Re: Double hires mode color artifacts

["Michael J. Mahon" <mjmahon@aol.com>]

Dirk Thierbach wrote:
> I'm looking for information on color artifacts in double hires mode,
> i.e. how adjacent colors "blur", or whatever other artifacts exist.
> Is there any documentation about this on the web, or maybe is there
> someone who'd be kind enough to explain it?
>
> 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.
>
> Thanks in advance for any help,

There have been several threads in this newsgroup on how composite
monitors render Apple II video.  Try searching Google Groups and
see if any of that helps...

The short answer is that the nature of analog NTSC processing in
composite monitors, including their filter response, is what
determines the appearance of an Apple II graphics screen.  The
analysis is, unfortunately, not simple--but it is feasible.

-michael

NadaPong: Network game demo for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

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