This is kind of a bad example just do to the quality but better than nothing I suppose, the one with the effect came off some other forum.
Original:

With Effect:

If you can see it, you only see the darker parts of the original, almost like an outline, and the lighter parts are transparent, and I have no idea how to do something like that.
This seems kind of similar:

Original:

With Effect:

If you can see it, you only see the darker parts of the original, almost like an outline, and the lighter parts are transparent, and I have no idea how to do something like that.
This seems kind of similar:
