Legacy ImageMagick Discussions Archive

I have just noticed that IM obviously accepts only integer values for the clip-limit, i.e. the contrast limit. Why that? I have used values between 2.0 and 3.0 quite frequently with Fiji in the past, with 2.0 producing a rather natural look, 3.0 a significantly artificial look and anything between, well, something in-between.

I applied CLAHE to my tire example:

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magick tire.jpg -clahe 25%x25%+128+2 tire_C2.0.jpg
magick tire.jpg -clahe 25%x25%+128+2.5 tire_C2.5.jpg
fc /b tire_C2.0.jpg tire_c2.5.jpg

With the binary compare yielding no difference:

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Version: ImageMagick 7.0.8-23 Q16 x64 2019-01-02 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2018 ImageMagick Studio LLC
License: http://www.imagemagick.org/script/license.php
Visual C++: 180040629
Features: Cipher DPC Modules OpenMP
Delegates (built-in): bzlib cairo flif freetype gslib heic jng jp2 jpeg lcms lqr lzma openexr pangocairo png ps raw rsvg tiff webp xml zlib

Thanks for the problem report. We can reproduce it and will have a patch to fix it in GIT master branch @ https://github.com/ImageMagick/ImageMagick later today. The patch will be available in the beta releases of ImageMagick @ http://www.imagemagick.org/download/beta/ by sometime tomorrow.

I have tested CLAHE in IM 7.0.8.24 beta today and it does shows difference between clip limits of 2, 2.5 and 3

The clip limit can be fractional, however, small changes in the clip limit does not necessarily mean a change in the distribution of excess pixels due to clipping.

Legacy ImageMagick Discussions Archive

CLAHE - no real value for clip-limit?

CLAHE - no real value for clip-limit?

Re: CLAHE - no real value for clip-limit?

Re: CLAHE - no real value for clip-limit?

Re: CLAHE - no real value for clip-limit?