matlab实现线性对比度展宽

clc;

clear all;

f=imread('1.bmp');

f=rgb2gray(f);

figure(1);

imshow(f);

[m,n]=size(f);

fa=40;

fb=120; 

ga=20;

gb=160; 

a=ga/fa; 

b=gb/fb;

b=(gb-ga)/(fb-fa);

c=(255-gb)/(255-fb);

for i=1:m

 for j=1:n

    if f(i,j)<fa

        g(i,j)=a*f(i,j); 

    elseif f(i,j)>=fa&f(i,j)<=fb

g(i,j)=b*(f(i,j)-fa)+ga;

     else

g(i,j)=c*(f(i,j)-fb)+gb;     

       end

     end

    end

figure(2);

imshow(g);