[SML] Moving Light Colour Mixing philosophy question

[Jerry Durand]

Mentioning intensity, a problem with additive is mixing range.

[I'm assuming below that levels are the same apparent intensity for R, 
G, & B]
If you want to have a range of colors, all apparently the same 
intensity, that means you might start with white where you set RGB to 
33% each.  But that means every other mix of colors also has to add up 
to exactly 99%.  You want pure red, no problem, R to 99%. But trying to 
mix some other colors gets tricky.

I just did a holiday toy with RGB LEDs and due to the nature of the 
hardware, I've only got 8 dimming levels for 0-100%  This gives exactly 
36 possible colors.  Plenty for a holiday toy, not so much for a stage 
production.

Oh, as for COB RGB, there's a problem with that. Most LEDs now are high 
blue nitride film type and the phosphor is in the silicone coating over 
the LED chip (the yellowish rubber blob).  These are brighter, cheaper, 
and shorter lived.  If you're happy with the pure color emitting older 
LED chips with no phosphor, then you could do a COB but I'm guessing 
there's currently not a lot of call for it. People buy what's currently 
made, so why change?

I guess you could also do a board with a bazillion small surface mount 
LEDs, like a video monitor, stripes of RGB, but I'll bet it wouldn't be 
cheap.

On 14-Jan-26 1:39, Riter, Andrew via Stagecraft wrote:
> Thank you all.  Interesting.  This could be a good discussion.
>
>
> I like Jerry's point of white source = all colours / RGB = spiky RBG versions of a colour, so subtractive is better colour.  But subtractive is also less intensity in the saturated colours.
>
> The question is more:  why are subtractive systems  CYM and not RGB?
>
>
>
> Andrew M. Riter
> Assistant Technical Director, Head Lighting Technician
> Chan Centre
>
> Phone 604 822 2372
> andrew.riter at ubc.ca
>
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