Category Archives: knowledge

eyes change colour?

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reindeer

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.

AIC2014

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logobig-full
As some of you may know, I was General Chair of AIC2013 this year. We had a great time in Newcastle and spent a week with over 600 delegates talking about colour. But time moves on and we are approaching 2014. I would therefore like to draw your attention to the next AIC meeting which is in Mexico in October 2014. The theme is colour and culture and the venue – Oaxaca – is stunning. I hope to see you there.

For further details visit http://www.aic2014.org/index_en.html

Where is colour mixing?

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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:

ColourMixing

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.

visible-a

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.

is there such a thing as visible light?

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I would argue that there is no such thing as visible light – or at least that the term visible light is a meaningless one.

Light is part of the electromagnetic spectrum which is describes electromagnetic radiation by its wavelength. An electromagnetic wave has both electric and magnetic field components. What is really very interesting is that depending upon the wavelength of the field the electromagnetic radiation has very different properties and we give it a different name.

electromagnetic-spectrum

When the wavelength is very long, the radiation is radio waves or micro waves. When the wavelength is very short, the radiation is x-rays or gamma rays. There is a narrow range of wavelengths (from about 360 nm to about 780 nm – a nm is 0.000000001 of a metre) to which our eyes are sensitive. Because we can literally see this radiation we call it light. I still find it amazing that light, x-rays, radio waves, and microwaves are all essentially the same thing (electromagnetic radiation) with just a change in the wavelength!! However, my point for today is that light is radiation that is visible – to talk about visible light would be bizarre since by its very definition light is visible. Technically, visible light is a pleonasm; pleonasm is a word derived from the Greek word “pleon” meaning excessive. Other examples of pleonasms – easily confused with oxymora – include the phrases end result and invited guests.

Colour Semiotics – a personal view

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Colour is an important component of many successful designs. It is interesting, therefore, to consider why certain colours are chosen in designs and under which circumstances the colour choices enhance the likelihood that the design will be successful. In this paper, four aspects of colour design (colour harmony, colour preference, colour forecasting and colour semiotics) will be briefly considered and one of these, colour semiotics, will be explored in some detail. Finally, the role of all four of these aspects of colour in the design process will be discussed.

Colour Harmony

Colour harmony is concerned with the relationship between colours. One definition of colour harmony is that it refers to when two or more colours are seen in neighbouring areas that produce a pleasing effect (Judd & Wyszecki, 1975). Many theories of colour harmony are ideological in nature and Itten wrote, for example, that ‘One essential foundation of any aesthetic color theory is the color circle, because that will determine the classification of colors’. In the last 150 years, Rood (1831-1901), Ostwald (1853-1932), Munsell (1858-1918), Itten (1888-1967) and others proposed various theories that were based on certain geometric relationships in a colour circle (or more generally in a colour space) being harmonious (Westland et al., 2007). For example, colour combinations whose representations in a colour space form the vertices of a triangle are considered to be harmonious according to some theories. Most of these theories were based on personal introspection and a belief that classical geometric shapes should frame the colour relationships that are harmonious but there is no a priori reason why this should be. Moreover, there have been few studies to robustly test whether theories of colour harmony can be justified empirically. However, when referring to colour harmony it is not always clear that authors are even referring to the same thing. Colour harmony has been used to refer to colours being pleasing, harmonious, and successful. In addition, it is generally accepted that ideas about colour harmony shift over time (Nemcsics, 1993) with fashion and taste and this has led some to claim that “It is quite evident that there are no universal laws of (colour) harmony” (Kuehni, 2005). Nor is it even clear that laws are even required since the majority of designers and artists naturally are able to select colour combinations that are harmonious (by whichever definition) without assistance. It is therefore, perhaps, useful to place colour harmony in the field of aesthetics.

