Optimal disparity estimation for stereoscopic video coding
First Claim
1. A method for reducing cross-channel luminance imbalance in an enhancement layer picture of a stereoscopic video signal, comprising the steps of:
- providing a search window which comprises at least a portion of the pixels in said enhancement layer picture;
providing a reference window which comprises at least a portion of the pixels in a reference picture of a base layer of said stereoscopic video signal; and
determining affine transform coefficients a, b of said reference window which minimize the least-square-error between luminance values of pixels of said search window and said reference window.
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Abstract
Disparity estimation between the right and left view pixel luminance values in a stereoscopic video signal is optimized by determining the minimum least-square-error between macroblocks of the right and left view pictures. Affine transform coefficients and disparity vectors which correspond to the minimum error are also determined and transmitted in the data stream for use by a decoder in reconstructing the right view picture. The scheme can be implemented either locally, at the macroblock level, or globally, at the picture level. At the macroblock level, least-square-error optimization may occur for each individual macroblock in the right view picture. In this case, affine transform coefficients are provided for each macroblock. At the picture level, the sum of the least-square-errors is minimized after the blocks of the right view picture are matched to the left view picture. In this case, only one set of affine transform coefficients are required for the entire right view picture. Or, block matching between an affinely transformed left view picture and the right view picture may be performed after minimizing the sum of the least-square-errors. The scheme is particularly useful in minimizing the effects of cross-channel luminance imbalances due to camera variations and scenes with significant changes in brightness or contrast, and is compatible with stereoscopic video systems such as the MPEG Multi-view Profile (MVP) system.
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Citations
18 Claims
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1. A method for reducing cross-channel luminance imbalance in an enhancement layer picture of a stereoscopic video signal, comprising the steps of:
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providing a search window which comprises at least a portion of the pixels in said enhancement layer picture; providing a reference window which comprises at least a portion of the pixels in a reference picture of a base layer of said stereoscopic video signal; and determining affine transform coefficients a, b of said reference window which minimize the least-square-error between luminance values of pixels of said search window and said reference window. - View Dependent Claims (2, 3, 4, 5)
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6. A method for reducing cross-channel luminance imbalance in an enhancement layer picture of a stereoscopic video signal, comprising the steps of:
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providing a plurality of windows which comprise respective portions of the pixels in said enhancement layer picture; providing a corresponding plurality of reference windows which comprise respective portions of the pixels in a reference picture of a base layer of said stereoscopic video signal; and determining affine transform coefficients a, b which minimize the sum of the least-square-errors between luminance values of pixels of said enhancement layer picture windows and said corresponding reference windows. - View Dependent Claims (7, 8, 9)
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10. A method for decoding a stereoscopic video signal with a reduced cross-channel luminance imbalance in an enhancement layer picture thereof, comprising the steps of:
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retrieving affine transform coefficients a, b from said stereoscopic video signal; said affine transform coefficients being determined by minimizing the least-square-error between luminance values of pixels of a search window and a reference window, wherein said search window comprises at least a portion of the pixels in said enhancement layer picture, and said reference window comprises at least a portion of the pixels in a reference picture of a base layer of said stereoscopic video signal; and using said affine transform coefficients to recover said search window pixel data. - View Dependent Claims (11)
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12. An encoder for reducing cross-channel luminance imbalance in an enhancement layer picture of a stereoscopic video signal, comprising:
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means for providing a search window which comprises at least a portion of the pixels in said enhancement layer picture; means for providing a reference window which comprises at least a portion of the pixels in a reference picture of a base layer of said stereoscopic video signal; and a disparity estimator for determining affine transform coefficients a, b of said reference window which minimize the least-square-error between luminance values of pixels of said search window and said reference window. - View Dependent Claims (13, 14)
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15. An encoder for reducing cross-channel luminance imbalance in an enhancement layer picture of a stereoscopic video signal, comprising:
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means for providing a plurality of windows which comprise respective portions of the pixels in said enhancement layer picture; means for providing a corresponding plurality of reference windows which comprise respective portions of the pixels in a reference picture of a base layer of said stereoscopic video signal; and a disparity estimator for determining affine transform coefficients a, b which minimize the sum of the least-square-errors between luminance values of pixels of said enhancement layer picture windows and said corresponding reference windows.
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16. A decoder apparatus for decoding a stereoscopic video signal with a reduced cross-channel luminance imbalance in an enhancement layer picture thereof, comprising:
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means for retrieving affine transform coefficients a, b from said stereoscopic video signal; said affine transform coefficients being determined by minimizing the least-square-error between luminance values of pixels of a search window and a reference window, wherein said search window comprises at least a portion of the pixels in said enhancement layer picture, and said reference window comprises at least a portion of the pixels in a reference picture of a base layer of said stereoscopic video signal; and processing means for using said affine transform coefficients to recover said search window pixel data. - View Dependent Claims (17, 18)
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Specification