An image processing system is provided that is capable of performing copying processes by connecting devices which specifications for processing image data are mutually different. In an image processing system comprised of an image reading device for optically reading original documents and converting these into electronic image data and a printing device for printing image data that have been received from the image reading device onto recording media, image processing circuits for processing image data in accordance with specified specifications are respectively incorporated into the scanning device and the printing device, and a device that may be set in accordance with specifications for processing image data based on given circuit arrangement information is used to comprise at least a part of either one of the image processing circuits of these devices. By setting the image processing circuit in accordance with specifications for processing image data on the basis of specification information of the image processing circuit of the opposing device, it is enabled to connect scanning devices and printing devices that are of mutually different specifications.