What caused me some problems (and this has happended before) is that the color is very "gritty" or "pixellated" which makes it hard to get a smooth blend without actually copying sections from the edge into the tile. Even that isn't a perfect solution, though, because if you're unlucky you get a kind of repeating pattern due to the small area you have to copy from. Have a look at the top of the tile below and you can see what I'm talking about.

None of this takes anything away from the quality of this tile, though. Good work!

//PikeWake