Tài iệu Photoshop cs5 by Dayley part 123 pdf

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Because ink and paper quality affect printer output so much, you cannot adjust the settings on a
printer to calibrate color output. Instead, printers use ICC profiles that are created by printing a
test sample with known output gamma, brightness, contrast, and color outputs. The sample test
print is then analyzed by a photometer (sometimes called a spectrophotometer) to determine the
actual output with known CYMK colors. Software that comes with the photometer then uses the
difference between the two to create the ICC profile. Although the cost of the photometer and
software is expensive, you can typically find an ICC profile for your printer/ink combination on
the Internet for reasonable prices (usually about $20–$30).
Using Color Management in Photoshop
Now that we have discussed the theory of color profiles, you are ready to configure and use the
color management settings in Photoshop. The following sections discuss how to configure the
color management settings in Photoshop, assign color profiles to images, and proof images using
different color profiles.
Configuring color settings in Photoshop
The color settings in Photoshop are configured using the Color Settings utility, shown in Figure 29.3.
Launch the color settings dialog box by pressing Ctrl/Ô+Shift+K on the keyboard or selecting
Edit ➪ Color Settings from the main menu. At first appearance, the dialog box may seem a bit
unfamiliar and daunting. The next few sections discuss each of the options available in the Color
Settings dialog box and hopefully dispel any apprehension of using them.
Tip
If you save your color settings as a preset file, you can use that preset in Adobe Bridge’s Suite Color Settings
dialog box (launched by pressing Ctrl/Ô+Shift+K in Bridge). Bridge’s Suite Color Settings utility allows you to
synchronize the color management profiles between Creative Suite applications. n
Settings
The Settings menu option offers a list of preset color configurations that set the color options for
the workspace and management policies for general purposes. If you really don’t want to take the
time to set up your own custom color configuration, you can use one of these presets. The presets
list contains presets for North America, Europe, and Japan that fall into the following categories:
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Monitor Color: Use this setting if you plan to use the images in a video or onscreen
presentation. This setting uses the Monitor RGB option, which uses the current monitor’s
color space and in effect acts like color management is turned off in Photoshop.
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General Purpose: Use this setting if you need to use the image for both print and
onscreen viewing. This setting uses the sRGB color profile that best supports most monitors
as well as the U.S. Web Coated (SWOP) v2 color profile for CYMK that works well for
printing.
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FIGURE 29.3
The Color Settings dialog box allows you to configure the color workspaces and the color management
policies.
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Newspaper: Use this setting for images that are intended for output to newspaper. The
CYMK workspace is set to U.S. Newsprint, and the Gray and Spot colors are set to use a
25 percent Dot Grain that works well for printing to newspaper-type material.
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Prepress: Use this setting for images that are intended for output to a printer. The RGB
workspace is set to Adobe RGB, which provides a good range of colors for printing; the
CYMK workspace is set to U.S. Web Coated (SWOP) v2, which works generally well for
printing.
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Web/Internet: Use this setting for images that are intended to be displayed on the Web.
This option sets the RGB workspace to sRGB, which is the best for supporting a variety of
computer monitors; the Gray workspace is set to Gray Gamma 2.2, which works best for
displaying grayscale images on a variety of monitors.
You also can save any custom configuration that you define using the Save button and then load it
later, even on another computer, by hitting the Load button.

