Created attachment 154877 [details] Visible banding on gradient after the filter is applied SUMMARY Using Gradient Map filter (either from Filter > Map, or Filter Layer) produces a visible banding, even on a higher bit depth canvas (16bpc). Segment and Stop gradient produces the same result. STEPS TO REPRODUCE 1. Create new document, preferably at 16bpc 2. Create a simple gradient (eg. Black -> White) 3. Add Gradient Map with a same gradient as before OBSERVED RESULT Visible banding occurred on the gradient (attached image) EXPECTED RESULT Gradient should be smooth, or at least as smooth as the original layer. SOFTWARE/OS VERSIONS Windows: 10 Pro 21H2 Qt Version: 5.12 ADDITIONAL INFORMATION It seems like the Gradient Map filter is processed with 8-bit precision regardless of the canvas bit depth. This can be observed by picking up the color on the gradient. The original gradient have a smooth transition, while the filtered one will have a bigger steps.
Created attachment 154878 [details] Original gradient before the filter is applied
Created attachment 154879 [details] Example krita document Try to toggle the Gradient Map filter layer on and off, then observe the gradient.
Thank you for the report. I can confirm the issue.
A possibly relevant merge request was started @ https://invent.kde.org/graphics/krita/-/merge_requests/1698
Git commit b9e615b1ff944c86b160232d9563570b511de3d1 by Merge Service, on behalf of Deif Lou. Committed on 05/01/2023 at 07:01. Pushed by merge-service into branch 'master'. Fix issue with banding in the gradient map filter Part-of: <https://invent.kde.org/graphics/krita/-/merge_requests/1698> M +16 -0 libs/pigment/KoColorSpace.h M +17 -1 libs/pigment/KoColorSpaceAbstract.h M +41 -0 plugins/color/lcms2engine/LcmsColorSpace.h M +12 -1 plugins/color/lcms2engine/colorspaces/rgb_u8/RgbU8ColorSpace.cpp M +1 -0 plugins/color/lcms2engine/colorspaces/rgb_u8/RgbU8ColorSpace.h M +6 -6 plugins/filters/gradientmap/KisGradientMapFilter.cpp https://invent.kde.org/graphics/krita/commit/b9e615b1ff944c86b160232d9563570b511de3d1
Git commit 58794306157146e0a40658554569d0f44d11db26 by Halla Rempt, on behalf of Deif Lou. Committed on 05/01/2023 at 09:04. Pushed by rempt into branch 'krita/5.1'. Fix issue with banding in the gradient map filter Part-of: <https://invent.kde.org/graphics/krita/-/merge_requests/1698> (cherry picked from commit b9e615b1ff944c86b160232d9563570b511de3d1) M +16 -0 libs/pigment/KoColorSpace.h M +17 -1 libs/pigment/KoColorSpaceAbstract.h M +41 -0 plugins/color/lcms2engine/LcmsColorSpace.h M +12 -1 plugins/color/lcms2engine/colorspaces/rgb_u8/RgbU8ColorSpace.cpp M +1 -0 plugins/color/lcms2engine/colorspaces/rgb_u8/RgbU8ColorSpace.h M +6 -6 plugins/filters/gradientmap/KisGradientMapFilter.cpp https://invent.kde.org/graphics/krita/commit/58794306157146e0a40658554569d0f44d11db26