I have LED lights in my bathroom that I can set to just about any color. Is there any color or set of colors that I can set them to to simulate red/green color blindness?
I dont think there’s going to be any configuration that would truly reproduce the experience of a colour blind person.
Since the human visual system has receptors that more or less map to red, green and blue, I think as a thought experiment, we can figure out what would happen if each of those colours were removed from the illumination
If you turn off red, you will have trouble differentiating the hue of red vs green objects, but green objects will appear darker in intensity than normal - i.e. A tomato will appear red, a lime will appear black, and white objects will appear cyan, as will the room lighting in general.
If you turn off green, the opposite will happen - green things will be green, red things will be black, room lighting and white objects will be magenta.
If you turn off red and green, you’ll have more or less no way to differentiate any colours - red and green things will look similar, but similarly *dark. White things and the room in general will appear blue.
(all notwithstanding any adjustment your perceptual system might do to try to perform white balance)
I don’t think any of these things would properly and completely represent what a red/green colour blind person experiences; as I understand it, they perceive red and green at the correct intensity, but cannot differentiate the hue
If you had monochromatic yellow light and also monochromatic blue light, this will leave you unable to distinguish red versus green. As to whether the experience would be the same, I think it’s that old question of whether you and I see the same color when we see green, or red, or whatever. A kind of meaningless question, really.
But the yellow light would have to be just one wavelength (or very narrow range of wavelengths). A combination of red and green that looks the same would not create the same effect.
That sounds like it might work, but that’s unlikely to be within the capability of a domestic colour-changing LED light fitting - it’ll be RGB or maybe RGBW, and probably fairly wide spectra as that’s what people want.
It’s possible that a really bad (or maybe really old) white LED might fit the bill - that is, bad in the sense of just being a narrowband blue emitter with a similarly narrowband yellow phosphor - but they don’t make them that way nowadays if they can help it, because consumers want high colour rendering index lighting. I do recall using some early white LED domestic light fittings that I think must have been very narrow band blue and yellow - because whilst the lights themselves looked really bright directly, they just didn’t seem to illuminate a lot of things in the room properly - presumably because a lot of the emitted colour was just being absorbed by objects that were not white, or the right shade of blue or yellow.
O my yes, absolutely. Better to have said “If you had monochromatic yellow light and also monochromatic blue light instead of what you have…”
And, I like the old white LED idea! Well met, Mangetout! I think it’s even a decent chance, because the yellow light is coming from a phosphor and (I think) those can be pretty narrow.
Lots of those made it into hotel rooms back in the day. I hated the darn things. As you say, the lamp was bright but the perception of the room was dim & weird.
I called it “the illusion of illumination”. But the hotel did save a few shekels on electricity. The joke was on them because IMO very few of those bulbs lived to anywhere close to their advertised lifespan, so the hotels’ total bulb + labor + electricity costs went up, not down as they’d hoped.
If you have programmable LED lights with a significantly narrow band output, you could approach an approximation I’d think where red and green objects can appear metameric. With a sufficient number of LED sources, you could at least approach “good enough”.
With a sodium lamp, you can simulate monochromacy (colorful objects appear in shades of grey)
Low-pressure sodium lamps used to be almost universal here in San Jose. They’re almost perfectly monochromatic at 589 nm, and indeed made things look pretty weird. That’s a higher wavelength than you’d want to achieve equal balance between red and green, but the middle-wavelength receptor still has a strong response at that wavelength, so it’s probably not far off (assuming you added some blue).
I’ve been trying different light settings and I can get red and green to look similar but when I set the lights to blue, browns completely disappear and many other colors get washed out.
Daylight
Blue
That should say “I can’t get red and green to look similar.”
You know, you can buy yellow LEDs. They’d probably have too narrow an output to let you distinguish reds from greens. I’m thinking of the little components with two leads out the bottom – you feed them (probably) 20 mA at whatever voltage they operate at, perhaps about 3 V. Maybe you feed them 6 V through a 150 ohm resistor, something like that. Or string a bunch in series, feed the chain 20 mA.