1. A color quantization method based on the HMMD color space, comprising: (a) dividing the color space into a reference quantization level by carrying out a color quantization using diff, sum, and hue; and (b) carrying out another color quantization of a larger level by subdividing at least one of the respective sub-regions or spatial regions having been divided by the color quantization of step (a) based on at least one combination out of diff, sum, and hue.