IMAGE PROCESSING APPARATUS, QUANTIZING METHOD, PROGRAM, AND RECORD MEDIUM

摘要

PROBLEM TO BE SOLVED: To improve image quality and avoid memory capacity increase by efficiently composing a threshold matrix and to cope with low costs and high grace output. SOLUTION: When input multiple-value image information is subjected to quantization processing to an output gradation number N (N: 2 or more integers) value by an error diffusion method, a specific threshold matrix is shifted based on a shift parameter independent of each constituent of input multiple-value image information, (N-1) decision threshold values when the input multiple- value image information is subjected to quantization processing to N values by the error diffusion method are generated, and the input multiple-value image information is subjected to the quantization processing to N values based on the generated (N-1) decision thresholds. COPYRIGHT: (C)2004,JPO