Research On Color Depth Of COLORO Color System And Its Conversion With CIE Color System

Colors always exude magical charm in human life,and colors in visual scenes help us to better process and store images.In order to meet the needs and applications of color in all walks of life,accurate digital representation of color has been widely developed.China Textile Information Center finally launched the COLORO color system by dyeing a large number of color samples.In order to promote the application of this color system in the textile industry,this subject first studied the color depth of the 3,500 color cards based on the COLORO color system,then discussed the conversion from CIE color system to COLORO color system.The main content and results are as follows:First,the Munsell color system was used to test the depth of the COLORO color system.The Munsell-V value of the color cards were obtained by the existing mature methods,and the average value of the Munsell-V value of the color card with the same COLORO lightness value were calculated,the results show that the CV values of color cards'Munsell-V values with the same COLORO lightness label are all lower than 5%.The correlation coefficient value and Pearson coefficient value between COLORO lightness label value and Munsell-V value are 0.9992 and0.9996 respectively,which indicating that there is a strong correlation between them,and the change law of the two value is consistent,that means the COLORO color system has the good iso-depth.Then Gall's formula was used to evaluate the color depth of the color card,the 1/1,1/3,1/9 and 1/25level standard depth corresponding to the COLORO color card lightness label value is increasing,its main distribution areas are 20-40,30-50,40-60 and 60-90,and the corresponding average values are 36,46,58 and 74 respectively,the most marked values of brightness in each grade are 27,36,55 And 75,the median values of the lightness labels corresponding to each grade are:32,43,55,and 77,whis is in line with the law that the color depth of the COLORO color system increases with the decrease of brightness.When used the 1/1 standard depth method in the ISO standard to evaluate the color depth of the color cards,it is found that the distribution area of the corresponding brightness value of the COLORO color card in the ISO standard 1/1 is 20-40,which is similar to the Gall's 1/1 grade result.The average of the COLORO lightness label value,the COLORO lightness label value with the largest number of color cards,and the median corresponding to the1/1 grade standard depth in the ISO standard are:33,27 and 30,and the number of color cards that meet 1/1 standard depth of the Gall's formula and ISO standard are 848 and 90 respectively.it can be inferred that the standard depth of 1/1 specified by the ISO standard is deeper.When evaluated the color depth of the color cards by the Integ value and the Color Value,the overall trend of the color depth of the color card is decreased with the increasing lightness label value,but the color depth value with the same lightness label value fluctuates greatly,so it is judged that the two formula are not suitable for the evaluation of the color depth of the color cards.Then this topic proposed the conversion method of CIE L~*,a~*,b~*values to the COLORO color system,the results obtained by using function fitting method and linear interpolation method to convert L~* value to COLORO lightness label value are similar,the difference between the two methods is not more than 5,and the total number of color cards exceeding 3 is lower than 6 and 7,respectively,that is the conversion results of the two methods have good accuracy.The difference of the convert from a~*,b~* values to COLORO color system used parabolic fitting method is between0-90,but the conversion difference used parabolic interpolation and hierarchical linear interpolation is less than 10,and there are 2380 color cards using hierarchical linear interpolation to convert the conversion difference below 1.When the fitting method and hue loop method were used to convert a~*,b~* values to COLORO hue label values,the distribution of the conversion difference is similar,when the hue label is 0-16 and 150-160,the corresponding maximum conversion difference is greater than 150.The linear interpolation and hierarchical linear interpolation were used to convert a~*,b~*values to COLORO hue label values,and the conversion difference values obtained are concentrated in the range of 0-15.Finally,based on the structural similarity between the COLORO color system and the CIE color system,the V-xy color spaces was established,and the interpolation method was proposed to realize the conversion from the CIE brightness factor Y,CIE chroma,and CIE hue angle to COLORO brightness,chroma and hue label values.And randomly selected the color card from the COLORO color system to test the feasibility of the conversion method.The results show that the conversion difference of chroma is large and its conversion value does not show regular changes.The conversion difference of lightness label value and hue label value is between 0-10,the hue conversion difference is large when the hue label value is 0-16.The chroma conversion difference of the trimmed color sample is still large,and the conversion result of the hue label value and the lightness label value has been improved,the main distribution interval of color difference is 0-5,and the conversion difference is also reduced to between 0-5,there's no longer a difference close to160.The Y,x,and y values of the color sample were used as input data,and the COLORO label value was used as output data,and the BP neural network was used to test the conversion results,the correlation coefficient between the predicted value and the converted value of the brightness label value and hue label value is between 0.9-1,and the predicted value has a different swing amplitude near the fitting line,which indicating that the conversion result has better accuracy.