[nzlug] JPEG/JFIF analysis tool?

[Nick 'Zaf' Clifford]

> It may be a good start anyway.  No licence statement so I assume it's
> in the public domain.
>
Bad assumption to make, and one which is quite critical when it comes to
the GNU GPL, and other open source licenses. Unlicensed works (works
that don't have a specific license) are NOT public domain. The author
does not even have to put a copyright statement to copyright his/her
work(s) (although it makes it easier to identify the work, obviously).
As there is no license, you have no right what-so-ever to distribute,
modify or copy the work. Unless of course the author has stated that you
may do so (which is effectively a license)

So, what can you do?
a) Contact the author, ask if he/she will release it into the public
domain, or an open source license. Otherwise ask for a exclusive use
license for it (allowing you personally to use it, shareware works like
this).

b) Assuming the source is not protected under any unwritten licensing
agreements, trade secrets, etc (think leaked windows xp source code with
copyright notices stripped off), then you could do a "clean room"
analysis on the code. eg use the code to work out the structure of
JPEG/JFIF and document the structure, then write your own code based on
that analysis. Note; in this case it'd be far easier just to look a the
JPEF/JFIF standard, its an open standard.