Patent ID: 7327879

Claim:
An image processing apparatus comprising: image inputting means; color analyzing means for analyzing a color used within an input image, the color analyzing means including (i) obtaining a sum of values of saturation of all pixels having an identical value of hue in an input image, based on a histogram of hue in which the obtained sum of values of saturation is set as frequency, (ii) defining hue having a maximum frequency as a representative hue, (iii) determining based on the sum of values of saturation at the representative hue, whether or not the input image is a monochromatic image and (iv) when it is determined that the input image is not a monochromatic image, (a) determining based on a variance of the histogram hue, whether or nor a plurality of colors is used in the input image and (b) determining whether the input image is multicolor image or a single-color image; mixing-ratio calculating means for determining a mixing-ratio of color components of red, green or blue, in accordance with a result determined which is a monochromatic image, a multicolor image or a single-color image; and converting means for converting the input image to a monochromatic image by mixing color components according to a determined mixing-ratio.