The importance of standard viewing conditions
"01000010 01101001 01100111"
Do you recognize the name of the movie above? It's a famous movie from the 80's you've probably seen. Come on, you must know it... What's that...? You can't read ones and zeros? Oh yeah, that's binary code. I'll bet the computer you are reading this on right now knows what it says. You and the computer are not on the same playing field, so you cannot communicate with it using it's native language.
It's kind of like if you're trying to communicate color with someone. Unless you are on the same playing field - seeing the same thing, you can't understand each other. It won't make sense. As I noted in an earlier blog, three things are necessary for our brains to perceive the sensation that we call color: An object, a light source, and an observer (human eyes). If there are any variables in any of these three things, a different color will be perceived.
Many things influence how we see color, so in the interest of keeping this blog short (I'm sure you're a very busy person) we will skip the biology (observer) part of the equation, and focus on the physics (light source). More on the biology thing later.
Visible light comes in many different flavors. It runs from red - yellowish to blueish and is measured on a scale known as Kelvin. The Kelvin scale is a thermodynamic temperature scale, and no, it is not named after Kelvin Klein, the guy that invented skin-tight, dark blue jeans in the 1970s. He was Calvin Klein. The kelvin scale is named for a Scottish mathematician and physicist, Kelvin, Lord William Thomson (1824-1907). Not that you need to know that.
Lord Kelvin views a color proof under
his own 5000K lighting standard
Just know that the sun at sunset or candlelight (warm light) is down around 2000K (2000 degrees kelvin) and an un-calibrated computer monitor or light from the north sky (cool light) is up around 9000K. Somewhere in the middle is 5000K, which is a more neutral, white light. In scientific (or color geek) circles, this scale is known as the correlated color temperature.
Getting back to the different variables when viewing color, let's take an extreme example: Look at a photo in a dimly-lit room with a single candle or 25 watt bulb. Then look at that same photo outside on a sunny day, and again in a typical office environment with warm white florescent lights humming overhead. Would you see anything different in the photos as you moved into the different environments? Sure, you could say that you would see more with more light as there would be outside compared to the dimly-lit room. But we're not just talking about more light, the light is a different temperature. As the color of the light source varies, so does the color of the object it is illuminating.
The GTI Color Rendition Demonstrator includes three different flavors of
light, showing how they produce three very different colors.
Theoretically, the best viewing condition to view a color proof is the environment in which the final printed piece will be viewed. In the case of a catalog, for example, that could be the fluorescent light in your kitchen, or the 40 watt incandescent vanity bulbs of your bathroom (Wait- do you take catalogs in the bathroom? Eeew.). I have actually had a client once that took color proofs home and looked at them at their kitchen table. Is that wrong? Of course not, the customer is always right, right? In this case, they weren't really right.
The fact is, you usually don’t know where the color that you are looking at will be viewed once it reaches the ultimate consumer. Especially in the case of portable material like catalogs and magazines. That’s why our industry has adopted a standard for viewing color: 5000K. The neutral white light of 5000K helps everyone involved in the color approval process to speak the same language. Standards in the graphic arts like this exist to help us achieve more balanced, consistent results throughout the workflow.
You may hear some people refer to 5000K as D50. This is technically wrong. D50 is known as a daylight spectral curve. The only thing that can create D50 is the big, burning bulb in the sky - the sun. 5000K is essentially the temperature of a light that is trying to simulate D50.
To help ensure that everyone involved in color approval process is using 5000K, I am developing a special hat that incorporates a 5000K light source under the visor. See the ad below for more information.