Bug report #7756

transparent pixel list values not applied to RGB raster if contrast enhancement inactive

Added by Mathieu Pellerin - nIRV almost 11 years ago. Updated almost 11 years ago.

Affected QGIS version:master Regression?:No
Operating System: Easy fix?:No
Pull Request or Patch supplied:No Resolution:duplicate
Crashes QGIS or corrupts data:No Copied to github as #:16656


User-added transparent pixel values are ignored when contrast enhancement is set to "no enhancement" with RGB rasters. I'm seeing this issue with LANDSAT-7 tiles

Steps to reproduce:
1. Open a new project, make sure the map canvas background color is white
2. Load a RGB-based raster (LANDSAT-7 3-band composite is perfect)
3. Open the raster's layer properties window
4. Make sure that the contrast enhancement is set to "no enhancement" in the Style tab
5. Go to the Transparency tab, and add a transparent value manually via button (set the transparency value to Red=0,Green=0,Blue=0,Percent Transparent=100
6. Apply the settings

At this stage, the raster should redraw with any black (RGB=0,0,0) value being transparent and see through. However, QGIS now fails to make the black values transparent. If you go back into the raster layer properties's Style tab and enable contrast enhancement - say "Stretch to MinMax", the user-set transparent values will be taken into account.


#1 Updated by Mathieu Pellerin - nIRV almost 11 years ago

Note: I'm not seeing this regression on a single band raster.

#2 Updated by Mathieu Pellerin - nIRV almost 11 years ago

I've actually uploaded a LANDSAT-7 3-band true color geotiff to facilitate the testing. It's available here: http://licadho-cambodia.org/raster/321.zip (64mb)

#3 Updated by Giovanni Manghi almost 11 years ago

  • Resolution set to duplicate
  • Status changed from Open to Closed

duplicate of #7748

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