You can invest in the highest quality proofing system money can buy. You can calibrate your equipment as accurately as possible and build high quality ICC profiles. You can properly set up your workflow and train all of your customers to properly set up all of their applications. You can ensure that your press is running at its optimal state, that your films and plates are accurately generated, that your press operators precisely control ink densities and all other press variables. You can basically do everything right and still not match the press to the contract proof — not unless the viewing conditions are correct.

Simply stated, if the lighting condition under which proofs are viewed by you and your clients is wrong, you and your clients might just be seeing things — literally — in a different light.

An often overlooked aspect of proper proofing and printing is ensuring that your carefully produced products are viewed in the prepress department, in your front office, in your client’s office, and in the pressroom under carefully controlled lighting conditions. In the graphic arts industry, proper lighting conditions are often stated as “noon daylight.”

So what color is noon daylight? How bright is it? What else do you need to worry about? And why does it make a difference?

Avoiding problems

Let’s tackle that last question first. The reason that you want to have your proofs and press sheets viewed under the correct lighting conditions is due to a phenomenon known as matamerism. If two colors appear to match under one lighting condition and do not match under another one, it is often said that the ink has matamerism.

Now, anyone who subscribes to the Apple Colorsync listserve, which I highly recommend, will know that there is much disagreement as to the exact definition of matamerism. The definition I cite here is the one most commonly used, even if it is not the most technically accurate one. What this all boils down to is if you evaluate a proof under lighting conditions different from that of your clients, you may make different color decisions that could cost you more time in prepress or even more costly, more time on press.

In order to ensure that we are comparing apples to apples as far as color is concerned, we need to have an evaluation area that utilizes a proper lighting situation. The most commonly used reference is the color of the light that the lamps emit, referred to as the color temperature of the light. The lower the number, the warmer the light; the higher the temperature, the cooler the light. Our reference point for this value is the color of the light for the graphic arts standard, often referred to as noon daylight, or approximately 5000 degrees Kelvin, with Kelvin being the scale used to reference color temperature.

Designing a proper viewing area is not as simple as going down to your neighborhood hardware store and picking up a couple of 5000K fluorescent tubes and installing them in an overhead lighting fixture.

True 5000K lighting that shows the characteristics of noon daylight lighting conditions would contain roughly equal amounts of red, green, and blue light. It is possible, however, to construct a lamp whose light output measures 5000K that emits a different proportion of red, green, and blue light. We must, therefore, look at other criteria when evaluating light sources — such as the color rendering index or CRI.

Simply, CRI indicates how close to actual daylight conditions the light generated by the lamp might be. A CRI of 100 means that colors viewed under that light source would match the colors seen when viewed under actual daylight conditions. You should look for lamps with a minimum CRI of 92 for use in a proof or pressheet viewing area.

No guarantees

Keep in mind that even a color temperature of 5000K and a CRI of 92 or higher does not guarantee an accurate viewing light source. Other factors such as light intensity, viewing angle and light evenness contribute greatly to the success of a proof lighting situation. Rather than trying to reinvent the wheel, take a look at lighting solutions from manufacturers such as GTI (www.gtilite.com), Just Normlicht (http://www.justnormlicht.com) or SoLux (http://www.solux.net).  And make sure that your clients are evaluating your proofs under the proper lighting conditions as well.

Failure to use proper viewing conditions when reviewing color matches will usually result in a disappointing color match as well as unhappy clients.

Although the cost of a properly engineered viewing system may seem higher than what you could assemble yourself after a quick trip to the hardware store, the increased investment required will be more than offset by the savings in time, reduced stress, shorter press makeready, and happier clients.

John Nate is a senior color specialist for Chromaticity Inc. He can be reached at jnate@chromaticity.com.