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Re: Double hires mode color artifacts

Jerry wrote:

Michael J. Mahon wrote:


I'm also working (slowly) on writing a table-generator for use by the
N-bit
shift-register algorithm this thread discusses.  I'm reading up on how
NTSC
TV decoders really work.  I've looked at the analogtv.c source (from the
Jamie Zawinski's xscreensaver), but I'd like to start with some code
that's
easy-to-understand.  His code is rather convoluted, IMO, by all the extra
signal degradations he put in.  Since I don't fully understand NTSC
decoding, I'd prefer to learn and build my algorithm up step by step.


Sounds good.  A faithful emulation does not need gratuitous errors,
like a jumping raster, a tearing raster, nonlinearity, or noise.

Although it *would* be nice to have the contrast, brightness, hue, and
saturation controls.  ;-)  (Adjusting them would perform a transform on
a standard table to produce the actual table to be used.)



Yes, I plan to put those in, and was thinking that I could just update the
lookup table and the video emulation would simply repaint with the
alterations.


It would be necessary to keep a master copy of the "standard" table,
otherwise, bits would be lost if you turned a control up and then
down again.


When it's done, it will be some fruit of the ideas of various people:
Linards T, Michael M, Vlad I, Andy M, and probably others.


And the result of *your* curiosity and persistence!



thanks.  I do feel a compulsion to understand NTSC decoding.


Fantastic!  ;-)

-michael

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Home page:  http://members.aol.com/MJMahon/

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