Image processing apparatus, method, computer program product, and image forming apparatus, detecting a halftone area based on a rearranged halftone dot detection result

摘要

A halftone pixel detection unit detects pixels near center pixels of halftone pixels by comparing a density difference between a target pixel and each of neighboring pixels of image data with a predetermined threshold. A halftone pixel rearranging unit rearranges the halftone pixels detected by the halftone pixel detection unit relative to the target pixel and a halftone-area detection unit detects a halftone area based upon a pattern of the halftone pixels that is rearranged.