[Music] [Applause] color color color is crazy for example at the end of this talk I'm going to convince every person in this room that these three colors up here are identical I work down the road at the national physical laboratory it's a big measurement Institute and uh what do you do when you've got a levels in art and physics you go and measure color that's what I did and this was one of the first things that I was asked to measure this is npl black it's a piece of nickel phosphide etched with a really powerful
acid eating away drilling holes deep into the substrate it looks like the Grand Canyon doesn't it light goes in gets trapped and cannot come out this is black it's the blackest black you'll ever see in fact you can't see it it's it's that black and it was so black we couldn't measure it we just said it's blacker than we can measure it was a disaster the most incredible thing is that it was invented by Dr Brown some of the colleagues at npl the national physical laboratory said it's a rubbish black because they weren't interested in
what it looked like to us but what it looked like in the infrared region of the spectrum and we can't see every type of radiation that we call light this is the spectrum that we can see we have a peak of sensitiv it in the green but it dies off Beyond Violet ultraviolet radiation would damage our eyes it would it would literally etch away destroying the subtle biology its power and at the higher end of the spectrum um infrared there's just not enough well in the light to excite excite our eyes so we have this
range of response to light and light is a human perception a color is a human perception as we see it so I'm going to just show you a little odd trick now here's an elephant um or a picture of an elephant please stare at the square in the center of the elephant in fact concentrate not just at the square but at one tiny quarter one corner of it okay stare stare stare now you're probably told off generally for staring at things women television but these things generally move it's quite unusual for you to stare at
something a static as this so an odd case is happening and something odd will happen as a result is it still there now I can't take a photograph of that with my color measuring apparatus that's that's an image I've etched into the retina in your eye your eye has got bored of seeing a pink elephant and parts of your retina have switched off that switching off carries on even when you're not looking at anything and so you see an after image you see an opponent color as it's known in the trade or a complimentary color
designers use these just let's have fun looking at another one you recognize the shape you know what's going to happen I've I've learned the complimentary colors of this well-known flag and by staring at one part of this thing I'd suggest the tip of the elephant's trunk um stare stair stare don't look left right up down don't wiggle yourself don't just just stare concentrate and you the image starts to go glassy doesn't it and in time you will become blind to that image you really will your eye will just switched off the negative version on your
retina or in your brain of that image will override everything and you'll see nothing be sensory deprivation I shall put you out of your misery blink look around the room is it's still with you in 2 days time there's nothing to do with me color is extremely persuasive and um when it comes to measuring it which is what I was given to do as a job it's impossible because it's it's it's part of a human experience um and we use this all the time here are some glasses of liquid and I'd love to do this
in the flesh but I'm just going to have to pretend this is a thought experiment think that you have these glasses of liquid with sugar in them perhaps put a bit of Fizz in there too let's color them oh PowerPoint is wonderful stare at those individually and you can almost taste the difference is that weird and believe me if you did physically taste those even though they were physically exactly the same apart from the color you would taste them differently there is this cross sense thing going on because color is built into your experiences you
associate it with things that you've experienced in the past and you it's really difficult to try and program computers and and robots that see things and are required to tell you what the color of something is to to include this in that experience report here are two images of faces a man and a woman no they're not they're the same picture they're the same slightly androgynous um image but I've changed the contrast on it and so one of them looks distinctly female one of them looks distinctly male and this is just tinkering with the contrast
on them imagine what you could do with color there's the paper reference what is color well color is something that modulates the Spectrum it reflects or emits or transmits some wavelengths of color that we can see more or less than other wavelengths it it Tinkers with the Spectrum and there are many many different ways of doing that they're all reported in this beautiful book here and I've just drawn a couple of images there to show you the sorts of colors that result from all these odd chemical and physical things going on there are some more
