A color image formation system in which transfer means for sequentially receiving plural color images is idled if raster image data for a color has not yet been converted from a page description language into the raster image. A page description language or other code data for a first color is converted into a raster image of the first color and an electrophotographic process is commenced whereby a laser beam is modulated in accordance with the raster image of the first color and the image formed by the modulated laser beam is transferred to rotatable transfer means. After image formation in the first color is complete, code data for the second color is converted into raster image data. If conversion of the second color is not yet complete but the transfer means has rotated to a position where it is ready to receive the second color, the transfer means is idled by continued rotation thereof and forcibly restricting laser beam illumination whereby the transfer means is fed blank to a predetermined position. The transfer means is idled until the conversion of second color is complete, whereafter the laser beam is modulated in accordance with the raster image of the second color to form the second color on the transfer means. Processing for third and subsequent colors is continued as above until a full color image has been formed on the transfer means.