| 摘要 |
PROBLEM TO BE SOLVED: To prevent occurrence of texture in the case that error spread processing is applied to multi-level image data so as to quantize the multilevel image data with a bit number less than that of the original multilevel image data. SOLUTION: An error sum section 100 conducts error correction by adding surrounding error information E from an error arithmetic section 104 to input image data DFij, a matrix superposing section 106 refers to an adding/ subtracting value designated by a random number in a matrix consisting of 8×8 pixels to apply an arithmetic operation to image data SFij after the error correction, and a quantization section 101 applies gradation processing to an arithmetic result by the matrix superposing section 106 by quantizing the result on the basis of a quantization threshold value TFij (in N bits with respect to input image data = M bits, M>N) from a CPU. |
