An image processing system includes: an image recording unit configured to record an output image corresponding to an input image on a recording medium; an image compression unit configured to compress the input image for transmission; and a determining unit configured to determine whether the input image is a color image or a monochrome image according to a first determination rule if the output image is to be recorded on the recording medium, and determine whether the input image is the color image or the monochrome image according to a second determination rule different from the first determination rule if the input image is to be compressed for transmission.