there are 15 and just incredible we live in a colorful world and yet there's enormous confusion about it and it starts when we're at primary school and we're required to teach or be taught what the primary colors are what are they oh already I hear four numbers being it's a trick question of course well let's start off with the question what is a primary color a primary color is well there sets of Elemental colors um which you can build to make all of the colors that exist fantastic um and that themselves can't be mixed to
make each other okay and there's a conventional wisdom that tells us there should be three primary colors three because we have three types of sensor in the eye that resolve color for us so I can create a color solid like this that contains all of the colors that exist they're all in there in theory but there is a theory there is a theory that there are primary colors and it kind of lets us down a bit let's let's think about projection systems televisions they have dots of red green and blue light they are the additive
primaries and by switching on and off these lights we can create any color we like so were we to switch off the blue lights there as viewed from a distance I think three times the distance of this lecture theater you'd see that not as dots of red and green but you'd see that as a as a uniform area of of yellow so those are the primary colors when you're adding light the additive primaries and um there we go we can mix together red and green and somewhere in the middle we'll get yellow and we can
ex we can make this go further and further and we can create all of the colors that exist oh no we can't there are some colors missing those deeper Violet Blues we can't reproduce them Faithfully on a television screen and I have to tell you this is fudged what you're seeing up there I'm not projecting the real colors in the right place um it's just a sort of an attempt to to render the colors that we can see I I there is no system that can reproduce all of the colors brilliantly it's just just an
artist's impression in a way so these are this is a color gamut if you like of colors on an additive system like a television set and you can only really create those colors inside there um the Psychedelic ham you're looking at by the way is based on the average perception of 17 human observers who were experimented on voluntarily in the 1920s seven of them down the road in Teddington at npl and 10 of them uh 10 more because cheaper there were students at Imperial College London and uh out of them they got this color model
and this very color model is in more or less every computer that we have today checking color and making sure that what you scan in what you photograph in what you display on the screen and what you print out there's a continuity of color there and it's a tricky thing because some of these things are using additive uh systems to present the colors on the screens and then some are other using this subtractive system that I'm about to explain to you and so there there's the Gam of colors that you can achieve with additive system
and let's try oh this is a typical inkjet output that's really rather Naf isn't it that's not a great range of colors if if you tweak the system if you have a really nice paper good reflectant you have some really good inks you can you can push the boundaries out there a little bit but there what you can create is is is not a great collection of all the colors that exist so the first thing you know what are the primary colors well there are no magic three sets of colors that will create all the
colors that are possible it just it's it's impossible but we are told that the additive primaries are red green and blue and you mix all these together mix all together you'll get white um and the subtractive primaries are these ones cyan magenta and yellow as used by print makers and artists they subtract light rather than add light and how does that work well here's a piece of magenta on ink on some paper we'll shine some light in onto it and we see what happens in fact what I'm going to do first is take the paper
away you have to bear in mind that the ink is actually slightly translucent the ink the light comes on penetrates the paper the ink uh and is absorbed some of it is absorbed remember I said colorful things are things that tamper with the Spectrum so this particular stuff has absorbed the green it's it's minus green magenta is minus green ah can you see where this is going cyan is minus red yellow is minus blue so we are taking away red green and blue light so if we take away red green and blue we take away
everything what are we left with black yes possibly not the blackest black that ever there was but a bloody expensive one do you know how much ink jet print has cost ink jet ink is phenomenally expensive it's more expensive per milliliter than the most expensive champagne you could ever expect to buy so the cheap option is to then use this fourth ink black which is actually Durk cheap it's just carbon really so that's why there are four inks used in the printing system to take away light to take away red green and blue I know
what you're thinking well I don't but I thought I'd put this slide up anyway how do I know what you call orange isn't what I call Blue does everybody see color the same way well the answer is um sort of tied in with this graph here this this does look rather as though someone's thrown a a psychedelic bed sheet over some old furniture and in fact it is a combination of these graphs here these are the three responses the three three different types of sensor in your eyee to different types of light one gets excited
