[link] is the place to go, but it's by no means perfect. You kind of have to use it as a starting point and then photoshop the hell out of it to get things looking right and even slightly symmetrical. I recommend using the advanced settings, fiddle with them till you get it kinda looking right, then just fix it later. Ooh, also, if you can, try and colour replace in either paint of photoshop any black with greys or something, because when you need to fix random squares to get them the right colour it makes it a lot easier, then you can always make them black once you've got it how you want it to look. Hope that helps!