While the built-in calibrator is accurate enough for most people, its small controls and use of gray scale makes it rather cumbersome and difficult to use. To the left you match the output intensity, and to the right you adjust the amounts of red, green, and blue in the gray color which performs this calibration step for all three colors.
Doing this for various levels of brightness (five in total for the built-in calibrator) then builds the correction curve for all the display's colors at once. The built-in calibrator (in the "Displays" system preferences) lets you to adjust color levels when you check "Expert Mode."ĭisplays have three colors (red, green, and blue) that are all addressed at the same time with the built-in calibrator by lumping them together as levels of gray, for which you then adjust the brightness and color offset values.
Matching the intensity to this point for various levels of brightness will give you an intensity response curve for that color, so the color output will remain linear over the full range of output intensities. The interleaved pattern represents the "true" midrange color between the darkest and lightest that the pixel can output for a given intensity level. Under advanced mode, the calibrator will step you through a series of intensity levels where you will match intermediate color output levels to known values portrayed by interleaved dark and light striped patterns.
This can be done with the built-in calibrator in Mac OS X, which is a good place to start for most people. The alternative to a hardware solution is to match color intensities to known values using software, and generate intensity response curves. These calibrators are very accurate, but at a cost of between $70 and $600, can also be rather expensive. There are a variety of approaches for creating ICC color profiles for displays, with the most accurate being the use of a hardware calibrator to measure output levels at various locations on the display to adjust color and gamma curves accordingly. Therefore, it's best to recreate the color profiles in the conditions where the display is to be used.
This is why the supplied color profiles may not necessarily be the best since they may have been created on a PC being used in fluorescent lighting, which may result in incorrect color adjustment for a Mac being used in a basement under incandescent lighting.
The accuracy of color profiles depends on a lot more than just the display, and takes into account numerous factors including the type of video card, the operating system, the drivers, and the environmental factors. Many manufacturers provide color profiles for their displays, and while they are fairly accurate, they may only be an approximation of the colors or may not be perfect for your specific setup.