I'm trying to use a tileset to build a map but I found that this started really killing my framerate. So I decided to try using TexPlay's img.splice to build up the final result image and just rendering that (rather than rending each individual tile).
Actually what I'm doing is allowing a map creator to be able to place two tiles on a given location. This way if there is some tile that has transparent pixels, they can choose what makes sense to be behind that tile on this particular map.
For instance, 4 tiles together make up a flower, but they don't fully fill out the 4 tiles of space, so all around it are transparent pixels so that a map creator could choose to make the secondary tile full green (if the flower is on grass), or grey (if the flower is growing through a crack in the cement or some such).
However, when I use TexPlay to build up this final pre-stitched result image, I get a black boarder around tiles that have transparent pixels.
To see what I mean check out https://github.com/lukebergen/the_editor
(sorry for the code, it's a bit messy at this point while I still flesh out the system)
If you swap "stich" to "false" in application/renderer.rb line 64 you'll see that the black boarders around the flowers go away.