two PGT based intra coding schemes are proposed: one is based on global image statistics and the other is mode-adaptive, i.e., the graph is adaptive to different directional modes defined in H.264/AVC. The simulations show the advantage of our proposed approach over standard intra predictive transform coding in terms of both prediction quality and coding gain assuming the model parameters are known at decoder.

关键词： Intra prediction transform coding graph transform transform coding Intra coding Line graph SLCO2A1 gene coding gain model parameters decoders

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