| Display technology is an important medium to convey visual information.From the early black-and-white display technology to the color display technology,and then to the advent of various digital display technology,people's pursuit of the display effect is getting higher and higher.The most important indicator of the display effect is the color gamut,which describes the ability of the display system to restore the color that can be seen by the human eye.The larger the gamut is,the higher the color saturation and the richer of the color is.At present,the existing display technology is basically based on the three primary color technology,which uses red,green and blue as light sources to produce color images.For the three primary color display system,the common way to measure the color gamut size is to mark the three primary color coordinates used by the system on CIE1931 x-y plane color map.The three primary color coordinates are connected into a triangle,and by calculating the area of the triangle we could get the color gamut of the display system.However,using the gamut area to measure the gamut size of the display system is not comprehensive on account of the fact that the stereoscopic color gamut considers the influence of brightness on the gamut.Compared with the flat gamut,the stereoscopic color gamut can more truly reflect the actual situation of the gamut index.The size of the the stereoscopic color gamut is represented by the gamut volume.The description of stereoscopic color gamut needs a suitable three-dimensional color space.CIELAB stereo color space is a more uniform and widely used color space.In recent years,the development of three primary color display technology is in full swing,such as LED display technology,OLED display technology,quantum dot display technology and laser display technology.These technologies are constantly developing in the process of industrialization,and thus the color gamut is constantly expanding.In the three primary color display technology,the spectral width of the primary color determines the size of the color gamut.Taking LED display technology and laser display technology as examples.The spectral width of the LED reaches about 40 nm,and the gamut coverage is 150%sRGB,while the laser can be less than 1 nm?and the gamut coverage is 226%sRGB.The gamut coverage of OLED and quantum dot display technology are between the two above.At present,most of the existing researches focus on the influence of wavelength combination,color spectrum width and color numbers on the color gamut of display system,but the white balance point in these researches is usually a fixed value,without considering the influence of white point change.As an important parameter of display system,white balance point affects people's feeling of viewing image by changing the intensity ratio of primary colors.Few previous studies have focused on the influence of the change of white balance point on the color gamut of display system under different primary color intensity ratio.In view of the fact that most display systems have the function of adjusting the white balance point color temperature or color temperature selection,it is necessary to explore the relationship between white balance point and the color gamut volume of display system.The main contents of this paper are as follows:1.Based on the algorithm of stereoscopic color gamut in display system,the change of stereoscopic color gamut when the white point coordinate of display system changes is studied theoretically.We divide the display system into two parts:large color gamut display system represented by laser display technologyand traditional small color gamut display system represented by LED display technology.The white balance point of the display system can be expressed by color temperature.Under the two display systems,the color temperature of the white point is set to 4000K,5000K,6500k,9300k,12500k and 20000k.According to the algorithm,the color gamut volume of the two display systems under the six color temperatures is calculated,and the relationship between the color gamut volume and the color temperature is obtained.The results show that,with the increase of color temperature,the color gamut volume shows a gradual increase trend,and the growth trend gradually slows down,no matter large color gamut laser display system or small color gamut LED display system.The color temperature increased from 4000K to 20000k,and the gamut of the two display systems increased by 19.35%and 20.38%,respectively.By changing the wavelength combination of the primary color,the same change rule can be obtained.2.It is not comprehensive to measure the gamut only by the gamut volume.The relevant research suggests that the gamut of the display system should be described by the coverage of the stereoscopic color gamut,that is,the gamut of D65 light source is used as the evaluation standard.The evaluation of the gamut of the display system is the process of calculating the volume coverage of the gamut of the display system relative to the target gamut.Based on this,we further explore the relationship between white balance point and gamut coverage,and get that when the white point color temperature is about 6500k,there is a maximum gamut coverage,which can respectively cover 74.55%and 52.73%of D65 gamut.It can be seen from the results that the laser display system with large color gamut has absolute superiority in color representation.3.In the above studies,the white balance points are all selected on the blackbody radiation track.In the actual display system,when the white balance point position deviates from the blackbody radiation track,it is usually described by the correlated color temperature.The distance between the correlated color temperature points and the blackbody radiation track can be expressed by the relevant color temperature offset?UV.We further study the influence of correlated color temperature offset on gamut coverage.Taking the large gamut display system as an example,we get the relationship between ?UV and gamut coverage under different color temperatures.The results show that when the color temperature is 7000K and ?UV is about-0.0025,the maximum value of gamut coverage will appear,which is 75.05%;In addition,considering different people's preference for white point color temperature,we find an optimal range of color temperature,that is,6000K to 12000k,and the correlated color temperature deviation meets-0.015<?UV<0.005.In this range,we can not only get a larger gamut experience but also can meet the personalized requirements.It is worth noting that for the case of small color gamut display system and other wavelength combinations,the conclusion is basically the same.In conclusion,we have got more comprehensive and complete results.This research can provide theoretical reference and basis for the selection of white balance point of display system.The main innovations of this paper are as follows:1.We innovatively connect the white balance point with the stereoscopic color gamut,and theoretically explored the relationship between white balance and gamut volume of display system.2.With D65 light source as the reference,and combined with the study of gamut coverage,the relationship between white balance point and gamut coverage is explored,and the best color temperature selection value is found when the white balance point is located on the blackbody radiation track.3.Considering that the white balance point deviates from the blackbody radiation track,the influence of the correlated color temperature offset on the coverage of the color gamut is studied,and the best selection range of white point color temperature is found.The results can provide theoretical basis for the selection of white balance and personalized customization of the display system,... |
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