Possible Duplicate:
Can I achieve a torchlight effect (lighter area around a light source) in a 2D game?
I want to have a picture as a background, say this:
Then I would like to apply a mask, just a circle with blurred edges, so it looks like this:
The idea is to simulate something emitting. Is this a good way of simulating light or should I use another method? And if so how? And I'm not really sure how to apply this method.