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comp.lang.ruby

Image manipulation. FFT, 2D Folding

Brian Schröder

11/28/2004 5:38:00 PM

Hello Group,

I want to do some image analysis and therefore I need to do a 2D FFT and inverse of images and fold some kernels about the image. Is there anything already available for this, or should I use narray, or is it generally a bad idea to do this in ruby?

Anybody has some experience with thoses things?

Regards,

Brian

--
Brian Schröder
http://ruby.brian-schroeder.de/quiz/det... (Spoiler ;)
6 Answers

David G. Andersen

11/28/2004 7:28:00 PM

0

On Mon, Nov 29, 2004 at 02:37:32AM +0900, Brian Schr?der scribed:
> Hello Group,

> I want to do some image analysis and therefore I need to do a 2D
> FFT and inverse of images and fold some kernels about the image.
> Is there anything already available for this, or should I use narray,
> or is it generally a bad idea to do this in ruby?

NArray, NImage, and FFTW would seem to be exactly what you're
asking for. (Note that if you install narray from the
freebsd port/package, it doesn't install nimage - you
have to go in and make it by hand for some reason).

-Dave

--
work: dga@lcs.mit.edu me: dga@pobox.com
MIT Laboratory for Computer Science http://www....

Brian Schröder

11/28/2004 8:00:00 PM

0

On Mon, 29 Nov 2004 04:28:17 +0900
"David G. Andersen" <dga@lcs.mit.edu> wrote:

> On Mon, Nov 29, 2004 at 02:37:32AM +0900, Brian Schr?der scribed:
> > Hello Group,
>
> > I want to do some image analysis and therefore I need to do a 2D
> > FFT and inverse of images and fold some kernels about the image.
> > Is there anything already available for this, or should I use narray,
> > or is it generally a bad idea to do this in ruby?
>
> NArray, NImage, and FFTW would seem to be exactly what you're
> asking for. (Note that if you install narray from the
> freebsd port/package, it doesn't install nimage - you
> have to go in and make it by hand for some reason).
>
> -Dave
>
> --
> work: dga@lcs.mit.edu me: dga@pobox.com
> MIT Laboratory for Computer Science http://www....
>


Thanks for the answer. I'm already playing with narray and it seems quite nice.

Regards,

Brian

--
Brian Schröder
http://www.brian-sch...

DaZoner

11/29/2004 6:20:00 PM

0


Where is NImage documented? I can't find it in RAA or at NArray's homepage.

"David G. Andersen" <dga@lcs.mit.edu> wrote in message
news:20041128192740.GA33316@lcs.mit.edu...
> On Mon, Nov 29, 2004 at 02:37:32AM +0900, Brian Schr?der scribed:
>> Hello Group,
>
>> I want to do some image analysis and therefore I need to do a 2D
>> FFT and inverse of images and fold some kernels about the image.
>> Is there anything already available for this, or should I use narray,
>> or is it generally a bad idea to do this in ruby?
>
> NArray, NImage, and FFTW would seem to be exactly what you're
> asking for. (Note that if you install narray from the
> freebsd port/package, it doesn't install nimage - you
> have to go in and make it by hand for some reason).
>
> -Dave
>
> --
> work: dga@lcs.mit.edu me: dga@pobox.com
> MIT Laboratory for Computer Science http://www....
>
>


Cameron McBride

11/29/2004 8:19:00 PM

0

Greetings,

> Where is NImage documented? I can't find it in RAA or at NArray's homepage.

it's a small addition to NArray.

% tar zxf narray-0.5.7p4.tar.gz
% less narray-0.5.7p4/nimage/README.en

Cameron

Brian Schröder

11/29/2004 8:27:00 PM

0

On Tue, 30 Nov 2004 03:47:49 +0900
"DaZoner" <bugmenot@world.com> wrote:

>
> Where is NImage documented? I can't find it in RAA or at NArray's homepage.
>

Documentation for NArray and related things is really thin. It works great, but it seems to be under development and not yet fixed.

Also the NArray interface is not perfect. (E.g. It does not include Enumerable and each yields a nil as last value.)

Regards,

Brian


--
Brian Schröder
http://www.brian-sch...

David G. Andersen

11/29/2004 8:35:00 PM

0

On Tue, Nov 30, 2004 at 05:26:59AM +0900, Brian Schr?der scribed:
> On Tue, 30 Nov 2004 03:47:49 +0900
> "DaZoner" <bugmenot@world.com> wrote:
>
> >
> > Where is NImage documented? I can't find it in RAA or at NArray's homepage.
> >
>
> Documentation for NArray and related things is really thin. It works great, but it seems to be under development and not yet fixed.
>
> Also the NArray interface is not perfect. (E.g. It does not include Enumerable and each yields a nil as last value.)

For what it's worth, I've found the author to be very responsive to
questions - I've submitted one bug and asked one very dumb question,
and he addressed both of them very quickly. Great package.

It could use some fleshing out. It'd be nice to be able to append
an element to the end of an array without having to explicitly resize
it (anyone figured out how to do that?), for instance.

-Dave

--
work: dga@lcs.mit.edu me: dga@pobox.com
MIT Laboratory for Computer Science http://www....