[turvas]

Originally Posted by tamlin

That's easy:

1. Make a new, transparent layer above your image.
2. Use your favourite selection tool to select the area that you want to be translucent.
3. Fill with white.
4. Lower opacity of layer to about 40%

Alternatively, you could do a fancier version by applying a white-to-transparent gradient to the top layer.

Yep. That's that. But the userbar designer also gives many good ideas.