We are colorblind.com

Tom van Beveren from the Netherlands put together a very comprehensive site on all sorts of stuff people should know, if they want to build/design a website which doesn’t exclude colorblind visitors. Because almost 5% of all people are suffering from some form of color vision deficiency, this is something every web publisher should care about.

we are colorblind


The site We are colorblind.com includes a lot of very interesting topics related to color blindness on the web. It is structured as follows:

Patterns for the Color Blind: A list of very useful patterns you can follow while you’re designing your web content. If you follow those patterns, colorblind people will definitely find their way around on your page.

Quick Tips: This section provides supportive information for all the patterns from the above mentioned list. If you dig into the quick tips you’ll learn more on how color blind people see the world and how you can use this information.

Color vision and web Tools: Hopefully this is an ever growing list of great tools to help you while you are building your web site or just on your way through the web.

Good and bad online Examples: The examples section gives a good overview of good solutions, which help people with color vision deficiency. The list also includes bad examples; web sites unusable by color blind visitors.

If you think about building a new web page, redesign your site or get your online content ready for colorblind visitors, make sure you visit wearecolorblind.com and follow the tips and patterns provided by Tom.

Tom: Really great work! Thanks.

Free Lecture: Colour Assessment & Diagnosis Test

color-assessment-diagnosis-test-lectureThe Royal Aeronautical Society will be holding a Lecture in London on 28 September relating to Use of New Technologies and Therapies in Aviation Medicine.

One of the speakers is Dr Robert Hunter, Head of Aeromedical Section, CAA. He will be talking about the new Colour Assessment & Diagnosis Test.

The Colour Assessment and Diagnosis (CAD) test is a newly developed test for colour vision deficiency in pilots. The CAD test is completely sensitive and specific for the identification of normal colour vision and the test is able to accurately and repeatably quantify the degree of colour vision loss in individuals with colour vision deficiency.

The pass/fail criteria are based on the point at which the degree of deficiency degrades performance in critical piloting tasks, the most critical task being the interpretation of the Precision Approach Path Indicator (PAPI) lights. Using the pass/fail criteria that have been established, 35% of colour deficient pilots will be granted unrestricted class 1 medical certification.

The presentation describes the background to the work including current tests for colour vision deficiency, an analysis of colour critical piloting tasks, and the CAD test.

If you are around go and join this free lecture. You can find further information about this talk at the Royal Aeronautical Society Conferences homepage.

Truelight Color Vision Test

Certain jobs in the film industry definitely require very good color vision. If you need to adjust specific hues and find a good balance of the colors in a picture, color vision deficiency would be quite a big handicap.

Just the other day I took a picture of a rainbow. It was such a beautiful one, but I couldn’t see the color spectrum so I had to ask my son, if it is really a nice one where you can spot the whole color spectrum. The same would happen if I would work as a professional in the film industry: Either I could ask somebody for help or I just would fail. My color blindness is just to strong to deliver good work.

Truelight Color Vision Test

Truelight Color
Vision Test

FilmLight is a leading company in the film industry and provides a simple online color blindness test on their website. This way you can perform a first check if you are ready to work with moving pictures. Can you spot the T? Check out their website to see the whole Truelight color vision test picture.

This color blindness test picture consists of three lines each showing six T’s. Four of them should be visible and you should be able to tell their orientation. You should also be able to guess the fifth correctly and the sixth is just visible under perfect conditions. The three lines of T’s relate to the three different types protan, deutan, and tritan color vision defects. The test is based on the color blindness confusion lines.

You can’t see anything? — No worries. I can only spot two T’s in the last line. Only if I bend my laptop display back and forth I see two more T’s, but not more.

If you did like this kind of test make sure to check out my color blindness tests or have a look at some other color vision tests online available.

Everybody is Color Blind

Are you colorblind? No, you don’t think so? — I am sure you also have some form of color vision deficiency or colorblind sensations. You don’t believe me? I’ll prove it in the following article.

I would like to show you four types of color blindness which are true for almost all of us. Starting with a very simple form we will definitely get into more details when it comes to small-field tritanopia, which strongly supports my statement that everybody is colorblind.

