Re: Reduce color saturation

On 16 Jul 2006 11:49:21 -0700, in sci.electronics.design "Luhan"
<luhanis@xxxxxxxxx> wrote:


martin griffith wrote:
On 16 Jul 2006 11:22:25 -0700, in sci.electronics.design "Luhan"
<luhanis@xxxxxxxxx> wrote:


TSM wrote:
Hello, I want to build a circuit with trimmers to reduce the color
saturation of a signal going to a monitor. The signal is made up of
these wires: R, G, B, Sync, GND.

Do I need some IC? Are there any schematics to look at?

Thank you

--
TSM

Hmmm, since there is no luminance signal, just 3 color signals, it
would appear to be nary impossible to do what you want. These are not
3 voltages, but time varying signals. So no matter how you set the
individual levels, you cant reduce the color without reducing the
overall signal.

Nicht var?

Luhan
Hmm, why do you think there is no luminance? All the broadcast cameras
I've used generally used RGB to the Camera control units, and they
worked, then DA'd in YUV. Since video distribution in RGB sucks
bigtime. CRTs tend to need RGB to drive the bits of metal that dangle
in the vacuum.
If you put 1V on the R channel it should show red and 0V will show not
a lot.
I could go on, but I'm sure Mike T will chip in




martin

I't must be possible in some way, even if you have to construct a
luminance/cromanance signal in an intermediary stage, reduce the
chomanance signal, and then regenerate as RGB.

Luhan
I agree that RGB>YUV> RGB is the cleanest way. Maybe one of those
overcomplicated SAA71xxx series ic's from Philips would do the trick


martin
.

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