Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!jarthur!elroy.jpl.nasa.gov!decwrl!limbo!taylor
From: gahooten@orion.arc.nasa.gov (Gregory A. Hooten)
Newsgroups: comp.society
Subject: Re: Manipulation of Courtroom Evidence
Message-ID: <450@limbo.Intuitive.Com>
Date: 23 Feb 90 18:28:18 GMT
Sender: taylor@limbo.Intuitive.Com
Organization: NASA - Ames Research Center
Lines: 12
Approved: taylor@Limbo.Intuitive.Com

This type of deception has gone on for a long time, and there is a whole
battery of tests that can be run to see if the photo is real.  One is to 
check for the consistency of background lighting, or the abrupt changes
in shading.  Remember that to make a forgery, you had to scan it in 
in the first place, edit it, and then get it back to a photo.  All of 
this can be done by an investigator.  As closely as you can look at
the photo, they can too.  There will always be bits that were not changed
to the correct pattern, or that were cut out of one photos background, and
placed into another.  These bits can be read.  It is easy to fool many 
people, but it is more difficult  to fool them for long.  

Greg