Editing Color printing (section)

===Color separation process===
[[File:Ephemera collection; Paper bag advertising Bile Beans Wellcome L0030503.jpg|right|thumb|200px|Two-color (red/blue) advertising]]
[[File:Still-life of fruit using 3-color process.jpg|thumb|The first widely reproduced image printed using the three-color process, by [[William Kurtz (photographer)|William Kurtz]] (January 1893)]]
Typically color separation is the responsibility of the color separator. This includes cleaning up the file to make it print ready and creating a proof for the prepress approval process. The process of color separation starts by separating the original artwork into red, green, and blue components (for example by a digital scanner). Before [[digital imaging]] was developed, the traditional method of doing this was to [[photography|photograph]] the image three times, using a filter for each color. However this is achieved, the desired result is three [[grayscale]] images, which represent the red, green, and blue ([[RGB]]) components of the original image.

The next step is to invert each of these separations. When a negative image of the red component is produced, the resulting image represents the cyan component of the image. Likewise, negatives are produced of the green and blue components to produce magenta and yellow separations, respectively. This is done because cyan, magenta, and yellow are [[subtractive color|subtractive]] primaries which each represent two of the three [[additive color|additive]] primaries (RGB) after one additive primary has been subtracted from white light.

Cyan, magenta, and yellow are the three basic colors used for color reproduction. When these three colors are variously used in printing, the result should be a reasonable reproduction of the original, but in practice this is not the case. Due to limitations in the [[ink]]s, the darker colors are dirty and muddied. To resolve this, a black separation is also created, which improves the shadow and contrast of the image. Numerous techniques exist to derive this black separation from the original image; these include [[grey component replacement]], [[under color removal]], and [[under color addition]]. This printing technique is referred to as CMYK (the "K" stands for ''key'', a traditional word for the black printing plate).

Today's digital printing methods do not have the restriction of a single [[color space]] that traditional CMYK processes do. Many presses can print from files that were ripped with images using either [[RGB color model|RGB]] or CMYK modes. The color reproduction abilities of a particular color space can vary; the process of obtaining accurate colors within a color model is called [[color matching]].