Seekey – Colorblinds See Otherwise Invisible Colors

Seekey tool
Seekey Tool

Are you red-green colorblind? Do you have a handy tool in your pocket which helps you in critical situations to tell certain colors apart? If not you might like to learn more about a tool called Seekey, which exactly can do that for you.

Seekey is a little tool consisting of two different light filters: a red and a green filter. Looking through them will change the way you perceive the color of the object you are focusing on. Based on the difference in color perception through the filters and without filter you can guess the correct color.

Let us have a look at a little example: It is always very tough for a red-green colorblind like me to spot the nice orange blossoms in our green garden. Those two colors just look so similar to my eyes. With Seekey this changes. Looking at the blossoms through the red filter, they get lighter while the surrounding green darkens. The green filter changes the effect and lets all the green lighten up compared to darker blossoms.

Seekey Color Key
Seekey Color Key

There are several color keys coming along with Seekey. Through those color keys you will learn how the color perception changes when looking through one of the two filters. The table to the left shows you an example for the colors red, green, orange and brown.

Kenneth Allblom is the inventor of Seekey. He is living in Sweden and distributing the tool either directly through his web page or otherwise it can be bought at opticians and in certain boat equipment stores in Great Britain, France, Sweden, Finland, Germany, New Zealand and Japan.

A study at the Karolinska Institutet in Stockholm Sweden even showed that the Seekey tool will assist red-green color deficient persons to achieve an 86% improvement at the Ishihara test for color blindness.

Seekey is a handy tool which can help every red-green colorblind person. Visit the Seekey homepage directly to get more detailed information about this little helper.

Future Employees to Take Color Blindness Tests on Their Own Expenses

The following story was sent to me by Dave. He is slightly colorblind and while applying for a job on the way to his new career he had to pass a color blindness test.

Unfortunately the new employer wasn’t really colorblind friendly. Read his story to learn more about the way he had to walk along.

I needed to pass a medical clearance in order to be qualified for training. This was no big deal…except for the Ishihara Plates.

Needless to say, I didn’t pass the Ishihara plates and needed to take subsequent “color deficiency” testing, which I needed to pay for at my own expense. The employer requires all of their employees to pass the Farnsworth D-15 AND the Farnsworth-Munsell D-100 if they have failed the Ishihara plates.

So, I went to my eye doctor and passed the D-15 with relative ease. My doctor thought that the D-100 was extremely overkill and completely unnecessary (partly due to the fact he did not own one). So I needed to spend $659.00 to purchase one myself to bring to my doctor to get tested on.

The D-100 is an amazingly intricate test and cannot be learned. So, I prayed that I would pass. I did very well (at least I thought so) on the test and scored an Error Score of 32. Which easily falls into the range of “Normal Discrimination”. The scoring break-down for the D-100 is as follows. Error Score of 0-16 “Superior Discrimination”. 17-100 “Normal Discrimination”. 100 and above “Poor Discrimination”.

Needless to say I didn’t need the D-100 and the company wouldn’t take returns, so I happily donated it to my eye doctor.

So, thanks for the site and giving me the hope I needed to pass the test!

Thank you very much Dave for sharing your personal story with us. And all the best in your new job and with your new career.

Is My Son Colorblind?

Colorful Bricks

When your child starts to learn colors the question of color blindness often arises. Does your child understand the colors correctly? He or she is mixing some colors or can’t name them correctly. Is this color blindness or is it just to early to know?

Many mothers and fathers ask if their son or daughter has a color vision deficiency. Here are some example questions of anxious parents:

  • My son has a hard time with red and yellow. Could my 3 years old be colorblind?
  • Is it too early to tell if my 2 1/2 years old son has problems with colors?
  • When should we test our son for color blindness?

Usually it is all about sons. Because of the inheritance pattern of color blindness, males are by far more often colorblind.

I would like to tackle the question about a possible color vision deficiency of your child with the following three points:

  1. Development of color vision in children.
  2. When to test your child for color blindness.
  3. Why you should check the color vision of your child.

Before I get into the details of the above three topics I would like to say a few words about color blindness itself. In each school class there is on average one colorblind child. Red-green color blindness is the most common form while the terminology is misleading. Every normal colorblind person has a very colorful visual spectrum—just a bit less colorful. This can range from almost the same vision as non-colorblind people to a quite reduced sensation of colors, but still a colorful one.

Only if you have a complete color blindness you would have monochromatic vision. This would allow you to see shades of gray but you couldn’t perceive any real colors at all. This type of color blindness only affects one out of more than 30’000 people and you would recognize it already at a very young age.

1. Development of color vision in children. At the beginning a newborn has to develop its vision. Only after a few weeks a baby can recognize high contrasts in colors like black and white. Color vision evolves steadily and at the age of about six month they have full color vision.

At the age of two a child starts to match colors. They can give you for example a block of the same color you’re holding in your hand. As colors can be matched they still can not grasp the naming of colors yet. This starts at about the age of three years. Only then your boy or girl will name the some main colors correctly.

