Today I received a physical copy of our new book – Universal Principles of Color – which made a nice start to the week. My co-author, Maggie Maggio, and I have worked so hard on this over what must be a a couple of years now. Because of the time difference (she is based on the west coast of USA and I in UK) we had countless late-night and early-morning meetings. But finally here it is. It can be a frustrating experience at times working with publishers but overall I am really happy with the outcome.
The above image is from the watermarked digital edition that I received last week. It shows the 100 topics that are discussed in the book. I like the idea that they are grouped in themes or pathways (which I think was Maggie’s idea) because it will make it much easier for the reader to navigate the book. I don’t think the book is intended to be read from front to back in one go but rather to be ‘dipped in to’. But these pathways provide a route through the book according to the readers’ interest and we thought hard about the order of the topics in these pathways for it to make sense. In the actual book the topics appear in strict alphabetic order so you can really see the value of including these themes which are also colour-coded for ease.
I hope people enjoy the book and find it useful. Each topic is delivered through a double-page spread. The challenge that we had was to take topics that are potentially complex but deliver them in a very concise way without comprising accuracy. I think we did ok but you will all be the judge of that.
The book is available on pre-order from Amazon now or at other places. If you pre-order it at Amazon you get a discount. It also helps us if you pre-order the book because apparently it does good things to the algorithms which dictate how many people will see this pop up on their Amazon page. So please pre-order to help us out if you were thinking of buying it.
Over the last year or two I have not posted as often to Colourchat as I would have liked. I have posting here for over ten years believe it or not. There are a number of reasons why I have been less active here just lately. One is that I have posted a lot on quora. And my posts on quora get more views than my posts on my own blog. And it is always nice to reach more people. On quora I don’t just write about colour. In my top-4 most read posts there one is about whether you need to be intelligent to get a PhD and one is about blindfold chess.
It’s slightly mad that my post about the attributes needed to undertake a PhD has about 1.2 million views – that is about 1.2 million views more than my most-read academic paper.
I have also been very busy over the last year working on a new book with Maggie Maggio. More of this later, but you can see the book here.
But another project I have been quite busy with has been The Colour Literacy Project. We started meeting before COVID actually and we all share a frustration that there is quite a lot of misinformation out there about colour. And a lot of people have misconceptions. At the end of the day, colour education leaves quite a lot to be desired in my opinion. So I am really happy to share the Colour Literacy webpage on colour misconceptions. You can see this here.
My contribution to the misconceptions page is actually rather minor. There are others in the Colour Literacy Project who have made much more valuable contributions than me. But the most important thing is that this page exists. It is, in my opinion, a brilliant teaching resource and I will certainly be directing my students to it when teaching starts this autumn at University of Leeds. Please take a look at it. Let me know if you agree with the misconceptions or if there are any misconceptions that you have come across that are not yet listed.
It’s quite a few weeks now since we had our Colour Conference in Leeds. It was so interesting and such a lot of fun. I know a few people who say things like, there is no point going to conferences these days. Covid showed us that you can give your presentation using Zoom or Teams. What is the point of wasting all of that money on physically going to a conference? Never mind, the environmental effect.
Well, I couldn’t disagree more. Perhaps in the future virtual reality will enable us to have remote conferences that provide brilliant networking experiences and mean that we don’t have to travel. I think it’s possible. But we are not there yet. In my opinion, the actual presentations at a conference are the least interesting things about a conference. I don’t go to a conference to listen to the talks. I go there to meet people.
The four photos from our conference that I have posted here sum up the brilliant conversations that happened. You simply cannot replicate this online with current technology in my opinion. As the Stereophonics so aptly put it – ‘maybe tomorrow.’
By the way, you can see all of the official photos from our event here.
This week we hosted our second Leeds Colour Conference following the successful event in 2019. You can see details of the event here. We had two keynote speakers who didn’t disappoint. The second keynote was given by Ján Morovič from HP who spoke about how many colours there are. It was a brilliant presentation. Not surprisingly, there was no single answer. Rather, Ján’s talk discussed why this is a difficult question to answer and why there is probably no precise answer. But in doing this he covered so much ground in his usual engaging style. It was by far my favourite talk of the conference.
However, his talk reminded me of something I posted on quora a year or so ago. My post was not as sophisticated as Ján’s talk of course but covers some related topics. I reproduce it below for your reading pleasure:
HOW MANY COLOURS ARE THERE IN THE UNIVERSE?
This is a really interesting question but it cannot be answered without first stating what colour is.
