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Journal ArticleDOI

Overlapped block disparity compensation with adaptive windows for stereo image coding

TL;DR: This work shows that OBM techniques can be successfully applied to stereo image coding, and takes advantage of the smoothness properties typically found in disparity fields to further improve the performance of OBM in this particular application.
Abstract: We propose a modified overlapped block-matching (OBM) scheme for stereo image coding. OBM has been used in video coding but, to the best of our knowledge, it has not been applied to stereo image coding to date. In video coding, OBM has proven useful in reducing blocking artifacts (since multiple vectors can be used for each block), while also maintaining most of the advantages of fixed-size block matching. There are two main novelties in this work. First, we show that OBM techniques can be successfully applied to stereo image coding. Second, we take advantage of the smoothness properties typically found in disparity fields to further improve the performance of OBM in this particular application. Specifically, we note that practical OBM approaches use noniterative estimation techniques, which produce lower quality estimates than iterative methods. By introducing smoothness constraints into the noniterative DV computation, we improve the quality of the estimated disparity as compared to standard noniterative OBM approaches. In addition, we propose a disparity estimation/compensation approach using adaptive windows with variable shapes, which results in a reduction in complexity. We provide experimental results that show that our proposed hybrid OBM scheme achieves a PSNR gain (about 1.5-2 dB) as compared to a simple block-based scheme, with some slight PSNR gains (about 0.2-0.5 dB) in a reduced complexity, as compared to an approach based on standard OBM with half-pixel accuracy.
Citations
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Patent
04 Aug 2009
TL;DR: In this paper, overlapped block disparity estimation and compensation (OBDC) is described and a variety of predictions may be used with causally-applied OBDC, where disparity compensation parameters or modes may be shared among views or layers.
Abstract: Overlapped block disparity estimation and compensation is described. Compensating for images with overlapped block disparity compensation (OBDC) involves determining if OBDC is enabled in a video bit stream, and determining if OBDC is enabled for one or more macroblocks that neighbor a first macroblock within the video bit stream. The neighboring macroblocks may be transform coded. If OBDC is enabled in the video bit stream and for the one or more neighboring macroblocks, predictions may be made for a region of the first macroblock that has an edge adjacent with the neighboring macroblocks. OBDC can be causally applied. Disparity compensation parameters or modes may be shared amongst views or layers. A variety of predictions may be used with causally-applied OBDC.

70 citations

Proceedings ArticleDOI
10 Dec 2002
TL;DR: This paper proposes a new method for the coding of residual images that takes into account the properties of residual image properties, and demonstrates that it is possible to achieve good results with a computationally simple method.
Abstract: The main. focus of research in stereo image coding has been disparity estimation (DE), a technique used to reduce coding rate by taking advantage of the redundancy in a stereo image pair. Significantly less effort has been put into the coding of the residual image. In this paper we propose a new method for the coding of residual images that takes into account the properties of residual images. Particular attention is paid to the effects of occlusion and the correlation properties of residual images that result from block-based disparity estimation. The embedded, progressive nature of our coder allows one to stop decoding at any time. We demonstrate that it is possible to achieve good results with a computationally simple method.

55 citations

Journal ArticleDOI
TL;DR: A new stereo image compression scheme that is based on the wavelet transform of both images and the disparity estimation between the stereo pair subbands and demonstrates very good performance as far as PSNR measures and visual quality are concerned and low complexity.

49 citations


Cites background from "Overlapped block disparity compensa..."

  • ...Keywords: Stereo image compression; Wavelet transform; Morphology; Disparity...

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Journal ArticleDOI
TL;DR: A novel approach, based on vector lifting schemes (VLS), which offers the advantage of generating two compact multiresolution representations of the left and the right views is proposed, which indicates a significant improvement using the proposed structures compared with conventional methods.
Abstract: Many research efforts have been devoted to the improvement of stereo image coding techniques for storage or transmission. In this paper, we are mainly interested in lossy-to-lossless coding schemes for stereo images allowing progressive reconstruction. The most commonly used approaches for stereo compression are based on disparity compensation techniques. The basic principle involved in this technique first consists of estimating the disparity map. Then, one image is considered as a reference and the other is predicted in order to generate a residual image. In this paper, we propose a novel approach, based on vector lifting schemes (VLS), which offers the advantage of generating two compact multiresolution representations of the left and the right views. We present two versions of this new scheme. A theoretical analysis of the performance of the considered VLS is also conducted. Experimental results indicate a significant improvement using the proposed structures compared with conventional methods.

45 citations


Cites background from "Overlapped block disparity compensa..."

  • ...A. Benazza-Benyahia is with the Ecole Supérieure des Communications de Tunis (SUP’COM-Tunis), 2083, Tunisia....

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Journal ArticleDOI
TL;DR: A geometric prediction methodology for accurate disparity vector (DV) prediction, such that it can largely reduce the disparity compensation cost, and a basic framework that can be implemented in most existing multiview image/video coding schemes.
Abstract: Many existing multiview image/video coding techniques remove inter-viewpoint redundancy by applying disparity compensation in a conventional video coding framework, e.g., H.264/MPEG-4 AVC. However, conventional methodology works ineffectively as it ignores the special characteristics of inter-viewpoint disparity. In this paper, we propose a geometric prediction methodology for accurate disparity vector (DV) prediction, such that we can largely reduce the disparity compensation cost. Based on the new DV predictor, we design a basic framework that can be implemented in most existing multiview image/video coding schemes. We also use state-of-the-art H.264/MPEG-4 AVC as an example to illustrate how the proposed framework can be integrated with conventional video coding algorithms. Our experiments show proposed scheme can effectively tracks disparity and greatly improves coding performance. Compared with H.264/MPEG-4 AVC codec, our scheme outperforms maximally 1.5 dB when encoding some typical multiview image sequences. We also carry out an experiment to evaluate the robustness of our algorithm. The results indicate our method is robust and can be used in practical applications.

