Patent ID: 6870641

Claim:
An image processing apparatus that receives image data represented by a tone value of each pixel, determines dot on-off state in each pixel by taking into account the tone value of the pixel, and converts the image data into a specific expression format based on the dot on-off state, said image processing apparatus comprising: a tone error registration unit that calculates a tone error arising in each pixel due to determination of the dot on-off state in the pixel, based on a result of the determination of the dot on-off state, and temporarily registers a preset number of the calculated tone errors in a temporary memory; a diffusion error storage unit that calculates diffusion errors diffused to each of non-processed pixels, which are in a neighborhood of the preset number of pixels and have not yet been subjected to the determination of the dot on-off state, based on the tone errors registered in the temporary memory, and stores the calculated diffusion errors into an error memory assigned to the each non-processed pixel; and a dot creation decision unit that determines the dot on-off state in each non-processed pixel, based on the tone value of the each non-processed pixel, by taking into account the calculated diffusion errors.