(A) Colorblind in the Darkness

When it is getting dark at dusk colors start to fade. You start to mix up colors and are not so sure any more when it comes to naming a specific color. So one could say that everybody is colorblind in the darkness.

I know this is not such a strong argument to support my statement, but it is a very good example to get an impression of how it feels like if you would have some form of color vision deficiency.

(B) Ultraviolet and Infrared Blind

Non of us can see both far ends of our color spectrum: infrared and ultraviolet. We name those colors but we can’t see them. This doesn’t necessarily means we are colorblind if nobody can see them anyway. But there are creatures who can see those colors.

A lot of people heard that bees can see ultraviolet light; which is true. But they don’t have a broader color spectrum as they also have only three different color receptors like people with normal color vision. Bees see less reds and more blues, that’s not really better than us isn’t it.

But there are some fish, some turtles and the whole family of birds who can perceive our whole color spectrum and also ultraviolet light. Birds have four different color receptors (tetrachromats) and clearly can see more colors than you and me. On the other side we have for example rattlesnakes which have some form of infrared eyes which can see the prey at night.

(C) Tetrachromacy

If you believe it or not but not only animals are tetrachomats but also humans can have four different color receptors!

Studies have shown that women who carry the color vision defective gene, can develop four different receptors in the eye and therefore have a broader color spectrum than the rest of us. This is a very rarely diagnosed phenomenon but definitely makes all of us colorblind compared to tetrachomatic women.

(D) Small-Field Tritanopia

And if you think the three points above don’t really prove that we are all colorblind this last point will definitely change your mind.

Normal color vision means you have three different color receptors: one peeking at red (L-cones), one at green (M-cones) and one at blue (S-cones). Together we have about 4.5 million of those receptors distributed all over our retina. Most of them are L- and M-cones and only about 7% are blue sensitive.

A closer look at the distribution of the color receptors shows, that in the very center of the retina, inside the fovea, there are no blue cones at all! As this spot is very small—you can think of visual field the size of a tennis ball at the other side of the court—this is called small-field tritanopia. See also my article about tritanopia to learn more about this type of color vision deficiency.

So in the center of our visual field we have no S-cones. This means only L- and M-cones can give us information about the colors in that spot and therefore we are all dichromats in the fovea. — And why do you don’t know anything about your central color blindness? Because your eyes don’t really focus on such a little point but often move around. This makes you believe, that you have trichromatic color vision over your whole visual field.

And because small-field tritanopia is true for all of us, everybody is at least a little bit colorblind! quod erat demonstrandum.

Color Blind Testing Guide for Pilot Applicants

If you want to become a pilot, you need to pass a medical screening including color vision—usually by taking a simple color blindness test. Even if you already received your pilots license, you have to go to a medical check up every 12 month, again including a color vision deficiency test.

cockpit-pilotsWhat are your choices to accomplish the FAA test for color vision—specially if this could be a problem for you as you know you don’t have perfect color vision? This article will show you the different possibilities you have to master this specific test on color vision deficiency.

There are two ways you can go to accomplish it. The first choice is always to take a usual color blindness test with your Aviation Medical Examiner (AME). If you can’t pass this first round there is the possibility of retesting using some other color vision deficiency test which is accepted by the FAA. Or you can choose the second way which includes some special form of a very job specific color vision testing. But be prepared because this specific test can only be taken once and thereafter there is no other color vision test allowed anymore!

Let me explain this step by step in more detail.

First way: Accepted Color Blindness Tests

Any of the following listed tests can be taken to examine your color vision. If you fail one of them there is always the possibility to take another test of the list. I think this is a good rule as you can always have a bad day or be to nervous. So make sure that you pass in the second round. And it is important to know, that no other color blindness tests are allowed!

