| 主权项 |
1. A method for establishing evaluation standard parameters, the evaluation standard parameters for evaluating the quality of a display image, the quality of the image being inversely proportional to the severity degree of the color shift phenomenon of the image, the method comprising:
taking pictures to a group of test images having different color shift severity degrees to obtain a sample picture group, and selecting a standard picture from the sample picture group by human eye; applying the Fourier transform to tristimulus values of pictures of the sample picture group to obtain a frequency distribution function corresponding to each primary color, wherein the frequency distribution function corresponding to each primary color is respectively expressed as:
F(ωx)=F [X]=∫−∞∞Xe−iωλdλF(ωy)=F [Y]=∫−∞∞Ye−iωλdλF(ωz)=F [Z]=∫−∞∞Ze−iωλdλX =,μ∫a bφ(λ) x(λ)dλY =,μ∫a bφ(λ) Y(λ)dλZ =,μ∫a bφ(λ) z(λ)dλ wherein F (ωx) ,F (ωy), and F (ωz) are respectively the frequency distribution functions corresponding to the red primary color, the green primary colors, and the blue primary color; F is an operator of the Fourier transform; X, Y, and Z, represent the tristimulus values of the red, green, and blue primary colors; λ is the wavelength; x(λ), y(λ), and z(λ) are spectral tristimulus values for the standard colorimetric observer; φ(λ) the reflectance of spectrum of a picture; (a, b) for the visible spectral range; μ is a scale factor; respectively filtering the frequency distribution function corresponding to each primary color to filter the noise; respectively applying convolution to the frequency distribution function corresponding to each primary color with a contrast sensitivity function of human eye in the frequency domain to obtain three convolution functions, the contrast sensitivity function of human eye is expressed as:
CSF(ω)=2.6×(0.0192+0.114×ω)×e(−0.114×ω)1.1 ;the three convolution functions are expressed as:
H(ωx)=∫−∞∞F(ωx)CSF(k−ω)dωH(ωy)=∫−∞∞F(ωy)CSF(k−ω)dωH(ωz)=∫−∞∞F(ωz)CSF(k−ω)dω wherein, CSF(ω) is the contrast sensitivity function of human eye; ω=√{square root over (ωx2 +ωy2)} is the spatial frequency and its unit is cycle / degree; ωx and ωy are the horizontal direction and the vertical direction spatial frequency; H(ωx), H(ωy), and H(ωz) are the three convolution functions; k is an offset value; the integral range is −∞: ∞; respectively normalizing to each of the convolution functions for obtaining an evaluation parameter of each primary color, the evaluation parameter of each primary color is expressed as:FactorX=H(ωX)F(ωX)FactorY=H(ωY)F(ωY)FactorZ=H(ωZ)F(ωZ) wherein, Factorx , Factory, and Factorz are the evaluation parameters; and wherein, the step of respectively normalizing to each of the convolution functions specifically includes: proceeding a center translation of an origin of each convolution function; calculating an absolute value of each convolution function at the origin; calculating a sum of the absolute values of the frequency distribution function corresponding to each convolution function; and calculating a ratio of the absolute value of each convolution function at the origin to the sum of the absolute values of the frequency distribution function corresponding to each convolution function; and selecting the evaluation parameters of the three primary colors of the standard picture from the sample picture group as the evaluation standard parameters. |
