I can't really tell from that, but.... one thing that may be worth doing is to switch to point filtering and grab pics from both android and iOS. If there are any differences, we'll see it there. It isn't anything to do with the source files, as you're using the same source files in both platforms. It isn't the atlas either, as that is shared too. It must be something about how its drawing it and hopefully point filtering will make that clearer.