Posted by: AG | April 11, 2009

Light and Color in Printing

Everyone knows what color is. You can even ask a child what the color blood is, and they’ll say “red.” Ask the color of grass, or sky, and you always get “green” and “blue.” It’s common knowledge, something we are born with. And everything has some color. Or does it? If we look at the sky during daylight we’d all agree the sky was blue. During sunset we can usually say the sky was orange, or golden. And during midnight, we say the sky is black.Can any of these simple observations be wrong?

To answer that, we can start with the dictionary’s definition of color:

“the quality of an object or substance with respect to light reflected by the object, usually determined visually by measurement of hue, saturation, and brightness of the reflected light.” Now compare that to the definition of black: “lacking hue and brightness; absorbing light without reflecting any of the rays composing it.”

Therefore, according to the normal definitions, black is not a color. In other words, if you take away all light, and nothing is reflected, then everything is black. And without light you can’t have any color since there’s nothing to see.At the opposite end of the spectrum (no pun intended) you have total light. Therefore, if you had a source shining at you with maximum saturation and brightness, you might only see something equivalent to an endless flash of light. What color is a “flash” of light? Is it typical for someone to say they saw a “white flash of light?” So by looking at this other extreme, some might claim that “white” was not a color either. So who’s wrong and who’s right?

Believe it or not, trying to make sense of the questions and explain the answers gets to the heart of both the printed page and the computer screen: how they differ in their production of color; how the artist can use those differences to create the images they want – either on paper or the screen.

In explaining the difference, you’ll be hearing terms like “additive color” and “subtractive color;” “reflective color” and “absorptive color;” “visible color” vs. “invisible color.” There will be terms that measure hues, saturation, and brightness. There are more such terms and concepts which will affect important decisions about the way a job is finally printed – such as paper color, paper coatings, inks, proofs, and comparing images on the screen with the printed piece.

In future articles on color I’ll try to deal with those topics


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