Share this page

Small ads

Tuesday, 20 February 2024

Does Colour Exist?

Speaker: Professor Stephen Westland

The guest speaker at the u3a Todmorden Members Meeting on 15th February 2024  was Stephen Westland, with a talk entitled 'Does Colour Exist?' He is Professor of Colour Science and Technology in the School of Design at the University of Leeds. His main interest is colour, and his approach to studying colour spans some quite diverse areas such as design, science and technology, and machine learning.
He began by answering the question posed in the title:  yes, colour does exist. But there was much more to come.  While colour does exist, it doesn't exist in the way we think it does. For instance, clothes are not coloured, and light is not coloured.

Stephen was wearing a yellow t-shirt, and said that everyone agreeing the garments colour was yellow, didn't actually mean that it was.  It was because we have been brought up to believe that it was, or is, and we are conditioned to think in this way.

He then showed the first of his slides, a photograph of a dress with horizontal stripes, which had appeared online nine years ago, and had created a media storm.

People looking at the photograph in 2015 thought the stripes were black and blue, while many others thought the stripes appeared to be white and gold. 

The first audience participation today showed that, indeed, the dress did look white and gold to some of us.

Stephen said that the actual dress is in fact black and blue in colour.

He went on to show us the colour spectrum, and mentioned the method that is used to remember the colours in it – Richard Of York Gave Battle In Vain, for red, orange, yellow, green, blue, indigo and violet.  Stephen said that these actually weren't the colours of the rainbow any more, because different colours have been added, plus language has changed over time.  Different bodies and organisations disagree about the colour spectrum, one of them believing that the colour spectrum contains a hundred colours.

We see colours when light travels into our eyes, and to the retina, a tissue which is covered with millions of light sensitive cells known as rods and cones. When these cells detect light, they send signals to the brain. The colours that we see on television, cinema and online are produced by the providers of the programmes and films etc, who use 'additive mixing' of red, green and blue lights.

Stephen said that the colours around us as we watched his presentation, and looking round at each other – the walls, screens, chairs – all that we could see,  were made up of all of the colours of the spectrum,  produced by the cone cells, and our brains. While most humans have three cones and are known as Trichomats, some women have four of these cones. 

The three types of cones are; long wavelength sensitive, medium wavelength sensitive and short wavelength sensitive.  The signals from the brain which enable us to recognise what we are looking at, and what colour we think it is, are only recognised because we have seen these things before, or we can guess at what they might be, based on what we have already seen during our lifetime.  All humans share this trait, and method of learning. Stephen provided a well known quotation which summed this up: 'I think, therefore I am'.

He said that one person in a million might only have two, or even one, of the cones and would subsequently see less of what we call colours.  Some animals, particularly aquatic specimens, have cones which help them to exist in their own environment.  He mentioned that whales and sea lions only have one of these cones and see their world as grey throughout their lives.  Other amphibians fare better, goldfish and shrimp have four and fifteen cones respectively.

Using short film clips, Stephen demonstrated how we can easily mistake one colour for another, or think we have seen a certain colour when they have been shown together, moved about, or contrasted with other colours.  Again, the audience had different ideas of what they had actually seen on the clips.

Two figures from the past had opinions about light and colour. Isaac Newton said, 'The rays, talking about light, are not coloured.  To speak properly, light has the propensity to induce in us the sensation of this, or that, colour'.   Some two centuries earlier, between 460 and 370BC, the philosopher Democritus said 'By convention, sweet is sweet, hot is hot, cold is cold;  but in truth there are only atoms and the void'

What is true about colour, is also true about sound. To demonstrate this, Stephen tapped the side of the lectern on stage with a piece of wood. Although we could hear what he was doing, Steven said that it wasn't sound, but was a vibration in the air which is detected by hair cells in our ears, and our brain interprets the vibrations as sounds in the same way that it interprets light as colours.  This organ also takes action when we touch something hot, and removes our hand, or fingers, from the heat source.

Stephen has previously asked his groups of students at university to think about how many colours there are, and has received varying replies, from thousands, or even millions, of colours down to just three, or even no actual 'real' colour.  He then asked them how many countries they think there are in the world.  The students were much more confident in trying to answer this – but they still couldn't decide on the exact number.  This was because they would know that some countries or territories are disputed by politicians and other leaders, and will guess at the number. But, unlike thinking about the number of colours, no one would suggest that there are an infinite number of countries.

Another of the slides shown was from the BBC website, which Stephen took issue with.  It said that primary colours are red, yellow and blue, and these could not be mixed from other colours.  It also advised that all other colours can be made by mixing the primary colours.  He said that all the statements on the slide were incorrect, and have been known to be incorrect for at least a century, but students would fail their exams if they wrote the acknowledged truth about colours.

He also recalled being hired to solve an advertising problem which involved a racing car.  A white symbol with a red background on the car's tailfin looked grey in comparison with another panel; white again, with black lettering on it.  He recognised this as assimilation, the white on the tailfin being affected by the colour surrounding it. The client said, in effect, that they weren't interested in the reason – just fix it.  Stephen did that by fixing a polymer patch over the symbol with a brighter, and slightly bluer shade of white.  Changing colours to improve the appearance of goods was, and probably still is, a common practice in the advertising world.

The presentation was enjoyed by our members, and Stephen answered many of our questions after the vote of thanks and a well deserved round of applause. 

Not yet a member? We're always delighted to welcome new members. Contact details: website at www.u3atod.org.uk or email at info@u3atod.org.uk.

Many thanks to Colin Sanson for this report


Previous U3A reports on the HebWeb - click here

We try to make sure that information on the Hebden Bridge Web is correct, but if you are aware of any errors or omissions, please email us.

If you have comments on HebWeb News or Features please make a contribution to our Discussion Forum

More News