I tried that on sprites but it doesn't work with grid geometry as well (so I think the problem lays in shops or vops). Whatever transparency mask I try to use with the texture - in the final render I ger slightly “white haze” in the areas where texture should be completly transparent.
I tried to shift range in vops to narrow my alpha image (and get rid off any possible grays) but this didn't help as well..
Did you premultiplied your alpha in image first or it is still unpremultiplied? Whatever is your case, try oposite one! Sorry, I don't have a clue right now but almost always problem of edges around a mask when appling texture takes from that issue…