Conversion of thumbdata files to jpg file format

There is really no way how you could get a JPG picture out a THUMBDATA file, which is what thumbdata to jpg conversion should likely represent.

It is just a cache file that contains thumbnail data for a picture that exist, or once existed in your Android phone. The problem is a .thumbdata file contains data from ALL pictures, not just single one, so there is no way how to get a single one, even in thumbnail form.

Open THUMBDATA file    Open JPG file