Tag Archives: green

Man Utd change sock colour

This weekend Manchester Utd played Middlesborough in the FA cup. We won’t talk about the result. However, so interesting that Utd changed the colour of their socks from black to white to make it easier for people with colour discrimination issues to enjoy the game. Above you can see a shot from the game with a simulation on the right of how it might look to a someone missing the L-class cone (red-green colour blind).

This comes just after I posted about the rugby game and the problem trying to discriminate between the red and green shorts of Wales and Ireland respectively. Given the news in that post that World Rugby is bringing in some legislation it does seem that colour blindness (as poor colour discrimination is often referred to) is finally being taken seriously.

Colour and Inclusivity

Interesting article today in the BBC about the colour of rugby shirts and the experience of viewers who may be colour blind.

According to one fan, the Irish and Welsh national kits are particularly difficult to distinguish for some people. As you can see from the simulation below, it is particularly challenging for protanopia (where the long-wavelength cone class is missing and the viewer is a dichromat).

Apparently, World Rugby has proposed new laws to help people affected by Colour Vision Deficiency (CVD), meaning teams may have to change kit from 2027 in the event of a colour clash.

However, it would not be difficult for one team to make their kit a little darker and one a little lighter to allow more people to enjoy the game and follow the action more easily.

In the image below, on the left you can see the original colours and on the right you can see the simulated colours for a protanope.

The top rows shows the colours that will be used in the match this weekend. The bottom rows show slightly shifted reds and greens that are more inclusive on the left, and their simulated appearance on the right.

Colour symbolism at Christmas

At this time of year my thoughts sometimes turn to the colours that we associate with Christmas: red, green, gold, silver and white, in various combinations. One of the things that I sometimes read about is where Father Christmas always had a red suit or whether he had a green one. I note that in The Lion, the Witch and the Wardrobe, Santa is wearing a dull brownish tunic.

Father Christmas in Narnia

Though apparently according to CS Lewis himself in the book: on the sledge sat a person everyone knew the moment they set eyes on him. He was a huge man in a bright red robe (bright as hollyberries) with a hood that had fur inside it and a great white beard that fell like a foamy waterfall over his chest.

https://www.thephantastic.com/home/narnia-always-winter-and-never-christmas

There are also annual stories about whether the traditional red we now associate with Father Christmas was influenced by Coca-Cola for marketing reasons. So, today I thought I would share this blog post about the truth of Father Christmas and red. It does refer to Coca-Cola who, I believe, had a role in popularising our current image of Santa but were not actually responsible for the colour change. This view is also reinforced by this blog post about Santa and red.

Anyway, the thing I read today that inspired me to write this post is actually this blog post which is about colour symbolism and Christmas.

Finally, if you want to explore the meanings that colours have in a more academic perspective here is a link to two papers that are free to read in JAIC – the Journal of the International Colour Association. One was written by me and Seahwa Won (who was my PhD student at the time) and you can see that one here. The other is written by José Luis Caivano and Mabel Amanda Lopéz, well known colour experts in Argentina, and you can see that here.

Why yellow and blue don’t make green

[and why we should stop teaching it in schools]

You will find images like the one above, that show that red, yellow and blue are the primaries and that yellow and blue make green.

Sometimes this is represented as a colour wheel:

So some people say yellow and blue make green. And you will find other answers that say that yellow and blue make black. How can this be?

Well, we need to understand a little science to get to the bottom of this.

The figure below shows what happens when you mix an ideal yellow dye with an ideal blue dye. The blue dye reflects light perfectly in about a third of the spectrum (and absorbs perfectly in the other two thirds). The yellow pigment reflects light perfectly in about two thirds of the spectrum (and absorbs perfectly in the other third).

The problem here is that the blue and yellow pigments (between them) absorb perfectly across the whole spectrum. The people who say that yellow and blue make black are saying so because of this argument.

Note that blue is a particularly bad choice of primary because it absorbs so broadly across the spectrum. [Making the blue even purer would only make the problem worse by the way.] Yellow is a good choice of subtractive primary because it only absorbs in one third of the spectrum.

The problem is, the people who say that blue and yellow make black are wrong of course. Every child knows this. In practice, if we measure the reflectance spectra for blue and yellow pigments they don’t look like those ideal ones I showed above. For a start, they are quite smooth. Here is a reflectance spectrum for a real yellow pigment. (The reflectance factor, by the way, is the proportion – or per cent – of light that the colorant reflects at each wavelength.)

Notice that with a real yellow colorant, it does not reflect perfectly in the middle and long wavelengths and it does not absorb perfectly in the short wavelengths. It reflects and absorbs to some extent all the wavelengths but it absorbs more at the shorter wavelength and absorbs at less the middle and longer wavelengths. The same is true of a real blue colorant; it does not absorb perfectly at the middle and longer wavelengths. The consequence of this is that you don’t get black if you mix blue and yellow. You would get black if the pigments were ideal but they are not. We live in the real world. However, you certainly don’t get a lovely bright green as shown in the colour wheel with red, yellow and blue primaries. You would get a dark desaturated murky dirty greenish colour. The main reason for this is that the blue is absorbing too broadly. Interestingly, if you look at the artist John Lovett’s page he explains that to mix a yellow and blue you should use a yellowish blue (and a bluish yellow). 

Now let’s see what happens when we mix cyan and yellow dyes. We’ll start with the ideal colours.

