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