When transmitting an image between a pair of computer image processing systems A and B, a common color image Z is used as a medium image, the medium image is read as digital data into the computer of the system B from the system A, the color of the digital image displayed on the monitor of the computer of the system B is adjusted to substantially match the color of the common image Z by operating the conventional color adjustment system of the computer, the deviation from the origin (zero point) of the color data displayed on the monitor (brightness, contrast, chroma, and color balance) is found, and, when transmitting any image through the system A to the system B, the color data of the digital image displayed on the monitor of the computer of the system B is corrected using the deviation as the correction value.