[Inkscape-user] linear transparency in bitmap patterns. Is it possible?

Is it possible to change the transparency of one part of the bitmap more than the other part?

You see this effect a lot, that the transparency is like a gradient.

For instance, look at the mirrored text in the following image:

http://ftp.gnome.org/pub/GNOME/teams/art.gnome.org/themes/splash_screens/Spl...

Of course, this image can easily be done in Inkscape, given that the font is available.

But imagine that the mirrored word 'gnome' is available as bitmap only. That can't be done easily, because you cannot change the transparency as a gradient. At least as far a I could figure out. Or maybe I am missing something.

Any suggestions?