Adobe PHOTOSHOP 5.0 User Manual page 98

90 CHAPTER 5
Reproducing Color Accurately
Adjusting the separation type and black
generation
In most cases, the Photoshop color separation
defaults produce excellent results. But when
necessary, you can modify the black generation
method, set new ink limits, and change the
separation type. If you have already converted the
image to CMYK mode, you must reconvert the
image after adjusting the separation options.
Note: The separation options don't affect output
from non-PostScript color printers (such as HP
DeskJet, Canon
Stylus ), because they generate their own black
™
values.
To adjust the separation type and black generation:
Choose File > Color Settings > CMYK Setup.
For Color Model, choose Built-in.
Bubblejet , and Epson Color
® ™ ®
The Separation Options area in the CMYK Setup
dialog box displays a graph based on current
settings showing how the neutral colors in the
image will separate. In the graph, sometimes called
a gray ramp, neutral colors have equal parts of
cyan, magenta, and yellow. The horizontal axis
represents the neutral color value, from 0%
(white) to 100% (black). The vertical axis repre-
sents the amount of each ink that will be generated
for the given value. In most cases, the cyan curve
extends beyond the magenta and yellow curves,
because a small extra amount of cyan is required to
produce a true neutral.
Choosing the separation type
By default, Photoshop uses the GCR type of color
separation. Select UCR if you want to use under-
color removal. Check with your print shop to find
out which to use.
Choosing the degree of black generation
For GCR separations, you choose the degree of
black generation, set ink limits, and indicate
undercolor addition.
Note: ICC profiles specify the degree of black gener-
ation.
For a color illustration of black generation,
see figure 5-2 on page 225.