New Scientist colour quiz

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New Scientist recently undertook an informal study to see if red is off-putting in a testing environment. 

They set up two quizzes, each consisting of the same 15 anagrams. One quiz was predominantly red and the other blue.

On every attempt to access the article, a pop-up appeared requesting that you take part in the test. The colour of the text and border of this box was randomly selected to be either blue or red, corresponding to the colour of the text and border of the anagram test to which it linked. They then gathered data on the click-through rate for both colours, and the relative success rate.

They got roughly the same follow-through rate for both colours – 8478 for red and 8550 for blue – so the colour of the pop-up did not seem to have an effect on how attractive a prospect it was to take part in the quiz.

They also found that the readers scored an average of 63 per cent in the quiz, irrespective of whether the text and boarder colours were red or blue.

See http://www.newscientist.com/article/dn18071-colour-psychology-quiz-the-results.html

the power of red

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An interesting article in New Scientist has explored the influence of colour on the choices we make; how we act and think. The article – http://www.newscientist.com/article/mg20327232.400-winners-wear-red-how-colour-twists-your-mind.html?full=true – quotes research published in Psychologial Science that revealed that the colour of clothing worn by competitors in a taekwondo contest affects the decisions even by experienced referees. In short, competitors wearing red were awarded 13% more points than those dressed in blue

 taekwondo

This builds on previous research published in Nature in 2005 – http://www.nature.com/nature/journal/v435/n7040/full/435293a.html – that showed that between 55% and 62% of bouts in Olympic combat contests were won by competitors wearing red when in fact red and blue should have won 50% each if colour had no effect. Robert Barton, from Durham University (UK) has argued that the colour red could influence the mind of the referee but could also affect the mental state and performance of the competitor.

Interestingly, 38 of the last 63 top division soccer titles in England have been won by teams in red (Manchester, United, Arsenal, Liverpool) and goalkeepers feel more confident about saving a penalty from a player in a white shirt than in a red one. Both of these facts were taken from papers published in Journal of Sports Sciences.

sustainable colour design

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chromaticity diagram and RGB gamut

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You may well have seen a typical diagram showing the chromaticity diagram and the gamut of an RGB monitor. The gamut is a triangle, of course, with the vertices formed by the chromaticities of the RGB primaries. See, for example, http://colourware.wordpress.com/2009/10/04/subtractive-mixing-why-not-rgb/.

However, that triangle is a little misleading. One problem is that we are only looking at the maximum chromaticities available – this does not imply that all of these chromaticities are available at every luminance level. Take the very vertices of the triangle – these occur for the RGB values [255 0 0], [0 255 0] and [0 0 255]. The luminance of the pure red [255 0 0]  might be 27 cd/m2, of the pure green [0 255 0] 56 cd/m2, and of the pure blue [0 0 255]  might be 6 cd/m2. (These are luminance values for a typical RGB monitor – your monitor will vary a little from this and depending upon your settings.) This means that the chromaticities of the points of the triangular gamut are only available at these respective luminance levels.

For the monitor just described the maximum luminance would be obtained when RGB = [255 255 255] and the luminance of this white would be 89 cd/m2. So for very high luminances the gamut is tiny since to achieve these high luminance values you need to have all three RGB guns firing and hence by definition the colour is going to be very desaturated.

For the typical monitor described above I have calculated the gamut of colours available at three luminance levels: 10 cd/m2, 40 cd/m2 and 70 cd/m2. I have plotted these below and coloured bright red the chromaticities that cannot be obtained at that luminance. So, for example, at 10 cd/m2 you can obtain most chromaticities but not the pure blue. The reason for this is the pure blue [0 0 255] would be only 6  cd/m2 – to get 10 cd/m2 you need to add a little red or green and this desaturates the blue.

At 40 cd/m2 you can obtain a much smaller gamut and at 70 cd/m2 the gamut obtainable is very limited. To get such high luminances on this typical RGB monitor you would need high R and G values and that gives you yellows and yellowish whites.

