Category Archives: news

colour helps you sleep

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Light in our natural environment tends to be bluer first thing in the morning and redder at dusk.

Researchers from the University of Manchester looked at the change in light around dawn and dusk to analyse whether colour could be used to determine time of day. They constructed an artificial sky beneath which they placed mice and they then measured the body temperature of the mice for several days and their body temperature was recorded. The highest body temperatures occurred just after night fell when the sky turned a darker blue – indicating that their body clock was working optimally. When just the brightness of the sky was changed, with no change in the colour, the mice became more active before dusk, demonstrating that their body clock wasn’t properly aligned to the day night cycle.

According to Dr Timothy Brown: “This is the first time that we’ve been able to test the theory that colour affects the body clock in mammals. It has always been very hard to separate the change in colour to the change in brightness but using new experimental tools and a psychophysics approach we were successful. What’s exciting about our research is that the same findings can be applied to humans. So in theory colour could be used to manipulate our clock, which could be useful for shift workers or travellers wanting to minimise jet lag.”

measure colour with your smartphone

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This looks interesting. Node is a way to add sensors to your iOS device. It allows you to measure all sorts of things, including colour if you have the node+chroma combination. The node costs about £100 and the additional sensors cost about £50 each. I am not sure how much the chroma sensor costs.

You can find further details here – http://variableinc.com/chroma-contact/

curved displays are the future

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Yesterday I spoke an an event to launch Samsung’s latest curved screen displays. The technology is really gorgeous and everyone who attended was wanting one of the new displays after seeing them.

I am convinced that curved screens will become ever more popular in the future because not only do they look good but they offer serious advantages for users who undertake intensive tasks – the sort of tasks that need a large desktop display rather than a mobile device. When it comes to desktop displays it is really quite simple – bigger is better.

Many people – and I am one of them – are what is known as ‘double screeners’. I have two screens attached to my desktop and my operating system is spread seamlessly across them because I wanted more screen space to work in. I recently carried out a survey – you can find more details here – which showed that 38% of British office workers are already using two or more screens attached to their desktop computers.

Of course, in an ideal world one very large screen would be better than two smaller screens. But there is a problem with most flat-screen technology which is that the LED/LCD pixels emit light straight out but emit a lot less light at an angle to the screen. This means that you look at a large flat screen the light reaching your eye from the edges of the screen is a lot less. Not only that but, because you are looking at the screen at an angle, text and other fine details can be distorted at the edge. Curved displays get around this problem and I am hoping to replace my two flat screens soon with a single Samsung curved display.

With a curved display the distance from the eye to the screen is the same across the whole display and the angle of view is also constant. Not only does this solve the colour and acuity problems I just mentioned but it means that users need to need fewer eye and neck movements. Given that many of us spending longer using a display than we do actually sleeping this could have a big effect on user well-being.

Our survey also showed that about 60% of office workers think it is important that the office technology they use looks good. This can help to motivate them and help them to feel good about themselves. The new Samsung curved displays certainly will satisfy these people.

What colour is the sky on mars?

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The cameras never lies. Or does it? Recently I had to take a photo for a medical case and before submitting it I had to sign to say that the photo had not been modified. I did this – but it was ridiculous of course. Many people have this idea that the cameras faithfully captures what the scene looks like and that, unless we intentionally manipulate the images (in photoshop, for example), then we have captured the truth. Nothing could be further from the truth – as the recent image of #TheDress showed.

The top photo above was taken and released by NASA in 1976 and shows a Martian landscape. The sky is blue. However, at the time, Carl Sagan said “Despite the impression on these images, the sky is not blue…The sky is in fact pink.”

You see the original image had not been colour corrected. Colour correction is a process that takes place on most cameras these days without the user being aware of it but in 1976 was not automatic. The process can compensate for the spectral sensitivities of the camera sensors (which may differ from one camera to another) or for the colour of the light source. The second picture (above) shows the colour-corrected image. Some people are now arguing, however, that the amount of colour correction applied by NASA is wrong and that the sky should not be as red as it appears on the second photograph. For the full story including some other nice images of Mars see here.

final word on the dress

Yesterday, I posted about The Dress that people see as either blue and black or white and gold. Following several radio and telephone interviews I wanted to have a final attempt to explain what is happening with the dress. It is quite an extraordinary phenomenon – yesterday the dress looked blue and black to me but my PhD student (looking at the same dress on the same screen) said it looked whitish and gold. When I came home last night and looked at the photo on my mac book, the same image that had looked decidedly blue and black to me before now looked whitish and gold. So what is happening?

The first thing is that it is nothing to do with the dress. The problem is with the photo of the dress. I believe that anyone looking at the dress in real life would certainly call it blue and black and also anyone looking at the manufacturer’s photo of the dress would also call it blue and black.

