Image processing apparatus, image forming apparatus, and image processing method

An image processing apparatus, comprising:

• a color conversion process section that converts color image data of a first color space obtained by scanning a document into color image data of a second color space based on a predetermined color conversion process;
• a halftone frequency recognition section that calculates a halftone frequency of the document based on the color image data of a first color space;
• and
• a process changing section that changes the color conversion process against the color image data obtained by scanning the document based upon the halftone frequency calculated by the halftone frequency recognition section,
• wherein the color conversion process section changes the color conversion process based upon (i) a result of segmentation process, which indicates a result of segmentation that is performed to at least determine whether the color image data of the first color space belongs to a halftone area, and (ii) the halftone frequency recognized from the color image data of the first color space.

An image processing method, in which a color conversion process is performed so as to convert color image data of a first color space into color image data of a second color space,

• said method comprising the steps of:
• obtaining the color image data of the first color space by reading out a document;
• and
• changing the color conversion process based upon (i) a type of the document and (ii) a halftone frequency recognized from the color image data of the first color space.

An image processing apparatus, comprising:

• a color conversion process section that converts color image data of a first color space obtained by scanning a document into color image data of a second color space based on a predetermined color conversion process;
• a halftone frequency recognition section that calculates a halftone frequency of the document based on the color image data of a first color space;
• and
• a process changing section that changes the color conversion process against the color image data obtained by scanning the document based upon the halftone frequency calculated by the halftone frequency recognition section,
• wherein, for a high frequency halftone document, the color conversion process section performs tone-oriented color reproduction for a high density area such that the tones in the high density area are accurately reproduced, and the color conversion process section performs tone-oriented color reproduction for a low density area such that density and color saturation are maintained and pale colors are accurately reproduced, and
• wherein the color conversion process section performs tone-oriented color reproduction for documents other than high frequency halftone documents such that contrast of the documents is maintained.

An image processing apparatus, comprising:

• a color conversion process section that converts color image data of a first color space obtained by scanning a document into color image data of a second color space based on a predetermined color conversion process;
• a halftone frequency recognition section that calculates a halftone frequency of the document based on the color image data of a first color space;
• and
• a process changing section that changes the color conversion process against the color image data obtained by scanning the document based upon the halftone frequency calculated by the halftone frequency recognition section,
• wherein the color conversion process section performs a black generation and under color removal process on color image data of a CMY signal so as to convert the color image data of the CMY signal into color image data of a CMYK signal,
• wherein, for a high frequency halftone document, the black generation and under color removal process removes only a small amount of under color, resulting in reproducible dark and vivid colors, and
• wherein, for documents other than high frequency halftone documents, the black generation and under color removal process generates a large amount of black color and removes a large amount of under color such that reproducibility of text is improved and sharp gray colors are reproduced.