I think, a while back, if you posted a picture on an entry over at RHDN, they insist it must be 256x224.some people are still not sure about what the vertical resolution of the NES is, or that it can switch between 240 and 224.
It seems they updated their policy...(either 256x240 or 256x224).
http://www.romhacking.net/?page=help&ac ... tionalhelp
Or, my memory is bad.