Adaptive spatial-temporal postprocessing for low bit-rate coded image sequences
First Claim
1. A filtering system for reducing artifacts in motion video sequences generated by block-based motion-compensated transform coding from a video decoder, comprising:
- a postprocessor connected to said video decoder, said postprocessor including;
an edge orientation detector;
a spatial filter bank, said spatial filter bank being configured to receive information from said edge orientation detector, said filter bank comprising a one-dimensional filter utilizing said information to generate spatially filtered video sequences; and
a motion-compensated temporal filter, said motion-compensated temporal filter receiving spatially filtered video sequences generated by said spatial filter bank, said motion-compensated temporal filter being configured to generate temporally filtered video sequences from said spatially filtered video sequences; and
a frame memory in communication with said spatial filter bank, said frame memory being arranged to receive spatially filtered video sequences from said spatial filter bank.
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Abstract
A 3D nonlinear postprocessing system and method are utilized to reduce coding artifacts produced by block-based motion-compensated transform coding. In the system and method, a separable 3D filtering structure is used: space-variant FIR-Median Hybrid filtering is used in spatial domain, followed by a motion-compensated nonlinear filtering in the temporal domain. By using this structure and method, the coding artifacts in a reconstructed image sequence can be effectively reduced without blurring edges or moving objects in the image sequence. Significant improvement in the picture quality of low bit-rate coded video sequences is thereby achieved.
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Citations
29 Claims
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1. A filtering system for reducing artifacts in motion video sequences generated by block-based motion-compensated transform coding from a video decoder, comprising:
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a postprocessor connected to said video decoder, said postprocessor including;
an edge orientation detector;
a spatial filter bank, said spatial filter bank being configured to receive information from said edge orientation detector, said filter bank comprising a one-dimensional filter utilizing said information to generate spatially filtered video sequences; and
a motion-compensated temporal filter, said motion-compensated temporal filter receiving spatially filtered video sequences generated by said spatial filter bank, said motion-compensated temporal filter being configured to generate temporally filtered video sequences from said spatially filtered video sequences; anda frame memory in communication with said spatial filter bank, said frame memory being arranged to receive spatially filtered video sequences from said spatial filter bank. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A system for filtering decoded noise-contaminated signals for video communication, comprising:
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a computer processor; means for filtering spatial artifacts from decoded noise-contaminated signals, said means for filtering spatial artifacts comprising an edge detector and a one-dimensional filter; means for storing signals from said decoded noise-contaminated signals for at least a current frame, a prior frame and a future frame; means for calculating a best matching frame from said prior frame and a motion-compensated frame; means for calculating an intermediate weighted average frame from said current frame and a best matching frame such that the motion-compensated frame is given less weight as the difference between said intermediate weighted average frame and said motion-compensated frame increases; and means for calculating a filtered frame from a weighted average of the intermediate weighted average current frame and said future frame, such that said future frame is given less weight as the difference between said intermediate weighted average current frame and said future frame increases. - View Dependent Claims (15, 16, 17, 18)
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19. A three dimensional filter system for enhancing decompressed motion video sequences generated by block-based motion-compensated transform coding, comprising:
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a one-dimensional space-variant FIR-median hybrid filter, said one-dimensional space-variant FIR-median hybrid filter being structured to reduce the effect of spatial artifacts generated by block-based motion-compensated transform coding on said motion video sequences; a memory to store least a portion of said motion video sequences, said memory being connected to said one-dimensional space-variant FIR-median hybrid filter; and a motion-compensated nonlinear filter, said motion-compensated nonlinear filter being structured to reduce the effect of temporal artifacts generated by block-based motion-compensated transform coding on said motion video sequences; wherein said one-dimensional space-variant FIR-median hybrid filter, said memory and said motion-compensated nonlinear filter are arranged in series. - View Dependent Claims (20)
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21. A method of processing and displaying decoded video image sequence signals generated by block-based motion-compensated transform coding, comprising the steps of:
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detecting the edge orientation of a pixel of said video image sequences; filtering spatial artifacts from said video image sequences using a one-dimensional filter for pixels determined to have an orientation in an edge region of said video sequence signals; storing at least a current frame, an adjacent prior frame and an adjacent future frame from said video image sequence signals; calculating a temporally filtered frame from a weighted average of said adjacent future frame, said current frame and a motion-compensated adjacent prior frame; and displaying said temporally filtered frame. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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Specification