transform predictive coding of pictorial data using the naturalness-preserving transform (NPT) is investigated. The hybrid coding system uses one-dimensional NPTs and parallel differential pulse-code modulation (DPCM)...
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transform predictive coding of pictorial data using the naturalness-preserving transform (NPT) is investigated. The hybrid coding system uses one-dimensional NPTs and parallel differential pulse-code modulation (DPCM) systems. The problem of determining the basis giving the minimum mean square error (MSE) for coding images is addressed. Results of coding schemes using the Hadamard NPT and the sine NPT are presented. Superior performance was achieved by adapting the NPT bases to image subarray statistics. The MSE improvement is higher at low bit rates.< >
A distortion-computation function D(C) is defined as the minimum expected distortion in computing some quantity while using no more than C computational units. In a communication framework, where the computational pro...
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A distortion-computation function D(C) is defined as the minimum expected distortion in computing some quantity while using no more than C computational units. In a communication framework, where the computational problem is to determine a representation that can be transmitted with expected rate not exceeding R, this gives slices of a rate-distortion-computation surface. The convexity of distortion-computation functions and rate-distortion-computation surfaces is asserted. transform coding is studied as a particular instance of this theory. Explicit comparisons between the efficacies of the Karhunen-Loeve transform and the discrete cosine transform for coding of a Gauss-Markov source are given. Results are also given on joint optimization of the block length and the computational precision.
In this paper presents a video-coding system that does not perform explicit ME/MC but instead relies on the DDWT to isolate moving signal features. To counteract the redundancy of the DDWT, a noise-shaping process inc...
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In this paper presents a video-coding system that does not perform explicit ME/MC but instead relies on the DDWT to isolate moving signal features. To counteract the redundancy of the DDWT, a noise-shaping process increases the sparsity of the transform coefficients, resulting in a high degree of spatiotemporally coherent regions of insignificant coefficients. The transform coefficients are coded with binary set-partitioning using k-d trees (BISK) in an algorithm (DDWT-BISK) that exploits both the within-subband spatiotemporal coherency as well as cross-subband correlation to achieve efficient coding. Whereas a prior DDWT-based coder (DDWTVC2) exploits correlation as it exists across subbands in the DDWT, our DDWT-BISK coder additionally exploits coherent regions of insignificant coefficients that occur within subbands, a coherence that must necessarily be substantial due to the sparsity imposed by the noise-shaping process.
In this paper, a high efficient arbitrary transform blocks hardware allocation framework is proposed, which can adapt the prediction tree structure and then improve the utilization ratio as well as a parallel hardware...
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In this paper, a high efficient arbitrary transform blocks hardware allocation framework is proposed, which can adapt the prediction tree structure and then improve the utilization ratio as well as a parallel hardware design to improve the data throughput. This method will configure an appropriate combination of five different size inverse transform units: Fast IDST, 4×4 IDCT, 8×8 IDCT, 16×16 IDCT and 32×32 IDCT. If the input video stream changed, it will reconfigure the combination and allocated the hardware resources to retain a high utilization ratio in hardware framework. Experiments show that the performance of the proposed method is improved from 48.8% to 96.2% under various conditions. The proposed method can enhance the efficiency of H.265 decoder.
In most low-power VLSI designs, the supply voltage is usually reduced to lower the total power consumption. However, the device speed will be degraded as the supply voltage goes down. In this paper, we propose new alg...
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In most low-power VLSI designs, the supply voltage is usually reduced to lower the total power consumption. However, the device speed will be degraded as the supply voltage goes down. In this paper, we propose new algorithmic-level techniques for compensating the increased delays based on the multirate approach. We will show how to compute most of the discrete sinusoidal transforms through the decimated low-speed sequences with reasonable linear hardware overhead. For the case where the decimation factor is equal to two, the overall power consumption can be reduced to about one-third of the original design. The resulting multirate low-power architectures are regular, modular, and free of global communications. Such properties are very suitable for VLSI implementations. The proposed architectures can also be applied to very high-speed block transforms where only low-speed operators are required.
In this paper, we present a simple but effective method to enhance the coding performance of shape-adaptive DCT (SA-DCT). By choosing the first processing direction (between horizontal and vertical) within each bounda...
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In this paper, we present a simple but effective method to enhance the coding performance of shape-adaptive DCT (SA-DCT). By choosing the first processing direction (between horizontal and vertical) within each boundary block for doing the 1D transform, the proposed method guarantees to achieve optimal rate-distortion results and actually outperforms the existing SA-DCT algorithms significantly. The proposed method is also applicable to arbitrarily-shaped coding based on some padding techniques.
The hybrid transform coding scheme that alternates amongst the asymmetric discrete sine transform (ADST) and the discrete cosine transform (DCT) depending on the boundary prediction conditions, is an efficient tool fo...
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The hybrid transform coding scheme that alternates amongst the asymmetric discrete sine transform (ADST) and the discrete cosine transform (DCT) depending on the boundary prediction conditions, is an efficient tool for video and image compression. It optimally exploits the statistical characteristics of prediction residual, thereby achieving significant coding performance gains over the conventional DCT-based approach. A practical concern lies in the intrinsic conflict between transform kernels of ADST and DCT, which prevents a butterfly structured implementation for parallel computing. Hence the hybrid transform coding scheme has to rely on matrix multiplication, which presents a speed-up barrier due to under-utilization of the hardware, especially for larger block sizes. In this work, we devise a novel ADST-like transform whose kernel is consistent with that of DCT, thereby enabling butterfly structured computation flow, while largely retaining the performance advantages of hybrid transform coding scheme in terms of compression efficiency. A prototype implementation of the proposed butterfly structured hybrid transform coding scheme is available in the VP9 codec repository.
In this work, a mechanism contributing to the blocking artifacts of standard block based transform coding schemes is stated and a simple solution is proposed for reducing its effect. The proposed solution can be easil...
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In this work, a mechanism contributing to the blocking artifacts of standard block based transform coding schemes is stated and a simple solution is proposed for reducing its effect. The proposed solution can be easily incorporated into the encoding algorithms of existing two dimensional (2-D) discrete cosine transform (DCT) based image and video coding standards (JPEG, MPEG-1 and 2, H-261, H-263) without the need for a modification in their bitstream syntax.
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