Created attachment 103841 [details]
Original hosto (bottom), curve histo (right), and wrong levels histo (left)
Filter "Levels" and Filter "Threshhold" shows wrong histogram. Looks like it scaled by ~ 1/0.75 or so. Bars becomes little fat also because of that bug.
That's because it is a LAB histogram, not a RGB histogram. Not sure what to do with this...
I saw a weird behaviour regarding this. If you switch to logarithmic and switch back to normal again it shows the correct one. Also i noticed that histogram (wrong one) is a bit pixelated, could it be that it is stretched horizontally beyond the graph?
I think that raghukamath is right here. Also, this bug must always have been in the levels filter dialog, since the histogram drawing code has never been touched.
Git commit 525da2eaa913dee3fcd3150afd97db730371368e by Boudewijn Rempt.
Committed on 02/05/2019 at 09:17.
Pushed by rempt into branch 'master'.
Fix displaying the levels histogram
There were some weird things wrong with the layout of the dialog,
and for some reason, some hard-coded sizes coupled with hard-coded
cutting off from the histogram pixmap.
M +8 -8 plugins/filters/levelfilter/kis_level_filter.cpp
M +2 -2 plugins/filters/levelfilter/kis_level_filter.h
M +13 -13 plugins/filters/levelfilter/wdg_level.ui