Colour Preference

Colour preference is also best placed in the field of aesthetics but is generally used to refer to a single colour – though the distinction between colour harmony and colour preference is being explored by the work of Ou and colleagues (e.g. Ou et al., 2004b). An early study was carried out by Guildford and Smith (1959) who asked 40 observers to assess the pleasantness of each of 316 Munsell samples according to an 11-point scale (where 0 and 10 corresponded to the least and most pleasant colours imaginable respectively). This study, like most others since, revealed a preference for blue and green colours and a dislike of yellow (on average, of course; individual results usually vary greatly). More recently, 208 participants undertook a simple forced-choice ‘color-picking’ task and the data revealed a robust cross-cultural sex difference (Hurlbert and Ling, 2007) with females’ hue preferences shifted to longer wavelengths when compared with those of males. Hurlbert and Ling suggested the sex differences may be linked to the evolution of sex-specific behavioural uses of trichromacy. Schloss and Palmer also recently studied colour preferences and found that despite, on average, participants preferring yellow hues to blue hues there was considerable variability between individual colour preferences. They proposed an ecological valence theory that suggests that people prefer colours that are associated with objects and situations that are affectively positive for them (Schloss and Palmer, 2010). However, in all of these studies, when observers are asked which colours they prefer it is not clear that they always respond with the same purpose in mind (that is, in what sense or context are the observers judging preference?).

Colour Forecasting

Colour forecasting is a particular phenomenon that relates mainly, but not exclusively, to the textiles fashion and interior design fields (Diane and Cassidy, 2005). It involves the prediction of future colour trends via an appraisal of past colour trends and an assessment of lifestyles associated with these trends. It is not at all clear that colour forecasting is a forecasting or predictive process at all and there is no empirical evidence that colour consumption is influenced by socioeconomic lifestyle factors at all (Stansfield and Whitfield, 2005). Despite this, colour forecasting is an important component in many colour-production industries. It could, however, be argued that colour forecasting should be placed in the field of marketing since the process could be argued to be more about telling consumers which colours they wish to purchase rather than predicting which colours consumers would like to purchase.

Colour Semiotics

Colour semiotics is concerned with the meanings that colours are able to communicate. Colours can evoke strong emotional responses in viewers and can also communicate meanings and or concepts through association. For example, in many western societies black is associated with death and the mourning process. Consequently, colour may play a role in imparting information, creating lasting identity and suggesting imagery and symbolic value (Hynes, 2008). There seem to be at least three different origins for colour semiotics. Firstly there is the emotional or visceral impact of colours. Colours can have a strong emotional impact and can even affect our physiological state. For example, red colours have been cited to raise the blood pressure and colours have been reported to affect muscular strength (Hamid and Newport, 1989; O’Connell, Harper and McAndrew, 1985). We fear the dark. Perhaps these effects are innate and have been present since the earliest days (the effect of red has sometimes been attributed to the colour of blood and our fear of black may relate to a primitive fear of the dark and unknown.) Secondly there are socio-economic origins. In western society purple became associated with wealth and royalty because purple dyestuff was more expensive than gold. Only extremely rich people could afford to wear purple and some organizations (e.g. the Christian church) chose to use purple to make a statement about their wealth and power. Thirdly, some colours meanings are cultural in origin. The association of red with luck in China and the link between pink for girls and blue for boys in western society may originate in and be reinforced by cultural behaviour and shared understanding. For example, in the United Kingdom pink was associated with young boys until about 1920 after which blue came to signify the male professions, most notably the navy (Koller, 2008). The importance of colour semiotics has been noted in corporate visual identities (Hynes, 2008), human computer interaction (Bourges-Waldegg and Scrivener, 1998), political communication (Archer and Stent, 2002), and as a marker for gender and sexuality (Koller, 2008). Koller undertook a study of the colour pink and found, from a survey of 169 participants, that 76 per cent of participants made the association of pink with femininity. Pink was also associated with romance (56%), sweetness (52%), softness (51%), love (50%) and several other concepts (Koller, 2008). Men were less likely to make synesthetic associations for pink than were females who also seemed to have a more differentiated schema for pink. In addition to the link between pink and femininity, Koller (2008) also found emergent associations of pink with fun, independence and confidence. However, although black is often associated with death it can have other meanings; for example it can be associated with power or evil, and the actual meaning in any particular situation depends upon the context in which the colour is used; it can also depend upon other aspects of visual appearance such as gloss and texture (Lucassen, Gevers and Gijsenij, 2010). Furthermore, the meanings for a colour can also depend upon culture and can vary over time. For example, in some countries black is not the colour that is most associated with death (white is used instead). The appropriate use of colour semiotics can impact greatly on the success of a design (particularly one that has a branding or marketing dimension). However, it is clear that colour meanings and associations can vary with a great many factors. On the one hand the connection of meaning and colour seems obvious, natural nearly; on the other hand it seems idiosyncratic, unpredictable and anarchic (Kress and Van Leeuwen, 2002). Indeed, social groups that share common purposes around colour are often relatively small and specialized compared to groups who share speech or visual communication (Kress and Van Leeuwen, 2006). Grieve goes further to suggest that colour per se does not elicit response, but the particular meaning or significance of the colour seems context-bound and varies from one person or situation to another (Grieve, 1991).

