[PATCH] gdal_merge.py alpha mask
|Reported by:||stefanklug||Owned by:||warmerdam|
gdal_merge.py doesn't handle tiff files with alpha masks so I've added this functionality.
My patch changes the behaviour of gdal_merge as follows:
- If a band is recognized as Alpha Band it is automatically treated as having a NODATA value of 0.
I'm not sure if this is the way to go. But it makes some sense, as the resulting alpha channel is a correct alpha merge, independent of the nodata value used for the other bands.
- If a band has mask flag GMF_ALPHA set, the mask band controls the parts that get written to the destination
Would be great if someone could review and possibly checkin the patch.