Double filters allow for tetrachromatic vision in humans

[Jim__]

From TechXplore:

Schematic of our filter-based cone partitioning method, consisting of two distinct transmission filters. Plot (a) shows the spectra of a sample pair of metamers, (i) and (ii), which appear as the same purple color and were experimentally generated using two different displays (CRT and LCD). The measured transmission spectra of filters 1 and 2 are given in (b); (c) shows a magnified view of one of the transition regions of the filters, demonstrating their angular response. The color samples in (d) represent the perceived colors of spectra (i-iii), where spectrum (iii) is CIE D65 white light, in the absence of any filters. The samples in d(i) and d(ii) are the same color (i.e., they are metamers), and d(iii) is pure white. (e) and (f) show the colors corresponding to spectra (i-iii) as observed through filters 1 and 2; spectra (i) and (ii) no longer map to the same color. Samples e(iii) and f(iii) are approximately the same perceived color, which is a consequence of the white-balance design constraint that is enforced to limit color clashing. Credit: arXiv:1703.04392 [cs.CV]
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Humans have three types of cone cells in the back of the eye to differentiate color. Some react to blue, some to green and some to red. The cones do their work by responding to the difference in wavelength of the incoming light. Such vision is known as trichromatic. In this new effort, the researchers have found a way of fooling the brain into seeing as if there were a fourth type of cone, by wearing glasses with two types of filters. The result is tetrachromatic vision.

To create the glasses, the researchers fashioned two types of filters, one for each eye. The filters remove some parts of the blue light spectrum. But the filters each remove a different part. When the filters are fitted into a frame and worn like regular glasses, the wearer is able to see colors that are normally hidden—metamers. In a sense, it is rather the opposite of what occurs with people who are color blind. They might see blue and red as the same, even though there is more light information there. Adding spectrum identification to color blind eyes allows for seeing more of what is already there. With the new combined filter system, a person is able to look at what appears to be an object that is all the same color, such as purple, and see more colors in it—those normally hidden metamers.

The team notes that it should be possible to extend the idea used to create their glasses to the other two colors that cone cells process, red and green, to create glasses that offer the ability to see six basic types of colors instead of the normal three. They plan to start with green. Such glasses, the team notes, might be used to spot counterfeit money, or to see a person in the jungle wearing camouflage.

a little bit more …

[Wounded Bear]

1. Cool stuff! Thanks for the link!

[Xipe Totec]

2. Now why didn't I think of that?

Oh, because I'm not a freakin' genius!

Kudos!

[mopinko]

3. i wonder what you get if you can already see tetrachrome.

i have taken those test for how many colors you can see. i always ace them. whether that is actually tetrachrome or not, i dont know enough to know.

but how cool would it for for someone who can already see subtle shades of colors to have that double?

want.

[Jim__]

5. My guess is that these glasses would give them pentachromic vision.

The reason I believe this is that these particular glasses are filtering out light in the short range (400 - 500 nm). My understanding of this article in wikipedia is that tetrachromacy in humans exists in the medium range:

Humans are usually trichromats.

In humans, two cone cell pigment genes are present on the X chromosome: the classical type 2 opsin genes OPN1MW and OPN1MW2. It has been suggested that humans with two X chromosomes could possess multiple cone cell pigments, perhaps born as full tetrachromats who have four simultaneously functioning kinds of cone cells, each type with a specific pattern of responsiveness to different wavelengths of light in the range of the visible spectrum.[19] One study suggested that 2–3% of the world's women might have the type of fourth cone whose sensitivity peak is between the standard red and green cones, giving, theoretically, a significant increase in color differentiation.[20] Another study suggests that as many as 50% of women and 8% of men may have four photopigments and corresponding increased chromatic discrimination compared to trichromats.[19] In 2010, after 20 years of study of women with four types of cones (non-functional tetrachromats), neuroscientist Dr. Gabriele Jordan identified a woman (subject cDa29) who could detect a greater variety of colors than trichromats could, corresponding with a functional tetrachromat (or true tetrachromat).[21][22] [23][24]

I am specifically looking at: One study suggested that 2–3% of the world's women might have the type of fourth cone whose sensitivity peak is between the standard red and green cones, giving, theoretically, a significant increase in color differentiation.

From reading that, I don't think they expect to find any humans with multiple cone cell pigments in the short range.

[mopinko]

6. that would sure be fun. or annoying as hell.

there is a color red that i just hate, especially in clothes, but also in flowers. i also love a red that is only slightly distinct from it. nobody else can tell the difference.
once lost a bet on the color of red for the americorp/city year red coat. i will go to my grave insisting that it is orange. and a lot of the other "city wear" is even more orange to me. but they srsly insist it is red.

i occasionally miss it myself. especially indoors, and under cheap florescent light, like most of the thrift shops i frequent.
every once in a while i will get a purchase home, see it in the daylight, and kick myself.

i have no doubt i am a true tetrachromat. above applies also to art making. it is a huge frustration that "my" red is quite hard to find. usually have to blend it myself.

would be cool if these glasses could split that out even more for me. i could finally have the red of my dreams.

[defacto7]

4. Not only for expanding visual perception...

but militarized as well.
Can't we just stop with helping the visually impared?