IMAGE COMPRESSION APPARATUS, IMAGE READER WITH THE SAME, IMAGE PROCESSOR WITH IMAGE COMPRESSION APPARATUS, IMAGE FORMING APPARATUS WITH THE SAME, METHOD OF IMAGE COMPRESSION PROCESSING, COMPUTER PROGRAM HEREOF, AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide an image compression apparatus which performs both of keeping a satisfactory picture quality and improvement of compressibility by performing proper JPEG compression processing according to the kind of the original of image data.

SOLUTION: Original image data input from an image input apparatus 1 is converted to a digital signal by an A/D conversion part 21 of the picture compression apparatus 2. After processing by a shading correction part 22 and an input processing part 23 (γcorrection) are performed to the digital signal, it is delivered to an JPEG compression part 26 and an original discrimination part 24. The original discrimination part 24 discriminates the kind of the original from the ratios of regions of dots/characters/photographs/base of the original image by the unit of the page. A parameter setting part 25 calculates an optimal compression parameter (a quantization table and a sampling ratio) by each page according to an original discrimination signal from the original discrimination part 24. The JPEG compression part 26 performs JPEG compression processing using the parameter, and outputs it as a JPEG code with encoding data.

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