How to manage colour on your PC

Most of you will have captured, manipulated and reproduced colour images via a range of devices and software. During this process you may have noticed colour changes and inconsistencies in your images.

For example, your digital camera pictures may have a yellow or red colour cast or there may be a red tinge on colour prints.

If you compare colour prints with the same image displayed on your monitor they will almost certainly look very different.

This is because assumptions are made by the operating system in an attempt to handle colour correctly as it passes an image from one device or piece of software to another.

This automatic colour handling assumes each device conforms to colour standards and that they all behave in a uniform way. But in practice each camera, scanner, display or printer captures or reproduces colour differently, which is the source of most colour problems.

Early operating systems that could handle colour had no built-in colour management. Apple pioneered the control of colour in operating systems and was a prime mover in establishing the Colorsync Consortium, known as the International Colour Consortium (ICC).

ICC profiles associated with each colour device are a shorthand summary of colour characteristics using a number of data points from which the full characteristics can be reconstructed. This has varying degrees of accuracy depending on the number of points used for the original profile.

Colour support
Microsoft’s operating system didn’t have any colour management features until Windows 98 and, until now, colour control has been decentralised, with individual colour profiles for each device accessed and controlled via their associated software drivers.

Current versions of Windows support the use of ICC profiles, although Vista will introduce a new colour management platform. The Windows Colour System (WCS) will offer centralised control of colour and a new colour infrastructure and translation engine (CITE).

Although WCS will not be available as an upgrade for Windows XP, colour tools are being made available for XP that are presumably spin-offs from the design work on Vista.

For example, the Color Control Panel Applet (a free download) centralises many colour settings in one place, lets you install and uninstall ICC profiles and check and assign different profiles to devices, and even includes a simple 3D gamut viewer so you can compare two profiles.

In general, Windows assumes that all colour outputs and inputs use the sRGB (Standard Red, Green and Blue) ‘colour space’ (see ‘Describing colour’ later and relies on third-party manufacturers’ compliance to this standard to correct for individual device characteristics. sRGB-compliant devices do not have to provide a profile or other support for colour management to work.

You can establish far better control of colour on your PC by understanding colour processes, allowing you to make informed decisions about what actions to take at various points in the process of capturing and reproducing colour.

By calibrating and profiling each colour device in your system to produce customised individual profiles, you can ensure that each one behaves in a known and optimal fashion.

In the first of this two-part series, we provide an overview of the concepts behind colour management and a general explanation of how colour management is achieved.

In the next installment we’ll look at some colour management calibration and profiling tools and how they are used in practice.