| 摘要 |
PURPOSE:To obtain three stimulus values even with no coincidence with an isochromatic function by supposing that the spectral reflection factor distribution of a color picture is approximated by the linear sum of three known spectral reflection factor distributions. CONSTITUTION:A color picture 1 is used as a subject for measurement of colors together with a light source 2 which irradiates the picture 1, the color sensors 3 - 5 whose spectral sensitivity are already known, and a matrix conversion part 6. In such a configuration, it is supposed that the spectral distribution characteristic of the picture 1 can be approximated with the linear connection p1.C1(lambda)+p2.C2(lambda)+p3.C 3(lambda) of three types of known spectral distribution characteristics C1(lambda), C2(lambda) and C3(lambda) based on the three spectral feature coefficients (p1, p2, p3). Then ST<-1> is obtained as a color correction matrix A by multiplying a matrix S which converts the coefficients p1 - p3 into three stimulus values of an XYZ color expression system by an adverse matrix T<-1> of a matrix T which converts the coefficients p1 - p3 into three color separation signals t1 - t3. The matrix conversion is applied to the signals t1 - t3 for acquisition of three stimulus values of the XYZ color expression system. These stimulus values are outputted as the color feature values. Thus the three stimulus values can be obtained even with no coincidence with an isochromatic function. |
