Re: image processing function list

[Jaroslav Hajek]

On Wed, Jul 23, 2008 at 1:53 PM, John W. Eaton <address@hidden> wrote:
> On 22-Jul-2008, bharat pathak wrote:
>
> |     Today morning someone was mentioning that he wanted to contribute
> |     towards the function library built up for image processing. Maybe the 
> missing
> |     functionlist can get him started.
>
> I think it should be obvious to anyone working on Octave, but it is
> probably worth repeating that if you are planning to contribute code
> to Octave, you should never refer to any Matlab .m files that you
> happen to have access to.  Code that you write and contribute to
> Octave or Octave Forge must not be derived from sources which are not
> freely redistributable (in a GPL-compatible sense).  Using non-free
> sources for "inspiration" or to understand an algorithm invites
> copyright infringement and puts the entire Octave project at risk.
>

Although I don't want to advocate getting inspiration in Matlab codes,
I don't think the situation is as dark as you suggest.
According to my understanding (stemming from reading Wikipedia),
copyright does not protect ideas - that's what patents do.
Copyright can only protect a fixed expression of an idea. So,
technically, if you inspect a Matlab code to get an idea how a
computation can be done, then implement it yourself (but not copy,
including copying by hand), you don't violate the Mathworks'
copyright, even if you actually refer to the Matlab m-file in
question.
If the idea ("a computer-implemented invention") is patented, you
*are* violating the IP, but this time regardless of whether you
actually copied or not (and that's one thing why patents suck).
Not that I would like to encourage others to scan Matlab's m-files for
getting ideas how to implement things, but I don't think that anyone
who ever inspected Matlab's files is lost for Octave forever. Just
don't copy any code (that's illegal) and don't plainly copy Matlab's
ideas (that's lame).
If my understandings of the legal aspects are incorrect, I'd welcome
if anyone explains more to me.

regards,


> jwe
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-- 
RNDr. Jaroslav Hajek
computing expert
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz