Subject:
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Re: Graphics Programming on the Apple II (was: Wow! This guy is good!)
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Newsgroups:
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lugnet.off-topic.geek
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Date:
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Wed, 7 Jun 2000 04:31:04 GMT
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Viewed:
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797 times
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In lugnet.off-topic.geek, Matthew Miller writes:
> John J. Ladasky Jr. <ladasky@my-deja.com> wrote:
> > A pixel was defined in a rather slippery fashion in Apple II
> > "high-resolution" graphics. A pixel was either one bit or two, depending
> > on the values of adjacent bits. The four basic colors were blue, violet,
> > green, and orange (no yellow!). You could only get white by having two
> > adjacent bits turned on. Two adjacent bits turned off = black.
>
> Check this out: <http://grc.com/ctwho.htm>. The "pixels" as you describe
> above aren't really whole pixels at all; rather they are subpixels, much
> like the red, green, and blue subpixels on a LCD display. This is exactly
> the concept Microsoft's Cleartype takes advantage of.
MS's Cleartype and the way Woz did Apple ]['s hires graphics mode are a world
apart, actually. And the Apple ]['s 1/2-pixel horizontal shifting was the
same on color monitors as green/black monitors -- that is, from the same video
signal if you split it and had it running both a color and a monochrome monitor
at the same time.
The green/purple color shifting had nothing to do with color CRT shadow masks
-- it was present on hex-grid TV's as well as Sony Trinitron TV's. It was a
function of the video chips in the Apple ]['s circuitry. A Trinitron-style
monotor, however, properly calibrated, would indeed be capable of something
similar as Cleartype, although you'd have a major challenge getting the
convergence and linearity to stay perfect.
--Todd
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