Association Insights: Calibration and Profiling for Soft Proofing

More creative and color-critical decisions are made on an LCD display than on any other device or media. More often than not, this is being accomplished using Adobe Photoshop. One of the most valuable and cost-effective uses of color management is using it for soft proofing. Yet, most are probably not using color management, Photoshop, and displays in this way to get the best possible color.

There are different types of soft proofs based on how they is being used. For printers, a soft proof is an accurate representation of what is to be printed on press. Printers must be able to prove this by holding an actual hard proof or press sheet next to the display and see the “same” color.

For photographers, a soft proof is a digital record of what the camera actually captured. The soft proof being displayed contains a very large color gamut and replaces the traditional color transparency. In this case, photographers are taking full advantage of the display and rendering the color that the she or he actually saw.

Hardware and Software

The display is the first important consideration when it comes to soft proofing. Liquid crystal displays (LCD) and, more recently, light-emitting diode (LED) displays work very well for soft proofing for a number of reasons. First, they are very bright and close to standard color viewing in a viewing booth. LCDs/LEDs also stay calibrated longer—important because consistency is the key to any proofing device. Finally, LCDs/LEDs last a long time and, for a relatively small investment in a quality display, you have a proofing device that can potentially last for years.

LCD/LED displays can either be standard gamut or wide gamut in nature. Standard gamut displays are capable of rendering the sRGB color space—perfectly acceptable for soft proofing for print production. However, as noted above, photographers may want to see a much larger gamut than what we can print; they want to see the colors that their camera could actually capture. In this case, a wide gamut display would be required that is capable of rendering the AdobeRGB 1998 color space—much larger than that of sRGB (Figure 1).

When it comes to measurement devices for calibrating and profiling a display, the choices are either a colorimeter or spectrophotometer. Colorimeters can contain three to seven filters when they “look” at color and do a reasonable job at an affordable price. Spectrophotometers however, are more expensive but take many more sample measurements across the visible spectrum. The more color samples that are taken, the more accurate the results.

Calibrating and Profiling a Display

The principle behind profiling involves a few sequential steps. These five steps are true for profiling any device:

1. Qualify the display—Determine if the device can be calibrated and profiled.

2. Calibrate—If the calibration changes and is unstable, then the profile is worthless.

3. Characterize—Measure the color samples.

4. Create and install the profile. (Note: Steps 2, 3, 4 typically occur together within the profiling software).

5. Test—You must test the profile to see if it’s working properly.

Qualifying the display involves making sure the device is even worth profiling, because some devices are not. First, perform a uniformity test. This will show how even (or uneven) the display is across a viewing area. To perform this test, create a 17 x 11-inch page with a 40 percent gray tint in InDesign, convert it to a PDF, and open it in full-screen mode in Acrobat. Note any unevenness across the display area. If there are major differences, don’t waste your time trying to profile this display—go and buy a new one.

Next, display calibration will set the device to a repeatable, consistent condition. Calibration is much more important than profiling. Always calibrate before creating a profile, and if you cannot get the device calibrated to the same (or similar) condition, then profiling is useless. Main points to consider as part of the calibration process are white point (color temperature), contrast (gamma), and brightness.