| 摘要 |
PROBLEM TO BE SOLVED: To provide an image processing apparatus, image forming apparatus and image processing method in which, when a read image is an achromatic image, regardless of a background color of a document or eccentricity of brightness, it can be accurately determined whether the achromatic image is a white-and-black binary image or a halftone image.SOLUTION: Brightness for each of pixels of image information read from a document is extracted and a center value variance σ, that is a value indicating how much brightness is separated from a center value M between a minimum value and a maximum value, that the brightness may take, and how much such brightness is present, is calculated based on the extracted brightness for each pixel. In the case that the center value variance σ is equal to or more than a predetermined threshold, the achromatic image is determined as a white-and-black binary image and in the case that the center value variance σ is less than the threshold, the achromatic image is determined as a halftone image. |
