A circuit for calculating a light reflected component with high accuracy. The circuit for calculating a reflected component of light reflected from an object having a rough surface comprises a means for storing the reflectance of an object in relation to the value .phi. or the value of cos .phi., letting a surface normal vector be denoted by a vector N, a light source incidence unit vector be denoted by a vector L, a line-of-sight unit vector be denoted by V, a half vector of the light source incidence vector L and the line-of-sight vector V be denoted by H and defining the inner products as NL=cos .theta., NV=cos .gamma., VH=cos .phi., NH=cos .beta.; a means for storing a luminance distribution in relation to the value of .beta. or the value of cos .beta.; a means for acquiring information on the reflectance term (F.sub..lamda.(.phi.)) of the reflected component according to the value of .phi. or the value of cos .phi. from the reflectance storing means; a means for acquiring information on the luminance distribution term (D'(.beta.)) of the reflected component according to the value of .beta. or the value of cos .beta. from the luminance distribution storing means; a means for acquiring information on max[0.5 cos .theta. cos .phi., 0.5 cos .phi. cos .gamma., cos .theta. cos .beta. cos .gamma.] which is the maximum value out of 0.5 cos .theta. cos .phi., 0.5 cos .phi. cos .gamma., cos .theta. cos .beta. cos .gamma.; a means for determining the reciprocal of the max[0.5 cos .theta. cos .phi., 0.5 cos .phi. cos .gamma., cos .theta. cos .beta. cos .gamma.] and acquiring information on the geometrical attenuation factor term G'(.beta., .theta., .gamma., .phi.) of the reflected component; and a means for acquiring information on the reflected component from the information on the luminance distribution term (D'(.beta.)) and information on the geometrical attenuation factor term G'(.beta., .theta., .gamma., .phi.).