Abstract: The color of certain object surface has a constant feature,irrelevant to the object surface shape.But the color of the image is variablebecause of the existence of highlights.To construct a physical modelof color reflection is a way to understand the image color correctly.Thispaper describes a method of computing light source color coordinates andobject color coordinates.Based on the Dichromatic Reflection Model proposedby Klinker et al,the method first makes plane fitting in the color cube byusing K-L transform,then separates the interface reflection componentsand body reflection components.Also the limitations of practical CCD camerasare discussed and the experiment results are presented.The color imagegiven in this paper refers to that generated by a color CCD camera frommonochromatic object under monochromatic light(not the light with singlewavelength).