I teach colour science at the University of Leeds. Whenever I have a new class I invariably start with the question: how many colours are there? (in the universe, is implied and sometimes I explicitly add, in the universe).
Within the first five minutes someone normally says that there are about 16 million; another person will say that there are an infinite number; and someone else will normally add that there are only three colours? Sometimes, I get someone who says that there are no colours (in the universe).
I then ask them how many countries there are in the world. Undergraduate students generally don’t know and to be fair I had to look it up. It turns out, of course, that the number depends upon whether you accept this or that country as being an independent country. However, the answer is about 186. Students normally give answers close to 186. Some may go as high as 300 and others as low as 150. But nobody says that there are as few as three. We don’t get answers to this question that range from 0 to infinity? Why?
The reason is because when we use the word country we have a good shared understanding of what the word means. When we use the word colour we do not. So that is where we need to start.
I think the two most logical answers are that there are zero or infinity. But let’s deal with 16 million and 3 first.
Those who say that there are about 16 million colours are aware that there are about 16 million different combinations of RGB on a typical emissive display. However, this is an arbitrary constraint of current technology, actually of commercial technology. When I was studying for my PhD (in the 80s I might add) I was not aware of any display that could provide 16 million combinations of RGB. We were happy with about 16. But in my lab today I have a display (actually the combination of a display and a graphics card) that can display about 1 billion different combinations of RGB. 24-bit colour displays (that can display RGB each with 256 values) are common. There doesn’t seem to be a consumer demand for displays with higher bit depth. But such displays certainly do exist and are used in research labs all over the world including in my own.
Those who say that there are only three colours in the world are referring to one of two ideas, both of which are fallacies. The first fallacy is that we can generate all colours by mixing three colours (called primaries) together. Of course, it has been known for a very long time that we cannot mix three colour primaries together to make all other colours. We cannot do this irrespective of whether we use additive or subtractive colour mixing. We can make all hues but hue and colour are not synonyms. If we try to make all colours by mixing three primaries we will find that we cannot match the chroma or saturation of some of the colours in the world. The second fallacy is that our visual system sees the world in RGB and creates all other colours from that starting point. This is ridiculous of course. Not only do we not see the world in RGB but it is not even true that we have three cones that are sensitive to just red, green and blue. I’m not going to provide a full explanation about this here but I have written about this quite a lot before. I will simply show the spectral sensitivity of the three cone types we have in our eyes.
Notice that the L cone class (which is sometimes referred to as the R or red cone) has sensitivity to (and therefore responds to) almost all of the visible wavelengths and that the maximum sensitivity of this cone is not even in the red region of the spectrum.
Now we can come to the idea that there are an infinite number of colours in the world. This idea is based on the belief that colour is a physical property of the world. According to this view, light at say 700nm really is red. It doesn’t just look red, it is red. This idea has been contested for a very long time. The earliest critique of this that I can find is by Democritus (460–370BC) who said:
For by convention colour exists, by convention bitter, by convention sweet, but in reality (there is only) atoms and the void.
According to this alternative view, perceptions such as colours, sounds, and smells do not exist in the world independently of us or other sentient beings. Imagine a world where there is no living sentient creature. A tree falls in the forrest. Does it make a sound? When the tree falls it generates a movement in the air called a pressure wave. It is only when that wave strikes the intricate structures of our ear that a physiological response is generated that ultimately results in our brains generating the perception of sound. Similarly, we touch a hot metal object. We experience pain. We would say that the pain is a property of the object. We experience the perception of pain which is our response to a physical property of heat. Sound is something that we experience as a response to a physical property (movement of air). Taking this view, we can say that colour is a response to sensing the physical property of light. Democritus is perhaps less well known than Newton who wrote something similar in the 1700s. He said:
For the rays to speak properly are not coloured. In them there is nothing else than a certain power and disposition to stir up a sensation of this or that colour.
According to Newton, light at 700nm is not red; it merely looks red to us. This might seem to be splitting hairs but the distinction is critical. It is why we sometimes disagree about a diagram similar to the one shown below.
The two small squares above are physically the same. You are probably looking at them now on a display. These two squares have the same RGB values. However, they don’t look the same. I quite like to use the terminology physical and perceptual colour (though I note that not every colour expert will agree with this classification). I would argue that the two squares are physically the same colour but perceptually different colours. The one on the right looks lighter, for example.
Some people will say that this is an illusion and they will say something like this.
The two squares are the same colour but they look different in colour because of the contrast with the respective backgrounds.
In fact, this is the view of most laypeople, I would argue.
