Bug report #16044
Raster: multiply causes NULLs to be painted in black
|Affected QGIS version:||master||Regression?:||No|
|Operating System:||Debian||Easy fix?:||No|
|Pull Request or Patch supplied:||No||Resolution:|
|Crashes QGIS or corrupts data:||No||Copied to github as #:||23959|
On current master, if I load a coloured TIFF, it is displayed correctly.
If I change the blending mode to Multiply, the NULLs (0s) are displayed black, and they remain black even if I switch back to Blending=Normal.
On 2.18, the same TIFF is displayed as expected.
See attached file.
#3 Updated by Paolo Cavallini almost 3 years ago
- load sample raster --> shown correctly
- Layer properties > Style > Blending mode > Multiply --> black areas appear
- Layer properties > Style > Blending mode > Normal --> black areas remain
- loading the same raster again --> shown correctly
Thanks for checking.
#5 Updated by Mathieu Pellerin - nIRV almost 3 years ago
Paolo, your going through the layer properties, not the style dock. Is that correct?
I suspect the problem has to do with the renderer losing track of the alphaBand value. When you see the black areas, try opening the style dock, go to the transparency tab and check whether the transparency band combo box is set to none (on your tif that'd be wrong) or "band 4 (alpha)".