Producing Consistent Color

Producing Consistent Color

(Photoshop)

Why colors sometimes don't match

No device in a publishing system is capable of reproducing the full range of colors viewable to the human eye. Each device operates within a specific color space, which can produce a certain range, or gamut, of colors.

The RGB (red, green, blue) and CMYK (cyan, magenta, yellow, black) color modes represent two main categories of color spaces. The gamuts of the RGB and CMYK spaces are very different; while the RGB gamut is generally larger (that is, capable of representing more colors) than CMYK, some CMYK colors still fall outside the RGB gamut. (See "Color gamuts

(Photoshop)" on section 91 for an illustration.) In addition, different devices produce slightly different gamuts within the same color mode. For example, a variety of RGB spaces can exist among scanners and monitors, and a variety of CMYK spaces can exist among printing presses.

Because of these varying color spaces, colors can shift in appearance as you transfer documents between different devices. Color variations can result from different image sources (scanners and software produce art using different color spaces), differences in the way software applications define color, differences in print media (newsprint paper reproduces a smaller gamut than magazine-quality paper), and other natural variations, such as manufacturing differences in monitors or monitor age.

About color management

Because color-matching problems result from various devices and software that use different color spaces, one solution is to have a system that interprets and translates color accurately between devices. A color management system (CMS) compares the color space in which a color was created to the color space in which the same color will be output, and makes the necessary adjustments to represent the color as consistently as possible among different devices.

Note: Don't confuse color management with color adjustment or color correction. A CMS won't correct an image that was saved with tonal or color balance problems. It provides an environment where you can evaluate images reliably in the context of your final output.

Photoshop follows a color management workflow based on conventions developed by the International Color Consortium (ICC). The following elements and concepts are integral to such a color-managed workflow.

Color management engine Different companies have developed various ways to manage color. To provide you with a choice, a color management system lets you choose a color management engine that represents the approach you want to use. Sometimes called the color management module (CMM), the color management engine is the part of the CMS that does the work of reading and translating colors between different color spaces. Color numbers Each pixel in an image document has a set of color numbers that describe the pixel's location in a particular color mode-for example, red, green, and blue values for the RGB mode. However, the actual appearance of the pixel may vary when output or displayed on different devices, because each device has a particular way of translating the raw numbers into visual color. (See "Why colors sometimes don't match" on section 102.) When you apply color and tonal adjustments or convert a document to a different color space, you are changing the document's color numbers.

Color profiles An ICC workflow uses color profiles to determine how color numbers in a document translate to actual color appearances. A profile systematically describes how color numbers map to a particular color space, usually that of a device such as a scanner, printer, or monitor. By associating, or tagging, a document with a color profile, you provide a definition of actual color appearances in the document; changing the associated profile changes the color appearances. (For information on displaying the current profile name in the status bar, see "Displaying file and image information" on section 48.) Documents without associated profiles are known as untagged and contain only raw color numbers. When working with untagged documents, Photoshop uses the current working space profile to display and edit colors. (See "About working spaces" on section 106.)

Do you need color management?

Use the following guidelines to determine whether or not you need to use color management:

. You might not need color management if your production process is tightly controlled for one medium only, for example, if you're using a closed system where all devices are calibrated to the same specifications. You or your prepress service provider may prefer to tailor CMYK images and specify color values for a known, specific set of printing conditions.

. You also might not need color management if you are producing images for the Web or other screen-based output, since you cannot control the color management settings of monitors displaying your final output. It is helpful, however, to use the Web Graphics Defaults setting when preparing such images, because this setting reflects the average RGB space of many monitors. (See "Using predefined color management settings" on section 105.)

. You can benefit from color management if you have more variables in your production process (for example, if you're using an open system with multiple platforms and multiple devices from different manufacturers). Color management is recommended if you anticipate reusing color graphics for print and online media, if you manage multiple workstations, or if you plan to print to different domestic and international presses. If you decide to use color management, consult with your production partners-such as graphic artists and prepress service providers-to ensure that all aspects of your color management workflow integrate seamlessly with theirs.

