MATLAB: Problem in Gray Level Manipulation

gray level manipulationImage Processing Toolbox

Hi all,
I tried to enhance a gray scale image by using the formula
   E(i,j) = round( I(i,j)^3/ f * M^2)
where
      M = max gray level of the image
      f = 0.8
The output should be a gray scale image, but I get a binary Image.
Thanks for your help in advance.
Code :
[x,y] = size(I);
I1 = repmat(uint8(0),x,y) 
M = max(I(:));
for i = 1:x
    for j = 1:y
        if I(i,j) ~= 0
          v = double(I(i,j));
          I1(i,j) = round( v^3 / f * M^2 );
          % disp(I1(i,j)); ' all manipulated pixels has value 255
        end 
    end
end

Best Answer

What are some values of z? Also, have you looked at I1 in the variable editor to verify that they're all 255 or 1? Have you tried to display I1 with [], like this:
imshow(I1, []);
which you need to do for floating point images? M^2 is in the numerator - is that what you want? The units seem all weird - you'll have an output that is proportional to gray level to the fifth power! Are you missing some parentheses? Like you want M^2 in the denominator? Where did you ever get this formula anyway? Do you have a citation for it?
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