Adobe PHOTOSHOP 5.0, Руководство пользователя, Страница: 106 / 400

CHAPTER 5 98
Reproducing Color Accurately
•
Avoid multiple conversions between RGB and
CMYK mode, because each conversion requires
color values be recalculated and rounded,
resulting in less accurate color.
•
When converting color values from one mode to
another, Photoshop uses the Lab color mode,
which provides a system for defining color values
in all modes. Using Lab ensures that colors are not
visibly altered during conversion—other than the
necessary remapping of colors to confine them to
a reduced gamut. (See “Color gamuts” on page 66;
“L*a*b model” on page 65.)
For example, when converting an RGB image to
CMYK, Photoshop first converts the RGB color
values to Lab mode using the information in the
RGB Setup dialog box. Once the image is in CMYK
mode, Photoshop converts the CMYK values back
to RGB to display the image on an RGB monitor.
•
The conversion from CMYK to RGB for screen
display does not affect the actual data in the file.
The conversion is performed on a copy of the data.
Preparing for CMYK conversion
Photoshop lets you preview CMYK colors prior to
making the conversion. You can also use the
Gamut Warning command in the View menu to
check for and correct any out-of-gamut colors.
(See “Previewing CMYK colors” on page 110 and
“Identifying out-of-gamut colors” on page 110.)
Using color separation tables
The Tables option lets you do the following:
•
Save the CMYK setup from the built-in model as
an ICC profile for use by other programs.
•
Load Photoshop 4.0 format separation tables.
To save the CMYK settings as an ICC profile:
1
Choose File > Color Settings > CMYK Setup.
2
Enter the settings you want. (See “Entering
CMYK setup information” on page 86 and
“Adjusting separation options” on page 89.)
3
For CMYK Model, choose Tables.
4
Click Save. Select a location, and then name and
save the new separation table. Then click OK.
To load a Photoshop 4.0 format separation table:
1 Choose File > Color Settings > CMYK Setup.
2 For CMYK Model, choose Tables.
3
Select Preview to display a preview of your
changes.
4
Click Load.
5
Select the table you want to use, and click Open.
The name of the table appears in the CMYK Setup
dialog box.
6 Click OK to use the table in CMYK conversions.
The table settings will be used the next time you
convert an image to CMYK.