You might consider doing a forum search for  ".jpa" file type.  This is a encrypted .jpg file.  And with some special applet code and  normal .jpeg's converted to .jpa they become unreadable with image editor software.

Or click here to read the thread:

http://www.easypano.com/forum/display_topic_threads.asp?ForumID=1&TopicID=599&SearchPagePosition=1&search=jpa&searchMode=allwords&searchIn=Thread&forum=1&searchSort=dateDESC&ReturnPage=Search

Dave