Within the

CMY color space The CMYK color model (also known as process color, or four color) is a subtractive color model, based on the CMY color model, used in color printing, and is also used to describe the printing process itself. The abbreviation ''CMYK'' refer ...

used in

color printing Color printing or colour printing is the reproduction of an image or text in color (as opposed to simpler black and white or monochrome printing). Any natural scene or color photograph can be optically and physiologically dissected into three ...

, a range of colors can be achieved by combining the three

primary color A set (mathematics), set of primary colors or primary colours (see American and British English spelling differences#-our, -or, spelling differences) consists of colorants or colored lights that can be mixed in varying amounts to produce a gamu ...

s. This combination can be thought of as a hue component (which will require a maximum of two primary colors) and a grey component (a mixture of all three, in an appropriate quantity to give the required saturation). If the grey component is replaced by black ink, the same color is being achieved by using two primaries and black. The substitution of black for the grey component is described as grey component replacement (GCR). In GCR, contrary to

under color removal In printing, under color removal (UCR) is a process of eliminating overlapping yellow, magenta, and cyan that would have added to a dark neutral (black) and replacing them with black Black is a color which results from the absence or comple ...

(UCR), the CMY values that add to grey all along the tone scale can be replaced with black ink. UCR only adds black to the CMY equivalent of what would have printed as a grey or near-grey. : Advantage: GCR uses less ink, and some of that ink is black, normally cheaper than the others. : Advantage: The areas where less ink is used are regions of high ink use, so the potential problems of drying and ink set-off are reduced. : Advantage: The resulting output is less susceptible to changes in the printing variables since not as much C, M, and Y require balancing. : Disadvantages: There may be potential quality issues associated with GCR. Sometimes it reduces the ability to adjust colors. It may create problems with balancing black halftone. A high amount of GCR causes the shadow areas to print too weakly, giving a low-contrast image.http://www.imaging.org/site/PDFS/Papers/2000/PICS-0-81/1613.pdf

References

{{reflist Printing terminology Print production ca:GCR es:GCR pl:GCR (DTP)

See also

References