  • Pseudoisochromatic Plates Color Vision Tests: This tests are the most common ones and also known as Ishihara plates tests, because the first and very well known plates were made by Dr. Shinobu Ishihara. It is reported that the AOC and the Dvorine tests are the easiest to accomplish for people with color vision deficiency.
    • AOC (1965 edition)
    • AOC-HRR (second edition)
    • Dvorine pseudoisochromatic plates (second edition, 15 plates)
    • Ishihara pseudoisochromatic plates (concise 14-plate edition, 24-plate edition, 38-plate edition)
    • Richmond pseudoisochromatic plates (1983 edition)
    • Richmond-HRR (4th edition)
    • Tools which display plates: Titmus Vision Tester, Titmus II Vision Tester, Titmus 2 Vision Tester, Titmus i400, OPTEC 2000 Vision Tester, OPTEC 900 Vision Tester, Keystone Orthoscope, or Keystone Telebinocular
    • Electronically plates by LEDs: APT-5 Color Vision Tester
  • Farnsworth Lantern Test (FALANT): This is the only test allowed which is not based on isochromatic plates. The FALANT test consist of two little lights showing one of the colors red, green, or white which have to be named correctly. It is reported to be the easiest test to accomplish.

For detailed information about the allowed number of errors in each test check the decision considerations for AMEs at the official FAA website.

Many people ask if it is allowed using color correcting lenses or glasses while taking a color vision test. Unfortunately the rules say clearly, that you are not granted to do so.

Second Way: Specialized Operational Medical Tests

If you fail the above tests and still want to try to get your license, there is a last chance for you. But it is very important to know, that this second possibility of test can only be done once and after that you are not allowed to take any other test again. So this is really your last chance!

The specialized operational medical test consists of five different test steps. The first two parts are subsumed under the name Operational Color Perception Test (OCVT) and you have to accomplish them during day light. The last three steps are called Medical Flight Test (MFT) including also in-flight testing.

  1. Signal Light Test (SLT): Identify in a timely manner aviation red, green, and white.
  2. Aeronautical chart reading: Read and correctly interpret in a timely manner aeronautical charts, including print in various sizes, colors, and typefaces; conventional markings in several colors; and, terrain colors.
  3. Read and correctly interpret in a timely manner aviation instruments or displays.
  4. Recognize terrain and obstructions in a timely manner.
  5. Visually identify in a timely manner the location, color, and significance of aeronautical lights such as, but not limited to, lights of other aircraft in the vicinity, runway lighting systems, etc.

Make sure you are fit while taking this test, as it can be taken only once. But if you can master it you will receive a Letter of Evidence (LOE) which means, you will never have to take a color blindness test again during your pilots career.

If you fail the color vision testing during your medical exam you will have the restriction of not valid for night flying or by color signal control.

There is also an interesting study about Unreliable Secondary Color Vision Tests for Pilot Candidates and you can also find a lot more information on this topic at Leftseat.com.

Most Mammals Are Colorblind orThe Evolution of Color Vision

Our color vision is based on three different types of visual pigments. This is called trichromacy and as a matter of fact, it is quite unusual in the animal kingdom.

The following information is a compilation of the article Color Vision: How Our Eyes Reflect Primate Evolution.

Animals have either only one visual pigment, like a few nocturnal mammals. Or they are dichromats, which means they have two different pigment types. This is true for almost all mammals—except the primates, which are most often trichromats. And some birds, fish and reptiles even have four different types which makes them sensitive also for ultraviolet light sources.

The questions arises now: How comes that we are trichromats?

1st step: It looks like that the short-wavelength (S) pigments are the most ancient ones, as they are found in almost all vertebrates.

2nd step: Similar forms to our medium- (M) and long-wavelength (L) pigments are also found quite often—and therefore very old. But only a few primates have both of them, so this has to be a recent evolution.

3rd step: Let’s say the M pigment existed (we actually don’t know). And then through some mutation of a few acids in the DNA the L pigment evolved. Now a first interesting step happened: Some female primates inherited one X chromosome encoding the M pigment and one X chromosome the L pigment and they became thrichromats! This way only female primates could be trichromats as only they have two X chromosomes (male = XY).

4th step: Now the New World primates evolved away from Old World primates. They still are carrying the information encoding color vision as described above. But in the lineage of Old World primates a next interesting development happened: A female primate merged the M and L encoding into one single X chromosome through mutation! This way also male primates became trichromats (thanks!).

