As a requirement of many modern image compression standards faced today, a computational complexity is observed due to the best mode selection in the intra-prediction stage. This computational complexity is tried to b...
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As a requirement of many modern image compression standards faced today, a computational complexity is observed due to the best mode selection in the intra-prediction stage. This computational complexity is tried to be reduced by various techniques without affecting the performance criteria of the image. In this study, a fast search algorithm, which simplifies the mode selection process of the intra-prediction algorithm and provides calculation with less number of modes is proposed. The hardware architecture of this proposed algorithm is implemented for realization. There are two main sections of the intra-prediction algorithm in image compression, namely the image prediction process and the mode selection process. In this study, main objective is to reduce the process time of the mode selection and the simplification of the hardware design. Sum of absolute difference (SAD) is a frequently used criterion to simplify hardware design. The algorithm searches for the most suitable mode in a single step, where the decision is based on the SAD criterion preferred for the simplicity. The proposed algorithm and related hardware architecture is tested by using various experiments. The number of the modes calculated is reduced effectively, while the process is kept within the acceptable limits in terms of peak signal to noise ratio (PSNR) and compression rate (CR) performance criteria. Therefore, the number of clock cycles observed is considerably reduced. The designed architecture is synthesized for the field programmable gate arrays (FPGA) board and the obtained results are given. In addition, these results are compared with the HM reference software where the corresponding results are in accordance with the reference software.
Modern perceptual image coders reach impressively high subjective quality even at low bit-rates but tend to denoise or "detexturize" the coded pictures. Traditionally, two independent parametric approaches, ...
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ISBN:
(纸本)9781538660959
Modern perceptual image coders reach impressively high subjective quality even at low bit-rates but tend to denoise or "detexturize" the coded pictures. Traditionally, two independent parametric approaches, known as texture and film grain synthesis, have been applied in the spatial domain as pre and post-processors around the codec to counteract such effects. In this work, a unified alternative, operating directly within the spectral domain of conventional transform codecs with tight coupling to the transform coefficient quantizer, is proposed. Due to its design, this spectrally adaptive noise filling tool (SANFT) enables highly input adaptive realizations by reusing the coder's existing optimized spatial and spectral partitioning algorithms. Formal subjective evaluation in the context of a "main still picture" High Efficiency Video coding (HEVC) implementation confirms the benefit of the proposal.
The first version of the High Efficiency Video coding (HEVC) standard was approved by both ITU-T and ISO/IEC in 2013 and includes three profiles: Main and Main 10 for typical video data with 8 and 10 bits, respectivel...
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The first version of the High Efficiency Video coding (HEVC) standard was approved by both ITU-T and ISO/IEC in 2013 and includes three profiles: Main and Main 10 for typical video data with 8 and 10 bits, respectively, as well as a profile referred to as Main still Picture (MSP) profile. Apparently, the MSP profile extends the HEVC application space toward stillimages which, in turn, brings up the question of how this HEVC profile performs relative to existing still image coding technologies. This paper aims at addressing this question from a coding-efficiency point-of-view by presenting a rate-distortion performance analysis of the HEVC MSP profile in comparison to other popular stillimage and video compression schemes, including JPEG, JPEG 2000, JPEG XR, H.264/MPEG-4 AVC, VP8, VP9, and WebP. In summary, it can be stated that the HEVC MSP profile provides average bit-rate savings in the range from 10% to 44% relative to the whole set of competing video and stillimage compression schemes when averaged over a representative test set of photographic stillimages. Compared with Baseline JPEG alone, the average bit-rate saving for the HEVC MSP profile is 44%.
This paper proposes a novel compression scheme with a tunable complexity-rate-distortion trade-off. As images increase in size and resolution. more efficient compression schemes with low complexity are required on-boa...
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This paper proposes a novel compression scheme with a tunable complexity-rate-distortion trade-off. As images increase in size and resolution. more efficient compression schemes with low complexity are required on-board Earth observation satellites. The standard of the Consultative Committee for Space Data Systems (CCSDS) defines a strip-based compression scheme with the advantages of a low complexity and an easy rate control [CCSDS, image Data Compression Recommended Standard CCSDS 122.0-B-1 Blue Book, November 2005]. However, future mission specifications expect higher performance in terms of rate-distortion. The scheme proposed in this paper intends to perform better than the CCSDS standard while preserving low complexity and easy rate control. Moreover, to comply with existing on-board devices, the proposed core compression engine still uses the wavelet transform but in association with a linear post-processing inspired from the bandelet transform. The post-transform decomposes a small block of wavelet coefficients on a particular basis. This basis is adaptively selected within a predefined dictionary by rate-distortion optimization. The computational complexity depends upon the dictionary size and of the basis structure. An extremely simple dictionary, reduced to the Hadamard basis, is proposed. The post-transform efficiency is illustrated by experiments on various Earth observation images provided by the French Space Agency (CNES). (C) 2009 Elsevier B.V. All rights reserved.
Efficient image sequence coding exploits both spatial correlation and temporal correlation. SPIHT is a powerful algorithm in exploiting spatial correlations for still image coding. Based on SPIHT, we present a novel a...
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ISBN:
(纸本)9781424442959
Efficient image sequence coding exploits both spatial correlation and temporal correlation. SPIHT is a powerful algorithm in exploiting spatial correlations for still image coding. Based on SPIHT, we present a novel approach to exploit temporal correlations for image sequence coding, while maintaining single frame, random access decoding. The socalled Differential-SPIHT takes advantage of inter-frame correlations by reusing the significance testing data of a SPIHT coded frame. From simulation results of videos and volumetric medical images, Differential-SPIHT offers significant reductions in bitrate from conventional two-dimensional (2D) SPIHT for the same reconstruction PSNR, while retaining the desirables features of rate scalability and computational simplicity.
