Yesterday early morning my wife said to me:
Have a look at this very nice sunrise. It’s in glowing orange colored shades – beautiful.
I took out our digital camera, took a photograph and here it is. It is nice but I don’t have a clue if it is orange or not. Have a look yourself.
Funnily enough, Orange and Sunrise are two of the three major telecom companies in Switzerland.
I borrow the wording Speedlinking from Darren Rowse the father of ProBlogger, which is a great pool of ideas for all kind of bloggers. Fortunately this blog was even featured once on Darren’s site as a blog case study, but let’s get back to here and now and delve into some articles about color blindness.
I even don’t spare you with this weeks most talked about feature for bloggers and others, the new Google Trends service which lets you feel like a detective while compare interesting search keywords against each other. After playing around with it for a while I would like to share the following outcomes:
Enough speedlinking for now. Thanks for joining me.
Related articles:
Blog Case Study
From Synaesthesia to Disabled Stickers
Some Pearls about Color Blindness
Color Blindness at the Blogosphere
Needless to say, if you want to know if you see the world through colorblind eyes you can take some tests and try to understand the results. Usually the tests at least can tell you if you have some sort of color blindness or not even though the results often don’t have a lot in common.
But tests are not always available, you can’t really rely on online tests and a visit to the doctor is expensive. So what to do if you want to know if you, your husband or wife, your child or a friend of you is affected by color blindness and you don’t have a computer with an online connection within reach or don’t want to fill the eye doctors wallet for a simple test?
Have a look at the questions below. If you or your person under observation can answer one or more of the following questions with YES, then most probably you are affected by some kind of color blindness.
This are eight questions which try to give you a clue about your color blindness. From my point of view we can even narrow them down to one simple sentence:
Do you feel colors?
If you look at a color you have to feel it and name it, as simple as this. Only as a child you learn them. Later on color names are something you know and you don’t have to think about what color it could be.
Being colorblind means, that you are guessing color names. Maybe just some, maybe all. But you are not sure if you are right or wrong. Arguing about color names is something for people with a good color vision. We colorblind don’t argue, we just take it as the others say if we haven’t guessed it right.
This analogy about perfect pitch and color blindness is a really good explanation to me. Most of us don’t feel notes. We can hear them and maybe guess them but that’s about it. Somebody with a perfect pitch can just name a note when he hears it because he feels it. It’s the same in the case of colors: People with normal vision feel colors and colorblind people can only guess them.
Related articles:
Perfect Pitch and Color Blindness
A Colorblind Decides on Colors
Supporting a Colorblind Husband
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My article about how Language affects Color Vision was featured at Science Notes: Go climb a tree!, the latest Tangled Bank which is a blog carnival about science and medicine, very broadly defined.
It was my first contribution to a blog carnival, and definitely not the last one.
You found a color which you would like to use on your web site but don’t know if it is purple or blue? Or this picture shows some nice details, but are they just brown or shiny red?
For somebody affected by color blindness colors can often not be named like a fork or a spoon but usually are guessed. So you are never sure if it is brown, green or red, you just guess and let yourself be overruled by somebody who knows it better.
What to do if you would like to know the names? In nature it is impossible as long as there are no special glasses which can label the colors you see… But on computers, where colors are always built up from values it is easy to label them. Unfortunately it is not often used and color names associated to the color values like RGB are a rare commodity.
The people behind the Colorblind web site at Telodo Bend did a great job. It offers a comprehensive list of colors with heximal and decimal values and most import including the according color names. The following charts are offered:
So if you want to build a new web site and would like to use some special colors, this is a great resource to check for specific color names and their corresponding color values.
Related articles:
Microsoft knows about Color Blindness
Choosing the Right Colors
Perfect Pitch and Color Blindness
People affected by color blindness do see a difference between the little green man who is walking and the red man who waits to turn green. Maybe the difference is not the same difference as you can see it, but there is a difference.
For my colorblind eyes the first and the second pictures are similar and the third is almost the same again. Only the last one is definitely different. It looks more like a grayscale picture to me.
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Photos taken by J. Ignacio Stark – 
Some rights reserved.
The photographs are shown in the following order: Normal – Protanopia – Deuteranopia – Tritanopia. Choose the one which is most suitable to you.
Related articles:
At the Traffic Light
5 Misbeliefs about Color Blindness
Actually the wording blue-yellow color blindness is misleading. People affected by tritan color blindness confuse blue with green and yellow with violet. So the term blue-green color blindness would be more accurate because the colors blue and yellow are usually not mixed up by tritanopes.
Tritan defects affect the short-wavelength cone (S-cone). There are two different types which can be observed:
Blue-yellow color blindness can be observed only very rarely. Different studies diverge a lot in the numbers but as a rule of thumb you could say one out of 10’000 persons is affected at most. In contrary to red-green color blindness tritan defects are autosomal and encoded on chromosome 7. This means tritanopia and tritanomaly are not sex-linked traits and therefore women and men are equally affected.
It can be observed that tritanopes usually have fewer problems in performing everyday tasks than do those with red-green dichromacy. Maybe this is because our society associates green with good/go and red with bad/stop, a pair of colors which accompanies us every day but a clear reason isn’t found yet by the researchers.
