| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain high-quality binary images for all the regions of bright, dark and intermediate portions even in a document image where character line image and a halftone image are mixed. Ž<P>SOLUTION: An edge amount detecting section 35 detects an edge amount indicated by a pixel of interest of a binarization target. A gain adjustor 30 multiplies a value obtained by a green noise matrix section C29 by a gain coefficient h corresponding to the edge amount, and calculates an adjusted value. Adders 21, 22 add the pixel of interest data to a distributed error, random numbers RND and the adjusted value, and supplies Pxy to a selector 23. The selector 23 supplies the pixel data Pxy to either a bright portion processing section 24, a dark portion processing section 25 or an intermediate portion processing section 27. The bright portion processing section 24 and the dark portion processing section 25 refer to an already binarized result to decide a binarized result Qxy of the pixel of interest data. The intermediate portion processing section 27 compares a threshold T monotonously increasing in accordance with the value of the pixel data Pxy with the pixel data Pxy, thereby deciding the binarized result Qxy of the pixel of interest data. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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