International Color Consortium

From Free net encyclopedia

The International Color Consortium was formed in 1993 by eight industry vendors in order to create a universal color management system that would function transparently across all operating systems and software packages.

The ICC specification, currently on version 4, allows for fidelity of color when moved between applications and operating systems, from the point of creation to the final print.

The main emphasis of the ICC is to define a format for ICC Profiles, which describe the color attributes of a particular device or viewing requirement by defining a mapping between the source or target color space and a profile connection space (PCS). This PCS is either L*a*b* or CIE XYZ color space. Mappings may be done using tables, to which interpolation is applied, or through a series of parameters for transformations.

To see how this works in practice, suppose we have a particular RGB and CMYK color space, and want to convert from this RGB to that CMYK. The first step is to obtain the two ICC profiles concerned. To perform the conversion, each RGB triplet R,G,B is first converted to the PCS using the RGB profile. If necessary the PCS is converted between L*a*b* and CIE XYZ, a well defined transformation. Then the PCS is converted to the four values of C,M,Y,K required.

A profile might define several mappings, according to rendering intent. These mappings allow a choice between closest possible color matching, and remapping the entire color range to allow for different gamuts.

ICC define the format precisely but do not define algorithms or processing details. This means there is room for variation between different applications and systems that work with ICC profiles.

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