Digital files are viewed on a wide range of equipment. If appropriate measures aren't taken, predicting what an image looks like when someone else sees it in her particular viewing environment can be difficult, if not impossible. That's why monitor calibration is the first step to managing color in Photoshop.
The idea behind monitor calibration is to establish a set of standards and get everyone to use them. These standards refer to the color temperature, brightness, and contrast of a monitor. A hardware calibration device is used to measure these display qualities and then allow you to adjust your monitor to bring them into alignment with the standards. This is called monitor calibration.
After you calibrate your monitor, the calibration device allows you to create a custom color profile that describes the way the monitor displays color. A color profile enables all the devices in a digital workflow to interpret and understand color so that they all speak the same language. Cameras, monitors, and printers all have color profiles.
A number of monitor calibration devices are available. Two of the most popular devices are the ColorVision Spyder3 Pro (shown in Figure 3-1) and the X-Rite Eye-One Display 2.