Adobe PHOTOSHOP 5.0 User Manual page 118

110 CHAPTER 6
Making Color and Tonal Adjustments
With certain types of separations, you must
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work in RGB mode anyway. For example, if you
separate an image using the Maximum Black
Generation option in the CMYK Setup dialog box,
it will be difficult, if not impossible, to make any
corrections requiring a significant increase in the
C, M, or Y components. To make these changes,
you must reconvert the image to RGB, correct the
color, and then reseparate the image—or you must
reseparate the image with a lighter Black Gener-
ation option.
Previewing CMYK colors
When adjusting out-of-gamut colors or making
color corrections in RGB mode, you can preview
CMYK colors in an RGB image.
To preview CMYK colors:
Choose View > Preview > CMYK, Cyan, Magenta,
Yellow, Black, or CMY. (To return to the normal
preview mode, reselect this option.)
CMYK equivalents for colors in the image are
displayed using the current separation and
calibration values in the CMYK Setup dialog
boxes, but no permanent changes are made.
Monitor CMYK colors as you edit in
RGB mode by choosing View > New View
to open a second window. Turn on CMYK
Preview in one window and leave it off in
the other.
Identifying out-of-gamut colors
The gamut is the range of colors that can be
displayed or printed in a color system. A color that
can be displayed in RGB or HSB models may be
out-of-gamut, and therefore unprintable, for your
CMYK setting. (See "Color gamuts" on page 66.)
Photoshop automatically brings all colors into
gamut when you convert an image to CMYK. But
you might want to identify the out-of-gamut
colors in an image or correct them manually
before converting to CMYK.
In RGB mode, you can identify out-of-gamut
colors in the following ways:
In the Info palette, an exclamation point appears
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next to the CMYK values whenever you move the
pointer over an out-of-gamut color.
In both the Color Picker and the Color palette,
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an alert triangle appears and the closest CMYK
equivalent is displayed whenever you select an out-
of-gamut color. To select the CMYK equivalent,
click the triangle or the color patch.
Out-of-gamut color indicator