Changing Scale From RGB to Gray

close all;
clear all;

A=imread('nameofyourimage.typeofimage');
%I recommend you to put your image in the same
%file which you save your code.

A_gri=rgb2gray(A);
%rgb2gray() function is convert an rgb image to
%gray scale.

figure(1);
subplot(211);
imshow(A_gri);
title('Gray Image');
subplot(212);
imshow(A);
title('RGB Image');