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);