Program for extracting Digicam setting information from Exif Jpeg headers
used by most Digital Cameras.
Things the 'jhead' program can extract from an Exif file:
 - Integral low-res Exif thumbnail
 - Shutter speed
 - Camera F-stop number
 - Flash used (yes/no)
 - Focus distance (some digital cameras store this element - very
   interesting)
 - Focal length (most zoom cameras store their zoomed-to focal length)
 - Equivalent 35mm focal length (Calculated from focal length, CCD size,
   and CCD resolution)
 - Image resolution
 - Time and date picture was taken
 - Camera make and model