Effect Of Sample Separation And Color-difference Magnitude On Perceived Color Difference

With the development of the times and the improvement of living standards,people have put forward higher requirements for color quality.In daily life,‘Color Management'appears more and more frequently,and the concept of color difference is becoming clearer.The existing color-difference prediction models have specific reference conditions.If people want to more effectively characterize and accurately evaluate the difference between the surface colors of the objects,then need to study and analyze the human visual discrimination characteristics and color-difference prediction models under different parameters.The main research work and innovative points of this thesis are as follows:(1)In order to further investigate the effect of separation and color-difference magnitude on perceived color difference,the experimental samples were made around the five color centers(gray,red,yellow,green,blue)with average color-difference magnitudes of 1,2,4 and 8 respectively.There were 460 pairs of printed color samples with separation.15 observers were organized to participate in the color-difference evaluation psychophysical experiment.(2)In order to investigate the influence of large,medium and small color-difference magnitude on visual assessment,and analyzes the data sets of different color-difference magnitudes by the methods of linear fitting,mathematical statistics and chromaticity ellipse fitting.The analysis results show that the color-difference magnitude has a great influence on the assessment of visual color difference,and the smaller the color difference is,the greater the uncertainty of color-difference evaluation of human vision is.(3)In order to investigate the influence of separation on visual assessment,using the methods of mathematical statistics,chromaticity ellipse fitting and Monte Carlo ellipse comparison to compare the data sets from gap color sample pairs and gapless color sample pairs.The comparison results show that the gap has an influence on the evaluation of visual color difference,and the influence gradually decreases as the color-difference magnitude increases.This thesis also uses the methods of chromaticity ellipse fitting and Monte Carlo ellipse comparison to systematically analyze the experimental data and the previously collected data sets.The analysis results show that the influence of the gapless is more obvious than the material on the visual color difference.(4)The experimental data was also used to compare and evaluate the performances of six color-difference formulas such as CIELAB,CIEDE2000,CIE94,CMC,CAM02-UCS and CAM16-UCS.The result shows that performance of CAM16-UCS is better.In this thesis,the color-difference formulas were optimized by the lightness parameter factor(k_L)and the chroma parameter factor(k_C)optimised method,the lightness parameter factor(k_L)optimised method and the power function optimised method.Three different forms of optimised schemes were proposed,and effectively improved the performances of the color-difference formulas.