You can't believe your eyes: there's no red in this traffic light

Better get this out of the way as soon as possible.


I have two friends who are color blind. Red and Green are big trouble. Blue is also a problem. It makes me wonder what a color blind person would say about this video, would it have the same effect on them? I will ask them but I won’t be able to before this topic closes :confused:

For the red/green colorblind, this is something that we are well aware of. I’ve worn what I could swear was a green shirt, only to be told that no, it was hot pink. I’ve seen red maple leaves as bright green even though I know they’re red, and brown dry grass as green. In low-visibility conditions, particularly with the old style Edison bulbs, I have had to look really intensely to figure out the stoplight color – and I’ve been convinced it was red only to see it turn yellow. When the world switched to the much brighter and easier to differentiate LEDs driving got a bit less stressful and probably safer. Yay progress.


If thine eyes offend thee, pluck them out. :man_shrugging:


The red doesn’t work for me. It comes across as like a black and red plaid sort of pattern.
But the other colors do

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I have red-green colorblindness, though I can mostly see red. Green is basically imaginary for me, though. I can see the reds in these examples.

The brown-orange thing, though, that is a nightmare for me. Without green, a large chunk of stuff is basically orangey, like grass. Traffic lights are white. Brown I can sometimes make out, but it often shades into reds and oranges.


yeah I’m seeing variation too, I think (among probably many factors) it is highly dependent on screen size. On my laptop it worked for all colors - but on the bigger screen at work the red looks like the Brawny guys shirt - like you say.

That’s “contractual obligation” in a bag.


I remember it was a real wtf moment when I realized a certain so-called black cat of mine, when seen at just the right angle in full natural sunlight, was actually just really dark red.

I guess same for so-called black pens and markers: nearly all of them are really dark blue or some other color when examined under a microscope.

But now I got me wondering, what about grey cats?


The effect here is that there is literally no red. The R value is zero on every pixel. Our brain is autocompleting the red that it knows should be there, much like it does with edges, shadows, and other things we’re well-equipped to perceive.

That sounds exactly like what you’re asking for, adding black. You mean a deeper color?


The grey is a mix of black pigments – melanin, so very dark brown if you care to dilute it like that – and light scattering from the structure of the hairs. :slight_smile:

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Old TVs had a dull grey screen when not in use but in use go even darker.

Light is weird.


Strawrot berries lose some lusciousness there. Gotta plan ahead for Twi’lek sexy times.


So, then, we don’t actually need red pixels any more?

A picture of my computer monitor using a photography loupe. The red diodes are lighting up. Any time you have a shade of gray or white that isn’t black (totally black as in an absence of all light) there is a full spectrum of colors in there. Neutral colors are just a more equal balance of those colors. A computer monitor, lcd, or CRT mimic how that works in natural light situations by reproducing it with RGB:

As bcsizemo mentioned (and demonstrated) in an earlier comment, if you turned off the red diodes you’d have an image that looks blue-green and you wouldn’t perceive red.

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But riddle me this (bear with me, really trying for that Pedant Pedant Badge here*): is red a matter of the frequency on the electromagnetic spectrum of light waves reflecting off of an object or is red a matter of the qualia?

I would argue that red only exists in our subjective experience of the color, rather than as a physical phenomenon. If a person sees something and experiences it as red, regardless of the frequency of the light waves, then it is red.

*As is the fashion these days.


Hardware and software engineer of 30 years experience. No need to mansplain computer monitors to me, thanks.

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Not trying to be a jerk. Sorry. Autopilot honestly no idea who I was replying to. Not here to offend anyone at all.


You’ll have to pry them from my cold dead red hand!