IMAGE CODING APPARATUS AND METHOD, AND COMPUTER PROGRAM AND COMPUTER-READABLE STORAGE MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide a technology of generating coded data from which a natural image is obtained without a sense of incongruity in character parts and line drawing parts by receiving an image wherein natural images, character images and line drawings are intermingled and adaptively switching between reversible coding and irreversible coding without a particular image gamut discrimination technology.

SOLUTION: An image coding apparatus disclosed herein is configured with: a resolution conversion section 106 for applying resolution conversion to M0×N0 pixel blocks of received image data to produce pixel blocks with a size of M1×N1; a first coding section 102 for generating irreversibly coded data in the unit of the pixel block converted by the resolution conversion section; a difference calculation section 107 for calculating an error between the pixel blocks obtained by the resolution conversion section and the pixel blocks before the resolution conversion; a second coding section 103 for generating reversibly coded data in the unit of the M0×N0 pixel block; a number of color information extract section for extracting information of number of color distribution in the M0×N0 pixel blocks; and an image discrimination section 112 for discriminating whether or not the M0×N0 pixel block has a pre-established characteristic on the basis of the number of color distribution information extracted by the number of color information extract section and the error.

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