Image data processing apparatus, method, and program that diffuses gradiation error for each pixel in target block

Abstract

There has been a demand to accelerate image data conversion through the use of the error diffusion method. To convert image data, it is determined whether a specified block process condition is satisfied on the basis of a gradation value for each pixel in a target block. When the block process condition is true, a process is performed to diffuse a gradation error for the entire target block and convert image data for pixels in the target block at a time. Even when the block process condition is false, it is determined whether to form a dot in the target block. When it is determined that no dot should be formed, a process is performed to diffuse a gradation error for the entire target block to the unconverted pixels in another block and convert image data for pixels in the target block.