Working Spaces
The Working Spaces settings allow you to configure the ICC color profiles that the RGB, CYMK,
Grayscale, and Duotone models use to display the images on your display while you are editing
them. Using the appropriate color model helps you edit and adjust your images so they look as
good as possible when they are viewed on the output medium.
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The following list describes some of the profiles available in each of the workspaces:
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RGB: Although there are many RGB color profiles, you likely will work with only two or
three. The most common ones are the Adobe RGB and the sRGB IEC61966-2.1 (sRGB).
The difference between the two is that the sRGB has reduced the gamut of colors it allows
around the outer edges. This reduces the number of colors that can exist in the image so
the colors are supported on the widest range of computer displays possible. That way, the
image looks exactly the same on all displays.
Another RGB color profile you may end up using is the Monitor RGB. It sets the RGB
working space to the current monitor space, which causes Photoshop to behave as if color
management was turned off. This is actually handy if you are outputting the images to a
medium that doesn’t support color management, such as a video or a presentation
application.
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CYMK: The CYMK color model is typically used for printed images. Therefore, each of
the available CYMK color profiles actually corresponds to a specific ink and paper
combination. When you convert an image from RBG to CYMK using the Image ➪ Mode ➪
CYMK color option, the CYMK color profile is used as a basis for the conversion between
the two color models.
The most common profile you will use is U.S. Web Coated (SWOP) v2. Other color
profiles may be provided by your printing press or by a printer manufacturer.
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Gray: The Gray color profiles define the dot grain used to display images converted into
grayscale using the Image ➪ Mode ➪ Grayscale option. There are two basic options: One is
to set the percent of dot grain, and the other is to use a gamma option that uses the
gamma setting of your monitor to define the brightness of the midtones in the grayscale
image. The most commonly used gamma option is Gray Gamma 2.2 because it supports
most of the current monitors.
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Spot: This specifies the dot grain to use when displaying spot color channels and duotones.
Color Management Policies
The Color Management Policies section of the Color Settings dialog box provides control over how
Photoshop manages the RGB, CYMK, and grayscale images that are opened. Many images already
contain ICC color profiles embedded in them, and the settings in this panel allow you to define
how Photoshop uses those files in relation to the color profiles defined in the Working Spaces
section.
For each of the three color modes, you can set the following options:
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Off: When Off is selected, color management is disabled in images that you open or
create. If you open an image with an embedded color profile, the color profile is ignored.
You should be careful if you use this option while copying and pasting from one image to
another, because although the color data is preserved, the colors may look different.
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Preserve Embedded Profiles: This is the default option and is the best option to ensure
the most consistent colors between images that are edited on different computers. When
this option is selected, Photoshop maintains the embedded color profile information.
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Convert to Working Profile: When this option is selected, Photoshop uses the color
profile in the image to convert the data in the image to use the working color profile. The

working color profile is then embedded in the image when it is saved.
The Color Management Policies also provide check boxes that allow you to turn on dialog
boxes that pop up if you open or paste data into an image that has a color profile embedded that
mismatches the working profile or is missing. The dialog box warns you and allows you to
determine at that time how to handle color management for that image, as shown in Figure 29.4.
FIGURE 29.4
Enabling the Ask When Opening and Ask When Pasting options in the Color Settings dialog box presents
notifications that allow you to handle images that either do not have an embedded color profile or have a
color profile that does not match the current working color space.
Note
Photoshop allows you to open multiple images that use different color profiles. This can be useful if you are
working on projects with images that are destined for different outputting. However, you should be careful if
you need to share pixels between images—for example, cutting and pasting or selecting colors from one image
that you want to be used in another image or sharing channels. n
Conversion Options
Photoshop also provides control over conversion between color profiles when you click the More
Options button in the Color Settings dialog box. Figure 29.5 shows the Conversion Options and
the Advanced Controls settings.
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FIGURE 29.5
The More Options button extends the Color Settings dialog box and allows you to configure conversion
and advanced controls for color management.
In the Conversion Options section, you can configure the following options:
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Engine: This allows you to specify the CMM that will be used to manage conversion
between color profiles. Typically, you have two options: Adobe ACE is provided by Adobe
and is available on both Windows and Apple; the other option is the default CMM that is
provided with your operating system—for example, Microsoft ICM on Windows or Apple

CMM on Apple.
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Intent: This option allows you to select one of the following options that determine how
the CMM interprets colors between color spaces:
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Perceptual: When this option is selected, all colors in the source color profile are
compressed to fit in the destination color profile’s gamut. Neighboring pixels are taken
into consideration so the colors are adjusted proportionally. This provides a better
perceptual translation because the relationship between the pixel and its neighbors is
more important than finding the closest matching color.
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Saturation: When this option is selected, colors in the source color profile that do not
exist in the destination color profile’s gamut are changed to the closest color value in
the destination color profile without considering neighboring pixel values. This can
result in a color shift that increases saturation in the image. Typically, this option is
used only for images with lots of solid colors and not for photographs.
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Relative Colorimetric: When this option is selected, colors are translated between
profiles by mapping white in the source color profile with white in the destination
color profile and then using that mapping to adjust the rest of the colors. This option
usually works very well; however, if you are converting a smaller color space to a
larger color space (CYMK to RGB, for example), a banding and dithering effect can
result in the darker areas of the image.
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Absolute Colorimetric: When this option is selected, Photoshop maps the colors
between the two spaces by mapping between the absolute lab coordinates in each
color profile. This option is used for hard proofing and simulating output on a specific