by more by the blue end of the spectrum and the other two kind of one more by the reddish and one more by the greenish part of the spectrum but it's quite subtle isn't it that's what's going in on inside the retina in the back of your eye and the different responses from these three species of cone sensor in your eye is that's what gives you the resolution of color in your lives now to measure how people see color we have to build rigs like this this is my boss Julie in 1989 we built this
phenomenal color mixing system we were mixing light and we were trying to work out how people saw light so there you go and essentially you might think okay we're working how people see light and then we'll build a sensor that is responsive to the red part Spectrum the green part Spectrum the blue part spectrum that that'll tell us what the color of things is great except not everybody sees color the same way do they so there's a sort of unhappy average thing coming in and that's where color starts to become crazy color is also affected
by many things my first job was actually as a botanist and I was required to match the colors or describe the colors of plants chrysanthemum specifically and we shipped these chrysanthemums in and we looked at them at Royal Horticultural uh Society uh color charts like we've got here and it was really really important it was written into the measurement protocol that a I wasn't allowed to be color blind and B we had to look at them inside these color matching cabinets which controlled the quality the type of light that was being used for the experiment
now if I'd have done the experiment the color matching experiment looking at these color matching charts uh comparing those against the color of the granthams um if if i' done that in daylight I'd have got a different result to if I done it in tungsten light do have done it here or under LED lighting or compact fluorescent the lighting is just as important color is a product of the light source something that changes the color of the light source and our eyes all of those change all of the time so here's a here's a bloke
looking at a a blue object and let's illuminate it with some blue light and hey it appears blue so let's change the color of the object to Red what color is a red object going to look like under blue light black fantastic you've passed GCSE physics question uh this is actually put in as a standard question and then they'll ask what what does that look like yeah again black because there's no blue light being reflected by green things and red things is there sometimes there is this is what I call the Trevor dressed in black
demo I used to be in a rock band I was actually the road manager and Trevor would go on stage dressed in a menacing black outfit illuminated by Blue parans thundering blue light onto him and what color did he look red what the point was that the lights that they were using not only were they letting blue light out through the filters but they were letting a little bit of red light through otherwise the filters would have just burnt out blue lights are the ones that always burn out in the blue blue filters on theatrical
lights are the first ones to burn out um because of the heat coming through melting them so they let through all of the infrared or as much as they possibly can and a little bit of the red too and Trevor's clothes I don't know why he didn't look at them under red light reflected they were supposed to be black but they had a little bit of reflectance and so they ended up looking red now if if I answered that in GCSE physics I fail also things flues you know about fluoresence things come on at one
color and come on offer another that's bizarre this is the house I was born in my parents were in the audience thank you you were there um and this is my grandmother's house actually it was a two generation thing and uh I the one thing I really remember from my grandparents house was Lego um used to build things in Lego and in the kitchen the blues just looked different to if you took the Lego into another room the blues looked vibrant and just a completely different color so I'd carry the Lego from one room to
the other and just think this is incredible what's happening to the blue I tried to reproduce this experiment at npl and completely failed because I couldn't find the particular type of fluorescent tube that my grandmother used to use that they're illegal now but for fun I switched on the UV light in my caling cabinet and I got this look at the yellow um just incredible but the blue is quite is quite vibrant there isn't it you can really see something happening in the blue the blue seems to fluores or at least reflect in an odd
sort of way particularly under that type of fluorescent tube I also noticed something else look at the Reds under all but the the bottom left the bottom right um the Reds look fairly syy but what's going on there that that's fluorescent that's definitely floressence some Lego bricks flues more than others it's the same with teeth when they try and match the color of your teeth it's important that they match for false teeth important that they match the degree of fluoresence that your teeth have too otherwise down the Disco pianos piano keys so color changes it
changes with the type of lighting that you have but also personally the way we experience color varies too um here are the brackets of generations my father and my daughter going for a lovely walk in a Blue Bell wood deep in thought and um I know I know that they're seeing completely differently because my my dear daughter how old was she then two two yes two years old I won't accumulate my father asking her how old he was then but this was earlier in the year um my my daughter still received a little bit a
