Patent ID: 7058230
Filing Date: 2006-06-06
Classification: G06T

Abstract:
1. A method for encoding image data representing a source image, the image data having a multiplicity of blocks each of which includes a number of pixels, said method comprising the steps of: (a) defining a plurality of sub-areas so that each of the plural sub-area has one or more of the multiple blocks; (b) performing an orthogonal transformation on tone values of the pixels in each of the multiple blocks to thereby obtain transform coefficients; (c) quantizing the transform coefficients of each said block to thereby obtain quantization coefficients; (d) counting the number of valid coefficients among the quantization coefficients in each of the plural sub-areas; (e) adjusting the quantization coefficients of the multiple blocks in accordance with a distribution of the numbers of valid coefficients over the plural sub-areas (that is, in accordance with a degree of appearance of the valid coefficients of each said sub-area), the numbers being counted in said step (d) of counting, in such a manner that the quantization coefficients are to be encoded to a desired data volume; and (f) encoding the adjusted quantization coefficients.