Welcome to my blog

I am passionate about sharing my knowledge about colour to anyone who is prepared to listen. I work as a professor of colour science at the University of Leeds, in the School of Design, but I have held academic posts in departments of Chemistry, Physics, Neuroscience, and Engineering. Sounds like a mixed bag, but my interest was colour chemistry, colour physics, colour neuroscience, colour engineering and colour design. You see I have come to believe that colour is the perfect meta-discipline and that to understand colour you need to be able to understand (but not necessarily be an expert in) different fields of knowledge.

One way to use this blog is to just browse through it and dip in here or there. However, another way is to click on one of the categories (that interest you) such as culture, design, fun, and technology and see posts in that area. You can find the categories on the right-hand side of the page if you scroll down.

You can also comment on the blogs. I really like this, even if you disagree with me. Someone once said to me if you put ten colour physicists in a room and ask them a question (presumably about colour physics) you’ll get 10 different answers. Well, I guess not all of you reading this are colour physicists. Given our different interests and backgrounds, and given the complexity of colour, it’s not surprising that we will disagree from time to time. And that is rather the fun part.

If you have a technical question you’d love me to answer you can click on Ask Me and post it there. You can also email me at s.westland@leeds.ac.uk

The Wizard of Oz

This week I had to mark about 50 essays that had been submitted for the Colour: Art and Science module I teach at the University of Leeds. One essay looks rather like another after the first 10 or so. So it was a delight to discover that one student had decided to focus on a movie – The Wizard of Oz – and demonstrate her understanding of colour by analysing this classic movie.

It reminded me of a story my mother told me. When she went to see the Wizard of Oz in the cinema (she would have been about 8 at the time) she had never seen a colour movie before. She was so much looking forward to this new-fangled and exciting technology. It’s hard to imagine how exciting that would have been – if every movie you had ever seen had been in black and white!!

Well, imagine her disappointment when the movie started and the movie was black and white after all. For those who don’t know, the movie starts off in black and white (in the Kansas scenes) and only turns coloured when Dorothy is whisked off by the tornado and dropped off in the land of Oz. It must have been a wonderful moment when the screen just turned full colour!!

Indigo – a colour of the rainbow?

From time to time I come across web pages and groups of people who get irrate about indigo being in the rainbow. There is even a facebook group called “Get Indigo out of the rainbow”. It was Newton who suggested that the rainbow contains seven colours: red, orange, yellow, green, blue, indigo and violet. It has been suggested that, at the time, Newton was trying make some anology with the musical scale and the octave (with its seven intervals) and hence was keen to identify seven colours in the rainbow or visible spectrum. Many modern commentators claim that only six distinct colours can be observed in the rainbow.

Interestingly, the facebook group referred to above would like to eject indigo from the spectrum on the basis that it is not a primary or secondary colour but rather a tertiary colour. The group shows the following colour wheel:

colour wheel

In this so-called painters’ wheel the primary colours are red, yellow and blue and the secondary colours are orange, green and violet. It is argued that since six of the colours in the rainbow are primary or secondary colours in the colour wheel and indigo is not, then indigo has no right to be there. This is wrong on so many levels it is hard to know where to start.

The first thing I would have to say is that this argument seems to ignore the difference between additive and subtractive mixing. Additive mixing – http://colourware.wordpress.com/2009/07/13/additive-colour-mixing/ - describes how light is mixed and the additive primaries are red, green and blue. The additive secondaries are cyan, magenta and yellow. Orange is not in sight – and yet surely if we are to make an argument for inclusion in the spectrum based on primaries (and/or secondaries) then it is the additive system that we should be using since the spectrum is emitted light.  

The optimal subtractive system primaries are cyan, magenta and yellow (with the secondaries being red, green and blue) though the artists’ colour wheel (which is like the painters’ wheel above) has red, blue and yellow as the primaries. 

In my opinion there is nothing special about the colours that we see in the spectrum. Indeed, orange is clearly a mixture of red and yellow and does not seem to me to be a particularly pure colour. I just do not think that arguments to exclude indigo from the spectrum based upon colour wheels or primary colours is valid. That said, I have already mentioned that many people believe that indigo cannot be seen in the spectrum as a separate colour; but this is a phenomenological observation not dogma. I am one of those who believe that indigo and violet cannot be distinguished in the spectrum and therefore I agree with the aims of the facebook group even if I do not agree with their arguments.