printer.
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Use Black Point Compensation: This simulates the entire dynamic range of the printer
to ensure that the shadow details in the image are preserved. This option should be
selected if you plan on using black point compensation when printing the image.
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Use Dither: When this option is selected, Photoshop mixes colors in the destination color
profile to simulate colors in the source color profile. This helps reduce blocky and banding
artifacts that can otherwise occur.
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Compensate for Scene-referred Profiles: This compares the video contrast when
converting from scene to output color profiles, similar to color management in After
Effects. This option is specific to working with video files in Photoshop.
Advanced Controls
In addition to the Conversion Options described in the previous section, Photoshop provides more
Advanced Controls options when the More Options button is clicked. In the Advanced Controls
section, you can configure the following options:
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Desaturate Monitor Colors By: This specifies a percentage to desaturate colors when
they are displayed on the monitor. Selecting this option helps you visualize the full range
of color spaces with a similar gamut of the monitor. However, this can result in color
mismatches between monitor display and output. Deselecting this option can result in two
distinct colors appearing as the same color on the monitor.
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Blend RGB Colors Using Gamma: This controls how RGB colors in the image are
blended together to produce composite data, such as blending layers or painting. Selecting
this option blends the RGB colors in the color space based on the gamma setting specified.

A gamma of 1.00 is considered “colorimetrically correct” and likely provides the fewest
edge artifacts.
Note
When you use Blend RGB Colors Using Gamma, layered documents look different when viewed in other
applications than they appear in Photoshop. n
Assigning color profiles to images
Photoshop allows you to assign color profiles to images. If the image already contains an embedded
color profile, that color profile is replaced with the newly assigned color profile, but the level
values in the image do not change.
To assign a color profile to an image, open the image in Photoshop and select Edit ➪ Assign Profile
from the main menu. A dialog box similar to the one shown in Figure 29.6 is displayed, and you
can set the following options:
Caution
Because layer adjustments, filters, and blending modes are based on the original colors, assigning a color
profile to the image may alter the appearance of the layers. You should always assign a color profile to the
image before you begin editing it if possible. n
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Don’t Color Manage This Document: This removes any color profiles from the document
that currently exist, and Photoshop displays the image according to the current working
color space.
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Working [Color Model] [Color Profile]: This adds the current working color profile to
the image and uses that profile to display it while editing.
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Profile: This allows you to select a color profile from a drop-down list that is embedded
in the image. Which color profile is used to display the image depends on the color
management settings described earlier.
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FIGURE 29.6
Using the Edit ➪ Assign Profile option, you can add a color profile to an image or replace the currently
embedded color profile.
Converting images to other color profiles
Photoshop allows you to convert images from one color profile to another. If the image already
contains an embedded color profile, you likely want to keep the colors intact when moving from
one profile to the next. Converting color profiles uses the color profile in the image to convert the
color levels to match a new color profile and then embeds the new color profile in the image.
To convert an image from one color profile to another, open the image in Photoshop and select
Edit ➪ Convert to Profile from the main menu. A dialog box similar to the one shown in
Figure 29.7 is displayed. Clicking the advanced option expands the dialog box; you can set the
following options:
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Source Space: This displays the source color space that was already embedded in the
image.
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Destination Space: In the basic dialog box, this option allows you to select the ICC
profile to convert the image. In the Advanced dialog box, this option allows you to select
the color mode and color profile to use when converting the image. This option often is a
better method to change the color mode because it gives you direct control over both the
color mode and color profile.
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Conversion Options: The Engine, Intent, Use Black Point Compensation, and Use Dither
options were discussed earlier in this chapter. The Flatten Image to Preserve Appearance
option is provided to overcome the problem of blending layers. The problem with blending
layers is that converting the layers individually and then flattening results in a different
pixel color than flattening first and then converting. This can be a tough choice if you are

relying on using the layers later.
FIGURE 29.7
Using the Edit ➪ Convert to Profile option, you can use the currently embedded color profile in an image
to convert the image to another color profile and embed that color profile.
Proofing images using color management
In addition to embedding color profiles in images and setting the working color management set-
tings, Photoshop provides quick proofing of images to see how they will appear in some of the
common color profiles. This process is known as soft proofing.
To set up the proofing color space, select View ➪ Proof Setup and then select the color space from
the main menu. The selected color space is used when proofing. Selecting View ➪ Proof Setup ➪
Custom displays the Customize Proof Condition dialog box, shown in Figure 29.8, where you can
set the following customized color proofing options:
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Device to Simulate: This allows you to select the color or device profile to use when
proofing the colors in the image.
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