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:

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.

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!!

favourite colour poll

good to be colour blind

Colour blindness is mainly a male affliction. Something like 8% of all men in the world are colour blind though, as I have mentioned before, this doesn’t mean that they cannot see colour but, rather, means that their colour discrimination is not as good as that of so-called normal observers (the rest of us, in common vernacular). See my earlier post. So we normally think of colour blindness as being something undesirable, something that ideally we would like to be able to cure.

Interesting then that new research at Anglia Ruskin University has suggested that colour blindness may even be an advantage. The study was led by Dr Andrew Smith and showed that colour-blind monkeys (tamarins, to be exact) were better than their ‘normal’ counter-parts at catching camouflaged insects (such as crickets). I guess what this means is that the camouflage is designed (I guess I should say, has evolved) to be effective when viewed by normal tamarins. So the colour-blind tamarins may be better off in some sense.

Dr Smith is also quoted as saying that there is some evidence that, in humans, dichromats (who have two classes of cone rather than three) may see better in dim light than trichromats. For further information see http://www.businessweekly.co.uk/academia-a-research/13403-colour-blind-monkeys-have-advantage-in-catching-camouflaged-prey.

trademarking colour?

Interesting article – http://thedrum.co.uk/opinion/2012/01/23/trademarking-colour about trademarking colour.

Follow @aic2012 on twitter for news about AIC’s 12th International Congress to be held in 2013. See https://twitter.com/#!/aic2013

changing eye colour

On my way to CIC – my favourite colour conference – http://www.imaging.org/IST/conferences/cic/.

A six hour lay-over in Chicago so no excuse not to make a few posts. The first interesting bit of news I just came across is a story in the BBC about a doctor who seems to have developed a laser technique to change eye colour.

Apparently 20 secs of laser treatment can remove the pigment in eyes so that brown eyes become blue. You can read more about the story here. Don’t try this at home though – they are still conducting safety tests and some experts think the treatment could lead to other health problems.

Gjøvik Color Imaging Symposium

A quick reminder that registration for the Gjøvik Color Imaging Symposium is still open. This is a tremendous colour conference and Gjøvik in Norway is a beautiful place to visit. Further details can be seen at http://www.colorlab.no/events/gcis11/program.

yellow is the new red

 

 
I am not the world’s expert on fashion but it seems that red has been popular all through spring and summer. I first came across the surge in popularity of red last year when a journalist contacted me to ask my opinion as to why there had been an increase in sales of red kitchen and personal electronic equipment. We both agreed that probably the choice of red may be caused by consumers using colour choice to be bold and energetic in contrast to feeling tied down and depressed by the financial recession. I then listened to the podcast for Spring 2011 on Color Outlook and learned that red has been a popular colour for interior design this year right across the USA.
 
Now it seems that red has been a popular fashion colour all summer but is due to be replaced in the autumn (or the fall, as some people strangely call it) by yellow; another vibrant and positive colour. For further details see the Babble blog.
 

14,000-year old cave painting found in South Wales

The earliest example of a cave painting in the UK has been found in South Wales. The faint scratchings of a speared reindeer are believed to have been carved by a hunter-gatherer in the Ice Age more than 14,000 years ago.

For further details see http://www.bbc.co.uk/news/uk-wales-south-west-wales-14272126.

meanings of car colours

I came across another study on which colours sell best, commissioned by a car company of course. Turns out that in Canada the most popular is silver/grey (22.3%) with black second favourite.

But more interesting what the second part of the study which purported to reveal what your choice of car colour says about you:

Silver: “Since silver and grey are technical colours, they communicate a sense of aspiration and at times, an embrace of futurism.”

Black: “Overall black communicates strength, aspiration and a respect for the classic and the elegant.”

Blue: “Darker blue is perceived as more traditional. However, a bright or light blue is the opposite and is seen as the least ‘classic’ of the other colour groups.”

Red: “A colour which screams sporty and energetic but in certain shades can also be associated with distinction.”

White: “White is clean and modern. Premium specialty whites (also known as ‘tri-coat whites’) are also associated with luxury and ‘premium-ness,’

My experience of buying cars though is that though I may have a preference for buying a car of a certain colour, since I normally buy a second-hand one, in the end it is just what is available in the model I would like (or close to it) and the price I would like to pay (or just above it). My current car is black. My last one was grey. I have also had white and maroon in the last 10 years. So don’t read too much into it.

 

colour conference in Taiwan

Just to let people know about an exciting colour conference taking place next year.

AIC 2012 “In Color We Live – Color and Environment”

Interim Meeting of the AIC, International Color Association

22-25 September 2012, Chinese Culture University, Taipei, Taiwan

For details, visit www.aic2012.org

odd coincidence

My name is Stephen Westland and my blog is called Colour Chat – because I like to chat (informally but hopefully in a way that is informed) about colour. Westland is a reasonably unusual name. Searching on google for my own blog today I noticed there is a company called Colourchat Services Ltd in Nairobi – guess what district they are in? Yes – Westlands. Coincidence or what? I wonder what this company does … perhaps they should sponsor this blog! Haha.