[zottel]

ATM I can only think of one thing that will work for sure: Emptying the cache and going to the page again.

The cache itself unfortunately saves everything as a file named <xyz>.cache—there's no easy way to find out which of the files are JPEGs or HTML files or whatever. (The unix command line utility "file" can tell you what kind of data actually is in a file, but there are just too many files in the cache to test them all by hand—you'd have to write a short script or something.)