First, thanks all for a great set of tools! Anyway, I've seen this mentioned in a post elsewhere, but there was no reply. I'm not sure who to 'blame', gdal or imagemagick, but it seems like the alpha channel embedded by imagemagick is NOT compatible with gdal. The transparency is NOT used. (since imagemagick has no clue about geo-data after image processing I use geotifcp to add that).
Example: gdalinfo bad-example.tif <<geo meta removed>> Band 1 Block=10020x1 Type=Byte, ColorInterp=Red Band 2 Block=10020x1 Type=Byte, ColorInterp=Green Band 3 Block=10020x1 Type=Byte, ColorInterp=Blue Band 4 Block=10020x1 Type=Byte, ColorInterp=Undefined A working file looks like this: gdalinfo good-example.tif <<geo meta removed>> Band 1 Block=10020x1 Type=Byte, ColorInterp=Red Mask Flags: PER_DATASET ALPHA Band 2 Block=10020x1 Type=Byte, ColorInterp=Green Mask Flags: PER_DATASET ALPHA Band 3 Block=10020x1 Type=Byte, ColorInterp=Blue Mask Flags: PER_DATASET ALPHA Band 4 Block=10020x1 Type=Byte, ColorInterp=Alpha I.e, it seems like the alpha from imagemagick is global but gdal expects a per dataset alpha ? _______________________________________________ UbuntuGIS mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/ubuntu http://trac.osgeo.org/ubuntugis/wiki