The really interesting question is why we see six (or even seven) distinct colour bands in the spectrum when the wavelengths of the spectrum vary smoothly and continuously? I have postulated some possible reasons for this in an earlier post – http://colourware.wordpress.com/2009/07/20/colour-names-affect-consumer-buying/ - but it is far from a complete and convincing explanation. It may explain why we see distinct colours in the rainbow, but why six and why those six in particular. Comments on this would be very very welcome.

#TheDress

I was asked to comment on the radio today about a dress which is topping the trends of social media in the USA in particular today.

2622C22600000578-0-image-a-32_1425001827044

The dress has sparked controversy because different people say that it is different colours. There is a group who say it is blue and black and another group who say that it is white and gold. What do you think?

I will give my explanation but it is not simple so …

Now, about 1 in 12 of all men in the world are colour blind. But if we consider the rest of the population you may be surprised to know that there is variability in our colour vision. This is mainly due to the colour receptors in our eyes. Put simply, some people have more red receptors and some people have more green receptors, for example. So we know that we don’t all see colour in the same way.

There is a second complexity and that is just because we use different names for a colour doesn’t mean we see it differently. This most often happens with brownish colours where some people will refer to it as more of a green and others will be adamant that it is definitely a brown. So words – colour names in particular – are not always very precise. We can see at least 3 million colours in the world and how many names do we have? A few hundred at least.

There is a third complexity which is that people think the camera never lies – that is, that they take an image of something using their phone and put it on the internet and everyone is seeing a faithful reproduction of the thing they took a picture of. Sadly, the camera does lie. Variability in the light that is used to capture the image, the settings on your display (whether you have a warm white or a cool white, for example) and how bright the light is in the room when you look at your screen – these can all dramatically affect the colour. Take a look at the picture below:

dress_original

This is the manufacturer’s photo of the dress. Taken professionally, I think most people would see it as blue and black. But the image that is on the internet is very different. I suspect it was taken in a very bright light and the colours are consequently a bit washed out.

So, in summary, the camera does lie. I think the lighting conditions under which the photo was taken were far from ideal and have changed the colours from how they would have appeared if you had been there. However, that is only half the story. Since people looking at the same image on the same screen are disagreeing with the colours. To fully explain what is going on you need to invoke the knowledge that we can sometimes see colours differently (because of variability from one person to the next) and even if we see the colour the same we might give it a different name (because colour names are crude ways to communicate colour).

Of course, fundamental to this is the idea that things are not coloured at all but your brain constructs a colour from the signals it receives in the eye. This allows us, for example, to discount changes in colour that may occur when the light source changes (this is known as colour constancy). We have evolved to discount the effect of light being bluer or yellower, for example, so that we normally see the colours that the object would have in neutral daylight. In the case of the dress image it may be that people are using different processing strategies and discounting the effect of the light source in different ways.

Which all goes to show that colour is complex. But if you have been reading my blog you already know that, don’t you?

guess what – red is sexy

red is sexy
Guess what? Another article that concludes that women wearing red are more likely to attract a mate. Scientist claims women are reflecting their sexual intentions ‘from the beginning’ by wearing bright red clothing. It’s a shocker!!! Who would have thought it!

It must be true because I read it in the Daily Mail.

Colour and Manchester United

van gaal

It’s not often I get to write about two of my favourite things at the same time. So I couldn’t resist remarking on a story today in the Daily Mirror about a colour code that Manchester United manager Louis van Gaal uses to describe different players in his squad. Apparently:

Blue:
“A blue player is intellectual and is always looking for structure and security in his job on the pitch.”

Red:
“A red player is creative, full of power, will want to work and is always focusing on the future.”

Green:
“A green player is very emotional, sensitive for different emotions or a different atmosphere in the squad.”

See the original article for the colours that the newspaper thinks that different players should be be allocated.

