An image processing system which is applicable to, in this case, a dental treatment, and which images, when a patient' (59) denture is to be produced, the dental part of the patient (59) while a plurality of lighting LEDs respectively having different wavelengths are being emitted by an imaging device (1A) to capture image data. The image data is transmitted to a dental filing system (2A) servingas a treating device, where color reproduction data is determined by computing. The color reproduction data is further sent to a dental laboratory (55) over a public telephone line. In the laboratory, a porcelain blending ratio calculation database (56) is searched to obtain denture porcelain blending data that matches the hue of the dental part of the patient (59), whereby a denture very close in color to the patient' (59) teeth is produced.