Thursday, April 25, 2013

How to see impossible colors, imaginary colors and other stuff about sight

There are 2 theories that are accepted currently explaining our ability to perceive light and colors.  We will explore both of these theories briefly and then learn how to mess with our eyes and brain to push the limits of our perception. The opponent-process theory explains color vision phenomena that result from the way in which photoreceptors are interconnected neurally; The trichromatic theory explains color vision phenomena at the photoreceptor level.

The way visible light is perceived is through cones and rods in the eye using using an opponent process theory. The color opponent process is a color theory that states that the human visual system interprets information about color by processing signals from cones and rods in an antagonistic manner.  The eye's primary light receptors, the cones, have certain overlaps in what light wavelengths they can perceive. To save energy, our eyes measure the differences between the responses of various cones rather than figuring out each cone's individual response.
Our interpretation of light wavelengths consists of a 3 Opponent Process made up of Blue vs Yellow, Green vs Red, and Light vs Dark even though we are Trichromats meaning we only have 3 cones in our eyes used to perceive Red, Green and Blue. Although it has been estimated that approximately 12% of Women are what is called Tetrachromats, meaning they have a 4th mutated cone they inherited from a color blind father, aka Dichromatic Deficient (a.k.a. Colorblind- meaning they have 2 good cones and 1 mutated cone). Not all Tetrachromats have a fully functional 4th cone however, I've read that only 2-3% of women with the 4th cone use it to any degree worthy of note although a scientist (I forget his name) surmised that if the world wasn't geared toward catering to Trichromatics that the number would be much higher.

In 1983, Hewitt D. Crane and Thomas P. Piantanida performed a series of experiments trying to "see" impossible color dyads (combinations) using a machine that emitted saturated colors to each eye which allowed for impossible wavelengths to be mix by the human brain when your brain consolidates the images transferred to it from each eye.
The four color names: red, yellow, green, and blue; Can be used singly or combined in pairs to describe all "visible light" (visible to us a.k.a. possible colors) Orange can be described as a reddish yellow, cyan as a bluish green, and purple as a reddish blue. Some dyadic color names (such as reddish-green and bluish-yellow) describe colors that are not normally realizable. By stabilizing the retinal image of the boundary between a pair of red and green stripes (or a pair of yellow and blue stripes) but not their outer edges, however, the entire region can be perceived simultaneously as both red and green (or yellow and blue).
Keep in mind that we are not talking about mixing colors here or you'd end up with:
Red+Green = Brown
Blue + Yellow = Green.

Well this process was long theorized to be Hardwired into our brains but it seems it is soft wired and can be hacked. Just cross your eyes until the white crosses are lined up and hold it steady until it stabilizes. Not everyone can see these impossible colors, some people just see the colors flashing over each other rapidly. I don't know what you'll see. There seems to be numerous perceptions of what people see. Keep in mind that computers do not actually make yellow, but then again we don't actually have a yellow cone receptor to perceive yellow anyways so whatever. But from what I understand the red-green should be an orangish/brownish/olivey color and the blue/yellow makes a silvery color

Imaginary Colors
We can also hack our brain to see imaginary hues of colors that we could never see otherwise. Because of the opponent system our eyes use, this means that as the red receptor is excited the green one is inhibited. This is how the system works, using this counterbalance, our ability to perceive ALL of the variations of color available is hindered. We can never see something as 100% green. But we sure can try, right?

Here is what is considered to be the range of human sight. Computer monitors, phones, etc. These all limit the range of this color gamut. If you google search "color gamut comparison" you'll see how quickly and easily our sight can be limited. But can it be expanded? Yes, and let me show you how.

Recall how the cones in our eyes work using the opponent theory, namely Red vs Green & Blue vs Yellow, when you see the color red, your red receptor gets excited just as much as your green receptor is inhibited, a counterbalance. If you want to see a greener green than any other green you've ever seen is actually very simple. You must fatigue your red receptor so it will get so tired it won't respond correctly. You do this by saturating your vision with red for 30 seconds or more, the longer the greater the effect will be when you look at something green. Disney uses this at their EPCOT center. they made the sidewalks a hue of pink to make their grass look a surreal green.

We are going to do this by looking at a combination of my 2 favorite colors, Cyan. This image has the full range of cyan that your screen can produce, but we can still use it to see a truer Cyan than you've ever seen before.

Move as close as you can to the screen without being uncomfortable. Now stare at the white dot in the middle of the red circle. Stare at it until you start seeing flashing rings of Cyan around the circle, stare at it for about 20 more seconds for good measure. Then move your head back and bask in the glory of true Cyan.

Also worth noting regarding the topic of all this, did you know Magenta and Pink do not actually have a wavelength? there is no pink light and no magenta light and no purple (no purple is not violet). there are no colors between red and violet. Because the wavelengths our brains and eyes turn into "colors" are simply interpretations of a wavelength frequency we probably shouldn't see colors that have no frequency. But our brains are amazing. Remember how our brains have short(blue) & medium(green) & long(red) cones but yet we still use the opponent process to make yellow vs blue despite the lack of a yellow cone? Well since we don't actually have a yellow receptor our brains use a combination of red and green (just like digital RGB monitors) to make a yellow color (which excites the medium, green cone combined with the long, red cone while leaving the short, blue cone alone); Well our brain applies the same imaginative solution to see the range of color that happens with excitement of  the blue(short) cone and the red(long) cone while having no medium(green) cone activation, thus the perception of the wavelengthless colors that make up the red+blue hues.

Ultraviolet is the range of wavelength that exists beyond violet, hence the name. Normally you cannot see UV light because the lens on our eyes filter it out. However if you get the lens removed you can see UV light. Famous painter Claude Monet had his lens removed on one eye due to cataracts. After the surgery he started including the blueish white color of UV light he now saw into the paintings he made. Here is the same painting he made using the vision from each eye.

Infrared cannot be seen by the human eye but you can remove the IR (infrared) filter from a camera and start making some interesting photography.


  1. The yellow/blue just alternated, and the red/green was just orange.
    no, really, all it is is orange
    (wow, I just put "is" twice and it makes sense)