Question

I have a greyscale image which has pixel values ranging from 1.000 to 1.003.

I would like to increase the contrast between the different pixels. I have tried imcontrast under imtool, but I’m not seeing any improvement visually.

Perhaps an idea would be to increase values of pixels >1.000. For example, it would be great if I could map 1.001 to 10, 1.002 to 20 etc. Would that increase contrast?

Answer 1

Try

newRange = 1.0;  %// choose the new maximum. (new minimum always at 0.0)
imgMin = double(min(image(:)));
imgMax = double(max(image(:)));
image = (image - imgMin) / (imgMax - imgMin) * newRange;

Then, you still need to watch for the possibility that the image may be blank (which would cause a divide-by-zero issue).

If the desirable range that you would like to amplify is not the true minimum or maximum, you can set imgMin and imgMax values manually.