Creating a viewing environment for color management Your work environment influences how you see color on your monitor and on printed output. For best results, control the colors and light in your work environment by doing the following:

. View your documents in an environment that provides a consistent light level and color temperature. For example, the color characteristics of sunlight change throughout the day and alter the way colors appear on your screen, so keep shades closed or work in a windowless room. To eliminate the blue-green cast from fluorescent lighting, consider installing D50 (5000 degree Kelvin) lighting. Ideally, view printed documents using a D50 lightbox or using the ANSI PH2.30 viewing standard for graphic arts.

. View your document in a room with neutral-colored walls and ceiling. A room's color can affect the perception of both monitor color and printed color. The best color for a viewing room is polychromatic gray. Also, the color of your clothing reflecting off the glass of your monitor may affect the appearance of colors on-screen.

. Match the light intensity in the room or variable lightbox to the light intensity of your monitor. View continuous-tone art, printed output, and images on-screen under the same intensity of light.

. Remove colorful background and user-interface patterns on your monitor desktop. Busy or bright patterns surrounding a document interfere with accurate color perception. Set your desktop to display neutral grays only.

. View document proofs in the real-world conditions under which your audience will see the final piece. For example, you might want to see how a housewares catalog looks under the incandescent lightbulbs used in homes, or view an office furniture catalog under the fluorescent lighting used in offices. However, always make final color judgments under the lighting conditions specified by the legal requirements for contract proofs in your country.

Setting up color management

Photoshop simplifies the task of setting up a color-managed workflow by gathering most color management controls in a single Color Settings dialog box. You can choose from a list of predefined color management settings, or you can adjust the controls manually to create your own custom settings. You can even save customized settings to share them with other users and other Adobe applications, such as Illustrator 9.0, that use the Color Settings dialog box.

Photoshop also uses color management policies, which determine how to handle color data that does not immediately match your current color management workflow. Policies provide guidelines on what to do when you open a document or import color data into an active document.

To specify color management settings:

1 Do one of the following:

. In Windows and Mac OS 9.x, choose Edit > Color Settings.

. In Mac OS X, choose Photoshop > Color Settings.

To display helpful descriptions of the options that appear in the dialog box, position the pointer over a section heading or menu item. These descriptions appear in the

lower area of the dialog box.

2 Do one of the following:

. To set up a predefined color management workflow, see "Using predefined color management settings" on section 105.

. To customize your own color management settings, see "Customizing color management settings" on section 107.

Using predefined color management settings

Photoshop offers a collection of predefined color management settings designed to produce consistent color for a common publishing workflow, such as preparation for Web or offset press output. In most cases, the predefined settings will provide sufficient color management for your needs. These settings can also serve as starting points for custom- izing your own workflow-specific settings.

To choose a predefined color management setting, choose one of the following options from the Settings menu in the Color Settings dialog box.

Color Management Off Uses passive color management techniques to emulate the behavior of applications that do not support color management. Although working space profiles are considered when converting colors between color spaces, Color Management Off does not tag documents with profiles. Use this option for content that will be output on video or as on-screen presentations; do not use this option if you work mostly with documents that are tagged with color profiles.

ColorSync Workflow (Mac OS only) Manages color using the ColorSync CMS with the profiles chosen in the ColorSync control panel. Use this option if you want to use color management with a mix of Adobe and non-Adobe applications. This color management configuration is not recognized by Windows systems, or by versions of ColorSync earlier than 3.0.

Emulate Photoshop 4 Emulates the color workflow used by the Mac OS version of

Adobe Photoshop 4.0 and earlier.

Europe Prepress Defaults Manages color for content that will be output under common press conditions in Europe.

Japan Prepress Defaults Manages color for content that will be output under common press conditions in Japan.

Photoshop 5 Default Spaces Preparation of content using the default working spaces from Photoshop 5.

U.S. Prepress Defaults Manages color for content that will be output under common press conditions in the U.S.

Web Graphics Defaults Manages color for content that will be published on the World

Wide Web.

