On Meta we proposed a project for the digital restoration of images. These images are typically public domain and they are often made available from a friendly archive. In the workflow of a restoration, there are several moments when a change is made that cannot be undone. When you work on restorations in a Wiki way, you have to save the work before such a change because this allows others to improve on them.
Images that are being restored may not be compressed because this introduces distortions that negate the restoration work. Once a restoration is completed, it may be compressed for use in Commons. For a normal illustration in a Wikipedia article compression is normal.
When you look at a really big picture, it can take quite some time before it is available to you; it slowly build from top to bottom. It is like watching paint dry. It makes more sense to start with an outline of the image and drill down for more details. Djatoka is open source software written by the Los Alamos National Laboratory that does exactly that. When I read its specifications, it makes me feel really entheausiastic. Have a look at this ox for instance.
So the next question is how do we make this functionality part of MediaWiki.