AMITIAE - Monday 14 October 2013

Testing for Color Blindness on the iPhone: Variations on an Ishihara Theme

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By Graham K. Rogers

Color Color Color

Late last year I had a look at an app that allowed users to check for color blindness. When I reviewed this at that time, I had a vague recollection of being tested back in the UK both at school and when I started a job. When I applied for a driving licence in Thailand, I was asked to take the same test.

This is the Ishihara Test for Color Blindness that was developed at the beginning of the 20th Century. It is so effective that nothing has superseded it. Although the Enchroma Test can indicate a problem, it is not officially accepted.

Because the Enchroma app was nicely organised - in terms of vertical and horizontal thinking - I used it for a writing task for some of my students. I wrote about this a few days ago. While helping the students with research for their writing, I found a number of apps that use the Ishihara test as a basis.

Three free apps are examined here: Color Blind Test (by Tomato); PseudoChromatic Color Blindness Test (by Cassiopeia Information Technologies); and Test de Daltonismo Lite (by Movisol. These apps should only be seen as a guide and only a professional, using a full set of test cards, would be able to give a proper analysis.

Color Blind Test

Using some cards from the Ishihara cards system, Color Blind Test is simple and straightforward. After an opening screen, the user is presented with a series of 6 of the cards. Each has a number in the center as is normal. Beneath each display are two buttons with a choice: one is correct, one is not.

Color Blindness Color Blindness

At the end of the run of cards, a panel appears. In my case, it informed me that there was "No Problem!!!" (with three exclamation marks), offering "Quit" or "Retry". When I deliberately made a single wrong choice, the final panel told me "You are color blind!!!". I was able to retry. If the user presses a button incorrectly, there is no returning.

PseudoChromatic Color Blindness Test

Despite the multisyllabic title of this app, it is rather simple. PseudoChromatic Color Blindness Test opens right into the test with a screen marked, Plate 1. There are back and forward arrows either side of this. At the top is a button marked Clear to the right. To the left is an Information (i) icon.

The information panel provides a text description of color blindness and the Ishihara Test with links to relevant online pages. There is also a brief (but necessary) explanation of how the app works. At the top left is a Done button. Top right has a button that links to other apps by the developer.

Color Blindness Color Blindness

This app is not really a test, but the 24 plates, show problems that those suffering from color blindness will show. It is possible to draw over the plate and the number (or shape) displayed. Pressing Clear will remove this. When the right arrow is pressed, the user sees a brief text on what they should or should not see.

Working through the app screens is slow and on occasion I was delayed by the appearance of a click wheel. This should appear when the Plate number is touched, but it was also on screen when I tried to press the right arrow at times. It may be my hefty thumbs that caused this.

Despite the slowness, it could be useful for home use; for example allowing a parent to check a child before a proper diagnosis is sought.

Color Blindness Test

The test app by the developer, Movisol, is eye-catching with its front page of a green London telephone kiosk, although as a child I had seen such in certain rural areas. As red-green deficiencies are common, the visual pun is effective. The title in Italian is as it appears in my iTunes installation, although in the App Store it is shown as Color Blindness Test Lite.

Color Blindness Color Blindness

After that opening screen, there is a text explanation about the Ishihara test and how to use the app. There are also four buttons near the bottom of the screen: Start; and Color Blindness Test+ (an in-app purchase of $1.99); Share (email); and a link, which confirms that this is not a diagnosis and offers other apps from the same developer.

The free version of the app has only 5 screens. Each shows a card from the Ishihara test. The user presses a Next button and a 3-button menu appears with two answers and "Nothing". The user selects one and a text appears explaining what should be seen by users. There is additional information in some texts to explain more about the particular analytical purpose of the screen.

Color Blindness Color Blindness

When all five screens are done, the app provides a simple analysis. If the result indicates a level of color blindness, the text changes to reflect this, adding the suggestion, "Consult your doctor for a full diagnosis". After this a Next button takes the user to a screen offering the premium version of the app. There are two buttons: "I want it" and "Later".


These three free apps are not diagnostic in terms of a medical opinion, but may indicate fairly quickly if there are indications of a color deficiency. In some countries, this could mean that certain careers are not open to a person, or that a driving licence may not be granted. It may be useful to know this sooner, rather than later.

Graham K. Rogers teaches at the Faculty of Engineering, Mahidol University in Thailand where he is also Assistant Dean. 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.



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