Saturday, 28 February 2015
The Emperor’s New Dress
If I were a clever writer, sadly I know I am not, I would write a parody blog providing scientific neurosciency explanation for why the King’s New Clothes do actually exist and simply cannot be seen by some people, but can be seen by others. The kind of twine that is used is of a sufficient luminosity that some people simply fail to see it and despite the fact that he is really properly clothed, to some people he appears butt naked. But Emperor's New Clothes is a very old phenomenon and that is exactly what has happened here. I would have been the little boy that cried out from the crowd.. “but he’s naked!!”… and, I daresay, would have been dragged off and beheaded. Hopefully those days are over, because here is my piece on #theDress #DressMeme.
Yes OK, I confess, I’m afraid this is yet another blog about the dress. I find whole phenomenon fascinating. It is hardly surprising that someone who teaches the neuroscience of the eye, the visual cortex, rods, cones and opsins etcetera finds this phenomena interesting. However maybe you will be surprised at my perspective on the whole dress meme thing.
So let’s start with a summary of the facts (I think this is how Clouseau would begin in the Pink Panther movies?): There is a dress apparently made by Roman that is black and royal blue. But a photograph of this dress has appeared where the colours are distorted and it looks gold and white or gold and pale blue. Some people looking at the golden pale blue dress photo say that they see a black and royal blue dress. …and the internet has gone wild. Scary.
There is also some confusion. The question is not what colour is the dress, we know that in the high street store it is blue and black and it has just shifted colour to produce a funny coloured photo. The squabble is that some people say that this specific picture looks blue and black. There is no mystery about how digital photos of objects look different to the original, colour balance, colour temperature, exposure all explain that merrily. The question is why some people say the gold looks black in this specific photo.
In response to this one scientist after another has trundled in to talk about perception differences between people, about the science of rods, cones, opsin proteins, wavelengths of light, processing in the visual cortex etc. but none of these “scientific” explanations explain the phenomenon.
My line is that the whole thing is nonsense. It is probably a case of the “King’s New Clothes”. There are a number of possible explanations from hoax to hysteria, otherwise known as “crowd syndrome”. If it is a hoax then how many how come so many people are a part of it? Well they aren’t really. My explanations are of hysteria, gullibility, or possibility sense of humour coupled to an innate sense of mischievousness in humans. My only amazement is how few people can see the obvious flaws in the logic of the so-called scientific or visual perception anomaly theories.
Now why am I so confident that this is not a phenomenal about rods and cones and differences of perception? Because you can analyse the picture in heavy-duty imaging software and just get a simple answer on the RGB (Red, Green, Blue) levels of each portion of the picture. It’s true to say that when I see purple what registers in my brain maybe quite different from what you see when you see purple, but the problem here is that on a computer screen the world is less ambiguous. “Black” in a digital photo means something quite specific. It means that the RGB levels are either 0,0,0 or just close to this. For info, a typical digital photo consists of an array of pixels each with an RGB colour mix and each R, G and B value has to be a number between 0 and 255. If they are all 255 that is pure white (255,255,255) and if we have black we have (0,0,0). Of course (1,1,1) looks black and it gets less black as you move further away from (0,0,0). So there are a number of points around the RGB envelope that look black. For example, below I have shown two very dark swatches. To me 40,40,40 looks pretty black. However, here’s the rub; we can analyse the gold in the photo and what do we get?
The figure shows the photo in question: and alongside it a swatch (A) coloured in the same colour OBJECTIVELY measured from the square using ImageJ software (NIH). B and C are just examples of darker fills. Below are three panels with the red, green and blue components separated, again in ImageJ, and the levels histograms from these presented below each. For the record, the "blue/white" part is (126, 137,178). There is no black guys.
So perhaps some people see 133,099,060 as black (“A” in the figure)? …and always have… OK that’s possible, but that would mean they always would have done. But millions of people have been viewing millions of gold dresses for years and how come no one spotted that gold looks black to some people before? It’s implausible. …and if it is true, well they are just colour blind in someway not observed previously.
Frequently optical illusions do occur, for example, running one colour, alongside another colour can give create an illusion that the second colour is different to its true colour. But you can “work it out” using objective analysis software (ImageJ et al.) as described above. Example: In theory… the red squares on the left look darker than those on the right?
Histogram analysis shows that the mean colour intensity is 180 in both cases. They really are identical.
So since the digital photo clearly has no black in it what are the other explanations:
- Confusion. People have seen that the original dress is really black and they are making the classical exam mistake of NOT answering the question. The question is not “what colour is the dress?”, the question is “what colour does the dress appear in this particular digital photo?”.
- Crowd syndrome. People are going with the flow. Some people will be prepared to say what they think they should say, what they think the crowd expects them to say, to an extraordinary degree. If we have an interview situation about this dress, with the interviewer asking what colour the guests see, s/he will be embarrassed if no one says black. So some people will inevitably just have to throw a life line by saying it looks black to them, even though it doesn’t.
- Sense of humour. Well we are all having fun aren’t we, and that will require some people to perpetuate the myth by saying that the gold parts of the photo appear black to them. Or the fun would stop.
…but visual illusion it isn’t :-)
Of course if 10% of sighted population do see 113,99,060 as black they will think this a really embarrassing diatribe. Such is life. I’ve done worse. There was even that one time……