Image processing apparatus and method for discriminating whether document is color document or black and white document, image forming apparatus and facsimile machine including the image processing apparatus and computer readable recording medium storing image processing program

An image processing method, comprising:

• an image reading step of scanning a document to detect pixel values of a plurality of color components of each pixel;
• a pixel color determining step of determining whether or not a color of each pixel is yellow based on the pixel values of the plurality of color components of each pixel detected in the image reading step;
• an isolated point determining step of determining whether or not each pixel is an isolated point based on the pixel values of the plurality of color components of each pixel detected in the image reading step;
• and
• a document discriminating step of discriminating whether the document is a color document or a black-and-white document based on the pixel values of the plurality of color components of each pixel detected in the image reading step while treating, without removing the isolated points determined by the isolated point determining step, the pixels, of which the color has been determined to be the yellow in the pixel color determining step and which have been determined to be the isolated points in the isolated point determining step, as black-and-white pixels.

A non-transitory computer readable recording medium that stores an image processing program which causes a computer to function as an image processing apparatus, the program causing the computer to function as:

• an image reading unit that scans a document to detect pixel values of a plurality of color components of each pixel;
• a pixel color determining unit that determines whether or not a color of each pixel is yellow based on the pixel values of the plurality of color components of each pixel detected by the image reading unit;
• an isolated point determining unit that determines whether or not each pixel is an isolated point based on the pixel values of the plurality of color components of each pixel detected by the image reading unit;
• and
• a document discriminating unit that discriminates whether the document is a color document or a black-and-white document based on the pixel values of the plurality of color components of each pixel detected by the image reading unit while treating, without removing the isolated points determined by the isolated point determining unit, the pixels, of which the color has been determined to be the yellow color by the pixel color determining unit and which have been determined to be the isolated points by the isolated point determining unit, as black-and-white pixels.