m=128; n=128;
fin=fopen('I2a.raw','r');
X=fread(fin,m*n,'uint8=>uint8'); fclose(fin);
Y=reshape(X,m,n);
Y=Y';
figure;
subplot(2,2,1);
imshow(Y);
title('I2a.raw');
subplot(2,2,2);
histogram(Y);
title('Histogram');
subplot(2,2,3);
imshow(histeq(Y,4)); 
title('level=4');
subplot(2,2,4);
histogram(histeq(Y,4));
title('Histogram');
