Patent ID: 8885221

Claim:
An image processing apparatus for performing error diffusion processing for each pixel in each region of an image divided into a plurality of regions, by scanning in both a first direction and second direction different to each other, comprising: a storing section, configured to hold quantization errors generated in quantization of pixels which have been quantized; a setting section, configured to set a diffusion coefficient set for diffusing, to a pixel of interest to be processed, a quantization error generated near the pixel of interest and held by the storing section, wherein the diffusion coefficient set is selected from a plurality of diffusion coefficient sets in accordance with a position of the pixel of interest and a scanning direction in a region of interest, and the diffusion coefficient set indicates pixels to diffuse the quantization error to the pixel of interest in pixels which have been quantized and ratios of diffusing the quantization error to the pixel of interest; a calculation section configured to multiply a quantization error generated in the quantization of a pixel close to the pixel of interest by a diffusion coefficient corresponding to the close pixel based on the quantization errors held by the storing section and the diffusion coefficient set by the setting section, and to calculate a sum of the multiplied value and a pixel value of the pixel of interest; and a quantizing section, configured to quantize the sum calculated by the calculation section as the pixel value of the pixel of interest, wherein a combination of the pixels to diffuse the quantization error indicated by a diffusion coefficient set selected in the first direction is different from a combination of the pixels to diffuse the quantization error indicated by a diffusion coefficient set selected in the second direction.