07-03-2020, 10:48 AM
I am using linux and gmic_gimp_qt (latest) and I do not get that error message. I did a bit of pixel measuring, reckon your screenshot is about 400% After resizing the repair -> banding-denoise filter worked ok, but not really a definitive test 
If you have recently upgraded either or both of Gimp / gmic_gimp plugin I would check that you have not inherited any old gmic files from a previous plugin. Some times old versions installed in the Gimp systems plugins folder rather than the User Gimp plugins folder. Unlikely but worth a check.
Everything clean? I have had a good search around and nothing really suitable came up for that type of banding.
Somebody might come up with a good procedure.
For the gmic_gimp_qt plugin error. The author of the plugin answers posts on https://discuss.pixls.us/ forum. I would ask there.
If you have recently upgraded either or both of Gimp / gmic_gimp plugin I would check that you have not inherited any old gmic files from a previous plugin. Some times old versions installed in the Gimp systems plugins folder rather than the User Gimp plugins folder. Unlikely but worth a check.
Everything clean? I have had a good search around and nothing really suitable came up for that type of banding.
Somebody might come up with a good procedure.
For the gmic_gimp_qt plugin error. The author of the plugin answers posts on https://discuss.pixls.us/ forum. I would ask there.