Despite the previously discussed context–‐dependence of colour semiotics most robust studies that have explored colour semiotics have done so for colour patches viewed in an abstract sense, devoid of context. The colour science community tend to use the term colour emotion instead of colour semiotics; for example, Gao et al. (2007) wrote that “The semantic words describing words such as “warm-cool”, “light‐dark”, “soft‐hard”, etc.”. The colour science community also tend to study bi-polar pairs of semantic words such as “soft-hard”. In these circumstances it has been found that there is an effect of culture but that it is limited (Lucassen et al., 2010). Indeed, even the medium (e.g. digital display or hardcopy paper) has been shown to have little effect on the emotions or meanings that observers attribute to different colours (Suk and Irtel, 2010). This would seem to contradict greatly with the earlier view (Grieve, 1991) that colour per se (without context) does not elicit response. Nevertheless, most formal studies in the last decade have explored whether there are cultural, gender or age effects in terms of the meanings associated with colours by observers when viewing colours without context (typically square patches of colour viewed on a computer screen). For example, one study (Gao et al., 2007) studied observers from seven countries (Hong Kong, Japan, Thailand, Taiwan, Italy, Spain and Sweden) who were asked to rate 214 colour samples each in terms of 12 bi-polar word pairs (e.g. soft-hard). The differences between the nationality groups were small despite the different cultural backgrounds. In another study (Ou et al., 2004a) 14 British and 17 Chinese observers assessed 20 colours in terms of 10 bi‐polar word pairs. The differences between the responses from the two groups were small with the exception of like‐dislike and tense-relaxed. Chinese observers tended to prefer colours that were clean, fresh or modern whereas this tendency did not occur for British observers. British observers tended to associate tense with active colours, whereas Chinese observers associated tense with the colours that were hard, heavy, masculine, or dirty. In a second study (Ou et al., 2004b) 8 British and 11 Chinese observers assessed 190 colour pairs in terms of 11 bi-polar word pairs. No significant differences were found between the UK and Chinese responses but some gender differences were found; there was poor correlation between male and female responses in terms of the masculine-feminine word pair and female observers tended to like colours that were light, relaxed, feminine or soft (whereas this association did not occur for male observers). It seems clear that colour per se does have meaning but the question of whether these meanings are consistent across culture, age and gender is not entirely clear. As Gage (1999) wrote, “To what extent different colours, such as red or black, have cross-cultural significance, is an altogether more difficult question.” Perhaps one reason why these formal studies have not been able to provide definitive answers to the question of whether colour meaning and emotion depends upon culture (and even gender) is because they have traditionally been carried out with quite small numbers of participants. The two studies by Ou et al. (2004a; 2004b) involved 31 and 19 participants respectively. These studies typically involved small numbers of observers in part because the experiments are carried out in laboratories using carefully controlled and calibrated equipment so that the exact specifications of the colours displayed can be known. One way to involve much greater numbers of participants is to use a web-based experiment and such a study is currently being undertaken by the author (Westland and Mohammadzadeh, 2012). Web–‐based experiments have several advantages including access to large numbers of observers and minimal interruption to observers and experimenter. Of course, the disadvantages are also numerous including potential sources of colour variation including, display technology, ambient illumination level, observer bias an, deficiencies and anomalies and operating software. However, currently responses have been collected for more than 2000 observers from over 50 countries worldwide and this work, when complete, has the potential to allow definitive conclusions to be drawn on the question of whether colour semiotics are invariant to cultural background and gender. The issue of how to address colour semiotics in a design context remains an open question and can currently only be addressed by ad hoc studies that contribute little to the theoretical debate.

