Image analysis – Image compression or coding – Transform coding
Reexamination Certificate
2005-05-17
2005-05-17
Mehta, Bhavesh M. (Department: 2625)
Image analysis
Image compression or coding
Transform coding
C382S166000, C382S170000, C382S233000, C382S248000, C375S240200
Reexamination Certificate
active
06895122
ABSTRACT:
The horizontal and vertical offset for the M×N DCT block boundaries are determined for a decompressed image originally produced by a DCT-based compression system, regardless of the amount of compression and/or cropping that had been applied to the image. The method includes the steps of: a) computing one or more selected DCT coefficients from nonoverlapping, contiguous M×N blocks of the decompressed image, beginning at a selected offset; b) computing a coefficient histogram from a set of values for each selected DCT coefficient obtained from the blocks of the decompressed image; c) computing a dispersion metric from each coefficient histogram; d) repeating steps (a) through (c) for a plurality of offsets within an M×N block; e) comparing the dispersion metrics corresponding to the plurality of offsets to determine the minimum dispersion coefficient histogram; and f) selecting the offset that corresponds to the minimum dispersion coefficient histogram as the offset for the DCT block boundaries.
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Hoover John E.
Jones Paul W.
Rabbani Majid
Eastman Kodak Company
Hung Yubin
Mehta Bhavesh M.
Woods David M.
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