However, it is my opinion that when they say something like this they are using two different definitions of the word colour in the same sentence without realising. I would modify their sentence to make this clear as shown below:
The two squares are the same (physical) colour but they look different in (perceptual) colour because of the contrast with the respective background.
They are some striking examples of this sort of illusion. For example:
In this image, the blue squares on the upper surface of the cube on the left are physically the same as the yellow squares on the upper surface of the cube on the right. By physically the same I mean that they have the same RGB values if you are looking at this on a display. If you print out this image and cut out the respective blue and yellow patches and view them out of context they will appear grey. In fact, the printer will have simply used a little bit of black ink in order to generate these blue and yellow patches. So where is the colour coming from?
I am happy to accept the terms physical and perceptual colour even though I have close colleagues who do not agree with me. They would argue that colour is perceptual and that there is no physical colour; there is only light. They would argue that light at 700nm, for example, is not red; it merely looks red. And they would have the likes of Democritus and Newton on their side.
If we accept for a moment that colour is a physical property then I think we could argue that the number of colours in the world is infinite. At least, for any practical purpose. I’m not an expert in quantum phenomena.
I have worked for my whole life to try to understand colour and to solve practical problems that arise in connection with colour. I work at the University of Leeds where I am Professor of Colour Science and Technology. In addition to my teaching and research I have undertaken consultancies with companies. These companies are concerned with textiles, automotives, food stuffs, cosmetics, dentistry, skincare, displays, printers, paints, inks to name but a few of the topics. You see, everything in the world that is manufactured is coloured and companies who manufacture those things invariably start to worry about how we communicate colours, how do we control colour, and how do we assess colour. And that is where I come in. In the 35-40 years of my professional career I have never come upon one instance of a company who cares about physical colour. They care about what colours look like. Because that’s what their consumers care about. Imagine a scenario where a consumer buys a suit and the jacket and the trousers don’t match. They look different in colour. And imagine that when they take the garment back to the store to complain the customer service agent says, “Don’t worry. They are the same physical colour. It’s just an illusion that they look different in colour.” It just won’t wash (pardon the pun).
Whenever I talk about colour or write about colour I am referring to perceptual colour. For me, if two things look different in colour, they are different in colour because that is how I define colour.
So finally we get to the people who responded that there are no colours in the world. They understand that colour is perceptual. They may even say that colours don’t really exist. However, I would disagree with them on this last point. To argue that colours don’t exist because they are perceptions is akin to arguing that pain is not real or that love does not exist. Not everything that exists in this world is explicitly physical.
Can a display with 16 million RGB combinations display 16 million colours? If you believe in the physical definition of colour you would presumably say yes. I would say no. Some of these combinations of RGB produce colours that are indistinguishable. According to my view of perceptual colour, if two stimuli (sorry to be technical at this point but if you have read so far I think you will allow me this) look the same colour, they are the same colour. And if two stimuli look different in colour they are different in colour. A while ago I published a paper that attempted to determine how many colours a smartphone could display. I ended up with an estimate of 2–3 million. I should declare that this work was supported financially by Samsung. But I still think the methods are interesting.
If you ask colour scientists in the world how many colours there are, most will say that this boils down to how many colours we can discriminate between. However, this is still a very difficult question to answer. And I have at least one close friend (who is a world expert in colour) who would argue that the question is ill-posed and cannot be answered. However, most estimates put the number somewhere in the range 3–8 million. My answer would be 3–5 million.
So there we have it: there are 3–5 million colours in the world.
You may agree or disagree with me. However, I hope – at the least – that you will agree that the question of how many colours in the world is an interesting and complex one. There is no easy answer that everyone agrees with. Certainly, it depends upon how you define the word colour. In my opinion, a lot of the disagreements that we see about colour stem from this problem that we don’t have a shared understanding of what the word even means. Some people, as I mentioned earlier, even conflate the words hue and colour and that is one of the many reasons why there are so many misconceptions around today about colour such as the fallacy that we can make all colours starting with three primaries.
Postscripts:
I post a lot on quora – mainly about colour but sometimes about other subjects such as academic and chess. If you want to read any of that you can see my quora page here.
Quora is free and I have no intention to ever participate in the quora program that monetises content. I really love quora as a platform. I have met some really nice (and incredibly knowledgeable) people there. The only thing that could make me leave quora would be if it becomes completely overrun with chatbots (thinking about it, that could be happening quite soon). But I do provide some paid content on a different site. A while ago I set up a patreon website where for a small monthly contribution you can get more focussed, detailed and intimate content. The idea behind this is to to generate ad curate high-quality content that will help people on their journey to understand colour.
