clldomps@cs.ruu.nl (Louis van Dompselaar) (04/08/91)
Hi there!
I'm working with Yamaha's V9958 videochip which can generate 19268 colours
in only 64k of video RAM.
For those of you who are not familiar (I guess that's quite a lot :-) ),
here's how it works:
Colour selection is made with four pixels:
7 6 5 4 3 2 1 0
Dot 0 Y1 | KL
Dot 1 Y2 | KH
Dot 2 Y3 | JL
Dot 3 Y4 | JH
The KL,KH,JL and JH values determine a kind-of 'base' colour, from
which each of the four pixels can differ with an intensity value Y.
The formulas are:
Y = B/2 + R/4 + G/8
J = R - Y
K = G - Y
Anyway, the question is: given four pixels with each individual R,G and B
values, how to determine the correct J and K for these pixels and the
Y values for each pixel individually???
Thanks for any help
Louis van Dompselaar
clldomps@praxis.cs.ruu.nl