The base equations are well known, but the specific scaling factors used by
the TIA aren't as well known. I believe what was done for the latest Z26
was to use the RGB output of a video capture card.
But if you are interested, here are the NTSC formulas.
R8 = 255 * ( Y + 1.402 * Pr )
G8 = 255 * ( Y - 0.344136 * Pb - 0.714136 * Pr )
B8 = 255 * ( Y + 1.772 * Pb )
where
Y = ( COLU AND 15 ) / ( luminance )
Pb = saturation * cos ( hue )
Pr = saturation * sin ( hue )
hue = 180 degrees - ( COLU / 16 - 1 ) * 24 degrees
saturation = 0 if ( COLU / 16 == 0 ), otherwise some value between 0 & 0.5
luminance = some value 14 or greater
(base formula from http://www.poynton.com/PDFs/ColorFAQ.pdf)
----- Original Message -----
From: "Adam Wozniak" <adam@xxxxxxxxxxxxxxxx>
To: <stella@xxxxxxxxxxx>
Sent: Friday, September 26, 2003 2:04 PM
Subject: Re: [stella] tia hue luminance
> On Wed, 24 Sep 2003, Adam Wozniak wrote:
> > What equations are used to convert 4 bit hue / 3 bit luminance to
> > RGB 8/8/8 ?
> >
> > I've seen tables for the conversions, but I'd like to know what
equations
> > are used.
> >
> > I am interested in both NTSC and PAL.
>
> Nobody knows?
>
> --
> adam@xxxxxxxxxxxxxxxx http://cuddlepuddle.org/~adam/pgp.html
> Will code for food. http://cuddlepuddle.org/~adam/resume.html
> "The dinosaurs are not around today because they did not have a space
program."
> -- Arthur C. Clarke
>
> --------------------------------------------------------------------------
--------------------
> Archives (includes files) at http://www.biglist.com/lists/stella/archives/
> Unsub & more at http://www.biglist.com/lists/stella/
----------------------------------------------------------------------------------------------
Archives (includes files) at http://www.biglist.com/lists/stella/archives/
Unsub & more at http://www.biglist.com/lists/stella/
