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abyqlik_com
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Are you colourblind? Do you actually know if you’re colourblind?  On the 3 occasions I have presented on this topic I have had a two male attendees admit to not knowing….. (until now...) that they were colourblind to some degree.

It is estimated that approximately 8% of men and 0.5% of women are colourblind. This large difference in probability is due to the fact that the genes that produce photopigments are carried on the X chromosome; if some of these genes are missing or damaged, color blindness will be expressed in males with a higher probability than in females because males only have one X chromosome, whereas women have two!
(http://en.wikipedia.org/wiki/Color_blindness)

The most common way to determine level of colourblindness is to take an Ishihara test. The test consists of a number of plates that contain patterns of different coloured/shaded dots. These dots form to show numbers and shapes that you can…. or in the case of colour blind people…. can’t see.

Can you see a number in this plate…… I can’t…. I am actually colourblind, which is quite ironic considering I work with QlikView visualisations every day. A person with “normal” vision should see the number 6, colourblind people will see nothing.

Ishihara1.gif

You can take the tests online on a number of websites :

http://www.tedmontgomery.com/the_eye/colortst/colortst.html

http://colorvisiontesting.com/ishihara.htm

http://www.colour-blindness.com/colour-blindness-tests/ishihara-colour-test-plates/

One great example I found is the image below. I cannot see any difference between the two images due to me being Red-Green colourblind. People in the office who have perfect vision could see a massive difference in the colours.…

globes.jpg

(Source: http://facweb.cs.depaul.edu/sgrais/colorvisiondefi.htm)

I often find that colour and the use of colour is something that is decided upon without much thought, hence me writing this. We have to be very careful when we decide on the colours we use in our charts and dashboards. In your QlikView objects, really think carefully about colours and the impact your choices will have on your users.  Ensure you use colour blind friendly palettes, and avoid using colours that are “close” together in tone, next to each other in charts such as scatter and bar charts.

There are a number of resources on the web to help you choose friendly colour palettes..

http://jiminy.medialab.sciences-po.fr/tools/palettes/

http://colorbrewer2.org/

So, choose your colours wisely, try not to use colours that are “close” together. Utilise the web resources to help determine your palette. If, like me, you are colour blind then these resources are a massive help!

Remember the number…. 8% of males are colourblind…this is a big number. This 8% could be the key decision makes or indeed the developers.

Wherever possible, colour should purvey meaning, not just used because it looks nice!

See more about this topic in this techincal brief Colour

ABY

2 Comments
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Adam:

Thanks for a good post. I am aware of red-green colour blindness in significant male population however ishihara test is new to me, which is good to know. These are necessary fundamentals in design as red, green and yellow are most commonly used for alerts. However these are default colors in QV and hence widely used. Can you suggest some good practises for picking colurs? I pick one colour (mostly grey) and use different shades of it, suggested by Stephen Few in "Information dashboard design".

Kiran Rokkam.

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abyqlik_com
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Creator

Hi Kiran,

Thanks for your comments.

Yes, the Ishihara tests are great. I had to do the test when I was in junior school in the UK.

When you are choosing your colour palette you have to take in to account things such as brand constraints and corporate policies, these can have a large impact on the selection of your key colours. We also have to be careful when using the "emotional" colours such as greens and reds unless we actually want to show alerts or good and bad. Working with a small number of colours or indeed shades of the same colour is the best way to work but when you do work with shades, you will have to be careful not to have the shades too close together as colour blind people like me will have difficulty distinguishing the different values!

Have a look at the technical brief and also the websites like http://colorbrewer2.org/

Cheers.

Adam.

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