The chromaticity coordinates and color spectrum calibration using tri-stimulus sensors and double light sources

Abstract

Generally, the instrument of color measurement can be divided into spectrophotometer and color meter. The former instrument use prism or grating to separate the light, it can achieve high accuracy but a higher price. The latter instrument use color filter, however there is no spectrum information with it. This article establishes a color measuring system and uses eigen-spectrum method in double light sources to calibrate the spectrum. The measuring system includes tri-stimulus sensors which were made by color filter. The tungsten lamp and Xenon lamp are used to be light source. The advantage of this measuring system is the higher accuracy and the lower cost. The eigen-spectrum method can calibrate the spectrum in less eigenvector. This method used singular value deposition to obtain basis function of spectrum set, which can be obtained by measuring. Because the range of the spectrum set was 380nm to 780nm, the eigenvector per nanometer from 380nm to 780nm can be obtained. In general, the color spectrum can be obtained with less eigenvector. The color difference in L*a*b* color space from 31.2398 down to 2.48841, and reconstructs the spectrum information.