5th step: This genetic mutation had such a strong advantage (seeing more colors = finding more good food) that X chromosomes encoding only one pigment were wiped out of the genetic pool.

This five steps of the evolution of color vision sound very interesting. But there are also some questions which arise when reading through, which make me think that we didn’t get to the bottom of it yet. Here are my questions:

  1. How comes that our ancestors suddenly could see the new colors only because of a new pigment type?
  2. Can really only one female primate be the source of our trichromatic vision?
  3. And why the hack are there still so many color blind people? Why is color vision deficiency in so many forms still that widespread?

The authors of Color Vision: How Our Eyes Reflect Primate Evolution have some answers ready. But I’m not sure if I can believe what they are writing.

And there is still no answer for my most important question. Maybe you have one? — Why is color blindness still such a common disease?

Color Blindness in Transportation

Brian Chandler—a red-green colorblind Traffic Engineer from Missouri—just started a new web site to discuss colorblindness and its effect on transportation. He named it Grey Means Go and gathered already some very nice examples.

Grey Means Go by Brian Chandler

If you tell somebody about your color blindness they often ask, if you have a driver license (“I’ll better watch out when you’re on the road :-)”). This is actually handled very differently in each country. For example in Romania you are not allowed to drive if you have any form of color blindness (visit Discromat by Vasile Tomoiaga to learn more about this).

Are colorblind drivers a danger to society?

Some say yes, others say no. Brian has at least some ideas, how to enhance certain aspects in transportation to help not only the drivers which are suffering from color blindness. Have a closer look at the following examples from Grey Means Go:

  • Reflective and even retroreflective backplates of traffic light signals help to identify the correct position of the light at night.
  • Yellow tail lamps increase the vehicle visibility and reduce reaction time in a significant way. But would this also be true for colorblind drivers?
  • Shaped signal heads which definitely are a great aid for colorblind drivers.

I’m looking forward to read more about this very interesting topic and I hope that also many other traffic engineers will take this issue more seriously.

WoW Improves Accessibility for Colorblind Gamers

If you are colorblind it can be sometimes quite hard to play certain games. Something as simple as a green team playing against a red one can be a big issue if you have a color vision deficiency.

World of Warcraft is one of the most played games around the world. Blizzard, the company behind the game, will introduce with the next patch (3.1) a module for disabled people. This includes a part for enhancing the interface for colorblind people. Some objects, which were traditionally color coded, can now be assigned to letters or symbols.

The people from AbleGamers, a community for disabled gamers, interviewed a lead developer from Blizzard, Tom Chilton. They wanted to learn more about this new colorblind option.

Here is a list of enhancements for colorblind WoW gamers. The listed features either support an already existing color coding or replace it.

  • Tags distinguish friendly, neutral, or hostile creatures and enemies.
  • Gear quality has additional text descriptions.
  • The three different coin types are labeled with single letters.
  • Recommended character level is listed as a number.
  • Learned recipes will be rated from + through to +++.

This sounds like quite a big step forward. As a colorblind less than part time gamer I am very happy about every little enhancement in the games I play. Almost never I can see the difference between color coded stuff in the first moment. So I either will learn it during the gameplay or just never really know what I am doing.

In the case of such a big game like World of Warcraft, there are obviously many more possibilities to enhance it for gamers suffering from color blindness. Here is one more example, taken from the same article:

Additionally, some things were overlooked in Blizzard’s version of this add-on. Rogues accumulate combo points as they attack their victims. These combo points are shown as red dots in an arc around the picture of the rogue’s target. As the points are accumulated, the red dots are filled in.

Someone who was colorblind to the color red would not be able to tell the difference between a red dot filled in with red and a red dot lightly shaded with red. One member of the player base identified this problem and created a specific add-on called Kast Combo Points that would change the way the points are displayed. This modification changed the red dots so that they are completely hidden until a combo point is awarded.

Dear colorblind gamer, I’m sure you will and already found your personal way to play the games you like. And if color blindness gets to much into your way, just play another game. Don’t forget, it’s just a game.