Tritan defects can not only be inherited but also acquired during one’s lifetime. In this case it even may be reversible and not permanent like an inherited color blindness. In the case of an acquired defect this is either evolving slowly for example simply through aging or coming instantly caused by a hard hit on your head.
The two photographs below give you some impression what tritanopes see. On the left side the actual photograph is shown as it is seen by people with normal color vision. On the right side you see the tritan counterpart where you can spot how blue-yellow color blindness influences the view of colors.
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Photograph taken by Ottmar Liebert – Some rights reserved
Read more about Deuteranopia and Protanopia—the other two types of color blindness.
Further readings:
Opsin Genes, Cone Photopigments, Color Vision, and Color Blindness
Does Occupational Exposure to Organic Solvents Affect Colour Vision?
Wikipedia: Color Blindness
Related articles:
The Biology behind Red-Green Color Blindness
Colorblind Population
Mike McLane’s son is colorblind but they didn’t really found out about it until his son was in the 4th grade. By knowing about his deficiency only afterwards teachers could support him and so Mike’s son didn’t receive bad test results anymore just because of his red-green color blindness.
That is why Mike created a Color Blindness Testing Poster. It can be used as an initial screening. Only if a child can not see the numbers and signs on it a doctor should be consulted for proper testing. The poster works very well with children of age 5 or 6 years, as Mike writes on his web site.
Hover over the image to unveil the signs
As for my person I just feel like a blind man when I look at all the dots. Only at the bottom to the left and right side I can see some lines and that’s about it. Nothing else! Well, if I look very close I can see some numbers. Somewhere I spotted the number 99 until my wife corrected me — it is the number 79.
There are approximately 8% of men affected by color blindness. As a conclusion there is about in every school class a child which has some kind of color vision deficiency and usually this isn’t recognized immediately. But if the teacher and the child would know about it there learning experience could be improved a lot.
Color blindness is frustrating not only for the affected child but also for teachers. It can lead to unexplainable test results, completely wrong answers and misunderstandings. If color blindness is understood a teacher can support affected children by choosing correct colors, supporting colors with signs and be a helping hand if colors are the source of understanding for example in biology classes.
Arlene Evans found out about this lack of information when she was working as a school teacher. That’s why she wrote a book on color vision deficiency for children to explain this phenomenon in simple words and pictures. She also gives some hints and tipps for everyday life. The book is not only a good source of information for children but also for teachers and helps to better understand color blindness and how you can support children affected by this deficiency.
Dear teachers, please learn more about color blindness, try to understand it, be aware of it whenever colors are involved or even buy one of this posters. You are confronted with color blindness every day — even if you don’t know about it yet.
Related articles:
Arlene Evans Books about Color Blindness
Colorblind Population
Color Blindness Test by Dr Shinobu Ishihara
Direct link to the Color Blindness Testing Poster web site.
Color Oracle is a full screen color filter released by Bernhard Jenny of the Institute of Cartography, ETH Zurich. Because the swiss federal institute of technology (ETH) is just around the corner of where I am living I proudly pass on some notes about this new tool.
As the tool is Mac only I couldn’t have a closer look at it because I am “PC only”. But the homepage gives some clues about the features of Color Oracle which are listed below.
As mentioned above if Color Oracle is turned on the actual full screen is appropriately simulated independently of the software you are using for designing your art.
And if you are not a proud owner of a Macintosh the team of Color Oracle provides some further links about similar tools and online possibilities for simulating colorblind vision.
Related articles:
Colour Contrast Analyser
Simulating Color Blind Vision
Colorblind Web Page Filter
Do you remember the early days of color television? Where only a handful of TV channels existed and programs were not running 24 hours a day and 7 days a week. Those days were the glory days of test patterns, also known as test cards.
The patterns were originally real cards used to calibrate the cameras. Soon they were replaced by patterns generated by test signal generators which could be used to adjust the equipment for optimal functionality.
Seen through colorblind eyes a modern LCD computer monitor has a many times better color reproduction than any color television. When looking at these pictures this feeling gets supported very much. The colors feel dull and almost interfere with each other. There is not a clear and crisp vision of the colors at all. This observation raises the question to me: Does somebody affected by color blindness have an even worse color impression on a color television compared to normal vision?
I don’t know the answer. Maybe some of you made some similar observations and share this feeling.
But let’s get back to the test patterns. If you look at the colors on the second and third image they are very badly chosen for somebody being red-green colorblind.
I will try to show you what I mean by listing my view of the colors starting at the left hand side:
The colors of the stripes 2 and 4 and of the stripes 5 and 7 are very close together for my eyes. These are very typical colors to be mixed up by protanope or deuteranope people. What perturbs me a bit is, that stripe number 6 is a clear red to me. No way this could be green even though I am red-green colorblind.
Further readings:
The Test Card Gallery
tv-testbild.com (German)
Wikipedia: Test Card
Related articles:
Green versus Orange
Colorful Ropes
Playing Trivial Pursuit with a Colorblind
Imagine the Green is Red