I didn’t realise how sophisticated reindeers are. It turns out they have two layers of fur to help them keep warm, are able to shrink the pads on their hooves to give then better grip, and can detect ultraviolet light which enables them too see in very dim light. And it also turns out that their eyes can change colour in winter so that their vision is more sensitive. Reindeers, like cats, have a reflective layer behind the retina (which is the inside of the eye ball where all the light-sensitive cells are) that helps them to see in dim light. This is why, if you see a cat at night, you might see the eyes shining; you are seeing light being reflected back at you from the cat’s tapetum lucidum (which is the technical term for the layer behind the retina). The light that shines back in most animals with this layer is golden but in reindeer it apparently shifts to blue in the winter. The shift to blue allows more light to be scattered and improves the vision of the animal.
The full paper can be read in the Proceedings of the Royal Society.
Imagine that we have three projection lamps at the back of a hall – one has a red filter and so produces a beam of red light, and the other two use filters to produce green and blue beams. We project these onto a white screen and get three circles of light (one, red, one green and one blue). We then move the angles of the projectors so that the circles of light overlap. We get something that looks rather like this:
Where the red and green light overlap we get yellow. We get magenta and cyan for the other two binary mixtures. So,
red + green = yellow
red + blue = magenta
green + blue = cyan
This is called additive colour mixing as I am sure you know. And if we mix all three primaries we can achieve white (or other neutral colours). The primaries could be single wavelengths of light – so we could use a primary at, say, 700 nm (for the red) and one at 450 nm (blue) and one at 530 nm (green). So green light (530 nm) and red light (700 nm) additively mix together and generate yellow. When this happens what is being mixed and where does this mixing take place? Take a few moments to consider this before reading on.
Notice I said that they additively mix to generate yellow – I specifically avoided saying that they mix to generate yellow light. When I sat down with a couple of students last week and asked then what they though they said that the red and green light mixed together to create yellow light and when I pressed them, they went further to say that the yellow light was at about 575 nm.
If we measure the part of the screen that is yellow we would see that we have some light at 700 nm and some at 530 nm. The wavelengths are not mixed; they don’t mix together to generate some third wavelength of light such as 575 nm. So no physical mixing takes place other than – I suppose one could argue – that the red and green lights are mixed in the sense that they are spatially coincident. But that’s not really mixing, for me, and certainly doesn’t even begin to explain why we have the sensation of yellow when we look at these wavelengths together. It also makes me think that additive colour mixing, if it can be said to occur anywhere in particular, occurs in the eye. And I do mean eye, not brain.
There are many reasons why I don’t like colour wheels of the type shown below:
The first reason is because it perpetuates the myth that the subtractive primaries are red, yellow and blue whereas the fact is that red, yellow and blue produces a rather small gamut of colours. It is certainly not the best choice of subtractive primaries though it is taught as dogma in many art and design schools and throughout children’s education. The problem is that whenever two colours are mixed together there is saturation loss; that is, the resultant mixture ends up being more desaturated than the two components were. The saturation loss is greatest when mixing colours on the opposite side of the colour circle where the resultant mixture can be almost grey. However, for certain choices of primaries, the saturation loss is greater than for others. If red, yellow and blue are used as the primaries then of course it is possible to generate any other hue. However, there is significant saturation loss and the above colour wheel gives completely the wrong impression. It suggests that mixing blue and yellow together, for example, results in a really bright vivid green.
The reality of pigment mixing is much more like the triangular colour wheel shown below:
In the above diagram it can be seen that mixing together yellow and blue results in a really muddy dark green. The purple resulting from mixing blue and red is almost black!! Now it is possible to mix together a blue and a yellow to get a better green. For example, mixing a greenish blue with a yellow will give a much more vivid green. Mixing a bluish red with a greenish blue will result in a lovely purple. We have a name for a greenish blue and a blueish red – we call them cyan and magenta. A much better colour gamut is obtained if we start with the primaries, cyan, magenta and yellow.
