I still maintain these issues of RGB, CYMK, additive, subtractive, etc. are
interesting but not really pertinent to the question of "what is color."
They are just ways of being more precise and sometimes more quantitative in
our color discussions.
On the other hand, the issue of color blindness and how people might "see
different things" when observing the same object is more pertinent to the
question.
Here, I think my color "definition" is still appropriate, but we simply
acknowledge some people have sensors in their eye that are not quite "up to
par" with the average person. And we also acknowledge the ultimate
interpretation of color is a brain process. It's just as difficult for me
to know what exactly you perceive as yellow as it is for me to know what you
are thinking.
However, in an attempt to understand this better, I have done a fair amount
of talking to color blind persons, both acquaintances and students. Since I
use spectrometers in lab, and some of the experiments involve discernment of
color, I have to give my students the following warning: "This experiment
requires that you be able to distinguish colors. This may be difficult for
some of you, especially if you have some degree of color blindness. If you
find you are having difficulty with the experiment, I am here to help you.
If you want to discuss your perception of color with me I would be
interested in such a discussion. If you would rather not discuss it I will
find ways for you to accomplish the experiment or substitute a different
experiment."
There may have been color-blind students who muddled through the experiment
without talking to me, but all of the students who have expressed difficulty
have freely talked about their color vision with me. This has lead me to a
much better understanding of what these persons perceive, and especially a
better understanding of some of the hardships they have endured.
In the United States red-green color blindness seems the most common. For
these people a red object, a green object, and a yellow object all appear
roughly the same. Depending upon the degree of the "blindness" they might
be able to see subtle differences, or almost no difference. If they can see
subtle differences they can often finally decide that this object is red, or
that object is green, but it takes more concentration, and differences in
brightness or overall room color can sometimes lead them to discern
incorrectly. I have heard story after story of traumatic kindergarten
experiences in which the exasperated teacher didn't understand why the
student couldn't "learn" red/yellow/green. I have concluded there is a
fairly wide range of red/green blindness. Some people just don't see any
difference at all; others see sufficient difference they can identify the
color most of the time, but not a quickly as I can.
A graduate-school friend who was red-green color blind came to my wedding.
At that time (over 20 years ago) the small town of Bluffton had a traffic
light that had only one light bulb for each level of lights. The top light
was red for one street and green for the other. The bottom light was
opposite. The middle light was yellow for all directions. My friend was
not totally color blind, but enough so that he mostly relied on red at the
top and green on the bottom. When he encountered this traffic light it did
not seem quite right to him. He saw the top light was illuminated, but he
thought it appeared more green than red. He parked his car and got out and
watched the light for several cycles and he finally figured it out. By
noticing the top was illuminated for both directions (or bottom, etc.) he
correctly concluded that one road had green at the top and the other road
had red at the top.
It's a good thing my friend had some degree of red/green discernment and/or
it was good Bluffton didn't have much traffic. That traffic light was
removed some years ago... I believe it is now illegal to have lights that
operate that way.
I once had a student from Japan who was blue-blind. I do not know if this
is correct or not, but he said blue blindness is more common in Japan than
in the United States. He could not distinguish between blue and black.
When looking at a spectrum (rainbow) he could see the red turn into yellow
and then to green, and then it just quit. That would be a case of the blue
sensor not being present or not working. Red/green color blindness is
usually a case of the red sensor triggering over too wide a range (both red
and green) or vice-versa.
Michael D. Edmiston, Ph.D. Phone/voice-mail: 419-358-3270
Professor of Chemistry & Physics FAX: 419-358-3323
Chairman, Science Department E-Mail edmiston@bluffton.edu
Bluffton College
280 West College Avenue
Bluffton, OH 45817