32 citations


Cites methods from "Overlapped block disparity compensa..."

  • ...[11] propose an improved overlapped-block-matching (OBM) technique and a disparity estimation/compensation approach using adaptive windows with...

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References
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Journal ArticleDOI

6,105 citations


"Overlapped block disparity compensa..." refers background in this paper

  • ...plexity because they require several (stochastic) iterations to estimate an optimal (pixelwise) dense DV field [ 21 ]....

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Journal ArticleDOI
TL;DR: The motion compensation is applied for analysis and design of a hybrid coding scheme and the results show a factor of two gain at low bit rates.
Abstract: A new technique for estimating interframe displacement of small blocks with minimum mean square error is presented. An efficient algorithm for searching the direction of displacement has been described. The results of applying the technique to two sets of images are presented which show 8-10 dB improvement in interframe variance reduction due to motion compensation. The motion compensation is applied for analysis and design of a hybrid coding scheme and the results show a factor of two gain at low bit rates.

1,883 citations


"Overlapped block disparity compensa..." refers methods in this paper

  • ...In addition, as in video, the DV field is normally computed for fixed-size blocks rather than pixels or features because fixed-size block matching (FSBM) achieves reasonable performance while being simple to implement [ 1 ], [2]....

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Journal ArticleDOI
TL;DR: This analysis establishes for the first time how (and why) OBMC can offer substantial reductions in prediction error as well, even with no change in the encoder's search and no extra side information.
Abstract: We present an estimation-theoretic analysis of motion compensation that, when used with fields of block-based motion vectors, leads to the development of overlapped block algorithms with improved compensation accuracy. Overlapped block motion compensation (OBMC) is formulated as a probabilistic linear estimator of pixel intensities given the limited block motion information available to the decoder. Although overlapped techniques have been observed to reduce blocking artifacts in video coding, this analysis establishes for the first time how (and why) OBMC can offer substantial reductions in prediction error as well, even with no change in the encoder's search and no extra side information. Performance can be further enhanced with the use of state variable conditioning in the compensation process. We describe the design of optimized windows for OBMC. We also demonstrate how, with additional encoder complexity, a motion estimation algorithm optimized for OBMC offers further significant gains in compensation accuracy. Overall mean-square prediction improvements in the range of 16 to 40% (0.8 to 2.2 dB) are demonstrated. >

473 citations


"Overlapped block disparity compensa..." refers background in this paper

  • ...An optimal shape for the overlapped window can also be considered, but the resulting improvement is not a significant one, given the proportional increase in the computational complexity [ 14 ]....

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Journal ArticleDOI
TL;DR: A three-state technique for reliable displacement estimation with fractional-pel accuracy is introduced, based on phase correlation, and for motion-compensation with block size of 16 pels*16 pels, 1/4- Pel accuracy appears to be sufficient for broadcast TV signals, whereas for videophone signals,1/2-pel Accuracy is desirable.
Abstract: The effect of fractional-pel accuracy on the efficiency of motion-compensating predictors is studied using various spatial prediction/interpolation filters. In model calculations, the power spectral density of the prediction error is related to the probability density function of the displacement error. Prediction can be improved both by higher accuracy of motion-compensation and by spatial Wiener filtering in the predictor. Beyond a critical accuracy, the possibility of further improving prediction by more accurate motion-compensation is small. Experiments with videophone signals and with broadcast TV signals confirm these model calculations. Sinc-interpolation, bilinear interpolation, and Wiener filtering are compared at integer-pel, 1/2-pel, 1/4-pel, and 1/8-pel accuracies. A three-state technique for reliable displacement estimation with fractional-pel accuracy is introduced. It is based on phase correlation. For motion-compensation with block size of 16 pels*16 pels, 1/4-pel accuracy appears to be sufficient for broadcast TV signals, whereas for videophone signals, 1/2-pel accuracy is desirable. >

346 citations


"Overlapped block disparity compensa..." refers methods in this paper

  • ...The performance can be increased further by adopting more elegant interpolation methods, such as an approximated ideal filter or Wiener filter [ 23 ], [24]....

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Journal ArticleDOI
TL;DR: It is proved that the rate distortion limit for coding stereopairs cannot in general be achieved by a coder that first codes and decodes the right picture sequence independently of the left picture sequence, and then codes anddecodes theleft picture sequence given the decoded right picture sequences.
Abstract: Two fundamentally different techniques for compressing stereopairs are discussed. The first technique, called disparity-compensated transform-domain predictive coding, attempts to minimize the mean-square error between the original stereopair and the compressed stereopair. The second technique, called mixed-resolution coding, is a psychophysically justified technique that exploits known facts about human stereovision to code stereopairs in a subjectively acceptable manner. A method for assessing the quality of compressed stereopairs is also presented. It involves measuring the ability of an observer to perceive depth in coded stereopairs. It was found that observers generally perceived objects to be further away in compressed stereopairs than they did in originals. It is proved that the rate distortion limit for coding stereopairs cannot in general be achieved by a coder that first codes and decodes the right picture sequence independently of the left picture sequence, and then codes and decodes the left picture sequence given the decoded right picture sequence. >

243 citations


"Overlapped block disparity compensa..." refers methods in this paper

  • ...Therefore, efficient alternatives to FSBM for DE/DC have been a main focus of the research on stereo image/video coding since the pioneering work by Lukacs [2], [ 4 ]‐[8]....

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