Bug confirmed here, I’m investigating…
Apparently, this is fixed with this patch : Fix CImg<T>::get_blur_guided(). · dtschump/CImg@6fbf12e · GitHub
It was a bug in the CImg Library function CImg<T>::get_blur_guided().
I’ll post new pre-release packages of G’MIC including this fix tomorrow 
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I’ll watch for it and report back when I get time
I’ve been finally able to post new binaries for the 2.2.2_prerelease version of G’MIC, including the bug fix for the guided filter.
Available for testing here : Index of /files/prerelease
Feedback appreciated !
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Thank you very much for this nice filter. Very, very good with old newspaper halftone images. I can achieve nice results in minutes, instead of half an hour.
edit: The preview options are incredibly helpful, especially the FFT difference preview.
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In the case of the clown image, the following G’MIC filter may also be interesting:
G’MIC Repair>Unstrip
a filter made by Jérôme Boulanger.
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