> Remember that standard graphic algorithms, such as GIF or JPEG, use industry
> standard mathematical algorithms to compress data and smooth insignificant
> variations. It is easy to use these algorithms to predict how color should
> have been smoothed and to detect bits that deviate from the expected values.
> The whole theory behind color smoothing is that any given bit might be
> random noise which should be overridden with calculations based on its
> neighbors. The same algorithms can be used to detect these bits that have
> unexpected values.
There is one program which is supposedly undetectable at embedding data
into JPEG images. http://www.outguess.com has some very sophisticated
statistical analysis behind it (see the papers on the web site).
The author has shown how to detect all the other JPEG embedders and
has constructed his software to be undetectable by the best methods he
could come up with. So far I am unaware of anyone showing how to detect
data embedded using his technique.
This archive was generated by hypermail 2b30 : Fri Oct 12 2001 - 14:40:53 MDT