The original image I do have is the one on the top of this screenshot, I would like it to have a black background. The problem as you can see below is the loss of clarity whenever it has a dark background.
Long story: I need that image to appear as a tile of a menu in a website (http://www.sharpmix.com/) that has a white background. I guess this is the way to go but I'm not a graphics designer at all, any ideas are welcome.
Thanks everyone, I've ended up with this: