The digital exercises I've been working on for the past few months have essentially been designed to help me choose the right colors for my paintings. Right now my color style is... I guess you could say "unique," and a lot of people seem to like it, but it's also made up largely of "happy accidents." Those are great, but I'd like to be able to be more deliberate with my choices. Figuring out how to do this has taken quite a bit of color theory knowledge; I feel like anyone who could actually use the information I'm providing here could probably find it elsewhere, but I think it's interesting so I'm going to type it up anyway.
Most people think of color in terms of "the color wheel," based on "the primary colors" but really the color wheel we all learned in elementary school is just one of many color wheels, based on one somewhat arbitrary set of primary colors. The colors always follow the same order--the order you see in a rainbow--but use different "primary colors" as points of reference, if any. (Isaac Newton's 7-color wheel (think ROYGBIV) turns white when spun rapidly, which is a cool little trick, but the 7-color model doesn't lend itself well to a 3-primary-color system.) Most color wheels are based on the pigments (made from minerals, plant matter, etc.) most accessible to painters and how they behave when mixed with each other. There are hundreds of commonly used pigments and they combine in extremely complicated ways, so the primary colors shift depending on which pigments you use. For example, your kid may use red, yellow, and blue watercolors to mix new colors, but your printer uses magenta, yellow, and cyan (a slightly greenish blue) as the primary colors. A color wheel based on the pigments printers happen to use would look like the one in the upper right portion of the diagram below.
Color wheels like the two on top of my diagram are called "subtractive," because if you combine two primary colors on it, the result is darker than either of the primary colors. If you combine all three in the perfect combination, you get gray or black. (In painting, you can get black by combining blue and orange or red and green without adding any actual black; your printer uses black ink in addition to the colored inks, which may have something to do with why the primary colors printers use are different.) The color wheel on the bottom (labeled "light") is also called the "additive" color wheel, because if you combine red, green, and blue, you get white instead of black.
The additive color wheel is generally the most "accurate" because it is based on the way our eyes perceive color. We have three types of light receptors in our eyes: one for red light, one for green light, and one for blue light. If the light hitting your eyes activates all three receptors equally, you see white or gray. Of course, it's way more complicated than that (it always is), but you can look that up on your own if you're curious.
Besides the fact that you are currently staring at a computer screen that uses additive coloring, some other examples are stage lighting and optical illusions called "after-images" where you wear your eyes out by staring at something, then look at something white and see the opposite. One of the images on the page I just linked to shows an inverse American flag; based on what you learned in kindergarten you might expect an inverse American flag to be green and orange (the complimentary colors of red and blue in the system you're used to), but instead it is cyan and yellow (the complimentary colors of red and blue in the additive color wheel).
Right now I am working on my colors on a computer (additive), but I also do oil paintings (subtractive). The two color systems are very different, and knowing how to find a particular color on the computer doesn't necessarily help my find it on a wooden palette. At this point, though, I'm mainly concerned with figuring out which color to use in the first place, and those skills should carry over just fine. (Besides, I also intend to keep making digital art for its own sake.)
You'd think all this color knowledge would make me an expert at painting in color. I think it helps; my paintings so far have certainly had some interesting use of color, which I wouldn't be able to do without knowing what I was doing at least a little. But I have a long way to go. My biggest weakness by far is in values (dark and light), as I said in my last post. So that's where I started.
My first digital value studies were done with just 5 shades of gray (well--three shades of gray, plus black and white):
I now realize that the white of my little palette has blended in with the white of my page. Just trust me, it's there. Anyway, I was trying to keep things as simple as possible, but it ended up not being as helpful as I'd expected, so I started using 7 shades, then 9. Eventually I settled on the 11-value palette you see below. (The smaller squares are black and white, but I usually didn't use those at all. Sometimes I divide the 9 middle colors into three groups: lights, mediums, and darks, leaving the extremes off until the last stages of painting.)
When it came time to start practicing in color, keeping it simple failed me again. I tried to make 3 copies of the above palette; one for red, one for green, and one for blue. That turned out to be practically useless in actually painting a landscape. So, far from keeping it simple, I ended up creating this monstrosity:
That still left me with a bunch of intense colors that rarely occur in nature--I'll explain what I mean by that in a second; first, some more color theory.
