I recently came across an odd JPEG file: Resolution 400x600 and a filesize of 2.9 MB. I got suspicious and suspected that there is some additional information hidden. I tried some straight forward things: open the file with some archive tools; tried to read its content with an editor, but I couldn't locate anything interresting.
Now my questions: What else can I do? Are there any tools available that analyze images for hidden data? Perhaps a tool that scans for known file headers?