Adobe Photoshop CS5 for Photographers - Martin Evening [48]
Figure 2.4 The X-Rite i1 Photo is a popular spectrophotometer that can be used with the accompanying software to calibrate and build an ICC profile for your display.
If all you are interested in is calibrating and profiling a computer display, there is no great advantage in choosing a spectrophotometer over the more economically priced colorimeter devices. Whatever you do, I certainly advise you to include a calibrator/software package with any display purchase.
The calibration/profiling procedure
Over the next few pages I have shown how to use the i1Match 3.6.2 software with an X-Rite monitor calibration device and described the steps that would be used for an advanced display calibration. Other calibration software packages will differ of course, but the basic principles should be similar to other software programs. The first step is to select the type of device you want to calibrate (in this instance, an LCD display) and then select the Basic or Advanced options.
White point
The white point information tells the video card how to display a pure white on the screen so that it matches a specific color temperature. Unlike the old CRT displays, it is not possible to physically adjust the white point of an LCD screen. For this reason, it is usually better to select the native white point option when calibrating an LCD display (as shown in Figure 2.5), rather than calibrate to a prescribed white point value. Remember that all colors are seen relative to what is perceived to be the whitest white in a scene and the eye will naturally compensate from the white point seen on the display to the white point used by an alternative viewing light source (see accompanying sidebar on the white point setup).
Figure 2.5 I like using the i1Match software because it is easy to set up and use. In this case, I wanted to calibrate and profile an LCD display. I set the white point and Gamma to ‘Native’ and the luminance to 120 candelas m 2, which is a recommended target setting for desktop LCD displays.
White point setup
There is a lot of seemingly conflicting advice out there on how to set the white point in a calibration setup. In the days when CRT displays were popular there was a choice to be made between a 5000K and a 6500K white point for print work. My advice then was to use 6500K, since most CRT displays would run naturally at a white point of 6500K, although some people regarded 5000K as being the correct value to use for CMYK proofing work. In reality though, the whites on your display would appear far too yellow at this setting. 6500K may have been cooler than the assumed 5000K standard, but 6500K proved to be much better for image editing viewing. These days, most LCD displays have a native color temperature that is around 6000–7000K and it is now considered best to choose the native white point when calibrating and profiling an LCD display.
The main thing to remember here is that your eyes adjust quite naturally to the white point color of any display, in the same way as your eyes constantly adjust to the fluctuations in color temperature of everyday lighting conditions. Therefore, your eyes will judge all colors relative to the color of the whitest white, so the apparent disparity of using a white point for the display that is not exactly the same as that of a calibrated viewing lightbox is not something you should worry about. As I say, when it comes to comparing colors, your eyes will naturally adapt as they move from the screen to the viewing lightbox.
Gamma
The gamma setting tells the video card how much to adjust the midtone levels compensation. You typically have three options to choose from here: 1.8, 2.2 or Native Gamma. Quite often you are told that PC users should use 2.2 gamma and Macintosh users should use 1.8 gamma. But 2.2 can be considered the ideal gamma setting to use regardless of whether you are on a Mac or a PC. You can build a correct display profile using a 1.8 gamma