Re: Double hires mode color artifacts

[Andy McFadden <fadden@fadden.com>]

Dirk Thierbach <dthierbach@usenet.arcornews.de> wrote:
> What I have seen so far is some basic information how colors are
> produced in the first place (determined by a 4 bit pattern distributed
> through 7 bits in every hires byte, aux and main memory interleaved),
> and that it works similar to the colors in lores mode. So I suppose
> the pattern must somehow determine the phase shift of the color
> carrier signal, and maybe influence intensity as well, and I guess
> when this changes gradually the colors will "blur", but I am
> completely missing any further details.

There's a //e technote that contained some basic info about the "sliding
window".  When implementing DHR conversion for CiderPress I sat in front of
my IIgs RGB monitor with a magnifier trying to discern a simple pattern,
and eventually gave up, since each pixel is modified by the colors that
come before and, in some cases, the colors that follow.  Since the RGB
output isn't subject to NTSC issues, I'm not really sure why it works
the way it does.  (The composite output was fuzzier but made a little
more sense.)

I ended up shipping with 4 different modes and letting the user pick their
favorite. :-)

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