When you choose a predefined configuration, the Color Settings dialog box updates to display the specific color management settings associated with the configuration. About working spaces

Among other options, predefined color management settings specify the color profiles to be associated with the RGB, CMYK, and Grayscale color modes. The settings also specify the color profile for spot colors in a document. Central to the color management workflow, these profiles are known as working spaces. The working spaces specified by predefined settings represent the color profiles that will produce the best color fidelity for several common output conditions. For example, the U.S. Prepress Defaults setting uses a CMYK working space that is designed to preserve color consistency under standard Specifica- tions for Web Offset Publications (SWOP) press conditions.

A working space acts as the color profile for untagged documents and newly created documents that use the associated color mode. For example, if Adobe RGB (1998) is the current RGB working space, each new RGB document that you create will use colors within the Adobe RGB (1998) color space. Working spaces also define the destination color space of documents converted to RGB, CMYK, or Grayscale color mode.

About color management policies

When you specify a predefined color management setting, Photoshop sets up a color management workflow that will be used as the standard for all documents and color data that you open or import. For a newly created document, the color workflow operates relatively seamlessly: the document uses the working space profile associated with its color mode for creating and editing colors.

However, it is common to encounter the following exceptions to your color-managed workflow:

. You might open a document or import color data (for example, by copying and pasting or dragging and dropping) from a document that is not tagged with a profile. This is often the case when you open a document created in an application that either does not support color management or has color management turned off.

. You might open a document or import color data from a document that is tagged with a profile different from the current working space. This may be the case when you open a document that has been created using different color management settings, or a document that has been scanned and tagged with a scanner profile.

In either case, Photoshop must decide how to handle the color data in the document. A color management policy looks for the color profile associated with an opened document or imported color data, and compares the profile (or lack of profile) with the current working space to make default color management decisions. If the profile is missing or does not match the working space, Photoshop displays a message that

indicates the default action for the policy. In many cases you will also be provided with the opportunity to choose another action. For detailed information on the color management decisions associated with different policies, see "Specifying color management policies" on section 108.

Working with policy warnings and messages

The predefined color management workflows are set to display warning or option messages when a default color management policy is about to be used. Although you can disable the repeated display of some warnings and messages by selecting the Don't Show Again option, it is highly recommended that you continue to display all policy messages, to ensure the appropriate color management of documents on a case-by-case basis.

(See "Resetting all warning dialogs" on section 56.) You should only turn off message displays if you are very confident that you understand the default policy decision and are willing to accept it for all documents that you open. You cannot undo the results of a default policy decision once a document has been saved.

Customizing color management settings

Although the predefined settings should provide sufficient color management for many publishing workflows, you may sometimes want to customize individual options in a configuration. For example, you might want to change the CMYK working space to a profile that matches the proofing system used by your printer or your service bureau.

It's important to save your custom configurations so that you can reuse and share them with other users and Adobe applications that use the same color management workflows. The color management settings that you customize in the Color Settings dialog box are contained in an associated preferences file called Color Settings.

Note: The default location of the Color Settings file varies by operating system; use your operating system's Find command to locate this file.

To customize color management settings:

1 Do one of the following:

. In Windows and Mac OS 9.x, choose Edit > Color Settings.

. In Mac OS X, choose Photoshop > Color Settings.

2 To use a preset color management configuration as the starting point for your customi- zation, choose that configuration from the Settings menu.

3 Specify the desired color settings (working spaces and policies). As you make adjust- ments, the Settings menu option changes to Custom by default.

For detailed customization instructions, see "Specifying working spaces" on section 107,

"Specifying color management policies" on section 108, and "Customizing advanced color management settings" on section 110.

4 Save your custom configuration so that it can be reused. (See "Saving and loading color management settings" on section 112.)

Specifying working spaces

In a color-managed workflow, each color mode must have a working space profile associated with it. (See "About working spaces" on section 106.) Photoshop ships with a standard set of color profiles that have been recommended and tested by Adobe Systems for most color management workflows. By default, only these profiles appear in the working space menus.

To display additional color profiles that you have customized or installed on your system, select Advanced Mode in the Color Settings dialog box. To appear in a working space menu, a color profile must be bidirectional, that is, contain specifications for translating both into and out of color spaces. You can also create a custom RGB, CMYK, Grayscale, or Spot working space profile to describe the color space of a particular output or display device. (See "Creating custom RGB profiles" on section 120, "Creating custom CMYK profiles" on section 121, and "Creating custom grayscale and spot-color profiles" on section 125.)

