LED yellow and green wavelengths

Papabravo

Joined Feb 24, 2006
21,159
I think it is a mistake to "assume" that each possible color has an equal chunk of the visible spectrum. Keep in mind that the colors available in an LED come entirely from electrons that change from one discrete energy level to another, emitting a photon of a discrete wavelength in the process. If there are no energy level changes in the LED material corresponding to a particular color, there is no color at that particular frequency. Individual colors from LED material do not form a continuum. They are discrete colors at a selection of wavelengths.
 

THE_RB

Joined Feb 11, 2008
5,438
Also the human eye has greatly differing sensitivities to different wavelengths.

Even if you picked 3 well chosen wavelengths and produced each of those at exactly the same lumens, it would NOT look "white" to the eye.
 

John P

Joined Oct 14, 2008
2,025
But note that we're all sitting here viewing this discussion on color screens (unless there's someone still using a monochrome monitor!) And those color screens have red, green and blue pixels which combine to provide white when it's needed, and we accept that as a "good enough" approximation of white.
 

bretm

Joined Feb 6, 2012
152
The additive colour 'wavelength' is subjective, i.e. as interpreted by the viewer's brain.
This is the most important point. How we perceive a color depends not only on the distributions of wavelengths, but also on the surroundings. See, for example, this image, where the two squares on the Rubik's cube are actually the same RGB pixel values:

 

bance

Joined Aug 11, 2012
315
As an experiment, colour around a punched hole in a piece of paper, with a permanent ink marker.

Then offer it up to your screen, and examine both ( or any) of the 'brown' squares and compare them to the orange square!

Steve.
 
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