Stereoscopic Color Gamut Theory Of New Generation Display Systems

Laser display is a new type of display technology,which has advantages of wide color gamut,high brightness and long life span.At present,gas lasers,solid lasers,semiconductor lasers and fiber lasers with different spectral line widths and central wavelengths can be used in laser displays.The spectral width and center wavelength of the light source can influence the color gamut and speckle contrast of the laser display system.However,To obtain a wider color gamut requires narrower spectrum line width of light source,while lower speckle contrast requires a relatively wider spectrum.The trade-off between the wider color gamut and speckle reduction becomes the problem before us.We urgently need a method to calculate the solid color gamut of a laser display system.Macadam's theory is an effective algorithm for calculating color gamut.Compared to traditional planar color gamut,Macadam's theory is used in CIELAB color space that is more uniform than CIEXYZ color space.It can also reflect the influence of brightness on the color gamut.However;this algorithm creates problems when calculating very peaked and discontinuous spectrum represented by laser displays.This paper is proposed to solve these above problems.The main research works are as follows:1.An algorithm to calculate volume of the solid color gamut suitable for RGB display system represented by laser display is proposed.By this method,we obtain the volume of color gamut of RGB display system with light sources of any spectral width at any center wavelength.We have solved problems that the predecessors left in their algorithm.2.We discuss how central wavelength of single primary color and spectral line width of single primary color influence the solid color gamut in the RGB display system.We reach the conclusion that the green light has the greatest influence on the color gamut of RGB laser display system.Through theoretical guidance,we choose red light with central wavelength of 660 nm and spectral line width of 10 nm;green light with central wavelength of 532 nm and a spectral line width of 5 nm;blue light with central wavelength of 465 nm and spectral line width of 10 nm as a reference for RGB laser display system.We choose this light source to make a trade-off between wider color gamut and lower speckle contrast.3.We expanded the RGB Macadam's theory into a multi-primary display system,enabling Macadam's theory to be applied to display systems with more than three primary colors.Such a theory for solid color gamut solves the problem of unreasonable increasing of the color gamut by adding a primary color with low brightness.The color gamut of four primary display system increase to 113%of that of RGB display system,while the color gamut of six primary color display system increase to 126%of that of RGB display system.4.Based on four primary color display system,We discuss the influence of spectral line width,color intensity and wavelength selection of primary color on the volume of color gamut.The relationship between the color intensities of primary colors in multi-primary color display systems is proposed.We optimized color intensities of four primary color display system with wavelength of 467nm,505nm,520nm and 630nm.When the four primary color intensity ratio is 1.0000:0.8353:0.8958:1.8500,the color gamut is the widest.5.Based on the geometric model of Macadam's theory,We study the physical meaning of the points,lines and surfaces on the Macadam color solid.The relationship between the number of points,lines and planes and the number of primary colors is discussed.The geometrical meaning is used to obtain the Macadam color solid without calculation.6.Based on psychophysical experiments,the shape of the MacAdam limit was verified.We measure the color gamut of different display systems by the ability of human eyes to distinguish colors.Through the identification experiment of 12 colors for 8 observers,we obtain the conclusion that the color gamut of laser display system is 49.48%more than that of the traditional xenon lamp.The standard deviation of this result is 8.7%.Highlights of the dissertation are as follows:1.We propose the concept that the primary color is an important difference between a illumination system and a display system.By introducing the primary color into the traditional Macadam's theory,the concept of the most saturated RGB value is proposed.It can be applied to the color gamut calculation of a series of spectrum such as very peaked spectrum and discontinuous spectrum.The application range of the original Macadam algorithm is greatly expanded.2.Based on the Macadam's theory of the RGB display system,We propose the correspondence of the planar color gamut standards such as NTSC,Rec.709,Rec.2020,and DCI-P3 in the CIELAB color space.It guarantees our theory's backward compatibility with planar color gamut standards.3.Based on the balance equation of the white balance point,it is concluded that To determine the intensity value of each primary color in the N primary color display system,at least the intensity value of(N-2)primary colors needs to be given.Furthermore,we discuss the influence of the intensity of the primary color on the color gamut of the display system.4.We combine the points,lines and surfaces of the Macadam color solid with the actual physical meaning.The physical meaning is that the vertices on the color solid represent points where all the primary color intensity values are 0 and 1,the ribs on the color solid represent points where all the primary color intensity take the values of 0 and 1 except for one primary color,and the surfaces on the color solid represent points where all the primary color intensity values are 0 and 1 except for two primary colors.Based on the geometric meaning of Macadam's theory,the conclusions in many color gamut calculations are reinterpreted5.From the numerical calculation and experimental analysis,We discuss the reduction degree of the CIEXYZ and CIELUV color space to the solid color gamut.Both results show that the CIEXYZ color space is closer to the actual situation of the solid color gamut than the CIELUV color space.