One of the things I’ve realized with The Eureka Room is that LEDs are good at some colors and not good at others.
Red, Blue, Green, Yellow – great. Purples and Cyans – amazing.
Brown? Not so easy.
I was trying to create some coffee looking images in the room and no matter what shade of brown I saw on the laptop screen, the LEDs just couldn’t get it done.
Then I realized I’ve never seen brown Christmas lights or brown light bulbs and I couldn’t even remember being in a room that had brown lighting from any source.
It turns out brown is a low intensity blue-yellow or red-green (sometimes faked by using green-yellow) that is by its nature pretty dark. Once I turn down the brightness and start approaching brown, the lights don’t even look like they are on at all.
You might be thinking, “isn’t blue-yellow just green”? Well.. with pigments. Not with light. But first a distinction.
There’s a difference between light and what we see as “color”. Light does not have color. Color is what we perceive. You can find some interesting discussion about it on Quora and this question on StackExchange explains the difference between light and pigments. Basically, light is a wavelength and pigments absorb everything except their wavelength. So a green pigment absorbs all colors except green (more or less) and reflects that “green” wavelength back, which our eyes interpret as a thing we call “green”.
We have 3 types of photoreceptors that each respond to a different color: red, green, and blue. Our brains are able to mix some of them (eg, red and blue), but have trouble interpreting a color mixed with its opponent color. For example, what is blue-yellow? These are referred to as “impossible colors”. From what I found on Reddit, our brain doesn’t know exactly what to do with this impossible color, so we see “brown”. If you want to know if you can see impossible colors, there’s a couple of tests on the impossible color wikipedia page.
Another interesting thing I found in my research: the way the eye interprets colors is just a theory and there’s some criticism towards it. More on that here.