Bug report #857

Option to ignore transparency values in "Load Min Max From Band" button

Added by cgs_bob - over 16 years ago. Updated over 14 years ago.

Assignee:ersts -
Affected QGIS version: Regression?:No
Operating System:Gentoo Easy fix?:No
Pull Request or Patch supplied: Resolution:fixed
Crashes QGIS or corrupts data: Copied to github as #:10916


I am working on a dem that has a nodata value of -9999. The person who created this also used the value -999 as a "novalue". So, I made -999 transparent. When I click on the "Load Min Max From Band" button, I wish it would not consider the transparent values.


#1 Updated by ersts - over 16 years ago

The NoDataValue should not be considered for sure. As for Transparent values, it may be possible to consider 100% transparency pixels as "no data" but this could lead to so other strange behaviour. This is an enhancement that should be reviewed by the Steering Committee.

#2 Updated by ersts - almost 16 years ago

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

The NoDataValue is now excluded in both the estimated and internally computed min-max.

As for the second idea, after some thought I don't think excluding 100% transparent values will be possible or really appropriate.

1) The raster class is currently heavily reliant on GDAL, and uses GDAL's GDALComputeRasterMinMax to get the estimated min-max values. This function does not have the ability to ignore values other then the nodatavalue - as far as I understand

2) The transparency setting is just that, a way to change the transparency of pixel values. It is not really an on the fly recoding capability. I think a simple raster reclassify plugin would be the way to go, which could be a great core feature as well but not something that will be possible for v1.0

This idea should be revisited toward v2.0

#3 Updated by Anonymous over 14 years ago

Milestone Version 1.0.0 deleted

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