What Is CMYK
CMYK short for Cyan-Magenta-Yellow-Black, and pronounced as separate letters. Based upon Sir Isaac Newton’s Colour Circle, Four colour process printing was originally developed in the late nineteenth century along with the halftone process for reproduction of continuous tone images (photographs) and has been used for over 100 years to reproduce colour images. The colours Cyan, Magenta, and Yellow appear directly opposite the Red, Green, and Blue on the Colour Circle devised by Newton over 300 years ago.
In the CMYK colour system equal proportions of Yellow ink plus Cyan ink produces Green, Yellow ink plus Magenta ink produces Red, and Cyan ink plus Magenta ink produces Blue (actually more like purple to most eyes). Various colour shades and values are achieved by varying the relative amounts of the four colours. Black ink is added to improve the quality of 3-color blacks, to provide added detail to images, to speed drying, and to reduce overall ink costs, thus the name: Four Colour Process.
The primary colours RGB, combined at 100-percent brilliance, produce white. The primary pigments CMY, combined at maximum concentration, produce black. Shades of gray result from the equal (but not maximum) brilliance of R,G, and B, or from equal (but not maximum) concentrations of C, M, and Y. If you have a paint or draw program such as Corel DRAW! That employs both the RGB and the CMYK schemes, you can investigate these relationships by filling in regions with solid colours using one mode, and examining the equivalent in the other mode. After a while you will develop an intuitive sense of how these schemes work, how they resemble each other, and how they differ.
CMYK cannot reproduce any colour that exists in the world, but it can produce a great number. It’s impossible to match things like a parrot feather, rose petal, or oak leaf, but the colour system can get remarkably close. CMYK is capable of creating so many different colours because we not only use inks in varying ratios to each other, but with a varying concentration, noted as a percentage. These combinations create colours that span the spectrum in hue (what we think of as colour) as well as tone, or intensity. It is important to note, however, that CMYK is limited by outside factors including the qualities of the paper, the integrity of the ink, and the halftone dot size.
Comparisons between RGB displays and CMYK prints can be difficult, since the colour reproduction technologies and properties are so different. A computer monitor mixes shades of red, green, and blue to create colour pictures. A CMYK printer instead uses light-absorbing cyan, magenta and yellow inks, whose colours are mixed using dithering, halftoning, or some other optical technique. Similar to monitors, the inks used in printing produce a colour gamut that is “only a subset of the visible spectrum” although both colour modes have their own specific ranges. As a result of this items which are displayed on a computer monitor may not completely match the look of items which are printed if opposite colour modes are being combined in both mediums. When designing items to be printed, designers view the colours which they are choosing on an RGB colour mode (their computer screen), and it is often difficult to visualize the way in which the colour will turn out post printing because of this.