If the idea of people conflating terms such as hue and colour intrigues you and you are interested in more such misconceptions I really encourage you to visit the Colour Literacy Project webpage and particularly to view their new page on colour misconceptions.
This week we had a three-day colour conference at the University of Leeds. You can see details of it here. This follows on from our successful event in 2019. COVID meant that it took 4 years to host our second conference but hopefully it won’t take so long for the next one. We had so many excellent speakers but one of these was Dimitris Mylonas (pictured) from Northeastern University London, UK who spoke about Colour Naming in Humanity-Centred Design. Dimitris is one of those people whose work I admire but I don’t get much chance to meet him even though we both live in the UK. I particularly like the use of on-line experiments in his research.
Last night I was chilling after the event finished and browsing youtube and I came across this interesting youtube video about the origins of English colour words. It is definitely worth a watch. It includes the idea that some ancient cultures didn’t have a word for blue and that they couldn’t see blue. Although I think it is true that they didn’t have a name for blue I am less convinced that they couldn’t see blue. As evidence for this people often cite Homer’s description of the sea as being wine dark in both the Iliad and Odyssey. If only I had seen this video the day before it would have reminded me to ask Dimitris what he thinks about this. I am sure he would have had something to say.
There was an interesting article in The Guardian today about a new blood test that can detect whether someone is sleep deprived. The idea is to use it to prosecute drivers involved in accidents who have had less than 5 hours sleep. According to the article driving after less than 5 hours sleep is as dangerous as driving after drinking alcohol. Experts are divided on the ethics of this.
This was particularly interesting for me for two reasons. Firstly, because this time last week I was on a flight from Manchester to LHR, en route to Texas where I took part in a couple of panel discussions about colour psychology having gone to sleep at 11:30pm the night before and left the house at 3:30am after fitful sleep for less than four hours. During the 1.5 hour drive from Leeds to Manchester in the early hours I had felt completely awake; however, I wonder whether I would be able to make this journey in a few years if the legislation is introduced.
But secondly, because my own research is concerned with the effect of light sleep and the devastating effects that lack of sleep can have on our health and wellbeing. A discussion about this topic actually came up during the Texas trip. I would encourage everyone to listen to Matt Walker’s superb TED talk – Sleep is your super power. We now know that light plays a crucial role in maintaining a healthy sleep schedule. Healthy sleep is entrained by exposure to bright light in the few hours after waking and to lack of exposure to light in the hours before going to bed. There is debate about the relatively importance of the light being blue. The light-sensitive cells in the retina that are implicated in sending signals to the hypothalamus in the brain (from where the release of hormones is controlled) are maximally sensitive to light at about 480nm but there is some evidence that longer wavelengths of light could also influence alertness (in other words, the cones may also be involved). Here is one of my own papers on this topic:
Lin J & Westland, 2020. Effect of long-wavelength light on electroencephalogram and subjective alertness, Lighting Research and Technology, 52 (6), 763-774.
There is already growing research into the use of light and light-related products to help us to sleep better. As public awareness of this issue grows it is inevitable that interest in to this topic will increase. Perhaps such products could be used to mitigate the effects of poor sleep in situations such as the one I was in last week.
I noticed a story today about a bull that escaped during a rugby game in France. Why would a bull even be there? I have no idea. But what interested me was the trope that was repeated in the article about the concern that one of the teams was wearing red shirts and that this could put those players in particular danger.
As you may know, bull fighters use a red cape during bull fighting events and this is popularly believed to be to enrage the bull.
However, it turns out that bulls are dichromats. They only have two types of cones – the light-sensitive cells in our eyes – and they are missing the long-wavelength cones. This makes them colour blind and red-green colour blind in particular.
It isn’t the case that bulls are enraged by red; it is the movement of the cape that irritates them. It is my understanding that the red colour is used so that the cape doesn’t show the blood. This was discussed in the first of my podcasts – do dogs see colour – which you can listen to here.
I don’t like Mondays blue. I do actually like Mondays, unlike The Bangles. But I don’t like blue. In this, I am out of step with the majority of people. Most studies on colour preference show that blue is one of the most preferred colours, irrespective of gender or culture. But, of course, some people don’t like it and I am one of those people.
The graph below is from one of my papers. It shows the per cent of people who selected each of 6 colours when we asked which was their favourite.
When we talk about liking or disliking a colour there are two caveats of course. The first is that there are lots of different blues. You might quite like one blue but not another. Most of the literature – including some of my own papers – not only focus exclusively on hue (as in the graph above) but only look at what we might call the focal colours of these hues. This grossly over simplifies the situation.
