A simple definition of light is visually perceived radiant energy. This visible light is a small part of the electromagnetic spectrum and ranges in wavelengths from 380 nm to 780 nm. Light is what energizes our visual system. Light reflected from objects into our eyes enables us to see.
Light enters the eye through the pupil, is focused on the retina, and is transmitted to our brain via the optic nerve. A significant part of our brain is dedicated to the processing of visual information.
Of all creatures on this earth, the human visual system is the most impressive. Birds may have sharper vision, felines may be more sensitive to motion, and horses may have almost a 360-degree field of view, but nothing can beat the combination of features humans possess.
The human eye allows good depth perception, excellent color perception, reasonable motion detection, and great visual acuity. We're going to concentrate on just two aspects for now, mainly light and color.
Color Perception is Subjective
One of the misconceptions about the perception of light is the fact that it is highly subjective. It is impossible to prove that any two people see a particular object in exactly the same way. This makes it a real challenge to scientifically measure certain attributes of lighting such as color and quantity.
We all tend to think of an object as having fixed colors. In reality, an object's appearance results from the way it reflects the particular light falling on it. Under pure white light, a green apple appears green because it reflects the green portion of the spectrum and absorbs the rest.
You might say the evaluation of color is somewhat subjective. What is the color of that green apple? One may say bright green; another light green; and yet another simply green. Who is correct?
The same thing can be said of the quantity of light. While it is fairly easy to determine when there is relatively more or less light on a given object or in a space, actual measurements must take into account the way the eye sees and how it responds to each color of the visible spectrum. Now let's look at the link between light and color. In fact, you could say that light is color.