11. Monochromacy
Caused by widespread
retinal rod or cone
defect/absence
Rod Monochromacy:
associated with Male Female
photophobia, light Monochromacy (all) 0.000001% 0.000001%
sensitivity and poor
vision.
Cone Monochromacy:
Otherwise normal vision.
RARE. VERY RARE.
http://en.wikipedia.org/wiki/Color_blindness
12. Dichromacy
Protanopia - Red
deficient: L cone
absent
Male Female
Deuteranopia - Green Dichromacy (all) 2.4% 0.03%
deficient: M cone Protanopia 1% to 1.3% 0.02%
absent
Deuteranopia 1% to 1.2% 0.01%
Tritanopia - Blue Tritanopia 0.001% 0.03%
deficient: S cone
absent
LESS RARE.
http://en.wikipedia.org/wiki/Color_blindness
13. Anomalous
Trichromacy
Protanomaly - Red
deficient: L cone
defect
Male Female
Deuteranomaly - Dichromacy (all) 6.3% 0.37%
Green deficient: M Protanomaly 1.3% 0.02%
cone defect Deuteranomaly 5.0% 0.35%
Tritanomaly - Blue Tritanomaly 0.01% 0.01%
deficient: S cone
defect
KINDA COMMON.
http://en.wikipedia.org/wiki/Color_blindness
15. Easier to remember ...
Total colorblindness
Any form of monochromacy
Red-green
Dichromacy (protanopia and deuteranopia)
Anomalous trichromacy (protanomaly and deuteranomaly)
Blue-yellow
Dichromacy (tritanopia)
Anomalous trichromacy (tritanomaly)
http://en.wikipedia.org/wiki/Color_blindness
16. I HATE THESE THINGS.
http://www.nlm.nih.gov/medlineplus/ency/article/003387.htm
The term “colorblindness” is actually quite lousy. A colorblind person is not “blind” at all -- he or she is just unable to distinguish a certain spectrum of colors.\n
Sorry about this one. While you may never be diagnosed with it, it is not a biological “bit” that is either on or off. There are varying degrees of color blindness, and no two people see color the exact same way. Likewise, “failing” a colorblindness test does not necessarily mean you are colorblind.\n
Perhaps a better way of saying this is that “it does not matter as much as it perhaps once did.” As long as new things are created, there is a potential for confusing a portion of the population.\n
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The retina is that area in the back that covers the entire inner surface aside from what is taken up by the lens/pupil/iris in the front.\n
This diagram is from 1928, but still holds true today. It represents the layers of the retina. For this diagram, light passes through this series of nerves and other cells to reach the “rods” and “cones” layer at the bottom. There are around 7 million retinal cones and 75 - 150 million retinal rods in a human eye.\n
Better diagram. The photo receptor layer at the back is where the rods and cones are located. These component work together to create a signal that is sent down the optic nerve for processing. The actual “image” is composed by the visual cortex within the brain.\n
The visible spectrum is represented by the three primary colors of red, green and blue. Incidentally, the alternate colors shown here of cyan, yellow and magenta represent the three primary colors used on a printing press. CMYK vs. RGB. Black and white is either the combination or absence of all the colors for a particular application.\n
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This deficiency is usually accompanied by other optical ailments. Studies find that these are truly one in a million cases. This is as close to what some folks think of as color “blindness” -- these folks may only be able to decipher a handful of colors.\n
Dichromacy means that a particular kind of photo receptor is missing, classified by what kind of visible wavelength it interprets (long, medium, short). This one is far more likely to occur than monochromacy, but still not the most common. My maternal grandfather has protanopia. Essentially, any variation of dichromatic colorblindness will not be able to discern certain colors no matter the external factors.\n
Trichromacy is a condition in which the cones are present, but are defective. This causes certain colors in certain lights to appear identical or just difficult to distinguish. As you can see, this is far more common. Mine can best be classified as deuteranomaly - my green cone receptors are defective.\n
So, like most lovely “gifts” that genetics give us, it is my parents’ fault. Colorblindness hangs out on the X chromosome. Specifically, my mother is a carrier for my grandfather’s genetics. If I have a daughter, there is a pretty good chance she’ll be a carrier.\n
This is a more succinct way of describing particular types of colorblindness. In my case, I am red-green colorblind, most likely attributed to deuteranomaly (defective green, or medium wavelength retinal cones). \n
Tests can diagnose colorblindness. I pass some that I shouldn’t, fail others I should have passed. It’s an inexact means to determine with a 100 percent certainty what kind of colorblindness somebody has, but it will indicate that the retinal photoreceptors are not quite firing correctly.\n
Based on what we know about colorblindness (and what we can teach a computer), there are ways to “simulate” what the world looks like to a colorblind individual. As you can recall from our previous examples, these relate to dichromacy.\n
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Red, Yellow, Green. The two on the right look nearly identical to me. If you use these to indicate the “status” of something (and it’s vital), I’m screwed.\n
Much better. Now, I have more than one cue to go off of to tell the status of an item.\n
This is the worst. Absent of any symbology or even a large surface area to compare against, color coded text is particularly difficult. It really is just a bad idea in general.\n
This is probably review for most of you, but computers assign values to color in order to render it consistently. Here are four examples of notations to express a color. I rely on these heavily to ensure I get the right color value.\n
It’s because of this that my dreams of being an astronaut, fighter pilot, radar technician etc. went up in flames. They do test these things. The recruiter’s list of “great military careers” got a lot shorter when I shared that.\n
Never hurts to have a second pair of eyes on anything. This is particularly important if a design decision has to be made.\n
