The Colour Pink Doesn’t Exist!
We’ve all been taught that the visible spectrum of light — every colour we can see — is represented in the rainbow. But this isn’t actually true!
When you hold up a crystal prism to a beam of light, you see red, orange, yellow, green, blue and violet and every colour in between coming out the other side. But where is pink? Where does it live in this rainbow?
(source needed)
To understand this, we have to understand that colours look different to our eyes because they have different wavelengths — ranging from 400 nanometres from purple to 700 nanometres for dark red. Most of the colours our brains ‘see’ correlate with specific wavelengths within those two numbers. All shades of green fall between blue and yellow in the spectrum and therefore have wavelengths that fall between those of blue and yellow. But if you look closely there’s no specific wavelength of light that looks pink.
Unlike what we learnt in our high school art classes the primary colours used in our eyesight (and video production) are red, green, and blue. To detect these colours our eyes have millions of rods and cones located on the retina at the back of your eyeball. All 120 million rods only respond to whether light is present or absent. The 6-7 million cones on the other hand are mostly found in a single focal point on the retina called the fovea and they are where the fun happens. They come in three types that are sensitive to the wavelengths corresponding to red light, green light, or blue light.
Now if you are a physics nerd you might remember that when sunlight hits an object, all colours of the visible spectrum are present. Typically most are absorbed such that the colour we see is the colour that is reflected.
With a banana every colour except yellow is absorbed
When all colours are absorbed we see black
When all colours are reflected we see white
This reflected light enters your eye and hits the rods and cones in your eye. Those three primary colours (RGB) are detected by their respective cones. However, what happens with that yellow wavelength from the banana? After all it does exist as a wavelength but our eyes lack the yellow-sensitive cones. Well in the absence of yellow cones, this wavelength activates the red and green cones so they fire together. Your brain (which is amazing by the way) translates these signals into a perception of yellow.
Sometimes when these mixed activations of cones occurs, one is dominant whereas the other(s) only partially activate. For example, violet light fully activates blue cones but only partially activate red cones. Likewise both orange and brown have red as the dominant cone with green partially activated.
Now back to Pink!
Pink is what occurs when red and blue cones almost fully activate (with red still dominant) whilst green is only activated a little/ not at all. In fact, pink should really be called “minus green,” because it’s the effect of white light once you omit green.
Notice, however, many of the colours we perceive, including cyan, brown and magenta as well as pink, do not actually exist on the visible spectrum of light as measured by wavelengths, yet we perceive them as distinct nonetheless. It is for this reason that some have opined that colour perception is "not actually a property of light or of objects that reflect light [but rather] is a sensation that arises within the brain”. This is distinct from what is commonly called qualia, the idea that what you experience as red is different from what I experience as red.
Conclusion: All colours are made up. But some colours are more made up than others
So what difference does this make … none at all – but it is very Fetch!
