Moving on from last weeks Creating Posters using PowerPoint, we turn our attention to Colour Vibration.
This is something we find from time to time. Whilst it can look great when used appropriately, more often than not, it’s a pain in the eye. Literally.
How much to you think about the colour combinations you choose for text, background and other visual elements? Do you think about audience members with colour deficiency? Those with contrast issues? Are you still using PowerPoint colour combinations or practices from the 1990s?
Let’s check it out!
What is Colour Vibration?
Colour vibration is where two colours of equal strength and brightness jockey for attention. This occurs due to highly saturated and bold colour combinations appearing to “vibrate”. It looks as though the colours next to each other merge and/or blur. In many instances, there is the illusion of movement or glowing edges, i.e., vibration.
Sometimes, if these colours are viewed for long enough, when you look away from the content you see an ‘after image’.
Let’s look at some examples. For this, we took some text from our parent web site. We just changed the colour of text and backgrounds to demonstrate colour vibration.
Example 1 (red / green):
Example 2 (blue / yellow):
Example 3 (pink / yellow):
Example 4 (red/green):
For more interesting effects of colour, illusions and afterimages, read this blog post: Colour Theory – colour interaction. It helps detail the perception of colour pairings.
When it comes to using colours, there are colour combinations which should be avoided. We have audience members to consider who may be living with:
- colour deficiencies
- contrast deficiency and/or
- other sight / sensitivity issues
Here, we highlight colour blindness. The most prevalent colour blindness is red/green followed by blue/yellow. In the colour combinations of examples 1 and 2 above, anyone with colour blindness were totally disadvantaged. They would not be able to see the text on screen, especially if the colours are of equal strength.
Following closely on from colour blindness, some audience members may have contrast issues. For example, two colours of equal strength may be hard for many audience members to differentiate. This is where it’s good to use lighter and darker colours to enhance contrast.
By simply making one of the colours lighter, this increases contrast. Anyone living with colour or contrast issues is now advantaged. It also reduces colour vibration as one colour is dominant. When the red/green slide had the green background colour lightened and half the slide made black and white, you can see there is contrast between the grey tones:
This doesn’t get over the colour blindness issue but the information can be seen regardless of colour. This brings us to Contrast Ratios.
You may have noticed the ratios at the bottom right hand corner of examples 1 and 2. This relates to the Web Content Accessibility Guidelines (WCAG) which has the WebAIM standards at AA and AAA. A good rule of thumb is to work toward the higher standard when creating anything digital.
This means we should have adequate contrast for whatever colour text we use on different coloured backgrounds of slides. Here’s the WebAIM colour/contrast checker where you can check you colour combinations and contrasts.
Your mission at AAA standard is to achieve the following contrast ratios on your slide content:
- titles minimum 4.5:1
- normal text minimum 7:1
Text at size 14 point is considered normal (or body text). Whereas, size 18 or larger and bold would typically be titles.
When using red text on a white background, the WebAIM results are as follows:
From the results, it fails normal text at AA and AAA standard. It passes the large text test only at AA Standard but it can be used for graphical objects where colour is not crucial.
NB: Colour should never be used in isolation to highlight important information!
Simply by darkening the red colour, all the standards and text tests can be passed:
It’s also good practice to consider everyone in your audience. You’re not creating content for just yourself! Be mindful that not everyone engages with colour, visual or auditory information the same way you do. We all have different perceptions and abilities.
This is where the WCAG guidelines help us create content taking into consideration different perceptions and audience member needs. It also widens our audience base and more people can engage with the content rather than being excluded. That’s a win for everyone!
Thank you. We appreciate you taking the time to stop by and read our blog.
Next week, we’ll be looking at infographics in PowerPoint.
Remember, the DigiKnow blog posts are released at noon on a Monday.
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