Patent Number: 6,167,154

Title: Image processing apparatus and secondary line feature indicative value calculating device

Abstract: When an original wherein a plurality of binary image areas in different density or the like coexist is printed by stencil making, tone characteristics of a tone image area are preserved and blur or extinction of a faint letter, or smear of a letter written on a dark background in a binary image area is prevented from occurring and print without incongruity due to density different is obtained. An image processing apparatus comprises first analyzing device which analyzes whether a target pixel is in a binary image area or a tone image area, second analyzing device which calculates a secondary line feature indicative value regarding density difference between a line and its background when the target pixel is composing a line in a thickness equal to or less than a certain value, judging device which judges the degree or likelihood of weather the target pixel is in a binary image area or a tone image area by a grade, based on analysis result by the first analyzing device and the secondary line feature indicative value, adopted-density conversion device which converts density of the target pixel based on the judgment result, and binary conversion device which upon necessity converts the target pixel having been density-converted into binary data.

Inventors: Renaud; Miel (Tokyo, JP), Hashimoto; Koichi (Tokyo, JP)

Assignee: RISO Laboratory, Inc.

International Classification: H04N 1/40 (20060101); G06K 009/34 ()

Expiration Date: 12/26/2017