Predicting user input is hard sometimes, that’s why we validate. If you design a system, that allows the user to give you very different inputs, in this case, extremely different pictures, that you still have to display in a reasonable way, it get’s a little tricky.
Designers on deviantart often upload designs, in this case web designs, as a really, really long picture, to show the best page layouts they designed for that project.
Once again, deviantart does something well and just cuts of the thumbnail if they exceed a certain aspect ratio. If the picture is too long, it gets a border at the bottom and casts a shadow over the lower part. The gallery above belongs to Eduardo Santos by the way.