References

Judd DB and Wyszecki G (1975), Color in business, science and industry, 3rd edition, John Wiley and Sons.
Westland S, Laycock K, Cheung V, Henry P and Mahyar F (2007), Colour Harmony, Colour: Design and Creativity, 1 (1), 1-15.
Nemcsics A (1993), Colour dynamics: Environmental colour design, Ellis Horwood.
Kuehni RG (2005), Color – An introduction to practice and principles, John Wiley and Sons.
Ou L-C, Luo MR, Woodcock A and Wright A (2004a), A study of colour emotion and colour preference. Part I: Colour emotions for single colours, Color research and application, 29 (3), 232-240.
Guildford JP and Smith PC (1959), A system of color preferences, American Journal of Psychology, 72 (4), 487‐502.
Hurlbert AC and Ling Y (2007), Biological components of sex differences in color preference, Current Biology, 17 (16), R623‐R625.
Schloss KB and Palmer SE (2010), An ecological valence theory of human color preference, Proceedings of the National Academy of Sciences, 107 (19), 8877-8882.
Diane T and Cassidy T (2005), Colour Forecasting, Wiley-Blackwell.
Stansfield J and Whitefield TWA (2005), Can future colour trends be predicted on the basis of past colour trends?: An empirical investigation, Color research and application, 30 (3), 235‐242.
Hynes N (2009), Colour and meaning in corporate logos: An empirical study, Journal of Brand Management, 16 (8), 545‐555.
Hamid PN and Newport AG (1989), Effect of colour on physical strength and mood in children, Perceptual and Motor Skills, 69, 179‐185.
O’Connell BJ, Harper RS and McAndrew FT (1985), Grip strength as a function of exposure to red or green visual stimulation, Perceptual and Motor Skills, 61, 1157-1158.
Archer A and Stent S (2002), Red socks and purple rain: the political uses of colour in late apartheid South Africa, Visual Communication, 10 (2), 115-128.
Koller V (2008), ‘Not just a colour’: pink as a gender and sexuality marker in visual communication, Visual Communication, 7 (4), 395‐423.
Bourges‐Waldegg P and Scrivener SAR (1998), Meaning, the central issue in cross–‐cultural HCI design, Interacting with computers, 9 (3), 287‐309.
Lucassen MP, Gevers T and Gijsenij A (2010), Texture affects color emotion, Color research and application, 36 (6), 426‐436.
Kress G and Van Leeuwen T (2002), Colour as a semiotic mode: Notes for a grammar of colour, Visual Communication, 1 (3), 343‐368.
Kress G and Van Leeuwen T (2006), Reading images: The grammar of visual design, Routledge. Grieve KW (1991), Traditional beliefs and colour perception, Perceptual and Motor Skills, 72, 1319-1323.
Gao X-P, Xin JH, Sato T, Hansuebsai A, Scalzo M, Kajiwara K, Guan S–‐S, Valldeperas J, Lis MJ and Billger M (2007), Analysis of cross–‐cultural color emotion, Color research and application, 32 (3), 223-229.
Suk H‐J and Irtel H (2010), Emotional response to color across media, Color research and application, 35 (1), 64-77.
Ou L‐C, Luo MR, Woodcock A and Wright A (2004b), A study of colour emotion and colour preference. Part II: Colour emotions for two-colour combinations, Color research and application, 29 (4), 292-298.
Gage J (1999), What meaning had colour in early societies?, Cambridge Archaeological Journal, 9 (1), 109‐126.
Westland S and Mohammadzadeh M (2012), http://www.keysurvey.co.uk/votingmodule/

Workshop in Wuhan

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Last week I went to Wuhan (China) where I was invited by the Department of Industrial Design at Huazhong University of Science and Technology to give a two-day workshop on colour and a lecture. In the workshop I asked the students to arrange a set of colour chips in a logical order. Here is the result.IMG_3666

IMG_3667

IMG_3668

Group 1
Group 1
Group 2
Group 2
Group 3
Group 3
Group 4
Group 4

The last four images show the final work by each of four groups. Group 3 were the best in my opinion. Of course, this task is difficult, if not impossible, in 2-d. Colour perception is at least 3-d and the dimensions are lightness, chroma and hue. The workshop task was designed to enable the groups to explore the ontology of colour perception. It was also good fun!!!

