| What are colour profiles? |
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A colour profile describes all the colours that a device can reproduce. It is a digital data file in a standardised format containing numerical values which define in absolute terms the complete colour gamut of a specific device. Devices that can be profiled include scanners, cameras, monitors, and printers. Colour management systems utilise these device specific profiles to predict how the colour numbers for each image pixel will need to be changed in order to preserve the same colour on each device in the workflow. A digital device either turns colours into numbers (a scanner or camera) or turns numbers into colours (a monitor or printer), and each device does so differently to all other devices. Some devices use RGB numbers, or values, to make colour from three data channels, some use CMYK values to make colour from four data channels, while others make colour from six or more data channels. RGB and CMYK are therefore data formats. Colour spaces are vaguely shaped like a football standing on its end. White is at the top, black at the bottom, with a range of grays in between. The various hues of the visible spectrum wrap around the circumference and colours go from gray to their most colourful as you move outward from the central axis. A horizontal slice through the middle would resemble the colour wheel used to pick colours in many graphics applications. Ektachrome E6 Film To provide a method to communicate colour unambiguously between different digital devices and their widely varying colour spaces, a standard profile format has been developed. The International Colour Consortium (or ICC, see www.colour.org) was established in 1993 to develop these standards. Their initial aim was to find a way for device specific profiles from different companies to work together as a colour management system. The ICC standard uses the device-independent colour spaces of the CIE (the International). |