Several well-known methods for lossy compression of stillimages are here analyzed to evaluate their performance for hyperspectral images. The lossy compression methods discussed are the JPEG standard, and four approa...
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ISBN:
(纸本)081944667X
Several well-known methods for lossy compression of stillimages are here analyzed to evaluate their performance for hyperspectral images. The lossy compression methods discussed are the JPEG standard, and four approaches based on the Wavelet Transform: the Embedded coding of ZeroTree wavelet coefficients, the Set Partitioning in Hierarchical Trees, a Lattice Vector Quantizer, and the new JPEG2K. Experiments are first performed on corpuses of natural grayscale stillimages to provide a general framework of the performance of each method. Then experiments are performed on several hyperspectral images taken with CASI and AVMS sensors. Experiments show that it is possible to employ the basic lossy compression methods for hyperspectral imagecoding. The wavelet-based approaches produce results consistently better than the JPEG: JPEG can not achieve compression ratios above 75: 1;on the other side, with EZT, SPIHT and LVQ compression ratios of 250:1 or higher may be reached. For JPEG2K, higher compression ratios than JPEG may also be reached, but with a PSNR quality lower than the three other techniques. At compression ratios about 8: 1, the wavelet methods yield results 1.5 dB better than those of JPEG. These results help to explain why JPEG2K standard uses the WT instead of the DCT.
The side-match finite-state vector quantization (SMVQ) schemes improve performance over the vector quantization by exploiting the neighboring vector correlations within the image. In this paper, we propose a neural ne...
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The side-match finite-state vector quantization (SMVQ) schemes improve performance over the vector quantization by exploiting the neighboring vector correlations within the image. In this paper, we propose a neural network side-match finite-state vector quantization (NN-SMVQ) scheme that combines the techniques of neural network prediction and the SMVQ coding method. In our coding scheme, the multilayer perceptron network is used to improve the accuracy of side-match prediction by utilizing the property of the neural network nonlinear prediction. The NN-SMVQ scheme not only has the advantages of the SMVQ scheme but also improves the coded image quality. Experimental results are given and comparisons are made using our NN-SMVQ coding scheme and some other coding techniques. In the experiments, our NN-SMVQ coding scheme achieves the better visual quality about edge region and the best PSNR performance at nearly the same bit rate. This new NN-SMVQ scheme is also simple and efficient for the hardware design. Moreover, the new scheme does not adversely affect other useful functions provided by the conventional SMVQ scheme. (C) 2002 Elsevier Science (USA).
Region-based functionality offered by the MPEG-4 video compression standard is also appealing for stillimages, for example to permit object-based queries of a still-image database. A popular method for still-image co...
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Region-based functionality offered by the MPEG-4 video compression standard is also appealing for stillimages, for example to permit object-based queries of a still-image database. A popular method for still-image compression is fractal coding. However, traditional fractal imagecoding uses rectangular range and domain blocks. Although new schemes have been proposed that merge small blocks into irregular shapes, the merging process does not, in general, produce semantically-meaningful regions. We propose a new approach to fractal imagecoding that permits region-based functionalities;images are coded region by region according to a previously-computed segmentation map. We use rectangular range and domain blocks, but divide boundary blocks into segments belonging to different regions. Since this prevents the use of standard dissimilarity measure, we propose a new measure adapted to segment shape. We propose two approaches: one in the spatial and one in the transform domain. While providing additional functionality, the proposed methods perform similarly to other tested methods in terms of PSNR but often result in images that are subjectively better. Due to the limited domain-block code-book size, the new methods are faster than other fractal coding methods tested. The results are very encouraging and show the potential of this approach for various internet and still-image database applications.
In this paper, we propose a coding algorithm for stillimages using vector quantization (VQ) and fractal approximation, in which low-frequency components of an input image are approximated by VQ, and its residual is c...
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In this paper, we propose a coding algorithm for stillimages using vector quantization (VQ) and fractal approximation, in which low-frequency components of an input image are approximated by VQ, and its residual is coded by fractal mapping, The conventional fractal coding algorithms indirectly used the gray patterns of an original image with contraction mapping, whereas the proposed fractal coding method employs an approximated and then decimated image as a domain pool and uses its gray patterns, Thus, the proposed algorithm utilizes fractal approximation without the constraint of contraction mapping, For approximation of an original image, we employ the discrete cosine transform (DCT) rather than conventional polynomial-based transforms. In addition, for variable block-size segmentation, we use the fractal dimension of a block that represents the roughness of the gray surface of a region, Computer simulations with several test images show that the proposed method shows better performance than the conventional fractal coding methods for encodingstill pictures.
Subband coding is important (1) to decompose an input signal into an adequate set of subbands considering the property of an input signal and (2) to assign an adequate bits in proportion with the power of each subband...
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ISBN:
(纸本)0819431249
Subband coding is important (1) to decompose an input signal into an adequate set of subbands considering the property of an input signal and (2) to assign an adequate bits in proportion with the power of each subband signal. Investigation of autocorrelation characteristics of several kinds of images reveals us an isotropic correlation model. Based on this theoretical image model, we have derived the optimum band partition that minimizes the quantization noise power of the reconstructed signal at the receiving end. In order to apply the above theoretical optimum band partition to the imagecoding, we propose the optimum band partition scheme based on an idea of a set of band blocks, and we present the calculation algorithm with the low computational complexity to determine the optimum band partition. Also, we propose two methods to exploit the non-stationary nature of images, and the filter bank configuration to realize the optimum band partition including these methods. The proposed optimum band partition shows better result than that of the blocking DCT in obtaining the higher compression rate and the higher image quality.
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