This is not yellow

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A few people have asked me about this interesting and entertainig youtube clip – This is not yellow.

It’s worth looking at. It makes the point that when you look at colours on the screen (whether it is your computer screen, your TV or your mobile phone) although you see a full range of colours, all that is there is mixtures of red, green and blue light. In principle this is true – in practice it’s a bit more complicated because the screen doe snot emit just three wavelengths. For practical reasons the RGB primaries on a display are more broad band. Nevertheless, the essence of what is being said is true; when you look at yellow on the screen it is not a single wavelength that you would associate with yellow that is being emitted. Hence, the “This is not yellow”.

However, the clip doesn’t go far enough. It suggests that this is a problem with displays and that when you see a real lemon, for example, you are seeing real yellow because the lemon absorbs all the wavelengths of light except yellow (which is reflected). Sadly this is not true either. Let’s look at the reflectance profile of a typical yellow object. I can’t promise it is a lemon but a lemon would be pretty similar.

yellow

What this graph shows are the wavelengths of light along the x-axis and, along the y-axis, the per cent of each wavelength that the yellow object reflects. Notice that it does not absorb all wavelengths excecpt the ones that would be seen as yellow in the spectrum (essentially about 580 nm). Rather, the physical yellow object reflects all wavelengths in the spectrum because the reflectance is greater than zero at all wavelengths. The physical yellow object also absorbs all wavelengths in the spectrum to some extent because the reflectance is less that 100% at all wavelengths. Obviously some wavelengths are reflected more than others. But it isn’t even the wavelengths at about 580 nm that are maximally reflected. The yellow object reflects more red wavelengths than it does yellow wavelengths. So why does the lemon look yellow? For the same reasons that the lemon looks yellow on the screen; because the light being reflected activates the cones in the human visual system in a certain way. So I am not knocking this video – rather, I want to say that it makes a good point about displays but that this point also relates to colours in the subtractive world. It raises the issue of what we mean when we say something is yellow either on a screen or in the physical world.

colour and accessibility

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Just came a across a superb article by Geri Coady, a designer and illustrator living in Newfoundland (Canada) about the importance of designers taking into account the fact that about 5% of the population in the world are colour blind. Well, it’s mainly men of course ….. but that’s all the more reason to take into account [joking].

Some really excellent advice about how to take colour blindness into account in design work. She talks about problems with the use of colour in London’s iconic underground map (see my blog about colour blindness and maps). She also comments on a game (Faster than Light) that has a colour-blind mode; I mentioned last week that SimCity was doing something similar. About time. It’s so lazy not to take colour blindness into account in the digital environment. There are also some great links to simulators.

chicken colour vision

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Most humans are trichromatic; that is, our colour vision is mediated by three types of light receptor in our eyes. These receptors are known as cones and the three types have peak sensitivity in different parts of the colour spectrum. We sometimes refer to these as LMS cones because of their peak sensitivity at long-, medium- and short-wavelengths light.

Some people (men, in the main) are colour blind and this is because they are anomalous trichromats (they have three cones but the spectral sensitivities are less optimal than they should be or they are dichromats (they are missing the L, M or S cone types). But what about other species?

Most mammals are dichromats including dogs and cats. However, many fish and birds have better colour vision than do we humans. I just came across an article that reports that chicknes have five cones compared with our three. The research has been conducted the Washington University School of Medicine in St. Louis (USA). It is suggested that birds often have more cones than we do because they descended directly from dinosaurs and never spent any part of their evolutionary past living in the dark.

what is it like to be colour blind?

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Another simulator on the market that shows you what your image or website would look like to someone who is colour blind. This one is from a company called ETRE – for further details see http://www.etre.com/tools/colourblindsimulator/

In the image series below the left image is normal and the ones in the middle and right show protonopia and deuteranopia respectively.

18eap7gi6et22

For more on colour blindness see my earlier post.