Background removal?

[Throwaway551]

I'm trying to upload a pattern that I can edit in another program, and I'm having trouble getting around the background generation that p2p uses.

If I set the transparency on the background to completely transparent, you convert it to white, which is fine for most cases.

So I changed the background to be a color that doesn't exist anywhere else in my pattern, but the pattern generation still blends in the "bad" background color, introducing new colors that aren't part of the color palette at all along the edge of the subject.(The edges on my image don't have transparency)

Would it be possible to have an 'Advanced' option to be able to choose what the background color is used on the output pattern for the transparent pixels that you replace with white?

Or maybe be able to choose to use a distinct, special symbol for the background that isn't used anywhere else in the pattern?

[lammert]

The current transformation of images is a two step process. The first step removes the alpha channel, and the second step matches the pixel colors to available thread colors. Using the alpha channel for background transparency is an interesting idea. I didn't implement it because I thought most users wouldn't be aware of transparent backgrounds, but I'll look into a way to make this usable for the advanced users.