There is a big image, but it's either a big CoV icon or a big CoH icon. The strange thing is that on the "My Characters" screen, in the "Img" column there is a little Custom Image icon.
The other strange thing is, when I uploaded the images (for 6 different characters), each time I was given a screen to select the viewable portion of my image and the image displayed just fine on that page. Since my images were already sized to 200x200, I didn't need to do anything.
I tried both jpgs and2 24-pngs, and have had the same result regardless.