When a site is being planned, an image mummifier should extract relevant information from supported images.
Probably at least Exif metadata from JPEG should be supported.
What "relevant" means is yet to be determined. It may parallel how HTML pages work, accepting any parseable metadata. In particular some some sort of title and copyright should be detected and extracted.
This means we'll probably have to take a closer look at what property we want to use for copyright. This could be some general property analogous to label and icon. Note also that the DCMI already has a dc:rights property.
Because users could be dumping original images into the source tree, some sensitive metadata may need to be filtered out. Maybe this could be configured. Maybe only known/configured metadata would be supported.