For information about a specified RGB or CMYK working space profile, see the Description area of the Color Settings dialog box. (See "Setting up color management" on section 104.) The following information can help you specify an appropriate Gray or Spot working space:

. For images that will be printed, you can specify a Gray or Spot working space profile that is based on the characteristics of a particular dot gain. Dot gain occurs when a printer's halftone dots change as the ink spreads and is absorbed by paper. Photoshop calculates dot gain as the amount by which the expected dot increases or decreases. For example, a 50% halftone screen may produce an actual density of 60% on the printed page, exhibiting a dot gain of 10%. The Dot Gain 10% option represents the color space that reflects the grayscale characteristics of this particular dot gain.

Proof (no dot gain), and printed image (with dot gain)

. For images that will be used online or in video, you can also specify a Gray working space profile that is based on the characteristics of particular gamma. A monitor's gamma setting determines the brightness of midtones displayed by the monitor. Gray Gamma 1.8 matches the default grayscale display of Mac OS computers and is also the default grayscale space for Photoshop 4.0 and earlier. Gray Gamma 2.2 matches the default grayscale display of Windows computers.

Specifying color management policies

Each predefined color management configuration sets up a color management policy for the RGB, CMYK, and Grayscale color modes and displays warning messages to let you override the default policy behavior on a case-by-case basis. If desired, you can change the default policy behavior to reflect a color management workflow that you use more often. For more information on policies, see "About color management policies" on section 106.

To customize color management policies:

1 In the Color Settings dialog box, under Color Management Policies, choose one of the following to set the default color management policy for each color mode:

. Off if you do not want to color-manage new, imported, or opened color data.

. Preserve Embedded Profiles if you anticipate working with a mix of color-managed and non-color-managed documents, or with documents that use different profiles within the same color mode.

. Convert to Working Space if you want to force all documents to use the current working space.

For detailed descriptions of the default behaviors associated with each policy option, see the table following this procedure.

2 For Profile Mismatches, select either, both, or neither of the following:

. Ask When Opening to display a message whenever you open a document tagged with a profile other than the current working space. You will be given the option to override the policy's default behavior.

. Ask When Pasting to display a message whenever color profile mismatches occur as colors are imported into a document (via pasting, drag-and-drop, placing, and so on). You will be given the option to override the policy's default behavior.

The availability of options for Profile Mismatches depends on which policies have been specified.

3 For Missing Profiles, select Ask When Opening to display a message whenever you open an untagged document. You will be given the option to override the policy's default behavior.

The availability of options for Missing Profiles depends on which policies have been specified.

It is strongly recommended that you keep the Ask When Opening and Ask When Pasting options selected.

Policy option Default color management behavior

Off . New documents and existing untagged documents remain untagged.

. Existing documents tagged with a profile other than the current working space become untagged.

. Existing documents tagged with the current working space profile remain tagged.

. For color data imported into a document using the same color mode, color numbers are preserved.

. For all other import cases, colors are converted to the document's color space.

Policy option Default color management behavior

Preserve Embedded

Profiles

. New documents are tagged with the current working space profile.

. Existing documents tagged with a profile other than the current working space remain tagged with the original embedded profile.

. Existing untagged documents use the current working space for editing but remain untagged.

. For color data imported within the same color mode between either a non-color-managed source or destination, or from a CMYK document into a CMYK document, color numbers are preserved.

. For all other import cases, colors are converted to the document's color space.

Convert to Working Space . New documents are tagged with the current working space profile.

. Existing documents tagged with a profile other than the current working space are converted to and tagged with the working space profile.

. Existing untagged documents use the current working space for editing but remain untagged.

. For color data imported within the same color mode between either a non-color-managed source or destination, color numbers are preserved.

. For all other import cases, colors are converted to the document's color space.

Customizing advanced color management settings

When you select Advanced Mode at the top of the Color Settings dialog box, you have the option of further customizing settings used for color management.

Specifying a color management engine

The color management engine specifies the system and color-matching method used to convert colors between color spaces. For information about the specified engine, see the Description area of the Color Settings dialog box. (See "Setting up color management" on section 104.)

