RESOLUTION CONVERSION PROCESSING METHOD OF BINARY IMAGE

PROBLEM TO BE SOLVED: To obtain an image having high image quality in a short time when converting resolution of a binary line drawing image or the like such as a character image. SOLUTION: A ratio of a main scan pixel number of the image before and after the resolution conversion is calculated, an interpolation bit wherein the main scan pixel number of the image after the resolution conversion is increased as compared to the main scan pixel number of the image before the conversion, or a thinning bit wherein the main scan pixel number of the image after the resolution conversion is reduced is calculated on the basis of the thinning ratio, the interpolation bit is set as the same kind of pixel as a left adjacent pixel, and the thinning bit is thinned. A longitudinal line slim mode line width pixel number that is a pixel number of integer-obtained by truncating a decimal place of a longitudinal line number in the image after the resolution conversion and a longitudinal line thick mode line width pixel number that is a pixel number of integer-obtained by rounding the decimal place are calculated on the basis of the calculated ratio of the main scan pixel number of the images before and the after the resolution conversion, and the image outputted by resolution conversion processing is uniformly processed to a line width mode designated by designation according to designation of a longitudinal line slim mode line width or a longitudinal line thick mode line width. A sub-scan direction is similarly processed. COPYRIGHT: (C)2008,JPO&INPIT