Re: Create Simulator for NTSC

[pausch@saaf.se (Paul Schlyter)]

In article <rRpAc.1408$1L2.191@fe1.texas.rr.com>,
Bryan Parkoff <bryan.nospam.parkoff@nospam.com> wrote:

>     I have captured TEXT (with green & violet -- Color Killer is disabled)
> for 40 column and 80 column, HGR, and DHGR screens from real Apple II.  I am
> trying to write C++ source code that it allows me to convert NTSC pixels
> into VGA BMP.  I do know how to write a simulator that it translates RGB
> screen from Apple IIgs into VGA BMP, but I can't figure how to do that it
> should be able to translate NTSC screen from Apple II+, //e, and //c into
> VGA BMP.

Check out:

http://www.stjarnhimlen.se/tv/tv.html#colorparams

There you'll find how the NTSC Y,Q,I are obtained from R,G,B:

Y = 0.30 R + 0.59 G + 0.11 B
Q = 0.21 R - 0.52 G + 0.31 B
I = 0.60 R - 0.28 G - 0.32 B

Now you want to do the reverse.  This is simply a matter of solving the
system of three equations above, treating Y,Q,I as known and R,G,B as
unknown.

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