The second thing is that there is more than one phenomenon going on. The reasons why my PhD student and I saw different colours in my office may be a little different from the reasons why I saw it one colour on my pc in my office during the day and another colour during the evening on my mac. So, although people might like a simple answer and a soundbite, in my opinion the explanation is necessarily a little detailed. But I will try to avoid too much technical jargon below.

The camera does lie
I think many people believe that when they take a photograph and put in on the internet and people look at, what people are seeing is a faithful rendition of the original scene. People take this for granted, I believe, without giving it much thought. Unfortunately, this is not guaranteed. There are many reasons why the colour someone might look at in an image might not be the same one that was in the original scene. Different cameras capture colour in different ways depending upon the type of camera, the settings on the camera, and the light under which the image is taken, to name just three factors. In The Dress image, the image looks over-exposed and the colours are washed out. The black is quite pale and has a colour tint and the blue is very washed out and insipid. Hopefully you can see where this is going already.

Different displays show colour differently
You can put the same image on a PC, a mac, a smart phone and a tablet and look at it. The colours will probably not be identical. Reds will probably be red and blues will be blue. But the colours are likely to be not exactly the same on the different devices. If you are looking at your screen from an angle, the colours may change radically. Also, if you are looking at your screen in bright sunlight the colours may look more washed out – though some smart phones and tablets try to ‘intelligently’ correct for this which might make the problem better or worse. The fact that I saw the colours differently in my office than at home could be due to differences in the devices I was using or could be due to the lightening environment, The lighting in my office is quite different to that in my home, for example.

People see colour differently – a little bit
About 1 in 12 men are colour blind. Very few women are afflicted. But even for the rest of us – so-called normal observers – there is variability in our colour vision. One factor for this could be that there are known to be differences in our eyes from person to person. This effect could be small but may be a factor in this story. More important is probably the fact that if sit in a dark room for a while and get used to the dark our vision will be different to it would be if we were outside in bright sunshine. This so-called ‘adaption’ is one way our visual systems deal effectively with such a wide range of brightness from dark rooms to brightly illuminated outdoor scenes. Someone coming into a room from outside (where the sun and sky are very bright) might very well see different colours on the screen than some who had been in the room for a much longer period. These adaption factors are well known in science.

People don’t always agree on colour names
There are at least 3 million different colours in the world. How many colour names can you think of that we could broadly agree on? Words like, blue, black, red etc. There are others like beige and taupe where we might agree less well. But include these and how many do you have? 30? 50? 100? And these names have to cover 3 million colours!! So each name is a category that covers quite a large range of colours. Last year I published a paper where we gradually moved a colour from yellow to green and asked people to tell us when the colour went from yellow to green. Not surprisingly, the point at which people told us the name changed varied from person to person. So there are some colours that some people will call yellow and other people will call green. Correspondingly, just because two people are calling a colour by different names does not necessarily mean that they are seeing it as a different colour.

My final explanation
Variabilities in displays, viewing conditions, observers and colour-naming boundaries can cause disagreement in how to name colours. Normally, this would not shift a black to a gold or a blue to a white. However, in this case, the image that has caused the controversy is not a faithful reproduction of the original. Because of the way the image was taken the black has shifted considerably away from the centre of the category that we would call black. And likewise for the blue. In my office today I would still call it black. But it was not a strong convincing black. It was a little pale and had a bit of colour in it. To be honest, I could understand why someone else might call it gold. The colour was on the boundary between black and gold and now differences between people could cause it to be classified as one colour or the other. When I came home, the colours had shifted for me. I don’t think my colour naming boundaries had shifted. Rather, I think this was to do with the lighting I was viewing the colour in, or the screen (a mac rather than my pc) or the angle I was viewing my screen at. Any or all of these factors could have shifted the colour so that it passed from the category I call black to the one that I would call gold.

Maybe the surprising thing is that these controversies do not happen more. Colour imaging scientists have been phenomenally successful in delivering colour imaging devices that satisfy consumers. Part of this work is done at the University of Leeds where I work but there are other places around the world who make great contributions including RIT in Rochester USA. And then there are some super bright scientists in places like Samsung, Apple, HP and LG who have worked hard to understand the complexities of colour perception and colour communication to the extent that people barely even think about these issues. However, there is more work to be done. Colour is still a major factor in people being dissatisfied when they buy something over the internet. When the product arrives it is sometimes not the colour they expected it to be. And colour fidelity is still not good enough for many medical applications. If you want to get involved in colour science please contact me. My email is s.westland@leeds.ac.uk and you can also find me @stephenwestland

#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.

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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.