Binary image forming device

摘要

It is possible to clearly extract objects such as characters and line figures by eliminating the effect of shading from an input image containing self-shaded objects and/or vaguely contoured objects together with distinctly contoured object and thereby to exact all objects clearly and completely. A sample point setting portion (102) sets sample points (30), a sample point shade calculating portion (103) determines an optical density of shading at each sample point (30) according to an optical density distribution of pixels in a reference block (40) including the sample point at the center thereof. A shade calculating portion (104) determines shade densities at the other points than the sample points and generates an shade image, shade removing portion (105) generates a shade-removed image by removing the shading effect from the input image by using the shade image. A quantizing portion (106) binarizes the shade-removed image and an image output portion (107) outputs the obtained binary image.