Category Archives: Tests

RGB Anomaloscope Color Blindness Test

The anomaloscope is the most accurate tool to classify your color blindness. Since it was developed by a German ophthalmologist just over 100 years ago it is used all over the world to check the severity of ones color vision deficiency and its specific subtype.

The classical anomaloscope is used to identify red-green color blindness. It consists of two different light sources which have to be matched. One source is a yellow lamp which can be adjusted in its brightness. The other one is made by a mixture of a red and a green lamp, whereas the mixture between those two colors can be calibrated.

According to the match the tool can tell you details about the following facts of your color blindness:

  • Red- vs. green-blindness,
  • dichromacy vs. anomalous trichromacy,
  • and the severity of your color vision deficiency,

As this tool is only available as a quite expensive equipment I tried to simulate it online. I knew that there is only a little chance to get the same results as the real anomaloscope. But I tried it anyway and designed the RGB Anomaloscope. As all computer displays are based on the colors red, green, and blue, it will always be a simple approximation of the real test.

The diagram below shows the test results as matching-lines of some red-green colorblind persons. Each point means that this person matched a certain red-green combination to some shade of yellow. Non-colorblind people would only match the point 50/50 with some variances.

RGB Anomaloscope Test Results Diagram
RGB Anomaloscope Test Results Diagram

Unfortunately the results didn’t turn out as I thought. I couldn’t find any split between red- and green-blind persons. Also it isn’t that easy to judge the severity of a red-green color blindness.

Anyway, the test is online and you are welcome to try it out. Maybe there will be some improvements in future releases of the RGB Anomaloscope Color Blindness Test, so stay tuned.

A big thanks to everybody who helped me to develop the test.

New Color Blindness Test – Looking for Red-Green Colorblind Test Persons

RGB Anomaloscope
RGB Anomaloscope

The anomaloscope is the most precise instrument when it comes to analyzing red-green color blindness. It was developed about 100 years ago and is still in use all over the world.

An anomaloscope is based on two different light sources which have to be brought to a match. You can match them by adjusting either the brightness of a certain yellow color or the proportion of mixture between a green and a red light. According to the matches you can make the eye specialist can give you detailed information about the severity and subtype of your red-green color blindness.

The RGB anomaloscope uses exactly the same approach but as an online tool. But because computer displays are solely build up from the three main colors red, green, and blue, the results can’t be just transformed to this online color blindness test. And that’s why I need you.

I’m looking for red-green colorblind persons who would like to help me to develop the RGB anomaloscope color blindness test. The test is now online available as RGB Anomaloscope Color Blindness Test.

What do you have to do? Simply use the anomaloscope, that’s all. If possible you can take the test under different light conditions and using different computers. This increases the chance to get an accurate color blindness test in the end. And—of course—you have to be red-green colorblind yourself.

RGB Anomaloscope Diagram
Color Blindness Test
Results Diagram

On the left side you can see my test results. Every dot represents a color match. As I’m strongly red-blind the matching area spans the whole possible spectrum.

If you would like to join and help me to develop this new online color blindness test just contact me. Please write me also about the subtype and severity of your red-green color blindness—as good as you know. You can check this at Which Type of Red-Green Color Blindness is It? After contacting me I will send you the link to the tool and the password to get in.

And please be aware we might not get the results which I would like to see. So maybe I can’t give you any better results than the ones you already have.

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.

Online Multiple Choice Color Blindness Test

Color Blindness Test - Grid Image
Color Blindness Test – Grid Image

The French optician Jean Jouannic offers an online color blindness test based on 31 images. If you take your time and answer all the multiple choices, you will get rewarded with a nice reporting and probability indicators for the different types of color vision deficiency.

The images are based on two different color judgment systems. The first one consists of images showing a grid with a base color. Letters or signs in second color are integrated into those images. The test is easy, either you can see something or you can not. There is also always a second option offered, but these are just to find out if you’re trying to cheat or not.

You can see one of those grid images on the left side. Unfortunately I can’t tell you the solution for this one, because I can’t see anything but the grid.

Color Blindness Test - Color Match
Color Blindness Test – Color Match

The second system is based on color matching. An image shows different colored squares and the multiple choice offers a huge variety of different possible answers to choose from.

If you have normal color vision, it shouldn’t be a problem to find the right solution. But with a more or less severe type of color blindness you will have quite some difficulties to match the offered color names to the shown image. If you don’t know what to choose there is always an option to say, that you can’t find a good proposal.

Because it is often not easy to make your choice, you should find your answer with a process of elimination. Choose the one which sounds most probably. If you are colorblind, you are aware of the problem that you often can’t name colors correctly. With this elimination process it is definitely easier to find a matching solution.

Enough of information. Here is the direct link to the just described multiple choice color blindness test.

