Similarity between two color areas

Abstract

The paper introduces a method to compare two areas of colors, with each area presenting a perceptual single major color such as on a piece of cloth or a piece of tile. Each color area contains a cloud of colors in similar hues and all colors present a scattered distribution in the RGB color cube. Existing color difference formulas comparing two single colors do not work well in this case. The new method presented in the paper includes two aspects, a new color model that better describes color distributions and the technique of comparing two areas of colors by their color distributions under the new color model. The new model uses cylindrical coordinates to describe the color features, and an area of colors shows a distribution pattern on each color feature. For two areas of colors that are perceptually similar, their distributions on each component of the new color model are compared for similarity, and a combination of these sub-similarities gives an overall similarity between the two areas of colors. The proposed method can be applied to many industrial processes where color similarity comparison is a main concern such as color fastness test of fabrics and tile classification by color.