AMITIAE - Friday 21 December 2012

Color Blindness Test from EnChroma: for the iPhone and iPad

apple and chopsticks


By Graham K. Rogers


Color blindness is a genetic disorder that causes a deficiency in the way some people see colors. The most common form of color blindness is in the way some people are unable to differentiate between green and red. I was first tested for colour-blindness in the mid-1960s prior to a school trip to France.

Some years later as part of the police advanced driving courses, one of the sight tests again involved color blindness: no point in learning to drive fast if you cannot see. In Thailand, this is also one of the tests for those wishing to hold a driving licence.


In most color blindness tests, a series of cards is used and the person tested is asked to identify a number hidden in each of the displays. Technology has moved on and in any optician's office there is an array of electronic analytical tools. A heads-up from Kelly Hodgkins on TUAW, took me to the Color Blindness Test by EnChroma on the App Store which I downloaded and examined myself.

color color color

Color Blindness Test (1)

After a quick display of a logo screen, the user is taken to a straightforward menu of four buttons. There are two items concerned with the testing - Start test and Test result - and two for information: about Color Blindness (Or Color Vision Deficiency - CVD); and About EnChroma.

That last item gives some information about the company and their eyewear products The app is, in some ways, an extended advertisement for the company, but as this brings a useful, functioning test app to users, this is an excellent way to use this medium. Not only do the immediate target customers have the benefits, but this could provide a quick and useful screening facility in those places where resources are limited.

The Information section explains in clear text what color blindness is, but does add a warning that the app does not provide a medical diagnosis. Nonetheless, such apps can give an indication that a problem may exist and lead to proper medical attention.

Color Blindness Test (2)

The test itself is preceded by a short text description in English. This is a well-thought out explanation: one screen; concise; informative. An object lesson in clarity. At the bottom is a button marked Start demonstration: not the test itself, one notes, although as befits a good demonstration it has the same processes as the test proper. The app may be used in either portrait or landscape mode although the screen and buttons are displayed differently. This made no difference to ease of use.


Three shapes are used, rather than numbers: square, circle, diamond. These are matched by four buttons at the bottom of the screen (or the side in landscape mode): the shapes, plus one button marked "Nothing". Each of these buttons also has a tiny icon of the shape, so the test can be used in situations where users cannot read English, with minimal instructions. The "Nothing" button is marked with a question mark (?).

Each of the demo test screens is a mix of neutral grey dots of mixed sizes with the shape in the centre. Each of the shapes is also made up of dots, but in the demo these were of a darkish pink.

After the demonstration, a screen confirming that the user seems to have a basic grasp of how to use the app is displayed. The screen also explains how the test itself gets harder. Indeed it does, although the screens that gave me (and others) most difficulty were in the middle of the test. Screens at the start and end seemed easiest.

In the test, backgrounds are a mix of neutral colors (not only grey) with the shape in another color. With each there is sometimes more, sometimes less contrast. As a control, some screens have no shapes (or so it seemed), but I looked hard nevertheless.

I tried first in really poor conditions: wearing sunglasses on a moving train. I was still able to see most of the shapes correctly. When I tested properly in good light conditions and wearing my reading glasses, I was sure of most decisions I made concerning the shapes, but with a number I had to use the "Nothing ?" button.

color color color color

I ran the test twice, with the first result showing no problem and the second reporting, "You are a mild deutan: color vision is shifted towards the red end of the spectrum. This is the most common type of deficiency. There was a recommendation for a suitable lens type from EnChroma.

With the information screen was a button that allowed me to request a report from EnChroma. An email was sent and almost immediately a report was returned. At the bottom there was a repeat of the warning that this was not a true medical diagnosis.

color report


This is an easy to use, free app with one main purpose: a quick screening for color vision deficiencies. Like many of the best apps, it does one thing and it does it well. There are no frills and the app is easy to understand, even for those who cannot read English. In some situations it could provide a simple check: a less than perfect result may indicate further testing is needed.

Owing to the simple format of the app and its ease of use, I was able make a teaching moment out of this by first having a group of Engineering students define, explain and describe colour blindness. I then talked them through the buttons and their functions while they took notes.

One of the students had a form of color blindness that caused him difficulties with certain shades and neutral colours (as he explained it to me). We ran the test with the panels displayed on a large screen in the classroom, discussing the process with his feedback and theirs, so that they might be able to analyse and write more effectively in the future.

During the class, another student downloaded the app onto his iPad, to allow himself another view of the screens. I saw that this used the full screen display for all the tests and was easier to handle than on my iPhone.

A quick look at the iTunes App Store shows that there are a number of other apps (some paid) that also allow testing for color blindness and other vision problems.

Graham K. Rogers teaches at the Faculty of Engineering, Mahidol University in Thailand. He wrote in the Bangkok Post, Database supplement on IT subjects. For the last seven years of Database he wrote a column on Apple and Macs.



Made on Mac

For further information, e-mail to

information Tag information Tag

Back to eXtensions
Back to Home Page