Wednesday, December 05, 2007

Let's talk about color!

Because my brain is still stuck back on the whole eye/color/spectrum thingie. And I don't have much to blog about; I'm still knitting. In the next week or so I hope to drag out the Mystery Knit (remember it?) do some photography and pattern writing, and get it up for sale. 'Tis the season for warm knits.

Anyway. Colors.

Meet the Electro-Magnetic spectrum.

(Image from here.)
Called the EM spectrum for short. You should have encountered this in middle school science, but if it was presented to you like it was presented to me, you rolled your eyes, thought "I'll never need to know this in a million years" and promptly forgot it. But there's all kinds of cool information to be had from it. Seriously. Take a good look.

What was never sufficiently explained to me in school was, it's a continuation of wavelengths. Meaning that the visible light part, in the middle, is just PART of all the 'light' that's out there bouncing around. All that other stuff is there, too. We just can't see it. By that standard, X-ray machines are nothing but cameras that take photos using a kind of light our eyes can't see. Cool, no? (From a technical standpoint, everything on that chart is 'radiation', which can be fun when you warn people about the copy machine putting off radiation. It does put off radiation - VISIBLE LIGHT. Haha. I'm such a bitch.)

The reason I'm putting this up there is because, with the tetrachromate issue of this past week in mind, I'd have SWORN that when the human eye started evolving or mutating, we'd have oozed off the 'visible light' scale into infrared or ultraviolet. And we'd start having humans who could see those extra few wavelengths. Once you're looking at the chart, it doesn't sound that insane; it'd be a simple matter of extra sensitivity in the retina. (There are critters on the planet who can see both ends of the spectrum we can't; mostly reptiles with the infrared, and mostly insects with the ultraviolet.) But instead, imagine my surprise, when it turns out that people are mutating to see MORE COLORS within the spectrum we already see. (And I might be one of them. Go figure.)

Anyway. Since I'm putting up more babbling info about this stuff, I thought I'd include something that was actually useful to knitters and crafters. Namely, why different light is such a big deal, when trying to see color. Here, take a look at the wavelengths put off by the sun, first:

As you can see, the sun puts off wavelengths of light all through the EM spectrum, not just in the visible light band. But MOST of the light put off is visible. (I doubt that's a coincidence. Mother nature's pretty smart about this kind of thing.) As you see from the chart, the sun puts off a fairly well-balanced amount of light in the visible spectrum. Thanks to us spending most of the history of the human race seeing by sunlight, this spectrum of light is what our eyes consider 'normal', and what it's most used to using.

With sun light, THAT MEANS THE LIGHT IS THERE, to bounce off whatever you're looking at, and get soaked up by your eyes. Compare that to the 'spectra' (specific wavelengths) put off by street lights (which are the worst in the world, for color vision).

See that top chart? That's the spectra put off by a low-pressure sodium light (also known as 'those really cheap street lights'). Now you know why everything looks orange under those lights; that's the only light it puts off, so that's all that can bounce off things to get soaked up by your eyes. Get the idea? (Cops hate these lights, by the way, because they're so notrious for fucking up color vision. They can find witnesses who saw a crime happen right in front of them, but can't say what color the getaway car was, or what color clothing the criminals were wearing, or even what color their skin was. You're reduced entirely to 'light' and 'dark'.)

Here are some more spectra for different types of light:

If you can't tell from the picture (it's pretty small), from top to bottom the artificial lights shown are: compact fluorescent, fluorescent, metal hallide, mercury vapor, high pressure sodium, and again, the low pressure sodium. You can see how unholy awful the low pressure sodium is, with the comparisons. You can also see how the old-school fluorescent will lead to some seriously funky color vision.

Unfortunately that chart doesn't have incandescent light, which is still the main at-home lighting used for most of the world. So after digging around some more, I found this:

Which isn't terribly helpful, but you can see how, even though it's better than most other types of artificial light, it still puts off more red than it should, particularly when compared to sunlight.

So there you go. More than you ever wanted to know about color.

And instead of no wisdom teeth, or super color vision, I really wanted the Power of Laundry. Damn. Maybe next time. I wonder if this would be good enough to get me into Xavier's School for Gifted Youngsters?


Alwen said...

Apropos of nothing in your post:

First link looks like nalbinding. Second one "wooden"?, maybe they meant woollen?

Netter said...

Working in publishing, light is important, especially when Dr. Jones's has spent $$$$$ for color prints and they don't look right. I remember in one of my first color seminars, the trainer said, go outside at noon and look at your proofs. That will give you the best idea of reproduction. We had to buy a special light box to check the color for some of our publications.

Kim said...
This comment has been removed by the author.
Kim said...

Thank you for this post. It's nice to have a visual aid and good explanation on why not all light is created equal and how different indoor lights effect how colour is viewed. Also the reason for "Why in the world would I have bought this colour. It looked completely different at the yarn store"

Sarah said...

Quick derail, because science is fun! :)

Yes, technically visible light is "radiation", but thankfully it's non-ionizing radiation, meaning that visible light doesn't cause cell damage or cancer. UV light is ionizing radiation - very energetic. This is also why I find it extremely unlikely that cell phone radiation is causing an sort of brain or skin cancer - it's not the right kind of radiation!

amy said...

Thanks, Julie, that was interesting. Nothing to do with knitting, but I hate most outdoor lights simply because they mess with your vision, no matter what spectrum they put off. They're sort of blinding, don't you think? And most of them actually make it easier for someone to break into a home, because they create deep shadows. The best have a sort of diffuser cover that scatters the light, making it gentler and also cutting down on light pollution. I live in the country, but our next door neighbors have so many fricking lights it's ridiculous. (One of them shines right into my bedroom window. This contributes to my strong feelings on night lighting!)

But yes, I'm always wary in a store. I've often taken yarn (or other items) over by windows to try to determine its true color.

Alwen said...

Amy's comment reminds me that my husband once had a set of those wrap-around cataract goggles, the ones that go over glasses and cover your eyes and peripheral vision.

* In purple. *

Talk about messing with your color vision! If I wore them long enough, my brain would adjust, and then when I took them off everything looked screaming yellow.

Caroline said...

Great mind thinks alike, no? You pretty much touched upon all the things I've been thinking about after reading about tetrachromacy. Most specifically, that _someone_ ought to get that cool UV-light mutation and then the X-men won't be far off. :D

On the yarn colour issue, my favourite LYS owner is okay with people taking the yarn outside to check the colour before they buy. She is wonderful.

Roxie said...

So that's why it's impossible to photograph red yarn indoors!

When I worked at Pendleton Woolen Mills as a weaver in in the fabric design department, they made sure the studio had skylights so we could see what color our yarn was.

Amy Lane said...

Screw color vision--if I'm going to Xavier's school of gifted youngsters, I want the ability to shrink my enemies to the size of ants so I can rip their legs off before I stepped on them. (Uhm...maybe Erik Lescher's school for gifted youngsters instead?)

Amy Lane said...

(P.S.) I sent your post to my science teacher friends. I think they'll really enjoy it:-)

historicstitcher said...

Cool post!

I love it when people find the science...though I know you think of it more than some.

I'm hanging around, just busy and somewhat quiet lately in the commenting department. I have been posting 3x/week, though!

Karen said...

Regarding alwen's comment above ... not sure where I'd mentioned anything about "wooden" on that page, but after some advice from a knowledgeable textile chum, the first link on was moved to a brand new page,