posted 02-28-99 02:23 PM ET
I posted this to comp.sys.ibm.games.strategic about a week ago. For those who miss it, here are all the types of colour blindness and the breakdown by gender:Type Men Women
Protanopia 1.0% 0.02%
Deuteranopia 1.1% 0.01%
Tritanopia 0.002% 0.001%
Cone monochromatism Very rare Very rare
Rod monochromatism 0.003% 0.002%
Protanomaly 1.0% 0.02%
Deuteranomaly 4.9% 0.38%
Protanopia: Severely reduced discrimination of reddish & greenish
contents of colors with reddish colors appearing dimmer than normal (rho
cones missing)
Deuteranopia: Severely reduced discrimination of reddish & greenish
contents of colors without any colors appearing dimmer than normal
(gamma cones missing)
Tritanopia: Severely reduced discrimination of bluish and yellowish
contents of colors (beta cones missing)
Cone monochromatism: No color discrimination, but approximately normal
brightnesses of colors (gamma and beta cones missing)
Rod monochromatism: No color discrimination (No cones present, truely
black & white vision)
Protanomaly: Some reduction in the discrimination of reddish and
greenish contents of colors, with reddish colors appearing dimmer than
normal (rho cones have a spectral sensistivity shift towards that of the
gamma cones)
Deuteranomaly: Some reduction in the discrimination of reddish and
greenish contents of colors, without any colors appearing dimmer than
normal (gamma cones have a spectral sensistivity shift towards that of
the rho cones)
For those who are not familiar with how the eye senses colors:
The eye has structures called rods (brightness detections) and cones
(color discrimination) which are very small (on the order of about .002
mm). In the normal eye, there are three types of cones: beta (max
sensitivity to blue (~440 nm) light), gamma (max sensistivity to green
(~550 nm) light and rho (max sensistivity to red (~600 nm) light). When
light is absorbed in a rod/cone in the retina, the molecules of the
photosensitive pigment are excited, and, as a result, a change in
electrical potential is produced. This change then travels through a
series of relay nerve cells, and eventually results in a series of
voltage pulses being transmitted along a a nerve fibrre to the brain.
The rate at which these pulses are procduced provides the signal
modulation, a higher rate indicating a stronger signal, and a lower rate
a weaker signal. Color vision is obtained when the signals of the
various cones are subtracted from each other.
If anyone is interested in more detailed explanations, I lifted all the
above information from the first chapter in "Measuring Colour" by R.W.G.
Hunt.