It’s very nice. We get a lovely green colour. Cyan is a great subtractive primary because unlike blue it absorbs in only one third of the spectrum (the red or long wavelengths). Note that it is precisely because the cyan does not look pure that makes it a great primary – that’s why I get so furious about people saying the primaries are pure colours. The cyan looks bluish-green because it reflects in two thirds of the spectrum and only absorbs in the reddish part. Neither the cyan nor the yellow dye absorb in the middle (green) part of the spectrum and therefore the result of mixing cyan and yellow is a lovely green. Except it is not quite true. Remember, this is for ideal pigments. Real dyes do not look like that. Refer back to the measured reflectance spectrum for the real yellow pigment. In reality cyan and yellow do make green but the green might be a little less saturated than you may wish for because of the unwanted absorptions by the two dyes in the areas of the spectrum where ideally they would not absorb. (It was the great Robert Hunt, who worked for many years at Kodak – for those who knew him – who taught me about unwanted absorptions.)

Have you ever seen this happen. Of course, you have. Whenever you use a printer (which typically uses cyan, magenta and yellow primaries) to get a green, the printer is using cyan and yellow to make the green.

Remember those people who say that you can’t make blue because – yawn – it’s a pure colour that can’t be made by mixture? Well, have you ever printed out blue on a printer? Of course, you have. Let’s look again at our ideal primaries and see if we can explain it.

That’s right. Mixing cyan and magenta makes blue. The cyan absorbs in one third (the red third) and the magenta absorbs in one third (the green third) but neither absorb the short wavelengths.

John Lovett explains that you can do a decent job of mixing red, yellow and blue dyes, but only if you allow yourself to use multiple blues and multiple yellows, for example. If you want to do the best job possible using only three subtractive primaries, then the best you can do is to use cyan, magenta and yellow. 

So finally you can see that the best subtractive primaries are cyan, magenta and yellow because the cyan is red absorbing, the magenta is green absorbing and the yellow is blue absorbing. And what is more, you now understand why this is the case (rather than accepting dogma). You also understand why there is a relationship between the CMY of subtractive mixing and the RGB of additive mixing.

The optimal additive primaries are red, green and blue (I will cover this elsewhere). And for this reason the optimal subtractive primaries are cyan (red absorbing), magenta (green absorbing) and yellow (blue absorbing). 

But don’t be fooled by this lovely subtractive colour mixing diagram. You might not get such lovely blue, green and red colours when you mix real CMY primaries (either on your printer or with inks/paints). Why not? Because of the unwanted absorptions.

If you want to to know more you could do worse that get a copy of Measuring Colour, now in it’s 4th edition, and authored by Hunt and Pointer. 

This post gets quite a few hits so I will take this opportunity to direct you to my short series of youtube clips that describe the issues discussed in this post in a visual way. You can see them here. If you want something a bit more technical check out this short lecture on colour primaries or visit my patreon.

Or visit my Patreon page here for more analysis like this

changing button colour increased conversion

button

It seems that only recently companies are carrying out what is known as split testing or A/B testing. Put two designs of a web site out and see which does best. Recently one company did just that. They had one web site with a green call-to-action button (as shown above) and another with a yellow call-to-action button. Changing the call-to-action button from green to yellow resulted in a 187.4% increase in conversions to their website. Is there some effect that yellow light could have compared to green? For example, could yellow light make users more impulsive?

According to Erika Dickstein it may be nothing to do with yellow at all but simply to do with the contrast – the yellow stands out better and therefore is more noticeable. Certainly more research is needed in this area.

cigarette packaging colour

smoking_248418k

New regulations – from 20 May 2016 – will see all cigarette packaging in the same drab green colour.colour with other standardised features such as opening mechanism and font, and with 60 per cent of the casing covered by text and images showing how smoking affects your health. The decision was made in Parliament on 15 May last year.

They have also been told to get rid of any misleading information from cigarette packs, and have been prevented from using words such as ‘organic’, ‘natural’ or ‘lite’, which could lead consumers to believe there is a healthy smoking option.

Further information can be found in this article in The Independent.

The images shown above are from a similar scheme in Australia.

green light may cure your headache

I get migraines. Not often. Just a few times each year. But when I get one I have been known to turn off the lights and go to sleep in my office. I have found that taking a pain killer and then going to sleep is the only way to relieve my symptoms. But a study in the journal Brain suggests that exposure to green light actually has a beneficial effect.

green

In the study 80 percent of subjects reported intensification of headache with exposure to high intensity of light, except green. Surprisingly, the researchers found that exposure to green light reduced pain 20 percent. They also found that the signals generated in the retina for green light are smaller than those signals generated for red and blue light. Researchers are now trying to develop a more affordable light bulb that emits pure narrow-band wavelength of green light and sunglasses that can block out all colours of light except narrow-band green light.

what colour is your passport?

passport colours

Whenever I am travelling to a conference and standing in a line at an airport it seems to me that everyone has either a burgundy passport like me or a red one if the are from USA. It turns out that most passports really are the same colour as this great infographic shows. Well, one of only about four colours so it seems. It’s interesting the way they are grouped; I wonder why Africa tends to use green or black. For the full story see. here.

why people have started to buy brown cars again

3-Beige-Golf-Rex

Interesting article by Ian Johnston in The Independent today about consumer colour choices for second-hand cars in the UK. Bucking the recent preference for silver, black and whit, the top 10 list of colour schemes includes green, beige, yellow and gold – colours that we associate with the 70s.

Please see the original article for further information.