<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/1999/REC-html401-19991224/strict.dtd">
clc;
clear all;
close all;
a=imread('cameraman.tif');
[m,n]=size(a);
for i=1:m
for j=1:n
if a(i,j)<=80
a(i,j)=255*ones();
end
end
end
imshow(a);