[gdal-dev] Support for the premultiplied alpha channels

Frank Warmerdam warmerdam at pobox.com
Sun Mar 16 14:51:07 EDT 2008


Tamas Szekeres wrote:
> Folks,
> 
> Do we have any support to use bitmaps with premultiplied alpha
> channels? I think there are some raster formats that can convey these
> types of images and the viewers can take care of this option.
> 
> The only thing I'd like to see is to be able to determine if the image
> actually uses premultiplied alpha regardless of whether the drivers
> actually support this or not at the moment.
> 
> But currently I don't see which is the right place to denote this
> option. I consider this is a dataset wide property rather that
> attached to a single band.

Tamas,

There is no GDAL way of expressing whether image bands are premultipled
with alpha (unfortunately).

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org



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