From looking at the demo, "Size" is ambiguous.  It could refer to the size of the image file (which is relevant for downloading) or the dimensions of the image.  Three things we should think about from a product perspective:

1) Figure out whether we should refer to it as "size" vs. "dimensions"
2) Add a unit to the string, like "pixels" eg:  "1680 x 1050 pixels"
3) Do a little research to figure out what other sites (flickr, picasaweb, smugmug, etc) do here and imitate them.