Horizen Review : Colour Calibration

The Importance of Colour Calibration

Understanding the basics of managing colour in your computer system.

Review Date 20 Mar 2003
Reviewed By Richard Millott © 2002

The Importance of Colour Calibration

For colour management to have any chance of working, it is important to create and maintain accurate definitions or fingerprints of all of the peripheral devices in YOUR computer chain. This done in two parts.

The first part, in setting up a colour managed system begins by getting each device into a known, standardized condition. This state is known as calibration or linearisa-tion and is an important part of maintaining consistency in an ICC workflow environment.

If I can use a skeletal metaphor for colour management, then calibration is the back-bone in controlling the colour from the input (e.g. digital camera or scanner) to the display (e.g. monitor or LCD screen) and to the printer (e.g. inkjet, dye-sub, images-etter or press).

For a monitor calibration you select a white point, modify the brightness and contrast and choose a tonal curve (also known as gamma). For an inkjet printer, calibration involves making sure the print head is clean and the proper paper and inks are in the machine and so on. In other words, each type of device has its own unique calibration procedures.

Once the calibration is done, the second part of the process is performed. This state is known as characterisation. To do this you build a custom ICC profile for each of the important devices in your workflow. These ICC profiles describe the particular col-our characteristics of your individual devices and when used by an operating system program, can convert the colours from one device to another. These ICC profiles are created by using colour measuring instruments which measure the range of colour each device produces (this is known as the gamut) and the tonal curves of each de-vice (the ways in which the colours change throughout the gamut).

The point of calibration is to enable you to maintain an accurate, repeatable, consist-ent and predictable production of colour. But without calibration the likelihood of your ICC profile remaining accurate is drastically reduced.