[sdiy] Modular Video?

[Rotwang the Mad Inventor]

Goddag! (Good day!)

At 12:09 2001-09-13 +0200, Synth-DIY wrote:

>However, a rasterizer would be lovely. So that one could convert a
oscilloscope
>like trace with voltagecontrolled XYZ into a dot on a normal TV. Then if
it would
>be possible to add Hue and Sauration control in addtion to the Z (Luma) it
would
>be great.

I have assigned a few braincells on that...
If I could get my "rasteriser" to work, It would provide a raw monochrome
(intensity) videosignal output, just a geometric pattern/shape. If this
signal was split and sent into three amplifiers with separately variable
gain, each one representing R, G and B, different hues as well as
saturation and luminance could be set under voltage control.

Now, just to begin somewhere; think of a system capable of generating an
x/y image. Then an additional "hue" parameter, how? 
I want to put a voltage at 0-1 volt (Or maybe I should stick to 0-10 volt?)
into a black box, and get three nonlinear functions (voltages) out of it to
drive the amplifiers:
http://www.acc.umu.se/~polarn-p/sas/video/RGB-kurvor.jpg

How do I obtain these transfer functions?
I remember someone talked about piecewise linear approximation, diodes and
stuff some time ago.
(I think it had to do with formant control in an speech synthesiser
experiment)
Could someone please enlighten me?

Then we may move on to control of luminance and saturation, but those are
just linear operations on the RGB representation. No problemo.

(Oh... before someone smacks me in the head about it... in reality there is
not much "linear" when dealing with colorimetry and human visual perception
etc etc, but I have to start out somewhere... :)

	Peace! 

	/P! the Mad Inventor