Specifying a rendering intent

Converting colors to a different color space usually involves an adjustment of the colors to accommodate the gamut of the destination color space. Different translation methods use different rules to determine how the source colors are adjusted; for example, colors that fall inside the destination gamut may remain unchanged, or they may be adjusted to preserve the original range of visual relationships as translated to a smaller destination gamut. These translation methods are known as rendering intents because each technique is optimized for a different intended use of color graphics.

Note: The result of choosing a rendering intent depends on the graphical content of documents and on the profiles used to specify color spaces. Some profiles produce identical results for different rendering intents. Differences between rendering intents are apparent only when you print a document or convert it to a different color space.

The following rendering intent options are available.

Perceptual Known as the Image intent in Adobe PageMaker and Illustrator 8, Perceptual aims to preserve the visual relationship between colors in a way that is perceived as natural to the human eye, although the color values themselves may change. This intent is most suitable for photographic images.

Saturation Known as the Graphics intent in Adobe PageMaker and Illustrator 8, Saturation aims to create vivid color at the expense of accurate color. It scales the source gamut to the destination gamut, but preserves relative saturation instead of hue, so when scaling to a smaller gamut, hues may shift. This rendering intent is suitable for business graphics, where the exact relationship between colors is not as important as having bright saturated colors.

Relative Colorimetric This intent is identical to Absolute Colorimetric except for the following difference: Relative Colorimetric compares the white point of the source color space to that of the destination color space and shifts all colors accordingly. Although the perceptual rendering intent has traditionally been the most common choice for photo- graphic imagery, Relative Colorimetric -with the Use Black Point Compensation option selected in the Color Settings dialog box-can be a better choice for preserving color relationships without sacrificing color accuracy. Relative Colorimetric is the default rendering intent used by all predefined configurations in the Settings menu of the Color Settings dialog box.

Absolute Colorimetric Leaves colors that fall inside the destination gamut unchanged. This intent aims to maintain color accuracy at the expense of preserving relationships between colors. When translating to a smaller gamut, two colors that are distinct in the source space may be mapped to the same color in the destination space. Absolute Colori- metric can be more accurate if the image's color profile contains correct white point

(extreme highlight) information.

Using black-point compensation

The Use Black Point Compensation option controls whether to adjust for differences in black points when converting colors between color spaces. When this option is selected, the full dynamic range of the source space is mapped into the full dynamic range of the destination space. When deselected, the dynamic range of the source space is simulated in the destination space; although this mode can result in blocked or gray shadows, it can be useful when the black point of the source space is darker than that of the destination space.

The Use Black Point Compensation option is selected for all predefined configurations in the Settings menu of the Color Settings dialog box. It is highly recommended that you keep this option selected.

Using dither

The Use Dither (8-bit/channel images) option controls whether to dither colors when converting 8-bit-per-channel images between color spaces. When this option is selected, Photoshop mixes colors in the destination color space to simulate a missing color that existed in the source space. Although dithering helps to reduce the blocky or banded appearance of an image, it may also result in larger file sizes when images are compressed for Web use.

Desaturating monitor colors

The Desaturate Monitor Colors By option controls whether to desaturate colors by the specified amount when displayed on the monitor. When selected, this option can aid in visualizing the full range of color spaces with gamuts larger than that of the monitor. However, this causes a mismatch between the monitor display and the output. When the option is deselected, distinct colors in the image may display as a single color. Blending RGB colors

The Blend RGB Colors Using Gamma option controls how RGB colors blend together to produce composite data (for example, when you blend or paint layers using Normal mode). When the option is selected, RGB colors are blended in the color space corre- sponding to the specified gamma. A gamma of 1.00 is considered "colorimetrically correct" and should result in the fewest edge artifacts. When the option is deselected, RGB colors are blended directly in the document's color space.

Saving and loading color management settings

When you create a custom color management configuration, you should name and save the configuration to ensure that it can be shared with other users and applications that use the Color Settings dialog box, such as Adobe Illustrator and Adobe InDesign. You can also load previously saved color management configurations into the Color Settings dialog box.

