[Gdal-dev] gdalwarp and -dstalpha

[Eric Sokolowsky]

I have experienced a strange (in my mind) problem with gdalwarp and the
-dstalpha option. When I use this option on a couple of particular images
that are reported as RGBA tiff files it turns them to grayscale. I am 
using gdal 1.2.5, but the same results seemed to occur with gdal 1.2.6.
If the source image is RGB (no alpha) the output image is RGBA, as I
expect. Is this normal/expected behavior? It would make more sense to me
to have "-dstalpha" always add an alpha channel if it is not there, and
to have a separate option "-dstnoalpha" to remove the alpha channel if
present, instead of "-dstalpha" toggle the alpha, if this is the intended
behavior.