Xante Colour ScreenWriter, Руководство пользователя

Страница: 252 / 446

8-6 Color Printing bb ______________________________________
Subtractive Theory
A printer’s output reflects light. It usually begins with white (paper)
and creates color by laying down inks that absorb (or subtract out)
specific proportions of red, blue, and green light. Cyan ink subtracts
out all red, magenta subtracts out all green, and yellow subtracts out
all blue. Adding all three inks in equal quantities, theoretically
creates black. However, manufacturing limitations prevent the inks
from creating a true black, so most printing systems add a black ink
to the three primary subtractive colors. Using Cyan, Magenta,
Yellow, and Black inks to subtract out red, green, and blue
wavelengths is referred to as CMYK printing.
Ink Density Variables
When you print in color, the ink density as well as the reflection and
absorption capabilities of the media can affect the output. (See
“Media Variables” later in this chapter for more details.)
To compensate for density, media differences, and printer conditions
XANTÉ created special color rendering dictionaries (CRD) and a
Transfer Curve feature for use with your printer.
CRD
The Color Rendering Dictionary converts the RGB data produced by
scanners, monitors, and photo CDs to CMYK data used by color
printers These files define the creation of specific colors in various
ink, printer, and media environments.
Transfer Curves
Transfer curves calibrate your printer for specific ink and media,
eliminating differences caused by environmental conditions and
printer age. XANTÉ’s provides a set of transfer curves. You can also
use XANTÉ’s Command Center to create custom transfer curves
adjusted to your specific needs. See “Color Management” later in
this chapter for additional information about creating and using
transfer curves.