Reconstruct JPEG Huffman Table?

The further I get into the study of the JPEG format, the more
questions I have :-)

Let's say I have a JPEG with everything BUT the huffman tables
included (perhaps it got corrupted) is it possible to reconstruct the
huffman tables?

Thanks again!
Jackson

On 28 Sep 2004, Jackson wrote:

> The further I get into the study of the JPEG format, the more
> questions I have :-)
>
> Let's say I have a JPEG with everything BUT the huffman tables
> included (perhaps it got corrupted) is it possible to reconstruct the
> huffman tables?

I'm not sure but I think there're some default tables defined.
If the JPEG file does not contain any huffman code tables you have to
use the "default tables" (which are defined in the JPEG standard)

I might be wrong, though. It's been a while since I tinkered with
the JPEG specification.


Ghis!
Sebastian

--
PGP-Key-ID (long): 572B1778A4CA0707

"Jackson" <jsmith193300@yahoo.com> wrote in message
news:680af4.0409280848.60a20c22@posting.google.com...
> Let's say I have a JPEG with everything BUT the huffman tables
> included (perhaps it got corrupted) is it possible to reconstruct the
> huffman tables?

If there was a *fast* way to do it, then the tables probably wouldn't be
included in the first place.  There might be a *slow* way.  Try all possible
tables, look at the picture...

Better yet, attack it like a monoalphabetic cipher...

-- Matt Mahoney