3
Managing color
We will begin with a brief introduction to color, including a description of one method of
mathematically quantifying color. Next, we will present an overview of a typical digital workflow,
and finally, we will discuss how color is maintained throughout that workflow.
The property of color
Color is a tricky thing. Nothing really has color; color is a perception, generated in the eye-brain
system in response to given stimuli. To perceive light, our eyes use three different receptors to decode
wavelengths of light into something that our brain interprets as color. The three different receptors are
each sensitive to different wavelengths, roughly corresponding to the red, green, and blue portions of
the color spectrum. Our eyes, then, perceive any color that we humans are capable of seeing by
combining different “output values” of the red, green, and blue receptors.
There are two different ways that the different wavelengths of light (corresponding to color) can be
created: light can be emitted from a source (emissive source), or can result from the wavelengths of
light that were not absorbed after light is reflected off of an object (reflective source). These two ways
of creating can be translated into two different “sets” of color—RGB and CMYK.
The RGB color set
We refer to the red, green, and blue (RGB) colors created from an emissive source as primary colors.
Specifically they are called additive primaries, because any color that a display device is capable of
producing is made by adding different intensities of each of these three colors of light. Since our eyes
are specifically sensitive to the three additive primary colors, electronic devices that generate light
(e.g. color television) are generally designed to emit light in the red, blue, and green spectrums. Such
devices are usually referred to as RGB devices.
Figure 1. The RGB and CMY primaries.
The CMYK color set
Objects that don’t emit their own light exhibit color by virtue of the wavelengths of light that are
reflected off of them. In other words, to produce a particular color, we have to subtract the proper
primary colors (because the surface that is reflecting will absorb different amounts of the three
additive primaries). For example, if blue light is the one mainly absorbed, leaving only the red and
green parts of the spectrum, the perceived color is yellow (red + green). Similarly, subtracting the
