A color image forming system allows color image formation using a color (special color) except for yellow (Y), magenta (M), cyan (C), and black (BK) normally used in color image recording. Palette tables in which data defining use of the special colors (S1 to S4) in addition to Y, M, C, and BK are supplied from a host image data supply apparatus to a printer. At the same time, image data is transmitted in the form of data for allowing selection of the defined data in the palette tables. The printer uses Y, M, C, and BK heads and heads of the special colors S1 to S4. A control unit in the printer stores each palette table for each color (508) and outputs a driving signal to the corresponding head on the basis of the corresponding palette table.