Color Basics Part 5 – How do we Measure Color?
Although individuals perceive colors differently, there are three general characteristics of color perception that everyone uses. Color can be plotted according to these characteristics. First, we can identify the basic color group, such as red orange, yellow, etc. This is called HUE. Also, we can identify the intensity, vividness or saturation of a color. This is called CHROMA. Lastly, we can tell if a color is light or dark. This is called the LIGHTNESS.
The 3 Dimensions of Color
All colors can be located in a three dimensional model of color space (a 3-D map of visible color) with hue, chroma and lightness as each of the three dimensions. With these three values, we can describe and measure color precisely.
Hue refers to the name of the color and identifies its position on the perimeter of the color wheel described earlier. When we pick a color on the wheel, we introduce the second dimension of chroma, or saturation. When we move towards the center of the wheel, the intensity of the colors diminishes until at the very center, there is no color. There is only grey. This would be a point of no chroma at all. To move to outer perimeter of the wheel, the chroma would be at its maximum and the colors most vivid and intense. Lastly, imagine hundreds (even thousands) of color wheels stacked on top of each other in one stack with our original wheel smack dab in the middle. In each wheel above our original, every color (including the greys) gets one tiny bit lighter. Each wheel is slightly lighter than the one below it, until the very top wheel contains all white colors. All colors the same. Now, back at our original wheel, move down one wheel where the colors get one tiny bit darker than the one above it. This darkness progresses until the very bottom wheel is solid black.
Contained in this 3-D color model contains millions of colors detectable by the human eye. Each location in this space has an address, or way to identify it, much like someone who lives on the corner of Main Street and 4th Avenue, on the 7th floor of a 10 story apartment building.
Early attempts to map visible color date back to the mid 1800’s. Over the years several color space models have been proposed. Most color space models today, however, define color in three dimensions and provide a scheme for representing color in terms of three coordinates; hue, chroma, and lightness.