Digital Photography 101: The basics of color theory

How to use color theory to improve your photography, part 1


Digital Photography 101: The basics of color theory


Can you imagine a world without color? It's such an intrinsic part of our lives that sometimes we don't even notice it. We only stop to think about color when we encounter a particularly jarring or particularly pleasing combination. But for a good photographer, color is a integral part of the constant image processing we do in our heads. We don't just see a composition in terms of lines and shapes; we see the colors in it and the way they work in harmony or opposition.

It's well known that color can affect mood and, like particular shapes and lines, can be used to evoke feelings of calmness and serenity or of tension and passion. Color can make or break a photograph, so it's a good idea to have some clue what it's all about. In part 1 of this two-part series, we'll explain the basics of color theory. In part 2, we'll go into more detail about how it applies to photography.

Defining color
First, a bit of technical explanation. Color, as we know it in regards to photography, is usually discussed in terms of hue, saturation, and brightness. 

kmg 300 color hue shiftHue is the color part of color. When we say a color is blue, purple, or yellow, we're generally talking about hue. Technically, hue is "the degree to which a stimulus can be described as similar to or different from stimuli that are described as red, green, blue, and yellow (the unique hues)." Makes perfect sense, right? If you really want to get into the nitty-gritty technical definition, check out Wikipedia's entry for hue -- but for our purposes, it's enough to say that hue is the actual color of the color. 

Hue can be adjusted in image editing software such as Photoshop or Gimp. In the images on the left, the top left image is the original photo. In the other three quadrants, we've shifted the hue by varying degrees, moving it more toward green, red, or blue. This can be particularly useful both to adjust for interior lighting or simply for artistic purposes.

You're probably familiar from childhood art classes with the traditional primary colors of red, yellow, and blue  -- those reflected light colors are known as painters' primaries. If you've worked with software like Photoshop or played around with your monitor or TV color settings, you might have noticed a different set of primary colors: red, green, and blue, abbreviated RGB. Those are the transmitted light primaries, and they create the colors you see in digital form in your camera or monitor. Printers work with yet another set of primary colors: cyan, magenta, yellow, and black, abbreviated CMYK.

Brightness (sometimes called lightness, value, or tone) refers to how light or dark a hue is. Again, the technical definition gets complex, but the basic concept is simply how much white or black appears in the color. In photography, this is easily adjusted by the exposure; an overexposed image is very light, while an underexposed image is very dark. 

kmg 300 color saturationSaturation (also called chroma) is the degree to which a color is colorful, as opposed to grayscale. According to Wikipedia, "the saturation of a color is determined by a combination of light intensity and how much it is distributed across the spectrum of different wavelengths. The purest (most saturated) color is achieved by using just one wavelength at a high intensity, such as in laser light. If the intensity drops, then as a result the saturation drops." Just how blue is that blue? A more saturated color looks more pure, while a less saturated color looks more dirty or diluted. Most colors found in nature are relatively unsaturated -- natural, pure color is fairly rare.

kmg 300 color  wikimediaSpinning through the color wheel
You may have seen a color wheel before -- in it, you can see each of the primary colors, separated by wedges (or triangles, as in this example) of the various hues that result from mixing the primary colors to varying degrees. The color directly opposite each primary color on the wheel is called its complementary color  -- those colors are green, violet, and orange.

Since colors and their complements are opposites, combining them creates a very strong contrast in an image and can create either harmony or tension, depending on the composition of the image. Combining colors that lie next to each other on the color wheel is called analogous harmony. For example, blue-green, blue, and blue-violet are analogous colors.

Intensity and harmony
One might think that we would logically see colors of the same saturation as having the same intensity, but that's not the case. On the color wheel, we see yellow as being much more intense than violet, and orange as much more intense than blue. To build a harmoniously colored composition, you might want to include more blue than orange, because the orange is more intense.

kmg 300 color duckyWarmer colors are more intense than cooler colors, and they tend to appear to advance toward us, while cooler colors appear to recede. It has been theorized that we perceive colors in this way because in nature, most things that are shades of blue or green are harmless, whereas bright yellows, oranges, and reds frequently indicate poison or other danger. This is why warning signs are commonly colored yellow, orange, or red, because we naturally pay attention to those colors.

Enough technical talk!
If all this technical mumbo-jumbo has your head spinning, don't worry. As with all aspects of photographic theory, these are guidelines, not hard-and-fast rules. Next week, we'll show you some examples of how these principles relate to photography in the real world and how you can use them to improve your own work. 

[Writing Credit: Katherine Gray.  Image credits: K. GrayAI2
]

Thanks to our friends over at Tecca for submitting this post.  Find more How-to tech articles & Gadget news at Tecca.com.  And, as always, if you have an amazing, colorful photo, post it up on Steve's Facebook Wall, or hit up the Steve's Forums to talk about this article, ask questions, or anything photography related.