The Three Key Problems Research Of Calculate The Tristimulus Values

In 1931,the International Commission on Illumination CIE recommended a system for color measurement that established the basis for modern colorimetry.Since then,especially in the past decade colorimetry has been rapidly developed.It is absolutely key technology in the many industries,such as colour television,color photography,textile,paint,and so on.Color can be described by its tristimulus values,and many kinds of tristimulus values have been used in the color industry.The color tristimulus values and CIE standard observer with CIE illuminant conditions vary.Industry often known tristimulus values to the problem of spectrial reflectance,therefore,the spectrial reflectance on the surface of the object has become an important topic subject to our depth research and evaluation.CIE tristimulus values are defined in terms of integrations and all the integrands involved have no analytical expressions:therefore accurate computation of the TSVs becomes a problem,a problem which has been noticed by scientific researchers possibly since the early 1930 s.Various computational methods are available and disagreements between these methods can be large.However,the problem is completely avoidable if a unified method is used to calculate.This paper introduce simply available methods including the CIE recommended method and the ASTM weighting tables,the Oleari method and the LLR method,together with a newly developed LWL method.This paper addresses some general practices for the computation of CIE tristimulus values,including different methods used for the interpolation,extrapolation,and truncation of data in the visible wavelength range.In each case,a quantitative analysis is presented on the basis of a dataset with 2365 spectral reflectances covering a wide color gamut,assuming six CIE illuminants and the two CIE standard colorimetric observers.For interpolation,it is found that among five tested methods the(cubic)spline method is the best one when the spectral reflectance factors are uniformly sampled over the visible wavelength range.For extrapolation,it is found that the second-order extrapolation method gives better results than the use of nearest available data points or linear extrapolation methods.With respect to truncation,considering five different usual truncated ranges it is found that the range from 360 to 780 nm provides more accurate results than the range from 380 to 780 nm currently recommended by CIE for non-fluorescent samples,and the use of the truncated range from 400 to 700 nm in the place of the CIE-recommended range of 360 to 830 nm leads to tristimulus values with considerably high color differences of up to 0.9 CIELAB units.