Relative amounts of pigments on an overhead projector (OHP) sheet printed by laser printer can be estimated by using spectral transmittance at each pixel of an optical micrograph, and the multi-layered pigments also can be separated into each component. The transmittance spectra were estimated from multiband images by the Wiener estimation method. In the experiment, relative amounts of pigments printed by one or two kinds of color pigments were estimated, and overlapping magenta and yellow pigments were separated into each category. The result was accurate as compared with separation based on RGB values.