I guess that is a mighty 'heady' title for a blog post from a guy who has been silent on this Light Minds blog for months. 
Well... I am breaking my silence. Fact is, I have been busy, but now I feel motivated to write, and hopefully that will continue! You can encourage me by offering your comments please!!
Why does additive color mixing matter? I'm talking about LEDs here. We entered the LED market about one year ago and I've spent the last year really thinking about how and why LEDs matter and where they are useful. I can't tell you I've reached a state of enlightenment (pardon the pun) but I have learned a lot along the way.
We have a new white paper posted in our shiny new Support area on etcconnect.com. The paper is about color mixing and how and why the multicolor system we use in our Selador Series LED fixtures matters. Additive color-mixing is in play here. Most of us who have designed lighting intuitively understand what additive mixing is. Those of us who have used watercolors get it, too. We add multiple colors together to get a new color.
Working in pigments, we normally think of this as red-yellow-blue. In lighting, we know that red-green-blue are the primary colors of light and we understand how to combine them from a theoretical point of view. But we also know it more intuitively. Led by intuition, we know that we can cool the lighting look down by adding blue. So, we work with the colors we have selected or the color changing devices we have, and we paint and layer. Contrast this with the fact that most of the color we are adding has been produced via subtraction, namely gels or CMY systems. Putting gel in a fixture invokes subtraction, and it feels quite normal.
While Cyan-Magenta-Yellow color mixing systems are subtractive mixing systems, they feel strange because they are 'active' systems. You have a cyan color (blue and green) coming out of the fixture - you add magenta and you get... well, what exactly do you get? Blue? That's intuitive! The magenta you are "adding" is actually a filter that is subtracting the green. In more recent years, we started controlling color using hue-saturation-intensity controls -- like color pickers -- adding a new skill to our design arsenal. We let the console -- and its knowledge of the color mixing systems -- do the adding and subtracting. So, my point is that we have many ways to manipulate color, some of them more intuitive than others, each with a set of strengths and weaknesses.
Enter LEDs. Colored LED systems use additive color in the fixture. This is a slightly new concept. Instead of using a powerful light source generating "white" light, then subtracting the colors we don't need, we begin with nothing and add only the colors we do need. From the designer's perspective, not much changes, right? I mean, you want yellow, you bring up red and start adding green. This is vastly more energy efficient, as long as the fixture can reach the color you are seeking at the brightness you want.
RGB is great in theory, but most designers who have worked with these "16 million color additive mixing LEDs" will testify that it is not that easy and your results may vary. I first learned about the difficulty of doing RGB color-mixing in college. I dutifully hung a cyc wash with scoops gelled in Rosco diffusion RGB. Then I began to explore the 16 million or so colors I should have had available. I found that it was very hard to get the color I wanted, at the intensity I wanted it. I felt as though I was working in more of a 16 color mode rather than 16 million color mode. Many of us probably learned over time that hanging a four-color wash improved our results. Then we discovered that if you wanted a particular color and had the luxury, hang that color!
We were figuring out imperially that "more color = better light." That is the very principle that the company that ETC acquired last year, Selador, brought to their LED fixtures. ETC Selador series fixtures start with seven different LED colors. Sounds good, huh? It does until you start from zero and now want to build the best-looking golden straw color you can. You can start with amber, add some green maybe, not too much. Should a little cyan play in? And doesn't that color actually have a touch of red? Well, you could try it. Actually, you could sit all day and try things like a kid with an endless supply of paint, water and paper.
When we combined ETC and the Selador concept, ETC simplified things a bit. We profiled these fixtures in our Eos, Ion, Element and Congo consoles and made them respond to our gel libraries. The fact is that LEDs are not perfect and can vary significantly from bin to bin and fixture to fixture (we are working on that problem, too!). But you can start with a language you know. Call up your Selador fixtures in a Roscolux 80 and you will get close.
Now I come back to the subject of this very blog post: additive color mixing. When you see what your ETC console and your Selador fixture present as Roscolux 80, pick up your brush and personalize it. We give you seven colors of toning to play with. Add a touch more cyan or red, save it as a color palette and use it again. In this model, additive color works intuitively. The designer gets to play. So... have fun!