To save a custom color management configuration:

1 In the Color Settings dialog box, click Save.

2 Name your color settings file, and click Save.

To ensure that the saved configuration appears in the Settings menu of the Color Settings dialog box, save the file in one of the following recommended locations:

. (Windows) Program Files/Common Files/Adobe/Color/Settings.

. (Mac OS 9.x) System Folder/Application Support/Adobe/Color/Settings.

. (Mac OS X) User/CurrentUser/Library/Application Support/Adobe/Color/Settings.

3 Enter any comments that you want to associate with the configuration, and click OK. The comments that you enter will appear in the Description area of the Color Settings dialog box when the pointer is positioned over the configuration in the Settings menu. To load a color management configuration:

1 In the Color Settings dialog box, click Load.

2 Locate and select the desired color settings file, and click Load.

When you load a custom color settings file, it appears as the active choice in the Settings menu of the Color Settings dialog box. If you load a settings file that has been saved outside the recommended location, it temporarily replaces the Other option in the Settings menu until another settings file is loaded.

Synchronizing color management between applications

The Color Settings dialog box represents the common color management controls shared by several Adobe applications, including Photoshop, Illustrator, and InDesign. If you modify and save over the current color settings file in any application other than Photoshop, you may be prompted to synchronize the common color settings upon starting Photoshop or upon reopening the Color Settings dialog box in Photoshop. Synchronizing the color settings helps to ensure that color is reproduced consistently between Adobe applications that use the Color Settings dialog box. To share custom color settings between applications, be sure to save and load the settings file in the desired applications. (See "Saving and loading color management settings" on section 112.)

Soft-proofing colors

A B C

Color-managed workflow:

A. Document space B. Proof space C. Monitor space

Keep in mind that the reliability of the soft proof is highly dependent upon the quality of your monitor, your monitor and printer profiles, and the ambient lighting conditions of your work station. (See "Creating an ICC monitor profile" on section 117.)

To display a soft proof:

1 Choose View > Proof Setup, and choose the proof profile space that you want to simulate:

. Custom soft-proofs colors using the color profile of a specific output device. Follow the instructions after this procedure to set up the custom proof.

. Working CMYK soft-proofs colors using the current CMYK working space as defined in the Color Settings dialog box.

. Working Cyan Plate, Working Magenta Plate, Working Yellow Plate, Working Black Plate, or Working CMY Plates soft-proofs specific CMYK ink colors using the current CMYK working space.

. Macintosh RGB or Windows RGB soft-proofs colors in an image using either a standard Mac OS or Windows monitor as the proof profile space to simulate. Neither option is available for Lab or CMYK documents.

. Monitor RGB soft-proofs colors in an RGB document using your current monitor color space as the proof profile space. This option is unavailable for Lab and CMYK documents.

. Simulate Paper White previews the specific shade of white exhibited by the print medium defined by a document's profile. This option is not available for all profiles and is available only for soft-proofing, not printing.

. Simulate Ink Black previews the actual dynamic range defined by a document's profile. This option is not available for all profiles and is available only for soft-proofing, not printing.

2 Choose View > Proof Colors to turn the soft-proof display on and off. When soft proofing is on, a check mark appears next to the Proof Colors command.

When soft proofing is on, the name of the current proof profile appears next to the color mode in the document's title bar.

To create a custom proof setup:

1 Choose View > Proof Setup > Custom.

If you want the custom proof setup to be the default proof setup for documents, close all document windows before choosing the View > Proof Setup > Custom command.

2 Select Preview to display a live preview of the proof settings in the document while the

Proof Setup dialog box is open.

3 To use a preset proof setup as a starting point, choose it from the Setup menu. If the desired setup does not appear in the menu, click Load to locate and load the setup.

4 For Profile, choose the color profile for the device for which you want to create the proof.

5 If the proof profile you chose uses the same color mode as the document, do one of the following:

. Select Preserve Color Numbers to simulate how the document will appear without converting colors from the document space to the proof profile space. This simulates the color shifts that may occur when the document's color values are interpreted using the proof profile instead of the document profile.

. Deselect Preserve Color Numbers to simulate how the document will appear if colors are converted from the document space to their nearest equivalents in the proof profile space in an effort to preserve the colors' visual appearances. Then specify a rendering intent for the conversion. (See "Specifying a rendering intent" on section 110.)

