To provide an image processing system and image processor, which converts inputted color image data into monochromatic image data to print the monochromatic image data, meanwhile can cope with the user's request of confirming original color image data in color with a simple operation and provides excellent economical efficiency and operability.

Color image data identification information is added to monochromatic image data to be processed in a prescribed format, to be printed and outputted to a recording medium. On the other hand, the color image data identification information are extracted from an inputted original image data, and color image data corresponding to the extracted color image data identification information are read from an image data storage means and visibly outputted in a prescribed format.