It couldn’t get much blacker

black
A few weeks ago I was taking my son to a birthday party and a journalist from The Independent phoned me to ask my opinion on Vantablack. This is the blackest material ever made. Whereas most black materials reflect about 4% of the light (or more) at all wavelengths, this new nano-material has really really low reflectance. It only reflects about 0.035% of the light. I gave a few comments and an article appeared in The Independent which was nice. I used to really like The Independent, back in the days when I read newspapers. The original article by Ian Johnston was very good imho.

However, a few days later the story was all around the world and I was often cited, all based on that one phone interview with Ian. The thing was that it was not even that big news. That is, yes, it is the blackest material ever made, but the truth is it is an incremental improvement in blackness beating the previous blackest material from a few years ago. My name even appeared in the Daily Mail. Most embarrassingly, I was interviewed on an American radio show. The reason I say it was embarrassing was that this new development actually had nothing to do with me and I didn’t want people thinking I was trying to claim credit. So when I agreed to do the radio show I told the researcher that they needed to be clear that this was nothing to do with me. I didn’t invent it. Imagine my surprise when John Hockenberry (that was his name, I believe) asked me, “So Dr Westland, what have you stumbled upon?”. Arghhhhh!!! Luckily, it was not a live interview because it actually got worse. A lot worse. So bad, that I could barely summon up strength to listen to it when it went out the next day. But actually, the editors did a good job and the final cut is not too bad. You can hear it here.

It would be nice to talk about my own work. I work in the area of blackness. One of the things I do is to ask people to rank different black samples in order of least black to most black. This allows me to discover, for example, that women prefer reddish blacks and men prefer bluish blacks. Also, asians prefer reddish blacks and caucasians prefer bluish blacks. I am developing a blackness index; a way to measure a sample and say how black it is or whether one sample is blacker than another. Why? Well, one application is for manufacturers of black ink for printers (which may be made from coloured inks). Different recipes produce different blacks. What if one recipe is chromatically neutral but another recipe is less neural (it has a slight hue) but is darker – which one is blacker?

black plants can save the world

leaves
About three years ago I posted about the question of why leaves are green. In this I postulated as to why chlorophyll (the green stuff in leaves) should be green; after all, this means that it only absorbing some of the wavelengths in the visible spectrum. In fact, I argued that it would be better if plants were black, absorbing all of the wavelengths in the visible spectrum. Now, someone on co.design is suggesting just that – that green plants absorb only about 2% of the possible energy and that scientists are thinking of turning them black. Presumably this would save the world because plants would be more efficient at converting harmful greenhouse gasses into oxygen. There’s catch though, apparently. If you make the plants black they get too hot and overheat resulting in cell damage. Actually, I also suggested this might be the case in my original article in 2011. Looks like black plants won’t save the world. They won’t even save themselves.

There’s nothing wrong with black carrots though – see here.

colour and branding

mcdonalds

According to Jon Feagain colour affects brand development in five ways:

    It helps boost perception

    It attracts attention

    It can help to emphasise or conceal information

    It can help you appeal to the right audience

    It can can help the audience digest information better

I think all of these things are true. However, to make the right decisions a good understanding of colour semiotics is critical in my opinion. Achieving that is easier said than done.

Structural colours

butterfly

Most colours around result from light being absorbed (electronic transitions) and scattered by dyes and/or pigments. However, there was an interesting article in The Guardian today about structural colour. Structural colour is quite common in nature; it occurs when light is scattered because of a regularity in packing or structure; the wavelength of the light that is most strongly scattered is determined by the repeat distance of this packing, which has to be comparable to the wavelength of the light.

new colour blog

I found this interesting blog about colour – it’s called Stories behind Colours and is written by Susan Mathen. It contains interesting posts that relate to meanings of colour and, particularly, the stories about where those meanings come from. Please visit it.

http://www.storiesbehindcolours.blogspot.co.uk/

different views of Leeds

Leeds

This year I hosted two Italian students as part of a European project. Silvia and Enrico both had the most fantastic design skills and both undertook projects about how to promote or represent a city – in their case, the city of Leeds where I work at the University of Leeds.

Here are two videos they produced at the end of their work here.

And here is a small diary about their time here in Leeds – http://colourdocks.wordpress.com/