mtalab图像灰度变换

clear all;
close all;
clc;

r=127;                              
x=-r:r+1;
sigma=20;
y1=exp(-((x-80).^2)/(2*sigma^2));
y2=exp(-((x+80).^2)/(2*sigma^2));
y=y1+y2;                       %双峰高斯函数，任意函数都可以

y=y/sum(y);         %归一化，使函数符合概率分布的sum(y)==1这样一个规律
x=x+r;
figure;
bar(x,y,0.000000000000000000000000000000000000000001)
xlim([0 255])
%  plot(y);            %待匹配的直方图
% imhist(y)
G=[];               %函数的累积直方图
for i=1:256
   G=[G sum(y(1:i))]; 
end

img=imread('1.jpg');
 img=rgb2gray(img);
[m n]=size(img);
hist=imhist(img);  %待处理图像的直方图
figure;
imhist(img);
p=hist/(m*n);           
figure;bar(p,0.0000000000000000000001)
xlim([0 255])
        %原图直方图

s=[];                   %待处理图像的累积直方图
for i=1:256
    s=[s sum(p(1:i))];
end

for i=1:256
    tmp{i}=G-s(i);
    tmp{i}=abs(tmp{i});         %因为要找距离最近的点，所以取绝对值
    [a index(i)]=min(tmp{i});   %找到两个累积直方图距离最近的点
end

imgn=zeros(m,n);
for i=1:m
   for j=1:n
      imgn(i,j)=index(img(i,j)+1)-1;    %由原图的灰度通过索引映射到新的灰度
   end
end

imgn=uint8(imgn);
figure;imshow(imgn)
imwrite(imgn,'1.jpg');
% figure;plot(imhist(imgn))       %新图的直方图
hist=imhist(imgn)
p=hist/(m*n);           
figure;bar(p,0.0000000000000000000001)
xlim([0 255])