SweetFX?

Hi I was just wondering what the legality of using SweetFX was? It don't mess with the game but from what i have seen online. Some people have really been able to deal with the washed out look on some of the graphics and make them alot crisper. Just wanted to get people opinion on where this is legal to use?

Thanks :)

It's not a ToS violation as far as I know. It's modifying the game but only on client side.

It's legal. A GM somewhere has stated long time ago. It doesn't modify the game. Same goes for all those overlays some people using.

Thanks for the replies @Evangela and @Riardon

Even it's illegal, i wouldn't give a damn.