This paper describes that according to the color spectral lightness theory of CIE and spectral character of target, the frequency spectrum of discreted metamerism can serve as the study to metamerism and as the determination of metameric object by optical-electrical image processing and the obtained pseudo image copy. Thus, the information can be extracted and determined accurately, so that it is beneficial to the analysis and judgment in chemical, crystal and biomedical image, etc. in the condition by medium copy. At first, the metamerism area is supposed according to the spectral characteristic, then, the discreted value changed by optical-electrical digital system is input into the image processing system. Under the support of hardware and software, the frequency spectrum of metamerism can be transformed. Having filtered it effectively in the frequency domain and having obtained the spatial domain image, the metamerism analysis can be done and the metamerism object can be determined from metamerism by usin image copy.