All colors can be classified by 3 characteristics: the first is hue, or where a color falls in the rainbow or on a color wheel. The second is value, or how light or dark something is. The last is called saturation, or intensity, depending on who you ask. Computer graphics use the term saturation, and I usually use that term as well. Saturation basically refers to how gray something is--the less saturated, the more gray; the more saturated, the more it looks like something that came out of a 6-piece crayon set.
Colors in nature are rarely highly saturated. If you want proof, open up any photograph in Microsoft Paint (or whatever) and use the eyedropper tool. Even brightly colored birds and flowers are far more gray than you would think. And most of the world isn't as bright as a petunia. It's filled with a lot of gray rocks, brown tree trunks, gray buildings, etc. Even the sky is more white than blue. (By the way, "brown" is usually just a desaturated orange.) To get at the neutral colors missing from the circular diagram above, I made another color wheel with pure gray in the middle and more saturated colors at the rim (These are all a medium value, but I didn't need to make a "light" saturation chart and a "dark" one because lighter and darker colors are automatically less saturated. I actually tried to make charts like that, but they weren't very helpful so I stopped.):
I actually haven't ended up using either of these wheels very much for digital work. The color picker in Photoshop gives me all the information I need, and I don't have to worry about mixing pigments on a brown palette so the wheels aren't totally necessary. Laminated copies of them will come in handy for oil painting though.
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There's another really interesting psychological aspect of color beyond the physiology of how eyes work. Your ability to label something influences your ability to perceive it--not just in art; if you learn the name of a type of tree, for example, suddenly you will see those trees everywhere. The same thing happens with naming colors. I never would have been able to distinguish "mauve" from pink or even purple if not for my conveniently labeled box of crayola crayons as a kid. If the only word for reds you have is "red," all pinks probably look pretty much the same to you. Once you learn how to distinguish "brick red" from "red orange" and "crimson" from "vermilion," suddenly you realize that there is more variation within a single color family (red) than a lot of people notice in the entire gamut of possible colors.
There's a fascinating Radiolab episode in which Jad and Robert investigate the history of using words to describe colors. Nowadays we think of blue as a very common color. It's probably the most popular favorite color; we sign documents with blue ink; "why is the sky blue" is among the first questions we expect children to ask. But the blue pigments we use to dye our clothing and ink have not been accessible to most cultures for all that long, and there are relatively few blue animals or plants, so for a long time blue was simply not a color that anyone thought about. When people did talk about blue things, they used the same word they used for green. To them, the sky wasn't blue at all; it was white.
I have been making art for my entire life, so naturally I tend to have a better grasp on the variety of colors available than a lot of people. And my favorite color has pretty much always been green, so you would think I would be especially good at distinguishing between different greens. But when I switched from doing black and white landscape studies to color, I realized I was having an infuriatingly difficult time painting plants. Green is notoriously hard to work with in oil colors because there are very few good green pigments, but I didn't expect that problem to carry over into my digital painting, where I need only click on the shade of green I need. So why was I having a hard time?
Turns out, I basically had a "blind spot" for different shades of green. Everything between teal and yellow looked pretty similar to me. I sort of wonder if having green as my favorite color has actually made this worse, since I like a specific shade (lime green) and tend to ignore other types of green when I am making color choices. It may also be that I am just as bad with other colors, but green is one of the most common colors in nature so my ignorance is more noticeable. Whatever the reason, I decided to make an entire color wheel of just greens in order to help me learn the differences. I used yellow and cyan as my endpoints, because once you get into teal and orange I feel like I am pretty good. The little pizza slice on the bottom is exactly a medium green, according to computer graphics anyway. As before, I made both value and saturation wheels:
Actually, the first version when from cyan to yellow-green, but I have since realized that many shades of what I considered a medium green are actually almost yellow. (Yellow is also my least favorite color, so this may have been subconsciously influencing my perceptions.) I'm still working on my color perception, but once I discovered that this was interfering with my landscape paintings, and for a few other reasons, I decided to start obsessively painting trees to train myself to get the different shades right. More on that later.