Some time ago I started examining metadata in jpeg especially embedded thumbnails. And I found many interesting things about it. Do you know that some photo cameras add additional thumbnail with resolution up to 640x480 px. It can be very useful in situations when you found broken image. For example:

1) We found photo image with car, but there is no car number: Photo.

2) We can see small thumbnail in exif segment, but number so tiny: Exif thumbnail.

3) But we can see big thumbnail in additional FPRX segment with numbers: FPRX thumbnail.

4) Profit!

I found about 10 different proprietary segment types which can contain additional thumbnail. Also jpegs can contain embedded audio. And I donít know any software (except my) which can read it. Is I am wrong?