Hi over there,
a month ago I reported to the list an issue with 'gimp-levels', I don't know if it was labeled as a bug, I have HUGE connectivity limitations and my only way to make this issues known is via the developer's list, if I could I would use the proper way of bug reporting, but sadly I can't.
I encountered some weird behaviour when using 'Desaturate' on a Layer generated by 'Filters->Render->Cloud->Plasma' in GIMP-2.8, here's the way to replicate the result:
Create a new image, 2400x3600 px, go to 'Plasma' like mentioned before and use '945795896' as the seed, I've used other seeds with the same result, but let's use this to exemplify, activate 'Use GEGL' in Colors and 'Desaturate' using 'Lightness' as shade of gray, you will see the "pixelation" I'm talking about from approximately pixels 1000 to 1600 in Width and 0 to 588 in Height, this occurs in some other areas of the Layer as well, likewise using different seeds or different shades of gray although in other areas of the Layer. 'Desaturate' with 'Use GEGL' deactivated gives the correct result, or at least the results given by GIMP-2.6 and GIMP-2.7.4, the other versions I'm using here.
Best Regards,
Aliet Expósito García

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