Complementary colors

Complementary colors are special pairs of colors that, when put together or mixed, cancel each other out to create a gray color like white or black. When these colors are placed next to each other, they make a very strong contrast and look really vivid. These pairs are also known as opposite colors.

Which colors are considered complementary depends on the color model being used. In modern color theory, using the RGB additive model or the CMY subtractive model, the complementary pairs are red–cyan, green–magenta, and blue–yellow. In the older RYB color model, the pairs are red–green, yellow–purple, and blue–orange. Opponent process theory suggests that the strongest contrasting pairs are red–green and blue–yellow. The pair black–white is common to all these theories.

These differences happen because traditional color ideas have been updated with newer, science-based theories, and because words for colors can be used in different ways. For example, blue can be the complement of both yellow and orange because many different shades, from cyan to blue-violet, are called blue.

In different color models

The traditional color wheel, used by artists since the 18th century, pairs colors like red and green, blue and orange, and yellow and purple. These pairs are called complementary colors because they cancel each other out when mixed, often creating a gray or black color. This model uses red, yellow, and blue as primary colors, with their complements made by mixing the other two primaries.

Modern technology, like computer monitors and televisions, uses the RGB color model, where red, green, and blue light combine to make different colors. Here, complementary pairs are red and cyan, green and magenta, and blue and yellow. When these pairs shine together at full strength, they create white light. In printing, the CMYK model uses cyan, magenta, yellow, and black ink, with complementary pairs like magenta and green, yellow and blue, and cyan and red.

In theory and art

The way colors affect each other has been noticed since ancient times. Early thinkers like Aristotle and Thomas Aquinas observed how colors look different when placed next to each other. By the 18th century, Isaac Newton created a circle showing colors that were opposites and created strong contrast.

Later artists and scientists explored how to use these contrasting colors, called complementary colors, to make paintings more powerful. For example, Claude Monet used orange and blue in his famous painting Impression, Sunrise, which gave the Impressionist movement its name. Other artists like Vincent van Gogh also used complementary colors to create strong effects in their work.

Afterimages

Further information: Afterimage § Negative afterimages

If you stare at a single color, like red, for about 30 seconds to a minute and then look at a white surface, you will see an afterimage of the complementary color—in this case, cyan. This happens because the parts of your eyes that sense red light get tired and send less information to your brain. When you see white light after that, it seems like the red is missing, so your brain shows you the opposite color instead. As your eyes rest, this effect goes away. This is one of many interesting things studied in the psychology of visual perception.

Practical applications

Complementary colors are very useful in art and graphic design because they make each other look brighter when placed side by side. They are also important in creating eye-catching logos and designing things in stores.

These colors have practical uses too. For example, life rafts and vests are often orange because it stands out well against the blue ocean. Red and cyan glasses help people see special 3D images, making pictures appear three-dimensional.