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Is false yellow true yellow when reflected?

by webboffin
Tags: false, reflected, true, yellow
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Jul30-13, 11:30 AM
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Quote Quote by webboffin View Post
So I was asking that if this "false yellow" was emitted to and reflected off a sheet of white paper would it be "true yellow"?
No. The spectrum of light reflected off the sheet of white paper is more or less the same as what goes into it.
Jul30-13, 12:24 PM
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Quote Quote by BruceW View Post
mm. you might be right about that. I've been in windows paint, using just blue only, and if you turn down the luminosity, I guess it looks a little bit purple-y. But still, I would definitely say it was blue if someone asked me. (or dark blue).
I'd be pretty surprised if your monitor was capable of reproducing pure 400nm light. You'd probably need a different light source to actually see what it looks like.
Jul31-13, 04:59 AM
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Quote Quote by webboffin View Post
Thanks for the replies guys. I have been reading through them all with interest and I guess what I was orginally trying to get to the bottom of in my question was as yellow say on a LED screen is points of red and points of blue light that seem to converge because they are such small points of light that Vsauce claimed that we were not seeing actual yellow. So I was asking that if this "false yellow" was emitted to and reflected off a sheet of white paper would it be "true yellow"? Instead of points of seperate red and blue light but real yellow light (Yellow spectrum).
This is the Vsauce link on this topic
Note: it's an appropriate mix of Red and Green phosphors that can give a match with Yellow.
R + B gives Magenta

Your idea of a "true yellow" is, perhaps, misplaced. Once the individual sources of colour are distinguishable (big pixels) your eye can resolve them so it sees them as individual sources of colour. If the sources are small enough (1mm / 0.1mm / 0.01mm / molecular ) the perception will be the same. A sheet of paper will just act as a diffuser and produce a good mix from a number of different coloured sources.

'Colour' is what you see and not what the source is doing. Three different makes of TV screen, with different Primary sources, can be made to produce the same, indistinguishable perceived colours over a vast range of scenes.

In order to produce a bright picture, TV displays use fairly broad band primary sources - they do not start off with three monochromatic sources.

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