Even Rouault <even.rouault <at> spatialys.com> writes: > > > > GDAL ECW driver does not have support for this. I wonder if it could be > > doable and if I should make a feature request. I also wonder if GDAL can > > decode ECW files which have transparency mask correctly. > > Jukka, > > I'm a bit confused by the above. If you look to the bottom of the page you > mentio,n you'll see a gdalinfo report with an alpha band. > > And I've just tried with a test file of the autotest suite: > > gdalinfo ../gdrivers/data/stefan_full_rgba_ecwv3_meta.ecw
.... > This is a ECWv3 file. I don't have an example with ECWv2 and the "appended" > mask, but I believe the driver should also likely be able to read/write this > (but I haven't a ECWv2 image with alpha handy) Hi Even, I apologize, I do not use ECW myself nowadays but I was reading this gis.stackexchange question which deals actually with FME http://gis.stackexchange.com/questions/153490/how-to-convert-tif-to-ecw-with-fme-maintaining-a-certain-value?noredirect=1#comment225797_153490 Then I read our ECW manual page http://www.gdal.org/frmt_ecw.html which does not talk anything about nodata, alpha, transparency etc. I just thought that we can't handle nodata any better than FME but obviously we can. I do not have SDK license so I could not test ECW output myself. Is the ECW transparency band created automatically if user has Read/Write SDK >= 4.0 and source data has either alpha channel or nodata set in GeoTIFF? ECW driver does not seem to have any creation option for that but perhaps it is not necessary. -Jukka- _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
