[MATLAB image processing] histogram normalization

I=imread (' cameraman.tif ');
Figure
Imshow (I);
Title (' 1yuantu ');
Figure
Imhist (I);
Title (' 2zhifangtu ');
[M,n]=size (I);% Calculate image size
[Counts,x]=imhist (i,30);% calculates a grayscale histogram of 29 cells (256 average gray values divided into 29 intervals)
%counts is the corresponding histogram value, X is the position
counts=counts/m/n;% calculating the values of each interval of normalized grayscale histogram
Figure
Stem (x,counts);% plot normalized histogram
Title (' 3guiyihuazhifangtu ');