When the color image is deduced on the color printer it is hidden and ???????? there are same processes which are characteristic for the polygraphic press (a color separation and rasterization), and their automatic performance is provided with parameters and printer setting. By preparation of the image for polygraphic execution by these processes it is necessary to control purposefully, being conformed to a task in view and with requirements of absolutely specific polygraphic enterprise (a service bureau and printing houses).

Generally a color separation represents color image sharing so that it has been again received as a result of printing by several monochromatic forms.

Color separation methods

For reproduction of color images by their typographical method subject to sharing on some images in such a manner that being printed with exact combination (?????????) certain colors the original color image is played back. Process of sharing of the image is called as a color separation (color separation) and is an essential stage ?????????? preparations of issuings (prepress).

Color separation can be fulfilled by two main methods.

Polnotsvetnye images (the scanned photos, works of painting and other realistic images) are divided into the separate images which press is carried out by standard polygraphic (triad) colors: blue (Cyan), magenta (Magenta), yellow (Yellow) and black (Black).

The images using ????????? colors with clearly expressed local colors (logos, a font, decorative elements), share on separate images for everyone ?????????? colors., their press is carried out ????????? by colors according to this or that library, for example, PANTONE. At ????????? color spanning as color for the press prepares in advance is much wider than colors and any components giving to it unusual shade can be imported to it (for example, "gilded", "neon", "fluorescent" and others). The layer with ????????? color can be used for creation of forms of a stamping or varnish coat plotting.

If the document contains ???????????? images and objects with plashech th colors a color separation can be fulfilled on a polygraphic triad with converting ????????? colors, but can take place and a combination of that and other method: except four bands for polygraphic colors can be deduced and separate bands for everyone ?????????? colors, including, for additional printing by the fluorescent, metallized colors or a lacquer covering.

Color separation support consists in hardware preparation (in particular, monitor calibration), document preparation (for example, creation ?????????, color palette determination), setting of parameters of a color separation taking into account requirements of printing process.

Stage 1. Monitor calibration

In color monitors color is synthesized by optical mixing of three basic colors ? red (Red), green (Green) and dark blue (Blue), forming color model RGB. In the same model there is a scanning of color illustrations.

The polygraphic press works with color model CMYK which is a mathematical model of the material (imperfect) dyes. Therefore the color space of model RGB cannot be adequately converted in color space which can transfer a combination of the material dyes. In this connection there is a problem of color spanning about which it is more in detail told in chapter 4.

Pure and bright colors of the monitor are good, for example, for a computer slide film, presentation but if the edited image is intended for polygraphic execution excessive brightness and very broad range of colors can serve as a noise for true representation of polygraphic result.

In this connection there is a necessity to adjust the monitor so that ?????????? on it more or less "came nearer" to polygraphic ???????.

The management system is included in composition of the program of adobe Illustrator 9.0 colors CMS (Color Management System) which allows to imitate display to the screen according to the installed profiles of devices, in particular, the monitor and the output printer. Look about it in chapter 4.