Egalisation de histogramme

clc;
clear all;
im=imread('lena.jpg');
[n,m]=size(im)
x=zeros(1,256);
for i=1:n
    for j=1:m
        x(im(i,j))=x(im(i,j)) 1;
 
    end
end
figure;
h=imhist(im);
subplot(2,1,1);bar(x)
subplot(2,1,2);bar(h)
so=0
for i=1:256
    so=(so x(i));
    so=(256/(n)^2)*so
end
figure
imshow(so);