little bit of violety ultraviolet light radiation into the back of right it's nearly all gone now my father those those days have long gone in fact the amount of blue light going into his eyes sorry Dad not much these days the the eye yellows in time it just yellows up just gets yellower and yellower and yellower which doesn't really matter to us it's as though we got yellow Spectacles on we just get used to it it's like changing the white point but it means that Blues become less vibrant to us in older age until we
have the cataract operation then it's [Music] whoa color changes the lighting level again back in that blue bell wood this is what the blue bells look like during the day but at night um when we start to lose the ability to use our color sensors another system comes into play we are equipped with night vision did you know that we have night vision we have rods that are more excited by uh lower levels of light and and can give us sort of an appreciation of what's going on we can't see color but we can see
contrast we can see objects just about as we stumble around in Starlight or Moonlight do that next time very low lighting levels look how not colorful things are so at dawn and dust a Blue Bell would the the blue and the violety blue of the blue bells just becomes violently light incredibly light so color changes according to to illumination level also to do with how much area you've got don't if you ever done decorating you get these tiny little swatches you think yeah that will look good and then you completely paint the whole of your
room and it looks completely different literally the way we see color varies according to how big an area we're seeing of it and those original experiments done in the 1920s at npl were a 2 Dee field of view that's a thumb at Arms uh length some more experiments done in the 19 50s looked at a 10 Dee field of view that's a hand at arms length and they found completely different perception of color over that larger area so next time you you're looking at colors for your room go like [Music] that there's I think called
catic adaptation and it's the the reason why we can adapt to different types of light source whether we're in a cave lit by Flame or whether they're outside lit by the sky and we had fun in the old days at M where we had this big metal vessel that every now and again we'd walk into and just change the internal color of the lighting you'd go in there it would be Bri green when you walked in then your eyes would just get bored with it in the same way that you your eyes got bored with
that um elephant image and you just think oh it's white and then you come out and the entire world had gone pink here's a cool one simultaneous contrast again I defy an instrument manufacturer or someone trying to measure color with robots to get this to work it it gets quite complicated can you see this is a A reproduction of something I I made um and please go home and make this yourself in lat years I've done it in Excel um just by coloring different cells but there there's only one pink thread there but can you
see it looks different according to what it's next to colors are affected by what are around them and artists know this to great effect so if you want to make yellow stars look yellower and blue skies look Bluer put them next to each other if you want to make greens look Greener and reds look redder then paint those red flowers on that green grass and one of my favorite artworks is this well it's a it's like a a bouncy castle that you walk around inside it it's called colorscape by Peter Jones and you just wallow
in the color it's just incredibly vibrant color as you go in there and you see incredible things happening As you move from one zone to the next lot of simultaneous contrast stuff going on in there this is almost my last slide I saw this uh artwork two days ago for the first time and again it's one of these odd tricky things where um there are actually only three colors there but they look like they're more because of this adjacency thing so I did promise you that I would show you three colors that looked identical but
they're not so let's start with this um it kind of depends where you are are but if you're really really close up to this and you look closely you can see a continuity of color going between the green and those inner Rings okay so the inner Rings up the top are green and that square is green so let's move the square down and that continuity is still there that's still the same green going across there that top green is the same as that bottom green do they look it do they look it a few okay
let's have this picture here the ey here and this Square here do they look as though they're kind of the same color there's a continuity of color rattling across there and in our funny sort of way that color there uh is this color here is kind of the same as that color there is okay all I'm going to do is move that square in the middle to the right I'm going to move I'm not going to change color in any way I promise you if we measured that color it would remain the same all the
time but you you watch it as it moves something odd will happen to it it appears to change color that's nothing to do with the display system up there I I really promise you so there are those three colors they are exactly the same I'm going to stop it's crazy
