On bug 19688 we've been debating auto-rotation of images using EXIF data. It strikes me that for standalone images (i.e. the current URL is "foo.jpg"), we could center the image and display some metadata below it (e.g. image size) like a real image viewer.
FWIW, Safari displays image size in window title.
Yep, and Chrome displays it in the tab title. That seems fine, but I imagine putting it (and other useful metadata? Maybe some stuff from EXIF tags if present? I am pretty ignorant here) on the page somewhere would not be unfriendly.