Footnote: Some people may look at the triangular colour wheel and think that the reason the colours are dull is that the red, yellow, and blue primaries used are not ‘pure’ enough. Nothing could be farther from the truth. If it was possible to make really vivid and bright red and blue pigments then the resultant colour gamut would be even smaller. Fundamentally, red, yellow and blue just don’t make good subtractive primaries.
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.
Many studies have been carried out over the last 50-100 years to look at which colours people like and which they don’t like. Although there is variability between individuals (not everyone likes the same colours) there is surprising consistency when the results of lots of different studies are compared. In short people like blues and greens and don’t like yellows and (to a lesser extent) reds. The hue parameter is probably the most important but brightness and colourfulness also affect colour preference. People tend to like brighter and more colourful colours than darker and less colourful ones. Just for fun, I have been running my own survey on this web site. You can still add your two-penneth worth if you like – please go to http://colourware.wordpress.com/2011/02/22/favourite-colour-poll/. Interestingly, my fun survey is also in broad agreement with all those previously published experiments. I found that people’s preferences were:
I am not sure what practical application there could be in knowing which colours are more popular. For example, my favourite colour is red but I probably wouldn’t want to buy a red coat. Though on average most people really like blue, this doesn’t mean it would be sensible to make a product blue without consideration of many other factors. In design, colour is almost always in context and that context makes all the difference in the world.
More interesting though is recent research I have read which proposes a reason why there is individual variation in colour preference. According to this idea, we like those colours that remind us of things that we like (we like blue skies and green grass). It could explain dark yellows and oranges are particularly unpopular; these colours are normally associated with some rather unsavoury things (dark orange is the colour of poo and dark yellow the colour of vomit). Further, if people have a strong affiliation with an idea/concept that is strongly associated with a colour, then they may have some preference bias towards that colour. It makes me think – I am a hug fan of Manchester United and red is my favourite colour; but do I like red because I like Manchester United or do I like Manchester United because I like red? I am too old to remember which came first.
Dollar General (http://www.dollargeneral.com) is a discount store based in the USA. They used distinctive yellow and black colour combinations in their advertising material. In March this year they filed a lawsuit against their competitor (Fred’s Inc) who they claim have damaged their business by copying the trademark yellow and black colours in certain marketing information.
The lawsuit accuses Fred’s of “unlawfully and deceptively” using Dollar General’s colour scheme and typeface in a new advertising campaign. The lawsuit says the only explanation for Fred’s moving away from a traditional blue-green color combination in its advertising is an intent to capture Dollar General’s brand awareness.
For further information see http://nashville.bizjournals.com/nashville/stories/2010/03/08/daily27.html
Atlanta’s transit system will rename a train route into the heart of the city’s Asian community in response to complaints that calling it the “yellow line” showed a lack of racial sensitivity. The Metropolitan Atlanta Rapid Transit Authority issued a statement Thursday afternoon announcing it would change the name of the line to the “gold line.”
In the UK, official taxis run by the council tend to be black. However, Derby – a city in the UK – introduced a new regulation in 2001 that all the official taxis should be yellow. Presumably this was to make them more distinctive so that members of the public would be more certain that they were getting into an official taxi rather than an illegal one. One of the taxi drivers – John Kirkham – painted his car yellow to comply but was then shocked to have his application for the renewal of his licence refused because he had used the wrong shade of yellow!
The council backed down after adverse publicity. If only they had specified the colour tolerance as part of their specification they would have had a much stronger case.
Another reason for choosing yellow could be safety. Many school buses in USA are yellow – presumably for reasons of safety. A number of regions in the UK have recently been trialling the use of yellow buses. Getting more school children to travel to School by bus is seen as being good for the environment and would free up the congested roads. In the USA more than half of all chidren travel to School by yellow buses according to the BBC – http://news.bbc.co.uk/1/hi/uk_politics/7610933.stm
The use of yellow for school buses in the USA was introduced in 1939. The colour – National School Bus Chrome Yellow – was introduced for reasons of consistency and also for safety because of its high visibility. Cost was also a consideration since manufacturers charged extra for special colours. In addition the black lettering was easily visible by contrast on the yellow background (as you can see in the picture below).
The approximate colour can be obtained by #FFD800 or [255 216 0] in RGB values.