Image analysis – Image compression or coding – Adaptive coding
Reexamination Certificate
2005-03-28
2008-09-30
LaRose, Colin (Department: 2624)
Image analysis
Image compression or coding
Adaptive coding
C382S250000, C382S251000
Reexamination Certificate
active
07430330
ABSTRACT:
A method of JPEG compression of an image frame divided up into a plurality of non-overlapping, tiled 8×8 pixel blocks Xi. A global quantization matrix Q is determined by either selecting a standard JPEG quantization table or selecting a quantization table such that the magnitude of each quantization matrix coefficient, Q[m,n] is inversely proportional to the aggregate visual importance in the image of the corresponding DCT basis vector. Next a linear scaling factor Siis selected for each block, bounded by user selected values Sminand Smax. Transform coefficients, Yi, obtained from a digital cosine transform of Xi, are quantized with global table SminQ while emulated the effects of quantization with local table SiQ and the quantized coefficients Ti[m,n] and global quantization table SminQ are entropy encoded , where Sminis a user selected minimum scaling factor, to create a JPEG Part 1 image file. The algorithm is unique in that it allows for the effect of variable-quantization to be achieved while still producing a fully compliant JPEG Part 1 file.
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LaRose Colin
Pequignot & Myers LLC
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