全局低照度图像增强matlab

 
clear;
clc;
close all;
%读入图片
A=imread('before.png');
% A= rgb2gray(A);
% mean2(A)
% std2(A)
%显示源图片
figure ;
imshow(A);
title('RGB Original Image')
%调用ALTM
outval = ALTM(A);
% mean2(outval)
% std2(outval)
%输出目标图像
figure ;
imshow(outval);
%图像增强函数
function outval = ALTM(I)
II = im2double(I);
Ir=double(II(:,:,1));
Ig=double(II(:,:,2));
Ib=double(II(:,:,3));
% 
% % % Global Adaptation
% input world luminance values
Lw = 0.299 * Ir + 0.587 * Ig + 0.114 * Ib;
% Lw = im2double(I);
% % % the maximum luminance value
Lwmax = max(max(Lw));
[m, n] = size(Lw);%[]矩阵表示
% % % log-average luminance
Lwaver = exp(sum(sum(log(0.001 + Lw))) / (m * n));
Lg = log(Lw / Lwaver + 1) / log(Lwmax / Lwaver + 1);
gain = Lg ./ Lw;
gain(find(Lw == 0)) = 0;
outval = cat(3, gain .* Ir, gain .* Ig, gain .* Ib);
% outval = gain .* Lw;
 
end

 

 效果如下：

原始图片before

 效果图片after

 原始图片

 效果图片：

 原始图片：

 效果图片：