The point of all this is that gamuts are three dimensional and looking at the gamuts in a 2-D chromaticity diagram can be very misleading.

chrom10

 

 

 

 

 

chrom40

 

 

 

 

 

chrom70

colour meaning

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At some point I intend to post something about colour meaning or what I like to call colour semiotics. However, in the meantime you may like to refer to this blog entry – http://dressdesigning.wordpress.com/2009/10/08/discover-how-to-understand-color-for-dress-designing/ – about understanding colour for dress designing (though the advice seems quite generic and not connected with dress designing at all). It’s a reasonable primer into the meanings of colour.

Colorgorize

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I just came across this website – http://www.colorgorize.com/about/

The first version of Colorgorize was published in 2007 as a project at the University of the Arts Bremen, Germany. Back then, Colorgorize was a Firefox add-on that could display similar colored websites to the website currently opened. Colorgorize was changed to a website in 2009 to reach a bigger audience. Today, thousands of websites are already analyzed and can be searched by colors.

Colorgorize is essentially a site where you can get inspiration for web-design colours and palettes. It works by shrinking imags of webapages that can be organized according to your colour preference.

registration for CIC

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Today is the last day you can register for the Color Imaging Conference in Albuquerque, New Mexico to qualify for the early-bird registration fee. This annual event is one of the foremost conferences in Colour Imaging and provides useful networking opportunities. The conference web site is http://www.imaging.org/IST/conferences/cic/

n145671048883_2273

two cultures?

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This week I was honoured to be the invited speaker at the 5th National Conference of the Italian Colour Group. I decided to address the meeting about two of my research projects that to some extent attempt to bridge the gap between art and science.

In 1959 CP Snow – a Cambridge University academic – delivered a famous lecture entitled The Two Cultures that led to heated and widespread debate. Snow argued that the lack of communication between the sciences and the humanities was a problem that inhibited solution to the world’s major problems.

I believe that Snow’s argument is still valid today. Interestingly I bought The Times to read on the plane to Palermo – where the colour conference was being hosted – and to my surprise that very day’s edition had a substantial article about The Two Cultures – http://www.timesonline.co.uk/tol/comment/columnists/guest_contributors/article6862299.ece

The Times writes that Snow said “There is something wrong with a civilisation, he said, where knowledge is so compartmentalised that people can count as highly educated and yet be wholly ignorant of huge swaths of what other highly educated people know. How could scientists not read Shakespeare? How could literary people never have heard of the second law of thermodynamics?”

In terms of colour, I believe there was more cross-over between the sciences and the humanities in the 18th and 19th centuries than there is now. I am not convinced that the problem that Snow articulated has gone away. Perhaps the divergence between the two fields is an inevitable result of specialisation? Possibly, but I don’t think so. I think there is room (indeed, a requirement) for specialists. However, we also need to find a way for people working in colour to in the arts and humanities and in the sciences to communicate more effectively to each other. Because, we have much to learn from each other.

In my experience some scientists do not want to communicate outside of their narrow discipline. Others, would like to but seem unable to do so without recourse to specialist language (e.g. mathematics). In the arts, if anything the willingness to communicate “across the gap” is even less. 

One organisation that has worked hard for many decades to encourage debate across the science-art divide is the AIC (the International Color Association”. You can find their website here – http://www.aic-colour.org/

I know from the nice stats that wordpress provide that a lot of people read my blog. But not many people leave any comments 🙁

It would be rather wonderful if – having read this – you left your view at the bottom. Is there a gap? Is it a good or a bad thing? How can we bridge it?

ps. I am not holding my breath waiting for the responses 🙂

subtractive mixing – why not RGB?

