[HN Gopher] Tetrachromatic Vision
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Tetrachromatic Vision
Author : surprisetalk
Score : 18 points
Date : 2025-06-14 14:53 UTC (3 days ago)
(HTM) web link (www.bookofjoe.com)
(TXT) w3m dump (www.bookofjoe.com)
| oofbey wrote:
| At some point the world's gonna figure this out and start making
| tetrachrome cameras and screens and it's gonna be the next big TV
| upgrade after 8k.
| carlosjobim wrote:
| Current technology is far more advanced than that, with
| hyperspectral cameras which can make images to identify
| different geological materials etc.
| _vaporwave_ wrote:
| Is there a simple (visual) way to test for this?
| varunneal wrote:
| Not publicly, but a few people in berkeley are working on it.
| Here is a paper from last year: https://imjal.github.io/theory-
| of-tetrachromacy. (Disclaimer: i am on this paper).
|
| They've prototyped displays that can test for it as well.
| glkindlmann wrote:
| This is so cool. For your figures, how did you decide the RGB
| colors of the 4D colorspace? Or did you convince ACM to print
| your paper with special inks? :)
| colechristensen wrote:
| Simple? No. My understanding is that the perceptual difference
| is much less significant than for colorblindness and while
| visual tests exist they are less reliable and less obvious than
| the visual tests for colorblindness.
| glkindlmann wrote:
| afaik not based on standard RGB displays. All widespread
| technology for digital color reproduction is based on RGB
| primaries, i.e. a 3D space of color, or rather a 3D submanifold
| of spectra inside the effectively infinite-dimensional space of
| spectra. It is feasible to test for color deficient vision
| (deficiency or absence of one or more cones, reducing color
| perception to a 2D or 1D space) because it is easy to sample 3D
| RGB space and behaviorally detect if colors that are different
| in 3D are conflated because in some viewer they project to the
| same location in their 2D or 1D "color" sub-submanifold.
|
| But we'd need a convenient way to sample a 4D space of colors
| (perhaps with 4 monochromatic sources?), and thereby generate
| different spectra that normal trichromats see as the same color
| (called "metamers"), but that tetrachromats could recognize as
| distinct. And, how the 4D space is sampled would have to be
| pretty carefully optimized to generate distinct spectra that
| have the same response with the M (medium or "green") and L
| (long or "red") cones (which are actually quite similar
| already!) while also generating different responses for the
| putative tetrachromat's additional code between M and L. And
| that isn't possible with any conventional display device.
| carlosjobim wrote:
| On the contrary, RGB displays should be excellent tools to
| determine if somebody has vision which differ from normal.
| Ask the person to adjust the color settings so that real
| world footage on the display looks like how they experience
| the real world. Then you will see if there's any divergence
| in color perception, since display images are direct light
| while real world vision is reflected light.
| glkindlmann wrote:
| Whether via direct or reflected light, spectra in
| trichromat's eyes are still projected down to a 3D space
| (the responses of the S, M, L cones). What you describe
| would still require a standardized and reliable way to
| probe an extra degree of freedom in spectra that
| conventional RGB displays can't access. The paper shared by
| varunneal explains it better than I can.
| carlosjobim wrote:
| If we assume that digital video/film recording will
| compress the spectrum to images which are composed of
| three colors, somewhere in the processes between the
| light hitting the camera and the light being emitted from
| a display to the viewer, that means any tetrachromatic
| person will notice a difference between the images and
| the real world.
| glkindlmann wrote:
| (in the awesome paper shared by varunneal, the metamers are
| named "keef" and "litz")
| postalrat wrote:
| Maybe if colors on a monitor or photographs don't match colors
| in real life? Like how a how black and white displays don't
| match. This would probably be pretty subtle differences.
| crazygringo wrote:
| > _The first known human tetrachromat, an English social worker
| identified in 1993, sees 10 distinct colors looking at a rainbow,
| whereas the rest of us see only five._
|
| What does this even mean? It's setting off my BS detector.
|
| I can see as many colors in the rainbow as I want, since colors
| are culturally determined. Cyan is prominently there in the
| rainbow, even though most people don't include it in the
| traditional "Roy G Biv" -- red, orange, yellow, green, blue,
| indigo, violet. Speaking of which, where did 5 even come from in
| that quote? I mean, the fact that we can argue over how many
| colors the rainbow has just shows how unscientific such a
| statement is.
|
| If there's anything potentially scientific here, you could say
| that humans see three primary colors associated with the three
| cones -- red, green, blue -- and therefore three intermediate
| colors -- yellow, cyan, magenta. A fourth cone between red and
| green means that it _might_ be possible to see 8 primary and
| intermediate colors instead of 6. But it also might not do much
| of anything at all, if it 's then mapped to our existing opponent
| process [1] that is fundamentally based on red vs. green and blue
| vs. yellow. In other words, it would just be a redundant or
| ignored sensory input to our conceptual color processing.
|
| [1] https://en.wikipedia.org/wiki/Opponent_process
| spondylosaurus wrote:
| When I learned about tetrachromacy as a kid I remember being
| devastated for like a week afterwards that I wasn't one too. It
| felt like discovering that superpowers _are_ real but that you
| 'll never have any :P
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