Patent ID: 7889394

Claim:
An image processing apparatus for processing multilevel image data including values of respective color components, comprising: an adding unit configured to add quantization errors to the respective values of the color components of a target pixel, wherein the quantization errors are obtained from pixels for which a quantization has been already completed; an output determination unit configured to perform the quantization to determine output values of the respective color components of the target pixel based on a combination of the values of the respective color components to which the quantization errors are added; an error calculation unit configured to calculate quantization errors of the respective color components of the target pixel based on the output values of the respective color components and the values of the respective color components to which the quantization errors are added; a distribution weight determination unit configured to determine distribution weights for the respective color components in accordance with a combination of the values of the respective color components of the target pixel; and an error diffusion unit configured to distribute the calculated quantization errors of the respective color components of the target pixel to values of the respective color components of neighboring pixels in accordance with the weights determined by said distribution weight determination unit, wherein the distribution weights for the respective color components are determined by said distribution weight determination unit to be the same value or different values to each other in accordance with a combination of the values of the respective color components of the target pixel, and wherein the determined distribution weights for the respective color components have the same value when the output value of the respective color components of the target pixel are equal to each other.