There are two ways color is mixed to make new colors. One is commonly known as admixing. The other is optical mixing, also known as optical fusion or perceptual mixing.
What is admixing?
Admixing is the process of blending pigmented color together to form a new color. So we take red and yellow paid and depending upon the proportions that we use we can get a red orange and orange or yellow orange. Or, we take blue and orange and blend them to create browns and gray.
Through admixing we create a color and then apply it to the surface. We can see what the color will be before we apply it. In optical fusion, 2 or more colors placed near each other create the illusion of new colors.
Admixing is used for pigment colors, including all sorts of paints and dry media, dyes, inks, crayons, food coloring, and other colorants. (Anything that has color contains pigment). When you are using devices or viewing computer or television screens, color is not admixed, but optically mixed.
What is optical color mixing?
Optical mixing, also known as partitive color, is the perception of color resulting from the combination of adjacent colors. In other words, when color is mixed optically, the blending occurs perceptually, and takes place between our eyes and our brain. The perceived blending of color increases with distance. When you look closely at a television screen or computer display you will see the screen is divided into a grid or network of pixels. Each pixel is capable of displaying different colors depending on the electronic information it is receiving. So a group of red pixels intermingled with a group of yellow pixels will not actually blend into orange, but will be perceived as orange (a mixture of red and yellow). What specific orange we see depends upon the ratio of red to yellow pixels involved.
This is all a very simple way of explaining the difference between optical color mixing and traditional admixing of pigments.
Optical fusion is accomplished with pigments as well as light. In 4-color process printing, four different ink colors — cyan, magenta, yellow and black — are laid down in various proportions and densities to create a full-color continuous tone image. Getting up close to a printed image reveals that the image is made of individual dots of color. The more dots and the smaller they are, the more refined an image appears.
Optical fusion also occurs in other media such as woven fabrics and mosaics.
Optical fusion is not a result of digital media.
About the time that photography started developing (pun intended) in the 1800s, Artist began experimenting with optical mixtures and light impression. The Impressionists, especially the Pointillists, laid down small areas of color and allowed them to fuse visually to create images. French artist Georges Seurat is known for his wall-sized paintings composed of colored dots.
Let’s take a look a work by Hippolyte Petitjean, a lesser known neoimpressionist painter. In the larger image, the individual colors are clearly seen. The artist used the proximity, size and frequency of the colored brushstrokes and the surface of the paper itself to create the impression of other colors that don’t exist in the painting but are perceived.
Since optical fusion requires small areas of color or distance, either by the actual size of the colored shapes or by increasing the viewing distance, we can reduce the size of the image, making the colors fuse optically into a continuous tone impression so the the image becomes more solidified.
Why is optical fusion important to understand?
There are a number of reasons:
Optical mixing helps us understand that color is perception. Our perception of color changes based on the quality of light, what colors are present in our visual field, and how colors interact with themselves and our visual mechanisms.
The colors you see on your device or computer display as you’re reading this article are constructed of tiny units — pixels — each with its own color assignment. The pixels fuse optically to create the colors you see.
When you admix colors, more often than not the resulting color will appear duller than the colors you began with. This is because any time non-spectral colors (hues) are blended, they lose saturation. Remember, you can mix pigment primaries — red, yellow and blue or magenta, yellow and cyan — to make an almost-black gray. Gray has no saturation. It’s truly neutral. With optical mixing, colors retain their saturation and can retain their brilliance. There is some “additive” dulling, but not to the extent of what happens when pigment colors are blended.
Whenever you print a digital image, the print, which is made of pigment colors, appears differently than what you see on screen.
We perceive and experience color in a variety of ways. Designers and artists need to build their perceptual skills and sensitivity to color nuances. Since we work in color, we need to understand how it works in order to make appropriate color decisions. While color tends to shift and change, it’s still a fact-based, scientific and objective design element.