[Physltest] [Phys-L] Re: LED mini-flashlight price break

[John Clement <clement@HAL-PC.ORG>]

Actually if you look at the current set of primaries used in TV, they cover
only a portion of the chromaticity diagram.  An alternate set might give
just as good reproduction.  Indeed Edwin Land demonstrated that only 2
colors can be used for very good, but not necessarily excellent
reproduction.  It is probably easier to get good reproduction with RGB.

The subject of actual color vision is very different from the engineering
model which uses the chromaticity diagram.  This is because the eye-brain
renormalizes the perception across color boundaries to make color vision
fairly constant and insensitive to the actual spectral balance.  Cameras do
not do this so when you think a scene looks good, the camera may record it
with a very different color balance.

So in reality there are a number of sets of colors which can be used.  But,
if you want consistent results, you have to pay attention to the standards
for color monitors which specify a specific set of primaries.  The colors
used in printers are probably likewise keyed to the monitor colors.

John M. Clement
Houston, TX

> The main reason that RGB is used for the primary additive colors is
> because the cones in human retinae have peak quantum efficiencies for
> those colors.  If human retinae had four different types of cones, then
> color theory would be based on four primary colors.
>
> Daniel Crowe
> Oklahoma School of Science and Mathematics
> Ardmore Regional Center
> dcrowe@sotc.org
>
> -----Original Message-----
> From: Forum for Physics Educators [mailto:PHYS-L@list1.ucc.nau.edu] On
> Behalf Of Frohne, Vickie
> Sent: Thursday, January 27, 2005 12:03 PM
> To: PHYS-L@LISTS.NAU.EDU
> Subject: Re: [PHYS-L] LED mini-flashlight price break
>
>         Technically, there are several sets of possible "primary
> colors." A set of primary colors can be loosely defined as three colors,
> that when mixed, produce all the other colors in the rainbow.   Cyan,
> Magenta, Yellow is a primary set, and so is RGB, which is the complment
> of CMY. Presumably one could define orange, green, violet (the
> compliments of RYB) as a "primary" set.  There is no compelling physical
> reason to favor any of these options over another.
>
> <snip>
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