Photoshop's color management system must know the color space of your document so it can decipher the meaning of the color values in the image.. Select this option, click the list arrow
Trang 1Photoshop's color management system must know the color space of your document so it can decipher the meaning of the color values in the image When assigning a profile to an image, the image will be in the color space described by the particular profile For example, a doc-ument's profile can be assigned by a source device, like a digital cam-era or a scanner, or assigned directly in Photoshop When using the Assign Profile command, color values are mapped directly into the new profile space
Assigning a Different
Profile to a Document
Assign or Remove a Profile
Open a document
Click the Edit menu, and then click
Assign Profile.
Select from the following options:
◆ Don't Color Manage This
Document Select this option to
remove any assigned profile
(the document becomes
untagged)
◆ Working RGB Select this
option to tag the document with
the current working space
profile
◆ Profile Select this option, click
the list arrow, and then select a
new color profile, which
removes the old one
Click OK.
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See Also
See ”Changing from Additive (RGB) to
Subtractive (CMYK) Color” on page 428
for more information on using and
working with CMYK images
Trang 2There are times when you will open a document that contains an embedded profile, and you need to convert it Photoshop gives you the option of tagging the document with another profile without converting the colors, or removing the old profile and converting the color space
Photoshop's Convert to Profile command gives you the ability to change the profile in a document In addition, you may want to prepare
a document for a different output destination, such as an inkjet printer
or 4-color press
Converting the Color
Space to Another
Profile
Convert the Color Space to
Another Profile
Open a document
Click the Edit menu, and then click
Convert to Profile.
Click the Profile list arrow, and
then select a new color profile
The document will be converted
and tagged with the new color
profile
Click the Engine list arrow, and
then select:
◆ Adobe (ACE) Adobe color
management (default)
◆ Microsoft ICM Windows color
management
◆ Apple CMM Mac OS color
management (Depending on
your operating system, your
options may vary.)
Click the Intent list arrow, and then
select an option
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See Also
Trang 3Select the Use Black Point
Compensation check box to map
the full color range of the source
to the full color range of the
destination profile
Select the Use Dither check box to
use with 8-bit color images; if you
select this option, Photoshop
dithers color pixels when
converting between source and
destination color profiles
Select the Flatten Image to
Preserve Appearance check box
to flatten a multi-layered
document
Click OK.
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Trang 4Once you've established that your document contains colors outside the CMYK color space, it's up to you to decide exactly how to correct the problem There are as many ways to correct color problems as there are tools, and each Photoshop user has their favorites Two meth-ods that are simple and powerful are using the Hue/Saturation
Adjustment and Photoshop's Sponge tool Understand that the primary reason a color won't translate correctly into the CMYK color space is due to the saturation values of the ink A monitor can produce more saturation in a pixel than a 4-color press can produce by mixing inks
Using
Hue/Saturation for
Out-Of-Gamut Colors
Use the Hue/Saturation
Adjustment
Open an RGB image
Click the View menu, and then
click Gamut Warning.
Photoshop displays any colors
outside the CMYK gamut with a
predefined color mask
Click the Image menu, point to
Adjustments, and then click
Hue/Saturation.
Drag the Saturation slider to the
left until all the masked areas
disappear
Record the Saturation Value used
Click Cancel.
Click the Select menu, and then
click Color Range.
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You can select the closest CMYK
equivalent of an out-of-gamut color in
Trang 5Click the Select list arrow, and
then click Out Of Gamut.
Click OK.
The out-of-gamut areas of the
image are now selected and
isolated from the rest of the image
Click the Select menu, and then
click Refine Edge.
Enter a Feather value of 5
This softens the desaturation of
the out-of-gamut areas of the
image
Click OK.
Click the Image menu, point to
Adjustments, and then click
Hue/Saturation.
Enter the Saturation value you
recorded from step 5
Click OK.
Press Ctrl+D (Win) or A+D (Mac)
to deselect the image areas
The image is now ready for
conversion to CMYK
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Color outside the CMYK gamut.
Did You Know?
Photoshop can automatically convert
all out-of-gamut colors to be within
the gamut area Simply convert an RGB
image to CMYK Open an RGB image,
click the Image menu, point to Mode,
and then click CMYK Color
Trang 6The Sponge tool method is a bit more work intensive; however, it gives you precise control over each out-of-gamut area of the image Since the Sponge tool decreases saturation values from the colors based on the speed with which the tool is dragged across the image, the key to successfully using the Sponge tool to restore out-of-gamut colors is to choose a soft-edged brush, and use smooth, even strokes Practice is the key to effective image restoration and color correction, and using a drawing tablet as opposed to a mouse will help in the control of the tool
Using the Sponge
Tool for Out-Of-Gamut
Colors
Use the Sponge Tool Method
Open an RGB image
Click the View menu, and then
click Gamut Warning.
Photoshop displays any color
outside the CMYK gamut with a
predefined color mask
Select the Sponge tool.
Click the Brush list arrow, and then
select a soft, round brush tip with
a small diameter from the brush tip
options
Click the Mode list arrow, and then
click Desaturate.
Enter a Flow value of 60%, and
then select the Vibrance check
box on the Control panel to
minimize clipping of strongly
saturated or desaturated colors
Click the Select menu, and then
click Color Range.
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Original RGB image
Trang 7Click the Select list arrow, and
then click Out Of Gamut.
Click OK.
The out-of-gamut areas of the
image are now selected and
isolated from the rest of the image
Click the Refine Edge menu, and
then click Feather.
Enter a Feather value of 5
This softens the desaturation of
the out-of-gamut areas of the
image
Click OK.
Slowly drag the Sponge tool over
an out-of-gamut area until the
color mask disappears
Continue through the document
until all the areas have been
corrected
Press Ctrl+D (Win) or A+D (Mac)
to deselect the image areas
The image is now ready for
conversion to CMYK
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Out-Of-Gamut colors masked
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Out-Of-Gamut colors removed with the Sponge tool
Did You Know?
You can hide selection marquees.
If the selection marquee is getting in
the way of seeing small out-of-gamut
areas, press Ctrl+H (Win) or A+H
(Mac) to temporarily hide the selection
marquee, and then repeat the
com-mand to restore the marquee
Trang 8One of the biggest problems with images displayed on a computer monitor is that they don't accurately represent the color space of a 4-color press There are ways that we can reduce the possibility of col-ors not printing correctly, but in the end the RGB and CMYK color spaces are different—in fact, they're exactly the opposite of each other Photoshop understands this, and gives you a way to view before
printing which colors will be out of gamut The term Gamut refers to the
colors that a particular device can display or print; in the case of a 4-color press, it would describe a 4-color that could be reproduced on that press The out-of-gamut test is performed on an image before the con-version into the CMYK mode Once you convert an image to CMYK it's too late to test, because Photoshop has already made the conversion
Working with the
Out-Of-Gamut
Warning
Work with the Out-Of-Gamut
Warning
Open an RGB image
Click the Edit (Win) or Photoshop
(Mac) menu, point to Preferences,
and then click Transparency &
Gamut.
Select a Gamut Warning color, and
then enter an Opacity percentage
value (1% to 100%)
Gamut Warning refers to the color
Photoshop uses to mask the
out-of-gamut areas of the image
Click OK.
Click the View menu, and then
click Gamut Warning.
Photoshop displays any color
outside the CMYK gamut with a
predefined color mask
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Did You Know?
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