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US 2003/0142750 A1Published application
Edge detection based on variable-length codes of block coded video
AssigneeEMC Corporation
InventorsSeyfullah H. Oguz, Ugur Sezer
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AssigneeEMC Corporation
InventorsSeyfullah H. Oguz, Ugur Sezer
Estimating the term…
Edges are detected in block coded video by a threshold comparison upon the lengths of variable-length codes used for encoding the differential DC coefficients of the pixel blocks. A thinning filter compares the code lengths of the differential DC coefficients of adjacent blocks in order to retain the edge indications of more significant edges and to exclude the edge indications of less significant edges. The edge indications can be split into substantially independent channels for luminance or chrominance, for edges having positive or negative horizontal gradient components, and for edges having positive or negative vertical gradient components. The edge indications for successive frames in an MPEG sequence are compared to each other in various ways in order to detect scene changes.
A method of detecting edges in a compressed video sequence, the compressed video sequence including at least one frame of block encoded video data, the frame of block encoded video data including variable-length codes for transform coefficients of blocks of pixels in the compressed video sequence, the transform coefficients including a respective DC coefficient for each of the blocks of pixels, each respective DC coefficient for at least some of the blocks of pixels being encoded as a respective variable-length code having a length indicating a certain range of differences in DC coefficient values between adjacent ones of the blocks of pixels, wherein the method comprises:
A method of detecting edges in a compressed video sequence, the compressed video sequence including at least one I-frame of MPEG video data, the I-frame of MPEG video data including variable-length codes for DCT coefficients of 8×8 pixel blocks in the compressed video sequence, the DCT coefficients including a respective DC coefficient for each of the 8×8 pixel blocks, each respective DC coefficient for at least some of the 8×8 pixel blocks being encoded as a respective variable-length code having a length indicating a certain range of differences in DC coefficient values between adjacent ones of the 8×8 pixel blocks, wherein the method comprises:
A method of detecting a scene change between I-frames of MPEG video data, said method comprising:
A method of detecting a scene change between I-frames of MPEG video data, each of the I-frames including a series of 8×8 pixel blocks, said method comprising:
Dependencies are inferred from the claim text.