[gdal-dev] Creating jpeg compressed tiff with alpha

[Even Rouault]

Yehiyam,

Your command worked fine. It is just that your expectations are wrong. It will
produce a mask band, and not a alpha band. This is indicated by the following
line in the gdalinfo report :

>   Mask Flags: PER_DATASET

(a mask band that is common to all the regular bands of the dataset)

Mask bands can be obtained with GDALGetMaskBand(). But admitedly, I guess that
few software packages are able to deal with them. For example, recent versions
of MapServer will try using mask band if no alpha band is found.

Best regards,

Even