Our Perception of Color
Light is colorless. In and of itself, it has no inherent
color. As a child you might have noticed this, especially if you got your hands
on a prism and held it to catch the rays of the sun and projected it onto a
sheet of white paper. Miraculously, that ray of light breaks into bands of
color. Rainbows are formed in similar fashion and offer a grander view of this
phenomenon, the full menu of ROYGBIV (red, orange, yellow, green, blue, indigo
and violet) colors that we can perceive.
This double rainbow resulted from the rays of the setting sun coming from low on the horizon after a storm. The diffraction of the light through water droplets in the sky acts as a kind of prism that reveals the spectrum of color.
While rainbows inspire awe and wonder, they also offer a
catalog of the color frequencies on the electromagnetic spectrum available to
humans. That range is
"sandwiched" between ultraviolet and infrared, which are
actually available to certain animals and insects, used for hunting and getting
around in environments in which we would be blind. (One of the peskier examples are mosquitos, who see us as a glowing target.)
Taken with an IR-modified sensor in a digital camera, this image shows how some creatures "see" into the higher end of the electromagnetic spectrum. In days past photographers had access to IR and "near" IR sensitive film that could do the same, often enhanced via a red filter mounted over the lens.
Stretch that spectrum wider and wider and you enter the
world of gamma and radio waves. We cannot, luckily I suppose, see all those
waves (consider how driving around with the radio on with both visible sound and light
waves coming from the speakers would affect the commute). Auditory nerves take
care of sound perception and eyes the visual, both of which are sorted out by
the brain. In short, we see color in a fairly narrow band of all the wavelengths
around us.
The eye contains receptors that work in concert with certain
frequencies, and we see those frequencies as certain colors. What we call
"red" is actually a wavelength of about 680 nanometers (one billionth
of a meter in frequency, or wave length); yellow light has a frequency of just
under 600 nanometers, a narrow gap indeed, but one that indicates the subtlety
of color perception. Blue light of the sky has a lower frequency, about 475
nanometers, caused by the scatter of shorter wavelengths by the air itself. If
that scatter resulted in a few nanometers difference we might see a red sky above our heads!
(If one needed a rational explanation of how psychics see
auras, it might be suggested that they are capable of perceiving color in
different ways, or that they can perceive in the fringes of the spectrum that
are invisible to the “normal” eye. Attributing physical or spiritual states to
certain color emanations is probably more poetic than clinical, and speaks more
to our emotional reaction to certain colors and shades than any diagnosis or
proposed course of healing.)
Without the "filters" of our visual system we would see the world in interesting, though not very helpful, ways. We can emulate this disorienting visual world with photography using slow shutter speeds and camera motion during long exposures.
Describing color as a neurological reaction to wavelengths
is in no way meant to denigrate its wonder, or reduce it to a mere scientific
phenomena. Let the idea sit for a while, and begin to look around. This might
open you up to seeing and appreciating the amazing energy that constantly
surrounds us. Take the time to watch a full sunrise or sunset and notice how the sky shifts in color. Being open to
that energy has lots of creative power. It’s a good way to explore ideas about how
color can be used as a vital tool for visual expression, and perhaps guide you in choosing the decisive moment to snap the shutter.
Next posting: Color Absorption and Reflection