My test results:
I am either suffering a very strong form of red-weakness (protanomaly) or am completely red-blind (protanopia). Let’s have a look what my test results tell me:

  • Correct answers: 21 (out of 31)
  • General indicator of color blindness: 29%
  • General indicator for color recognition: 71%

Only an indicator of 29% to be colorblind? In a first moment this looks strange to me, because I’m definitely colorblind—and not only just a mild form. I think the color matching images are the answer for this low percentage. Because of my color vision deficiency I can’t name any of the shown colors. But using the elimination process I still often found the right answer.

The next list shows all the indicators split up into the different types of color blindness.

  • Deuteranopia indicator: 3%
  • Deuteranomaly indicator: 29%
  • Protanopia indicator: 39%
  • Protanomaly indicator: 0%
  • Tritanopia indicator: 0%
  • Tritanomaly indicator: 0%

Ok, that looks good to me. A 39% percent chance to be red-blind is still a bit low, but at least it is ranking highest. A little strange is the fact, that there is a bigger chance to have some form of deuteranopia than to be red-weak.

What I like about this color blindness test:
It is available online, free to use, you can easily fill out the multiple choice forms and best of all, it shows you your results in a second and offers a whole range of indicators.

And what I don’t like so much:
The color matching images are too complicated to find your solution and don’t work as they should. I’m not so sure about the accuracy of the results, and apart from the test page everything else is just available in French.

But anyway, this is another great opportunity to find out more about your color vision. Maybe you like to try some other color blindness tests and compare the results. Or if you like, just share your indicators with us in the comments section.

Stroop Test – Can You Read the Colors?

In case you’re not colorblind, naming a color is an easy thing. But naming a color if it is a colored word of another color name (e.g. green) is definitely not that easy to accomplish.

Stroop Test
Stroop Test

The Stroop Test was described by John Ridley Stroop back in 1935. He took some color names and just colored them differently. Try it out yourself with the graphics below. Don’t read the words but say aloud the color names you see.

Did you do well? Even if you have normal color vision, after the first two lines you start struggling because the wrong names are very distracting. And how did you perform, if you have some type of color blindness?

For me it looks interesting and I can see some differences in the colors. But it’s definitely just a guessing game. Colors I can almost not distinguish and therefore have big problems to name them in this graphics are:

  • BluePurple
  • OrangeGreen

Do you know, what I like the most about this? It’s the color Red I can spot easily, despite the fact I’m red-blind…

City University Online Color Vision Test

The City University of London has a well know Department of Optometry and Visual Science. They invest a lot in research for color vision and color vision deficiency which includes their own color vision clinic.

A well known color blindness test called City University Color Vision Test is available in a print version and often used to identify tritan deficiencies. This test is derived from the well known D15 color arrangement test and is based on different plates, where out of four dots the one which comes closest to a fifth dot has to be selected. If you only have very mild form of color blindness, you will pass this test. But on the other side the City University Test allows to identify the type and approximate severity of color blindness.

City University Test
Can You Spot It?

Now for all of us, looking for a way to test one’s color vision abilities online, they developed a web based color vision test. The test is a little (very uninteresting) movie, consisting of pictures which look like the one right here. In each picture there is a square, which might be hidden if you are suffering from some type of color blindness.

The movie is twelve Mb long, so you need a fast link to play it. But if you can play it, you will have to chance to find out if you are suffering from some type of color blindness. There are some facts which are really great about this test:

  • The test is not only made to detect red-green color blindness, but also for people suffering from blue-yellow color blindness. This is not often the case. Specially the well known Ishihara Plates tests are only for red- or green-weak respectively -blind persons.
  • Different severities of color blindness are covered within this test. If the square is not visible to you for only a few seconds, there is a big chance that you are suffering some type of color vision deficiency.
  • It’s the most simplest color blindness test, covering a big range of deficiencies. You only have to watch and see, if you always can spot the square.

There is of course also a downside to this. Through this movie you won’t find out how severe it is and which type it is. You don’t even get a feeling, because you don’t know if you can’t see the square for let’s say ten seconds, what this means. Is it just a mild form of color blindness or not? Only the eye specialist will be able to tell you for sure.

Maybe you already have downloaded the web-based color vision test and watched the movie. If the square disappeared for you for some time, you might like to compare your results to my ones. From other online tests and what my doctor told me once upon a time I know, that I have some form of very severe red-weakness or red-blindness. And my test results are:

  • Square disappeared 1. time from 0:16 through to 0:26.
  • Square disappeared 2. time form 1:04 through to 1:11.

What are your results? It would be great to have some others to compare with. But always keep in mind, that online color blindness tests can’t tell you the truth because there are to many factors like display settings and illumination which affect the test results. To get a proper screening you have to visit your eye specialist.