6 If needed, select any of the following:

. Simulate Paper White to preview, in the monitor space, the specific shade of white exhibited by the print medium described by the proof profile. Selecting this option automatically selects the Simulate Ink Black option.

. Simulate Ink Black to preview, in the monitor space, the actual dynamic range defined by the proof profile.

The availability of these options depends on the proof profile chosen. Not all profiles support both options.

7 To save your custom proof setup as a preset proof setup, click Save. To ensure that the new preset appears in the View > Proof Setup menu, save the preset in the Program Files/ Common Files/Adobe/Color/Proofing folder ( Windows), System Folder/Application Support/Adobe/Color/Proofing folder (Mac OS 9.x), or Library/Application Support/ Adobe/Color/Proofing folder (Mac OS X).

Changing the color profile of a document

In some cases you may want to convert a document's colors to a different color profile, tag a document with a different color profile without making color conversions, or remove the profile from a document altogether. For example, you may want to prepare the document for a different output destination, or you may want to correct a policy behavior that you no longer want implemented on the document. The Assign Profile and Convert to Profile commands are recommended only for advanced users.

When using the Assign Profile command, you may see a shift in color appearance as color numbers are mapped directly to the new profile space. Convert Profile, however, shifts color numbers before mapping them to the new profile space, in an effort to preserve the original color appearances.

To reassign or discard the profile of a document:

1 Choose Image > Mode > Assign Profile.

2 Select one of the following:

. Don't Color Manage This Document to remove the profile from a tagged document. Select this option only if you are sure that you want the document to become untagged.

. Working color mode: working space to tag the document with the current working space profile.

. Profile to reassign a different profile to a tagged document. Choose the desired profile from the menu. Photoshop tags the document with the new profile without converting colors to the profile space. This may dramatically change the appearance of the colors as displayed on your monitor.

3 To preview the effects of the new profile assignment in the document, select Preview.

To convert colors in a document to another profile:

1 Choose Image > Mode > Convert to Profile.

2 Under Destination Space, choose the color profile to which you want to convert the document's colors. The document will be converted to and tagged with this new profile.

3 Under Conversion Options, specify a color management engine, a rendering intent, and black point and dither options. (See "Customizing advanced color management settings" on section 110.)

4 To flatten all layers of the document onto a single layer upon conversion, select Flatten

Image.

5 To preview the effects of the conversion in the document, select Preview. This preview becomes more accurate if you select Flatten Image.

Embedding profiles in saved documents

By default, a tagged document will have its profile information embedded upon saving in a file format that supports embedded ICC profiles. Untagged documents are saved by default without embedded profiles.

You can specify whether or not to embed a profile as you save a document; you can also specify to convert colors to the proof profile space and embed the proof profile instead. However, changing the profile-embedding behavior is recommended only for advanced users who are familiar with color management.

To change the embedding behavior of a profile in a document:

1 Choose File > Save As.

2 Do one of the following:

. To toggle the embedding of the document's current color profile, select or deselect ICC Profile ( Windows) or Embed Color Profile (Mac OS). This option is available only for the native Photoshop format (.psd) and PDF, JPEG, TIFF, EPS, DCS, and PICT formats.

. To toggle the embedding of the document's current proof profile, select or deselect Use Proof Setup (available for PDF, EPS, DCS 1.0, and DCS 2.0 formats only). Selecting this option converts the document's colors to the proof profile space and is useful for creating an output file for print. For information on setting up a proof profile, see "Soft- proofing colors" on section 113.

3 Name the document, choose other save options, and click Save.

Obtaining, installing, and updating color profiles

Precise, consistent color management requires accurate ICC-compliant profiles of all of your color devices. For example, without an accurate scanner profile, a perfectly scanned image may appear incorrect in another program, simply due to any difference in color space between the scanner and the program displaying the image. This misleading repre- sentation may cause you to make unnecessary, time-wasting, and potentially damaging

"corrections" to an already satisfactory image. With an accurate profile, a program importing the image can correct for any gamut differences and display a scan's actual colors.

