Jigsaw solver

[mensanator at aol.com]

Tim Churches wrote:
> mensanator at aol.com wrote:
>
> >bearophileHUGS at lycos.com wrote:
> >
> >
> >>This can be interesting:
> >>http://science.slashdot.org/science/05/03/01/2340238.shtml
> >>
> >>Bearophile
> >>
> >>
> >
> >Hey, that DataGlyph demo works pretty neat.
> >
> >
> ...
>
> >Of course, being an old System Test Engineer whose job it
> >was to figure out how to break software, I couldn't let
> >this challenge go unanswered.
> >
> >So, picking up the gauntlet, I broke it in 5 seconds.
> >
> >
> ...
>
> >Naturally, the real answer is none of the above.
> >
> >And the damage can be undone in 5 seconds also.
> >
> >And, under the right circumstances, an undamaged
> >DataGlyph could suffer the same fate (which also implies
> >that the damaged DataGlyph could be read under the
> >same circumstances).
> >
> >ObPuzzle: how did I "damage" the image?
> >
> >
> You created a mirror image.

Damn. Too easy. But think how much fun you could have
with a salesman if your DataGlyph was printed on a
transparency (hence, the right circumstances being
right side up or upside down).

I once made an employee id badge that I would slip
into the salesman's stack of test badges. The employee's
name was CHECKSUM ERROR. What a laugh riot.

>
> The system can be made resistant to that problem by only allowing
> palindromic messages to be encoded, such as "Madam I am Adam.", 'Able

> was I ere I saw Elba." and "Named under a ban, a bared nude man."

Why couldn't they simply encode your input as a palindrome?

   Input: Mary had an aeroplane
Encoding: Mary has an aeroplaneenalporea na dah yraM

And then simply divide in half when decoding.

>
> Seriously, I am surprised that the Xerox demo does not try flipping
the
> image around various axes. It would be trivial to add these
> transformations. Well, trivial to flip images along a few, obvious
axes,
> but not along every possible axis.

That's why it took me all of 5 seconds - the time needed to
select the Flip Horizontal menu item in Windows Paint.

>
> What I want to know is whether any open source implementations of
this
> technology are available. No doubt it is patented to death by Xerox.

Has that ever stopped anybody?

> 
> Tim C