Nickyitis – An Epidemic of Humorous Proportions

Most everyone has had some experience in mixing paint and knows that mixing blue and yellow makes green and mixing blue and red gives us purple (not to mention that red and yellow produces orange). Is the same thing true for light? You know we can have blue light or red light or, in fact, any color at all. So what would happen if a red spotlight and a blue spotlight were aimed at the same spot on the wall? What would we see?

The answer to this question is most definitely not obvious. Consider the fact that nothing in the world "has" a color of its own.  That orange? It’s not orange. The hope diamond? Not blue.

Have I completely lost it? Not at all. This topic was discussed briefly on September 17th and today we’ll go into it in more depth. The only thing the world around us can do is reflect the light that hits it. How much it reflects determines what color we see. Not what color it is. Because, as I’m going to persuade you, the property of color isn’t something that objects possess. They just have the property of rejecting color. Sort of sounds philosophical but it’s not really. It’s just physics. And we’ll examine some of this physics with the following pic:

Notice how it starts with yellow, shades through green, and ends up being cyan. (Big point here – it’s cyan and not blue. True blue is a much darker shade and many would say it has some purple in it. But we’ll get to that in a bit.)

So, where did this pic come from? From this:

Two squares, created in Photoshop, one yellow and other cyan. The originals were only 1 pixel wide and what I’m showing you here is a much larger image than the original so can actually see it.

I took these original single colors of yellow and cyan and asked Photoshop to enlarge the image to the size of that yellow/green/cyan pic. The default when upsizing is to blend the colors so that the resulting image looks "good." In this case we weren’t really enlarging a normal picture but a very sharp edged image. Photoshop’s blending is sophisticated and with color acts to multiply the two colors. In other words, it "mixes the paint." Hence in the middle we get those shades of green, yellow-green closer to the yellow and blue-green closer to the cyan.

Okay, remember how I mentioned that blue and yellow paint make green? Well, now we’ll see why. The pics from 09/19/2009 showed squares of red, blue, and green and also a light blue, a pinkish-purple and yellow. The real names of these squares are actually cyan (C), magenta (M), and yellow (Y). Together with black (K) they make up the CMYK color scheme that you’ve probably seen on your graphics program or on the color printer cartridges for your printer. They’re the basic colors used in printing (hence the ones used in your color printers). BTW, the "K" associated with black stands for "key."

From examining the closeup picture in that post we saw that  cyan is created by adding green and blue and yellow is made from the addition of red and green. That means that cyan paint absorbs the red in the incoming light (leaving blue and green) and yellow paint absorbs blue light (leaving red and green).

Well, when you mix the two paints you’ll be absorbing both red (because of the cyan paint) and blue (because of the yellow paint). If you have red, blue, and green coming in and absorb both red and blue what does that leave you? Why, green! And so that’s what we see. Mix cyan and yellow to create green.

Just so you aren’t forced to simply take my word for it I’ve created a little demonstration. I made two long rectangles in Photoshop, one cyan and other yellow. Just like that yellow/cyan square above but much taller. Each color is only a single pixel wide.

Then I repeated this pattern 95 times, creating a box that’s made up of cyan and yellow lines. It looks like this (again, enlarged so you can see the individual components):

Note that it already looks greenish. I really assure you that the only colors appearing in it are the two I’ve already shown – cyan and yellow. It’s looking green because your eyes are having a hard time distinguishing the individual yellow and cyan pixels and is basically seeing both at the same time and place – something that should produce green.

Finally, I reduced the image it to push it beyond your eye’s resolution limits:

See how it now simply appears to be a green square? Yet there’s absolutely no green in it – just cyan and yellow. The details are now too small to be resolved by your eyes and so you see the same overall effects as if you’d really mixed the colors – we’ve mixed paint on a computer screen! 

Pretty neat, eh?

- And that’s today’s word from the bird