A fast algorithm for color image quantization using only 256 colors

Abstract

AbstractIn the recent workstation for CAD and CG, a color map display is often used, which can display 256 colors selected from 224 (approx. 16000000) colors using a look‐up table. Even in the computer system with such a color display with such a limited number of colors, it is desired that the continuous color image should be processed. In most cases, by determining colors which are important to the image (representative colors), the color image can approximately be displayed without much degrading the image quality. This paper proposes a new method for the approximate display of the color image by 256 colors. In the method, RGB color space is successively partitioned to determine 256 representative colors, so that the quasi‐optimum solution is obtained in the sense of the least‐mean‐square error. By the proposed method, a highly accurate approximate image is obtained with several times faster speed, compared with the traditional methods. The work memory required in the program is only 100 to 200 kBytes, which is less than in the traditional method.