Tone Deafness vs. Color Blindness

Musical Notes
Color-blind, tone-deaf or just
foto by Daily Dog

I am colorblind and fail every single test on color blindness. Maybe this sounds familiar to you; so let us have a look at some other -ness trait test which might give you a better feeling

Somebody suffering form tone deafness has problems in differentiating between distinct musical notes. In common language it’s also often referred to a person who has problems in reproducing a series of notes. Compared to colorblind people who might not be very much interested in colorful art or paintings, if you are tone-deaf you might not be the greatest fan of music or just sing when you are by yourself and know, nobody is listening to you.

Before you take the test checking your overall pitch perception ability be assured that color blindness is not in any way related to tone deafness. And now just relax, sit back, shut off your tv and your beloved radio station and test your musical skills.

I hope your results weren’t disappointing. Or if they were not that good I hope you at least perform well on the color blindness tests.

My results were 86.1% correct. A result I’m very much proud of because—you know—my color blindness test results look much worse.

Ishihara Plates Color Blindness Test in a Leaflet

Unfortunately those leaflets are not available anymore. But you can find the whole set of 38 Ishihara plates in my article: Ishihara’s Test for Colour Deficiency: 38 Plates Edition.

Just recently I found this new Web 2.0 application where you can produce your own leaflets. A leaflet is a miniature web site which can be created online and distributed through an URL or an embedding link.

I thought this could be a great way to show the 35 Ishihara plates to test your color blindness. All plates show a big circle consisting of many little colorful circles. Because the circles differ in color and brightness it can get really tough for a colorblind person to see the shown numbers or traces.

If you take the following color blindness test be aware that those pictures were scanned and are now reproduced by your display. This can alter the colors. Because a color blindness test relies solely on correct color reproduction you shouldn’t take the results for granted. If you really want to check your color blindness you should see your local doctor.

Could you perform as you expected? Or did the plates show that you really are red-green colorblind? I hope you could spot at least the number in the first and the trace in the last plate, otherwise you may have a real severe color vision problem…

Color Blindness Test based on Confusion Lines of the CIE 1931 Color Space

This is the third and last part of a series, where we have a closer look at a color blindness test which is based on the confusion lines of the CIE 1931 color space. In the first part I introduced the CIE 1931 Color Space and the second part was looking a bit deeper into the theory of Confusion Lines.

Most tests which check for color blindness are based in some way on confusion lines. But I would like to focus your attention on this test which is regenerated for every single trial based only on confusion lines.

The author of the test describes the design for his color vision test as follows:

  1. For each color vision deficiency (protanopia, deuteranopia or tritanopia) test, five confusion lines are selected randomly. Three points on each confusion line that can be distinguished by the normal observer are chosen.
  2. For each test, a confusion line is selected randomly. A point is selected randomly among the set of three. It is displayed in the upper test panel at a random luminance in the form of random dots. The three points are displayed in the lower three panels at a random luminance and also in the form of random dots.
  3. The subject is asked to check one of the lower panels which color matches that of the test panel.
Color Blindness Test - Example Screen
Color Blindness Test – Example Screen

As I described in part two of this series, colorblind people can distinguish only a handful of wavelengths of the color spectrum. Compared to normal vision it is around 10% to 20%. But if you are affected by color blindness you automatically start to interpret a difference in lightness as a different color. This makes you think to see more colors than you actually can distinguish.

If we look at the description of this color blindness test this is exactly the point of it. It plays with the lightness and adjusts the three choices to the same lightness, which makes it really hard to get the match if you are colorblind.

I took the test. It showed me cruelly – cruelly again, that I am very much colorblind. But let us have a look at my results. I took each color blindness test three times and completed each time 50 decisions. What is amazing to me is, that in all three tests the results didn’t differ a lot, or better said almost none. Let me start with the best results:

My Tritanopia test results

Run Correct Wrong Correct%
1 47 3 94%
2 49 1 98%
3 47 3 94%

Most of the time I could tell a difference between the three choices. But still I had to guess every single time. I suppose the problem is that I can’t name the colors I see, I just see different colors and nothing more. (→ Tritanopia Test)

My Deuteranopia test results

Run Correct Wrong Correct%
1 31 19 62%
2 30 20 60%
3 35 15 70%

The results are much worse compared to the first test. Although I still could distinguish usually one of the three colors from the other two it was more of a guessing game than really knowing anything. (→ Deuteranopia Test)

My Protanopia test results

Run Correct Wrong Correct%
1 26 24 52%
2 24 26 48%
3 25 25 50%

This color blindness test was pure guessing. I couldn’t tell a color from the other and I am very much amazed of the results. The lightness adjustment made it impossible to me to match them correctly. (→ Protanopia Test)

The results of this color blindness test in three parts approve the outcomes of other tests. I am protanopic or at least affected by a very strong protanomaly and as the doctor would say: “You are completely colorblind.”

More information about the color blindness test based on confusion lines and the online tests itself can be found at the Color Vision page of biyee.

This was the third and last part of this series. The other parts can be found at
Part 1: CIE 1931 Color Space
Part 2: Confusion Lines