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glasses to make humans to see in greyscale? Answered

when we put on glasses we see the world in certain hues of other colors, would a combination of filters enable someone to see things in black and white? what combination of what materials might this be? are there any other ways this might be possible?


In dim light, human vision becomes "black and white", as our cones are rather less sensitve than the rods in our central vision. So, really well fitting, dark glasses might work in some way.

Good point! If you can cut light down to nighttime levels (without a full moon, which is enough to start seeing color by), and count on the user's night vision being good enough to get by with that, this should indeed work.

Trivia point: The brain circuitry for focusing our eyes uses only brightness, not color. An image which is made up of colors that all have the same brightness can be very frustrating to look at -- you know it's sharp, but your eyes just refuse to stop tyring to refocus when you look it it.

You would need to make some sort of transparent filter that will not allow coloured rays to pass.
If you shine a light through a red filter onto a picture with red and blue on it, the red will look red and the blue will just look black. This is becasue there are no blue rays to reflect off the blue into your eyes. So, you would need to invent a filter which only alows white rays through.
Im not sure if this is possible, but if dogs and cats can do it, why cant we?

Alternatively (this one is probably just nonsense) you could use a combination of all the colours of the rainbow filters to rule out every colour. This could, however, result in just a black piece of plastic.

Sorry, that doesn't work. There's no such thing as "white rays" -- white is a mixture of the other frequencies..So, yes, if you filter out every color you get black.

Dogs and cats are not completely colorblind, as far as I know; I believe they are missing one of the three types of cone cells we have, and thus see only two colors plus intensity. Websearch would confirm that.

That's my understanding as well. I believe they say dogs see in Sepia tone, Cats, however, I *think see in color. (although whether they see with the same spectral range as humans...idk)

I see... Well thanks for corecting me anyway!

Doesn't white light only shine at the point of cessation?

Very dark shades, like steve' says.


It might be possible to filter things so we were seeing only one color -- redscale, for example. Since the human visual system tries to compensate to some degree for lighting of various colors (the Land Effect seems to take advantage of this), it's possible that after wearing glasses of that sort for a while we might start seeing things as shades of gray under a red light rather than shades of red.

Finding something which filtered strongly enough yet still left enough light to see by might be challenging, though.

Might be easier to just use a heads-up display and a camera.

Agreed. to the tee. I was writing my own response when I finally bothered to look below. Sure enough Ork said the same thing

a) filtering would knock down the intensity since much of the luminous intensity is provided via color, and
b) a heads-up display with B& W camera would mimic the effect well.

Impossible to make although it would be cool.