Page 98 - Graphic Design and Print Production Fundamentals

4.2 Colour Science

Alan Martin

The Colour Event

The first challenge in dealing with colour in graphic reproduction is to learn to think of colour as an
event rather than as an attribute or characteristic of a particular object.

Colour is an event because it requires the participation of three components at a particular point in
time to take place. In addition to the object, we require a light source and an observer. Only with
the interaction of these three things — object, light, and observer — can we have a colour event or
experience.

We need some help from three branches of science, physics, physiology and psychology, to understand
how the object, light, and observer contribute to the colour event. If you like memory aids, you can use
the acronym POLO to remind you of the three science P’s and the object, light, and observer.

Object

The object and light fall under the domain of physics, while we need both physiology and psychology to
describe the observer’s role in the colour event.

The object’s role is to interact with light, and the object can either reflect light back from its surface
or transmit light through itself. Reflectance and transmission are the two potential interactions. The
majority of objects are opaque, so most of the time we are dealing with the reflection of light. If an object
is semi-opaque, and transmits a portion of light, we refer to it as translucent.

Light

Visible light is a tiny sliver of the total electromagnetic spectrum. The electromagnetic spectrum
contains all forms of energy, ranging from kilometre-long radio waves at one end and progressing
in shortening wavelengths down through microwaves, infrared waves, ultraviolet waves, X-rays, and
finally, gamma waves with wavelengths of a subatomic dimension (see Figure 4.1).

Visible light is nestled in-between the infrared and ultraviolet range (see Figure 4.2). The progression
from longest to shortest wavelength is from red (following infrared) to violet (preceding ultraviolet) in
the 700 to 380 nanometre (millionths of a metre) wavelength distribution.

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