Improving DCT-Based Coders Through Block Oriented Transforms
This paper describes a pre-processing for DCT-based coders and more generally for block-based image or video coders taking advantage of the orientation of the blocks. Contrary to most solutions proposed so far, it is not the transform that adapts to the signal but the signal that is pre-processed to fit the transform. The blocks are oriented using circular shifts at the pixel level. Before applying these shifts, the orientation of each block is evaluated with the help of a selection based on a rate-distortion criterion. We show that the insertion of this pre-processing stage in an H.264 coder and applied on residual intra frames can improve its rate-distortion performance.
KeywordsPrediction Mode Intra Prediction Circular Shift Intra Prediction Mode Block Orient
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