[vorbis-dev] Integer wavelet video codec (source and test program)

[Marshall Eubanks]

"Martin C. Martin" wrote:

> Hmm, that's not the formula I'm familiar with.  YUV comes to us from
> color television.  When color was introduced, everyone still had black
> and white TVs, so it had to be backwards compatible.  Therefore, they
> ued the following formula:
>
> .299 r + .587 g + .114 b
>
> That more or less corresponds to the sensitivity of our eyes.

Hello;

NTSI standard YIQ is

Y       |  0.299    0.587  0.114   |   R
          |                                      |
I    =  | -0.596   -0.275  -0.321  |  G
         |                                       |
Q      | -0.212   0.523    0.311   |  B

This is a matrix equation, the inverse transformation can be found from the matrix inverse.

There are a bunch of other color transformations for different standards and applications.
I'm sure some web site lists them all...

Marshall

>
> I don't have the formulas for U and V here, I could look them up if
> you really need them.
>
> - Martin
>
> On Wed, 7 Feb 2001, Lourens Veen wrote:
>
> > Hi,
> >
> > I have a question about the yuv->rgb and rgb->yuv formulas. They work
> > out to:
> >
> > u = r - g;
> > v = g - b;
> > y = g + 1/4*r + 1/4*b;
> >
> > I understand that green is generally more important than blue and red
> > but isn't this a bit radical?
> >
> > Lourens
> >
> >
> > Holger Waechtler wrote:
> > >
> > > Hi everybody,
> > >
> > > I wrote last time some code to do video compression using a 3d integer
> > > wavelet transform. Since it uses a reversible lifting scheme and avoids a
> > > lot of floating point operations compared to Jacks initial Tarkin code,
> > > this should be somewhat faster and allow lossy+lossless compression.
> > >
> > > The current implementation is very experimental, but nevertheless I would
> > > be happy if some of you would take a look on the source available at
> > > http://www.informatik.hu-berlin.de/~waechtle/w3d-0.1.14.tar.gz (about 9k).
> > >
> > > Comments, ideas, help and contributions are always welcome.
> > > Please cc me in replies, I'm not subscribed on this list.
> > >
> > > - Holger

T.M. Eubanks
Multicast Technologies, Inc
10301 Democracy Lane, Suite 410
Fairfax, Virginia 22030
Phone : 703-293-9624
Fax     : 703-293-9609
e-mail : tme at on-the-i.com     tme at multicasttech.com

http://www.on-the-i.com http://www.buzzwaves.com

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