The second caveat is that although it is fine to talk about colour preference in an abstract sense, in practical terms you might like a colour in one context but not another. To give a ludicrously simple example: you might like a red car but not a red wedding dress. So we need to talk about context in a professional design scenario.
I am writing this because today I was walking in Leeds and heading towards the university where I work and I was reminded of this interesting blue structure that appeared a few years ago.
To say I don’t like it is an under statement. I think it is horrid. I cringe every time I see it. I generally don’t like blue but this particularly colour of blue is the most horrible.
Sometimes in Leeds I would go to a coffee shop that is associated with Harvey Nichols. They have rebranded it as Rabbit Hole Coffee. Imagine my shock when I saw the horrible blue that they used.
In a design context there is a role for blue and for this sort of blue. It is used quite a lot by Greggs and Tesco.
In these two cases it is a good use of the colour blue. In my opinion it looks cheap. And for Greggs that is fine. They don’t pretend to compete with Harvey Nichols. They want to communicate to their consumers that what they sell is not expensive and that is great. And it also works well for Tesco (although it is a slightly different blue to the blue used by Greggs). Tesco don’t specifically want to communicate that they are cheap but they do want to communicate that they are good value. Definitely not on the pricey side, as we say in the UK.
So even though I don’t like blue personally I can endorse its use by Tesco and Greggs. But the University of Leeds and the Harvey Nichols cafe? I think it is a really poor choice. I would have much preferred the lovely Leeds (legacy) green which you can see on the structure just to the left of the blue tower. Even a lovely red would nice. These are the University of Leeds brand colours, which have a gorgeous dark red,
I’m off to Texas on Monday for Texas Design Week. I will be taking part in two panel discussions – one in Dallas and one in Houston – invited by Harlequin (part of the Sanderson Design Group) with whom I have been collaborating for a colour of years now. Last year I did something similar in Atlanta for Atlanta Design Week so I know what to expect. And we have done have half a dozen or more such panels in the UK over the last 24 months. I will be sharing the platform with designers of course and my role is to bring some findings from the world of colour science to the table. The mix of science and design in the discussions is always a lot of fun.
My relationship with Harlequin started when I was asked to write a white paper about colour and its effect on people at home and in the workplace. You can download that white paper here if you are interested.
Talking about colour in our lighting lab
In the white paper Soojin Lee and I identified two different ways in which colour (and light) can affect us. We referred to them as emotional and physical.
The emotional effect is often caused by associations; we associate certain colours with certain ideas or memories. We might find a blue room relaxing, for example. There is some commonality between people (because we all live in the same world) but at the same time there are differences between individuals. This is the same reason why, for example, blue is a colour liked by lots of people, but that we can find individuals who don’t like blue. I am one of those.
The physical effect is more to do with the direct effect of colour and light on our physiology. For example, we need exposure to lots of light in the morning and we need to avoid such exposure at night, to keep our circadian system in a healthy state and to enjoy good quality sleep. There is evidence that blue light, in particular, is alerting and can keep us awake. Because we all have the same physiology there tend to be fewer individual differences in these effects.
Sometimes these two effects are contradictory and can even occur at the same time. It’s why a blue bedroom (blue-painted wall, blue curtains or blue bed linen) can be relaxing whilst at the same time exposure exposure to bright blue light can be alerting.
So is blue alerting or relaxing? It depends. It doesn’t actually make any sense to ask the question in that abstract way. We should ask whether blue lighting or blue paint, for example, is relaxing – and then we can have a meaningful response.
I am not a fan of colour trends. What I mean by that is that I think sometimes there is an urge to generate new colour schemes twice a year which feels a little forced to me. And it is one of the reasons why we over consumer. This is particularly the case with clothes where – in the UK in particular – we buy clothes far too often. Our consumption of textiles is generally not sustainable.
But that said, I am not saying that there is no such thing as colour trends. Certain colours – and colour combinations – become desirable at certain times and I don’t think the whole thing is artificially generated. I just think the changes are not as rapid as the colour forecasting industry would have us believe.
But I am old enough to remember the 70s and I remember well the desirability of brown and olive green bathroom suites, for example. Nobody would use these colours as the basis of their interior design colour schemes today — would they?
Well, today I read that brown is replacing dark blue as a favoured colour for interiors when a moody dramatic look is the aim. The article in Livingetc suggests that the use of brown – a more muted colour – is more natural in its feel and that sales of brown-hued paint are rising. There are some interesting examples of the use of brown in the online article.
