We just launched a major change to the image uploader. Animated Gifs are still a PITA, so if you're going to be 1337 with that go for it.
However, for a standard .jpg you can use a photo of any size and crop it how you see fit.
A quick word on blocking ads
It looks like you are using an ad blocker. That's okay. Who doesn't? But without advertising revenue, we can't keep making this site awesome. Click the link below for instructions on disabling adblock.