Anything bigger than 500x600 would work just fine! I just need it bigger than that so that I can crop and scale without losing any quality of the image (because the gradient I use does tend to pixalate quite a bit). The smallest I'd say you could go with is 500x500 (a normal instagram picture is something around this size, I think). If you're really having problems, message me off anon and we can talk about it. I might be able to find a good picture for you.