pkg load image;

pic = randi(256,10);

hold on

imshow(mat2gray(pic));
cols= size(pic,2);
rows= size(pic,1);

ints = (0:255);
ints(:)=0;


for k = 1:1:256
ints(k)=sum(pic(:)==k-1);
end

figure;
for c =1:cols
  for r = 1:rows
    val=pic(r,c)+1
    ints(val)++;
  end
end

xaxis = (1:1:256) ;
plot(xaxis,ints,'r');
hold off;