Under Color Removal or Under Color Reduction is used when separating LAB or RGB to CMYK. The goal of under color reduction is to reduce the CMY parts in black pixels in order to reduce the overall color coverage.

Colours from only one or two primary colours, e.g. pure cyan or pure red from magenta and yellow, are not affected by UCR. The UCR process is only used for colours consisting of all three chromatic colours.

The method is permanently implemented for separations via a CMYK ICC profile and cannot be changed. The limitation of the maximum ink application to 330 or 300% is a result of UCR, because higher ink applications would on the one hand prolong the drying times considerably, and very thick layers of ink can become cracked, e.g. when folding paper.

A second process is GCR – Gray Component Replacement.


Ugra is the Swiss Centre of Competence for Media and Printing Technology. The UGRA is particularly active in the areas of control agents and certifications.

Color accurate Proofs have to contain a media wedge, one of which is developed and published by the UGRA and Fogra. The latest revision is currently the Ugra / Fogra Media Wedge V3.0.

The Proof.de metamerism card is based on the UGRA color temperature indicator which can be used to check the correct lighting of digital proofs and prints. It can be purchased in the store of Proof.de:

UGRA Color temperature indicator

Weblink: www.ugra.ch

Uncoated paper

Refers to all papers that have not been finished with a coating application.

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