And it will take another one to three years to name colors accurately. It is said that a child has developed normal color naming between the age of four and six years.

2. When to test your child for color blindness. As we learned in the above section that color vision and color naming evolves slowly the question arises, when is the best moment to test your child for a possible color vision deficiency.

First of all you shouldn’t just check your child for color blindness if there isn’t any evidence for a possible color vision deficiency. It wouldn’t really help you because there is also a possibility that a color blindness test shows a deficiency if there isn’t any. So if you have some evidence, when should you test?

Test for color blindness just before your child will enter kindergarten.

Most of you will ask now, why shouldn’t I test earlier if my son or daughter shows problems with color matching and color naming? I would like to give you a few arguments, why you shouldn’t test earlier.

  • Before kindergarten-age your child might not have developed complete color naming abilities.
  • You shouldn’t push to hard on such things like color vision. Give your child time to learn and understand the concept of colors.
  • Don’t make yourself crazy with a possible and often wrong diagnosis of color blindness of a very young child.
  • Try to understand your child and don’t try to analyze everything. This way you will understand your child much better and you will be able to help him or her much better.
  • It won’t really help your child and you if you know to early about its color blindness. Because your child will not really understand it or he/she will already feel like “having a handicap”.

3. Why you should check the color vision of your child. As I said before, don’t just check in anyway but only if there is some evidence. But if you think your boy might be colorblind, let him check or try some of the online color blindness tests.

And why? Because this way you will learn more about his color vision ability AND know his main problem colors (like red and green) AND last but not least you will understand and learn how to support him and can pass this knowledge on to his teachers.

Even if there is one colorblind child per class on average most teachers are not aware of color vision deficiency and most often don’t know how to handle it. They either don’t know what they can do to help a colorblind child or don’t know the colorblind children in their classes.

If you know about the color blindness of your son, you can not only support him but also help others to understand his vision and how they can help him.

Picture taken by Leonardo Sagnottisome rights reserved.

5 Online Color Blindness Tests

Do you ever wanted to test your color vision? Are you not sure if you might suffer from some type of color vision deficiency? Here are five ways to test online if you are colorblind or not and also to give you a clue about the type of your color blindness.

Color blindness tests are often used check if you fulfill some job requirements. Certain professions like police officer or pilot most often require very good color vision. But also a lot of mothers are curious about the color vision of their children.

The following five checks are quite different but serve the same purpose. So if you take a few of them—or even all five—you will get a quite complete picture of your color vision abilities. Please add your thoughts, ideas and maybe even your test results in the comments section.

Ishihara Plate 23
Ishihara Plate

1. Ishihara plates color blindness test.

This plates are named after a Japanese professor and by far the best known test for red-green color blindness. They are made out of many colored circles and are showing a number, which can only be seen if you are not colorblind.

The test can tell you if you either are red- or green-blind, but can’t tell you a lot about the severity of your color blindness. Ishihara plates are often used by eye doctors to check for color blindness.

D-15 Color Blindness Test
D-15 Color Blindness Test

2. Farnsworth Dichotomous Test (D-15).

The Farnsworth D-15 test is also a very well known and belongs to a category of color blindness tests called Color Arrangement Tests. All these tests are based on different colors—in this case 15 of them, sometimes consisting of up to 100 different hues—which have to be arranged in the correct order.

According to the order you choose a tester can find out if you are suffering from a red-, green- or blue-color deficiency.

City University Test

City University CVD Test

3. City University Dynamic Colour Vision Test.

Professor John L. Barbur from the City University London does a lot of research in the area of color vision and color blindness. He and his team developed a computer color vision test based on the same principle as the Ishihara test.

They are offering the City University Online Color Vision Test also on the web in a very simplified version. The City University color vision test is good to test for any type of color blindness.

Color Blindness Test - Example Screen

Color Blindness Test at

4. Color Vision Test at

This great online test has no long history or well known institute in the background. It is simply a Color Blindness Test based on Confusion Lines of the CIE 1931 Color Space.

But a very good one which is available online.

You have three different tests, one for each type of color vision deficiency: protan, deutan and tritan defects. And the test results tell you a lot more about the type of color blindness you are suffering from.

Color Blindness Test - Color Match

Color Blindness Test – Color Matching

5. Multiple Choice Color Vision Test.

The French optician Jean Jouannic offers an Online Multiple Choice Color Blindness Test based on 31 images. The images are either hidden signs and letters or a handful of colors which you have to match to a choice of color names.

As colorblind people show great difficulties matching color names to colors, this is another appropriate method to test color vision.

The test has some nice statistics when you have finished and tries to quantify your color blindness in detail.

You should know, that all online color blindness tests are not truly reliable. Because of different display settings, display gamma values and ambient light situations you can’t rely on the results of online color vision deficiency tests. They will show you the direction, but for a reliable result you have to visit an eye specialist.