On 09/28/2010 07:29 PM, Even Rouault wrote:
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
Even,
thanks for the info. I already was afraid it wouldn't...
I'll go and write 4band rgba tiffs directly, then.
Best,
Vincent.
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.
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