color prism, graphic design, business promotion

Light, Color, and the Human Eye

Published: 10/20/2014

While this principle may seem complex, the core of it is quite simple. Everything you see is due to light. The only real question is: what is the source of that light?

To first understand this concept, let's discuss the human eye. From what you may or may not remember from junior high biology, light passes through the pupil, is filtered through a lens (your cornea), and then is visually flipped and projected on the back of the eye, where receptor cells (cones and rods) interpret the light image and translate it back to the brain. The interesting thing about this is the dynamic range of human vision is in the ballpark of ten million colors; however, this number depends on the individual, as some seven percent of the male population has some form of color blindness, compared to .04 of one percent of women.

So what does this mean in relation to color? When an object emits light, such as the sun, a light bulb, a neon tube, or your computer monitor, that radiant light blends together in what's known as the additive light spectrum, more commonly referred to in tech circles as RGB because red, green, and blue light is what is blending together or adding to create new light hues.

So why is a blue shirt blue or an apple red? They don't emit light. Instead, the ambient white light is absorbed by the surface of the object, excepting the color you see. This "subtracts" all but that color, which is reflected back to the eye.

You may have even noticed when you change out the cartridge in your office printer that the colors are cyan (bluish), magenta (reddish), yellow, and black, also known as CMYK. The first three colors can make most colors you could print, and the black is used to improve the contrast of these colors. Unusual colors such as metallics or fluorescents have additional chemicals or actual metal to produce these effects.

So what does all of this mean? The white light spectrum includes everything we can and cannot see (infrared and ultraviolet). RGB refers only to our visual range (additive light) and CMYK refers to the colors we can print (subtractive light). As a graphic designer, when I create a website, I'm dealing with additive light from my computer monitor (RGB). However, if I am printing a brochure, a banner, or a business card, I'm dealing with subtractive color (CMYK). Even though I'm designing it on a computer, I'm dealing with an RGB representation of a CMYK color. Understanding how light and the medium of my project interact helps me design with more accurate and vivid colors, allowing me to better communicate my client's message.


Author: Marc Steffensen
Position: Creative Director
Marc Steffensen is the Creative Director at Business Promotion and has been with the company since 2009. He has been a professional graphic designer since 2005 and a graphic artist since the mid '90s. Marc's interests are eclectic within all things "nerd" culture, from music and movies to games and collectables. He is an amateur barbeque chef and likes to "fire up" his smoker, even in the middle of winter.

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