Thanks for the comments guys. I worked on my technique a little

and got rid of the dreaded white halo problem. To double-check my work, I pasted the fixed .png's onto a black background (see preview), so they're all nice and clean in the game.
I also went through the in-game rosters and made a couple more portraits that imo needed a little fixin' up, cause the originals look downright silly, the player's look/hair has changed, and/or couldn't find good ones to download. There's probably gonna be some overlap with portraits that others are working on, or haven't released yet, in any case, I figured I'd put a few together myself.
Cheers, Tibs
