Colorspace FAQ (was Re: editing?)

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You mentioned below that you are prodding Vektor to
write something up on color spaces.  Have you looked
at the colorsapce FAQ? If not, here's a link.

http://www.faqs.org/faqs/graphics/colorspace-faq/


-----Original Message-----
From: Erik Walthinsen [mailto:omega@xxxxxxxxxxxxxxxxxx]
Sent: Friday, March 22, 2002 12:48 AM
To: video4linux-list@xxxxxxxxxx
Subject: Re:  Re: editing?


On Fri, 2002-03-22 at 00:27, Gerd Knorr wrote:
> >    Application writers need to either get over the fact that they should
> >  be building a lib since none of the kernel folks have.  libcolorspace
is
> >  a step in that direction.
> URL?

libcolorspace is a project that's part of the http://codecs.org/ stuff,
most of which is software I've been writing over the last year or so. 
libcolorspace is a recent addition, with the current code in CVS having
been written as a prototype by Wim Taymans, who's also a GStreamer
hacker.

vektor and wtay and I were hashing out stuff in IRC today, trying to
figure out what we really mean by libcolorspace.  My initial plan was
for it to be a repository for high-speed color conversion routines, such
as yuv2rgb for MPEG decoding, etc.  I've written a very fast MMX
conversion routine I'd love to a) compare against others, and b) see
people use.  So have others.

Where things get nasty is when you realize how much there is to color on
its own, not even taking into account the various aspects of sampling
and packing.  vektor is our resident expert on the color issues, and
I've been prodding him to write a page or 3 on what all the color issues
are as they're relevant to computer video and graphics, written for
someone who has a decent idea of the basics, and CS in general.

I've talked with the gcms author, who sounds like he's interested in
getting the whole ICC profile stuff integrated as well.  The trick in
all this is to keep in mind that the end goal of the library is to
convert images from one colorspace/format to another.  Quickly.  To that
end there will have to be a large collection of predefined colorspaces,
and fast mechanisms to select the appropriate hand-coded conversion
routine if it exists, or pick the best of the more general routines.

There's a devel mailing list on codecs.org that people can subscribe to
(http://lists.sourceforge.net/lists/listinfo/codecs-devel) if they want
to discuss libcolorspace or any of the other projects on codecs.org. 
It's silent now, maybe we can fix that <g>

      Erik Walthinsen <omega@xxxxxxxxxxxxxxxxxx> - System Administrator
        __
       /  \                GStreamer - The only way to stream!
      |    | M E G A        ***** http://gstreamer.net/ *****
      _\  /_



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