Image processing system for adaptive coding of color document images

摘要

An image processing system includes an input part for reading an image from a color document containing a multilevel gradation graphic image and a text image, a region separator part for separating the image into a plurality of elemental blocks having MxN picture elements according to a type of image data that is contained in each elemental block, whether the elemental block contains a black-and-white line portion of the image or a halftone portion of the image, and an encoding part for encoding image data in the black-and-white line portion through an encoding process appropriate for bi-level image data and for encoding image data in the halftone portion through an encoding process appropriate for multilevel gradation image data so as to produce a compressed image.