Once you obtain accurate profiles, they will work with all applications that are compatible with your color-management system. You can obtain profiles in the following ways, with the most precise methods listed first:

. Generate profiles customized for your specific devices using professional profiling equipment.

. Use the settings in the Custom CMYK dialog box to describe your device, and then save the settings as a color profile. (See "Creating custom CMYK profiles" on section 121.)

. Obtain a profile created by the manufacturer. Unfortunately, such profiles do not account for individual variations that naturally occur among machines (even identical modes from the same manufacturer) or from age.

. Substitute an available profile that may be appropriate for the device's color space. For example, many Mac OS scanners have been optimized for an Apple RGB monitor color space, so you might try using an Apple monitor profile for these devices; for a

non-profiled Windows scanner, try substituting the sRGB color space. Be sure to proof images created with the profile before using the profile in production.

Adding device profiles to the color management system

You can add color profiles to your system so that they appear as choices in the Color Settings dialog box. To minimize confusion when working with profiles, delete any profiles for devices not used by you or your workgroup. Once you have added a profile to the recommended location on your system, you may need to load it or restart Photoshop so that the profile appears in the Color Settings dialog box.

Note: In Mac OS, you can organize the ColorSync Profiles folder by creating additional folders within it, or adding aliases to other folders. However, nested folders may cause conflicts with some applications, such as Adobe PressReady.

To add profiles to your system:

Copy profiles to one of the following recommended locations:

. (Windows 2000) WinNT/System/Spool/Drivers/Color.

. (Windows NT ) WinNT/System32/Color.

. (Windows 98) Windows/System/Color.

. (Mac OS 9.x) System Folder/ColorSync Profiles.

. (Mac OS X) Users/CurrentUser/Library/ColorSync.

Note: If you use ColorSync 2.5 but have used earlier versions, some profiles may still be stored in the System Folder/Preferences/ColorSync^T Profiles folder on your hard disk.

For compatibility with ColorSync 2.5 or later, store profiles in the ColorSync Profiles folder in the System Folder.

Updating profiles

The color reproduction characteristics of a color device change as it ages, so recalibrate devices periodically and generate updated profiles. Profiles should be good for approxi- mately a month depending on the device. Some monitors automatically compensate for phosphor aging.

Also, recalibrate a device when you change any of the factors that affect calibration.

For example, recalibrate your monitor when you change the room lighting or the monitor brightness setting.

Creating an ICC monitor profile

Your monitor will display color more reliably if you use color management and accurate ICC profiles. Using an ICC monitor profile helps you eliminate any color cast in your monitor, make your monitor grays as neutral as possible, and standardize image display across different monitors.

On Windows, you can use the Adobe Gamma software (installed with Photoshop) to create a monitor profile. On Mac OS, you can use the Apple calibration utility to create a monitor profile. In addition, there are hardware-based utilities that you can use to create a monitor profile. Be sure to use only one calibration utility to display your profile; using multiple utilities can result in incorrect color.

Calibrating versus characterizing a monitor

You can use profiling software such as Adobe Gamma ( Windows) or the Apple calibration utility (Mac OS) to both characterize and calibrate your monitor. When you characterize your monitor, you create a profile that describes how the monitor is currently reproducing color. When you calibrate your monitor, you bring it into compliance with a predefined standard, for example, the graphics arts standard white point color temperature of 5000

Kelvin.

Determine in advance the standard to which you are calibrating so that you can enter the set of values for that standard. Coordinate calibration with your workgroup and prepress service provider to make sure you're all calibrating to the same standard. However, if you have implemented a good color management workflow, you need not calibrate all monitors to the same standard; you simply need to characterize each monitor to produce accurate profiles.

About monitor calibration settings

Monitor calibration involves adjusting video settings, which may be unfamiliar to you.

A monitor profile uses these settings to precisely describe how your monitor reproduces color.

Brightness and contrast The overall level and range, respectively, of display intensity. These parameters work just as they do on a television set.

Gamma The brightness of the midtone values. The values produced by a monitor from black to white are nonlinear-if you graph the values, they form a curve, not a straight line. The gamma value defines the slope of that curve halfway between black and white. Gamma adjustment compensates for the nonlinear tonal reproduction of output devices such as monitor tubes.