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| Understanding Color/Color reproduction | Index | Home |
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UCR (undercolor removal) and GCR (gray component replacement) |
UCR (undercolor removal)
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The inks available in the current printing technology do not allow superimposing each of the four CMYK colors on top of each other before each ink has dried. Images with strong tones can be reproduced by increasing the density of all four colors, but beyond a certain density the ink refuses to coat, and begins to peel off. In order to prevent this phenomenon, printers use a process called UCR (undercolor removal), in which the CMY ink components are removed wherever black ink will be printed. It is not a simple thing to remove all such areas, and each printing company relies on its own technology. |
GCR (gray component replacement) is an alternate way of expressing gray. The gray areas which would otherwise be printed by CMY inks, are printed as black halftones. |
Processing the UCR |
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