Research of the chromaticity coordinates and color spectrum calibration using tristimulus sensors and eigenspectrum method

Abstract

The purpose of color measuring instrument is judging the color information by scientific method, which may instead of the human's eyes. Generally, the instruments of color measuring have two kinds, spectrophotometer and color meter. The former measures spectrum by usage of prism or grating to separate the light, this could achieve high accuracy but with a higher price. The latter obtains tristimulus from color filter; however there is no spectrum information with it. This article establishes a color measuring system and uses eigenspectrum method to correct the average inaccuracy. The measuring system includes tristimulus sensors which were made by color filter, and Xenon lamp as light source. The advantage of this measuring system is the higher accuracy and the lower cost. The eigenspectrum method can correct the average inaccuracy in less eigenvector, which can save the time. 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. This article establishes a color measuring system, which has three sensors and uses Xenon lamp as light source, to acquire the color spectral reflectance. This article also uses the eigenspectrum methods to correct the average color difference in L*a*b* color space, which from 31.2398 down to 4.8401, and reconstructs the spectrum information.