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In a previous post I spoke about the difference between additive and subtractive mixing and why the additive primaries are red, green and blue or RGB for short – http://colourware.wordpress.com/2009/07/13/additive-colour-mixing/

The chromaticity diagram – see http://colourware.wordpress.com/2009/09/28/colourchat-audiovisual-guide-to-the-chromaticity-diagram/ – has a very useful property. If you plot the chromaticities of two lights, then the straight line that joins the two points on the chromaticity diagram show you the additive mixtures that can be obtained by mixing together the two lights. If we take three lights, then the additive mixtures that can be obtained are defined by the triangle that is formed if the chromaticities are the vertices of the triangle. Ok – that’s a bit of a mouthful so let’s have a practical example. The triangle in the diagram below shows the gamut that can be achieved when we have three additive primaries that are positioned at the corners of the triangle.

rgb_gamut

 From this diagram it should become obvious why the additive primaries are RGB. Say, we chose, two reds and a cyan as the three additive primaries – well, the triangle would be tiny. In other words, the gamut would not be very big. The biggest triangle in the chromaticity is one whose vertices are formed by a red, a green and a blue. WhichRGB will give the biggest triangle? I don’t know – it’s been something that has been puzzling me for the last few days and I’ll come back to this in a later post. But certainly any RGB triangle is pretty large as long as the red, green and blue primaries chosen are reasonably saturated.

So what happens if we choose RGB as the subtractive primaries? Subtractive colour mixing describes how inks and paints mix together to form colours. The first thing to point out is that subtractive colour mixing is not additive and linear – you remember I said that when you mix two lights together the colour mixtures all fall on the straight line that joins the  two points in the chromaticity diagram that represent the two lights? Well, this is only true for additive colour mixing. So to work out the gamut for subtractive systems is not an easy thing to do. However, if you do select the three subtractive primaries as RGB you’ll get a gamut that looks something like this:

rgb_subgamut

Notice that the gamut is concave. Mixing red and green lights produces a nice yellow. You can test this by going into your colour-picker in software such as Photoshop or Powerpoint and setting the RGB values to be 255:255:0. You’ll get a nice yellow. But mixing red and green paints – it will give you a similar hue to yellow but you’ll get something quite desaurated; most likely you’ll get a brown. So using RGB as the subtractive primaries would not be a very good thing at all.

It turns out that additive and subtractive colour mixing are very related. The best subtractive primaries are the ones that control the amount of red, green and blue light reflected. A yellow dye applied to textiles, for example, mainly absorbs short wavelengths in the blue section of the spectrum, allowing the other wavelengths to be reflected by the textile. The “other wavelengths” that are reflected give yellow. But the important point is that the yellow dye absorbs blue. Similarly, a magenta dye absorbs green and a cyan dye absorbs red. This leads to the idea of the optimal subtractive primaries being those that are cyan, magenta and yellow or CMY. This leads to a gamut somewhat like this:

cmy_gamut

The biggest gamut for subtractive mixing is obtained by using CMY as the primaries. But weren’t you taught at school that the subtractive primaries are red, blue and yellow? Almost certainly you were – and this is because it is accepted dogma at most art colleges and in many art and design textbooks. But it is quite easy to show that the optimal primaries – those giving the largest gamut – are CMY not RBY. If you were building a colour-reproduction system using only three colours such as a printer you would come to the conclusion – as companies such as HP, Xerox, and Epson have done – that you get the largest colour range with CMY. So why has it become commonplace for artists to refer to red, yellow and blue as the primaries? Could it be a colour naming and language issue – that they really mean cyan when they say blue and it’s just a naming error. Possible, but not likely in my opinion.  I think it is more likely that most artists are not overly concerned that RYB gives a smaller gamut than CMY because they rarely restrict themselves to three primaries. An artist would typically use 6 or more primaries. For example, they might use two blues (one that is reddish and one that is greenish), two reds (one that is yellowish and one that is bluish) and two yellows (one that is greenish and one that is reddish) in order to easily be able to mix a wide range of colours. The (mis-)identification of RYB as the subtractive primaries has much to do with colour wheels. I like to keep each of these blog posts reasonably concise – if I start writing about the problems of colour wheels now I will be writing for another 2 hours. And it’s nearly midnight now so colour wheels will need to wait for another day!