Color Vision 2

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