In this paper, vee study high-fidelity image compression with a given tight L-infinity bound. We propose some practical adaptive context modeling techniques to correct prediction biases caused by quantizing prediction...
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In this paper, vee study high-fidelity image compression with a given tight L-infinity bound. We propose some practical adaptive context modeling techniques to correct prediction biases caused by quantizing prediction residues, a problem common to the existing DPCM-type predictive near-lossless image coders. By incorporating the proposed techniques into the near-lossless version of CALIC that is considered by many as state-of-the-art algorithm, me mere able to increase its PSNR by 1 dB or more and/or reduce its bit rate by 10% or more. More encouragingly, at bit rates around 1.25 bpp or higher, our method obtained competitive PSNR results against the best L-2-based wavelet coders, while obtaining much smaller L-infinity bound.
This article examines the problem of 3D scalable mesh and texture coding. The triangular mesh topology is encoded by an edge-based conquest strategy, while positions are encoded using a multiple prediction method asso...
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This article examines the problem of 3D scalable mesh and texture coding. The triangular mesh topology is encoded by an edge-based conquest strategy, while positions are encoded using a multiple prediction method associated with an adaptive arithmetic coder. Moreover scalability is obtained on the positions via a bitplane coding technique, adapted to float numbers. Then, texture is approximated by a hybrid technique mixing affine interpolation and discrete cosinus transform applied to the triangles of a a hierarchical nested mesh.
This paper reviews the main algorithms Sor speech coning at low, and very low, bit rates, from 50 bps to 4000 bps. Then the HSX technique for coding at 1200 bps and a new segmental method with automatically derived un...
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This paper reviews the main algorithms Sor speech coning at low, and very low, bit rates, from 50 bps to 4000 bps. Then the HSX technique for coding at 1200 bps and a new segmental method with automatically derived units for very low bit rate coding are presented in details.
Image coding is discussed in two phases;one is transformation of image signals using a coding model, and the other is entropy coding which assigns a code to a transformed sequence. A well-known example of the latter i...
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Image coding is discussed in two phases;one is transformation of image signals using a coding model, and the other is entropy coding which assigns a code to a transformed sequence. A well-known example of the latter is arithmetic coding. Because arithmetic coding makes dynamic adaptation rather easy, it is used in efficient entropy coding of signals, such as image signals, whose statistical characteristics vary locally. Though adaptation is an effective measure to achieve efficient coding, it requires longer processing time and larger hardware size. The authors have proposed multialphabet arithmetic coding with a 1/2(n) rate approximation, whose algorithm is simple. This arithmetic coding can be performed with an extremely small amount of multiplication, and it can be extended to adaptation simply by recalculation of cumulative approximate probability. In this article, we will propose a method that optimizes update timing in adaptation, and show that we obtained satisfactory results in efficiency and coding speed. (C) 2000 Scripta Technica.
In this paper, we evaluate the performance of Discrete Fourier Transform with small overlap in Transform-predictive-coding-based coders - e.g. Transform Coder eXcitation (TCX) and Transform predictive coding (TPC). Th...
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In this paper, we evaluate the performance of Discrete Fourier Transform with small overlap in Transform-predictive-coding-based coders - e.g. Transform Coder eXcitation (TCX) and Transform predictive coding (TPC). Three different time-frequency analysis techniques are compared : the Discrete Fourier Transform, the Modified Discrete Cosine Transform (MDCT) with 50% overlap and the Discrete Fourier Transform with 3% overlap. We show how a DFT with small overlap is more attractive, in a transform-predictive-coding based coder, than a simple DFT or a high frequency resolution MDCT.
We study high-fidelity image compression with a given tight L/sub /spl infin// bound. We propose some practical adaptive context modeling techniques to correct prediction biases caused by quantizing prediction residue...
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We study high-fidelity image compression with a given tight L/sub /spl infin// bound. We propose some practical adaptive context modeling techniques to correct prediction biases caused by quantizing prediction residues, a problem common to the existing DPCM-type predictive near-lossless image coders. By incorporating the proposed techniques into the near-lossless version of CALIC that is considered by many as the state-of-the-art algorithm, we were able to increase its PSNR by 1 dB or more and/or reduce its bit rate by 10% or more, more encouragingly, at bit rates around 1.25 bpp or higher, our method obtained competitive PSNR results against the best L/sub 2/-based wavelet coders, while obtaining much smaller L/sub /spl infin// bound.
Error resilience techniques have already become an important part of video coding over error-prone channels. In this paper, we present an error resilient codec which is based on H.263 data partitioned slice mode. It e...
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Error resilience techniques have already become an important part of video coding over error-prone channels. In this paper, we present an error resilient codec which is based on H.263 data partitioned slice mode. It employs several error resilient techniques including data partitioning, reversible variable length coding, error detection and localization, error concealment etc. In order to check out the error resilience performance of the codec, we use error patterns to simulate W-CDMA channels. The simulations are conducted on H.263 sequences at 64, 128 and 384 kbps. Simulation results show that the error resilience algorithms applied by the codec are effective. Both the subjective and the objective quality of the reconstructed image show a remarkable improvement.
Though most lossless image coding techniques use a raster scan to order the pixels for context-based predictive coding, other scans, such as the Hilbert or Peano scan, have been proposed as alternatives with potential...
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ISBN:
(纸本)0780362977
Though most lossless image coding techniques use a raster scan to order the pixels for context-based predictive coding, other scans, such as the Hilbert or Peano scan, have been proposed as alternatives with potentially better performance. However, a general understanding of the merits of different scans has been lacking. In previous work, the authors had presented a framework in which the effect of pixel scan order on lossless compression can be quantitatively analyzed, so that comparisons of different scans can be made. Assuming a quantized-Gaussian and isotropic image model with contexts consisting of previously scanned adjacent pixels in a distance constrained neighborhood, it was found that the raster scan is better than the Hilbert scan. In this paper we further develop our arguments and show that for a large class of scans, which we call axial symmetric scans, the raster scan is indeed optimal. We would like to note that many common scans including the Hilbert scan fall under the class of axial symmetric scans.
The quad-tree structured motion-compensation technique effectively utilizes the motion content of a frame as opposed to the fixed size block motion compensation technique. The authors propose a novel quad-tree structu...
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The quad-tree structured motion-compensation technique effectively utilizes the motion content of a frame as opposed to the fixed size block motion compensation technique. The authors propose a novel quad-tree structured region-wise motion compensation technique that divides a frame into equilateral triangle blocks using the quad-tree structure. Arbitrary partition shapes are achieved by allowing 4-to-1, 3-to-1 and 2-1 merge/combine of sibling blocks having the same motion vector. We propose an optimal code scheme and a temporal predictive coding for the quad-tree. Simulation results show that our techniques reduce the bit rate by 40% as compared to other methods.
Presented is an embedded coding strategy for wideband signals using the multimode transform predictive coding (MTPC) framework. The design uses many of the inherently layered features of the original non-embedded MTPC...
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Presented is an embedded coding strategy for wideband signals using the multimode transform predictive coding (MTPC) framework. The design uses many of the inherently layered features of the original non-embedded MTPC including iterative bit assignments and frequency domain coding. The design also uses the mode decision of the MTPC to adapt the layering strategy to the type input signal. The result is a high quality embedded wideband coder with multiple enhancement layers and little compromise in performance when compared to non-embedded MTPC designs.
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