Batch rename to remove multiple prefixes

[sourbob]

I've got a huge mess of .jpg files all named like this:

bunch.of.data.specific.to.folder.file.is.in-folder.jpg

I have thousands of images with thousands of variations of that prefix. They are now all just being renamed like this:

folder.jpg

The other info is now in their folder names, so the long file names are redundant.

So how would I do this?

[Stefan]

Use fixed name 'folder'