Vincent, The TIFF format doesn't allow storing the alpha component, so it is ignored.
See the TIFF specification, section 5 : http://partners.adobe.com/public/developer/en/tiff/TIFF6.pdf Possible workarounds : * work with RGBA tiff * add a mask band Best regards, Even Le mardi 28 septembre 2010 16:24:18, Vincent Schut a écrit : > Hi, > > I'm creating a geotiff with colortable using the python bindings, > however, the alpha value of the colorentry is lost / always set to 255 > (says gdalinfo on the output image). > Does gdal/geotiff with colortable not support rbga? > Or, what am I doing wrong? > > Testcase is below: > > > from osgeo import gdal > gtiff = gdal.GetDriverByName('GTiff') > ds = gtiff.Create('/home/vincent/test.tif', 1, 1, 1, gdal.GDT_Byte) > ct = gdal.ColorTable() > ct.SetColorEntry(1, (100, 100, 100, 100)) > ds.GetRasterBand(1).SetColorTable(ct) > > gdalinfo on /home/vincent/test.tif says 100,100,100,255 for colorentry 1... > > using gdal from svn, internal geotiff. > > Regards, > Vincent. > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
