1. An image processing apparatus, comprising: a limited color conversion processing section that extracts a plurality of pieces of color information constructing image information and converts the plurality of pieces of color information into color information representing specific colors to which each of the plurality of pieces of color information belongs; a by-color separation processing section that separates the image information containing the color information converted to represent the specific colors by the limited color conversion processing section for each of the specific colors; a compression determination section that determines a compression system for each color as to each of pieces of image information, said each of pieces of image information being separated by the by-color separation processing section for each of the specific colors; a compression processing section that compresses said each of pieces of image information for each of the specific colors according to the compression system for each color determined by the compression determination section; and a layered structure forming processing section that collectively outputs said each of pieces of image information for each of the specific colors compressed by the compression processing section.