In article ,
 "Michael J. Mahon"  wrote:

> John B. Matthews wrote:
> > In article ,
> >  "Michael J. Mahon"  wrote:
> > 
> >> John B. Matthews wrote:
> >>
> >>> http://home.woh.rr.com/jbmatthews/a2/lores.html>
> >>>
> >>> I have a clear memory of the NTSC video red being a dark shade, as 
> >>> Linards suggests. I have no idea why the Applesoft manual calls it 
> >>> "magenta," which I identify with a secondary
color having sRGB 
> >>> components (0xFF00FF). Of course, the html rendering is itself a 
> >>> function of the monitor's calibration.
> >>
> >> Color 1 has only one bit of four set, so its luminance value is
> >> 25% of white.  The hi-res colors (not white and black) all have
> >> two bits set, and so have a luminance value of 50%, so lo-res color
> >> 1 is definitely a "dark" shade.  (Note that
0xFF00FF has a luminance
> >> of 67%--very much a "light" color.
> > 
> > Ah, thank you, Michael. This sheds light (no pun:-) on Linards' 
> > derivation, which matches my recollection. I remember the
"yellow" being 
> > more of a gold and the "brown" being a muddy green, but
I'd swear there 
> > were two different grays. I'm curious why his table shows the two grays, 
> > [5] and [A], having the same sRGB 0x808080. Is that that the difference 
> > in luminance, also?
> 
> No, the two grays are visually identical (though they may produce
> different artifacts when they border other colors).  They are both
> devoid of any chroma, and both have 50% luminance.
> 
>  From a video signal point of view, they each are 7MHz waveforms,
> but of opposite phase.  Since they contain no 3.58MHz signal, they
> do not produce any color.
> 
> On a hi-res monochrome display, both have two white lines and two
> black lines, but one is WBWB ($A) and the other is BWBW ($5).

Thanks, David & Michael:

_-_-_-_- [5] BWBW

-_-_-_-_ [A] WBWB

It took me  a minute to realize those were waveforms and not a sig:-)

-- 
John B. Matthews
trashgod at gmail dot com
home dot woh dot rr dot com slash jbmatthews
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