数字图像处理-图像增强： MSRCR Method For Image Processing

% MSRCR Method For Image Processing
% Test for Digital Image Processing
% By Gu Jinjin 2012/10/16-17
% Refer to Retinex processing for automatic image enhancemen
% And thank videoandimage08's help for sharing me some Info 
% ------
clc;clear all;

% 读取图像灰度值
I = imread('test.jpg');
IR = I(:,:,1);
IG = I(:,:,2);
IB = I(:,:,3);

% 转换为 double 类型
IR_double = double(IR);
IG_double = double(IG);
IB_double = double(IB);

% Set Gaussian Parameters
sigma1 = 5;
sigma2 = 20;
sigma3 = 240;
% 矩阵化网格向量
[x,y] = meshgrid((-(size(IR,2)-1)/2):(size(IR,2)/2),(-(size(IR,1)-1)/2):(size(IR,1)/2));

% 计算高斯环境函数 Fk
gauss1 = exp(-(x.^2+y.^2)/(sigma1*sigma1));
% 归格化 Fk = k*Fk
Gauss1 = gauss1/sum(gauss1(:));
gauss2 = exp(-(x.^2+y.^2)/(sigma2*sigma2));
Gauss2 = gauss2/sum(gauss2(:));
gauss3 = exp(-(x.^2+y.^2)/(sigma3*sigma3));
Gauss3 = gauss3/sum(gauss3(:));

% 计算MSR，MSRCR
for i = 1:3
    % MSR Part
    if i == 1
        Ii = IR;
        Ii_double = IR_double;
    elseif i == 2
        Ii = IG;
        Ii_double = IG_double;
    else 
        Ii = IB;
        Ii_double = IB_double;
    end
    % 将图像转换到对数域
    Ii_log = log(Ii_double+1);
    % 对图像傅里叶变换，转换到频域
    f_Ii = fft2(Ii_double);
    fgauss = fft2(Gauss1,size(Ii,1),size(Ii,2));
    fgauss = fftshift(fgauss);
    % 卷积
    FI1 = ifft2(fgauss.*f_Ii);
    minv = min(min(FI1));
    FI1_log = log(FI1-minv+1);
    % 计算R， MSR公式
    R1 = Ii_log - FI1_log;

    fgauss = fft2(Gauss2,size(Ii,1),size(Ii,2));
    fgauss = fftshift(fgauss);
    % 卷积
    FI2 = ifft2(fgauss.*f_Ii);
    minv = min(min(FI2));
    FI2_log = log(FI2-minv+1);
    R2 = Ii_log - FI2_log;

    fgauss = fft2(Gauss3,size(Ii,1),size(Ii,2));
    fgauss = fftshift(fgauss);
    % 卷积
    FI3 = ifft2(fgauss.*f_Ii);
    minv = min(min(FI3));
    FI3_log = log(FI3-minv+1);
    R3 = Ii_log - FI3_log;
    % 加权求和得到 MSR R(x1,x2)
    Wk = 1/3;
    R = Wk*R1 + Wk*R2 + Wk*R3;
    
    % 计算 alpha, 取f() = log
    %N = 3;
    %alpha = log(N*Ii_double)-log(IR_double+IG_double+IB_double);
    %CR = alpha.*R;
    % MSRCR
    % 设定参数
    G = 192; b = -30;
    alpha = 125;
    beta = 46;
    CR = beta*(log(alpha*Ii_double+1))-log(IR_double+IG_double+IB_double+1);
    CR=G*CR.*R+b;

    % 转化为灰度值
    R = mat2gray(abs(R));
    CR = mat2gray(abs(CR));
    % figure,imshow(Rr);
    if i == 1
        MSRr = R;
        MSRCRr = CR;
    elseif i == 2
        MSRg = R;
        MSRCRg = CR;
    else 
        MSRb = R;
        MSRCRb = CR;
    end
end
% imshow
% 将三通道图像拼接
IMSR = cat(3,MSRr,MSRg,MSRb);
IMSRCR = cat(3,MSRCRr,MSRCRg,MSRCRb);
% 显示原始图像
figure,imshow(I);
% MSR处理后图像
figure,imshow(IMSR);
% MSRCR处理后后图像
figure,imshow(IMSRCR);