Thanks, guys (and good to hear from you, Martin). BUT, it won't work. Opacity doesn't seem to work with a projected image. At least, I can't get it to work, or my brain has been deteriorating lately.
Strangely, in a simple setup, there's no haze, but in the mountain file there is. Maybe it's the clouds that have an influence....
Anyway, here's some file to play with, see what you can make of it. Changed the TIF to a JPG, for posting.