Color management part 3
Working with color profiles
About 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 between the scanner and the program displaying the image. This misleading representation
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 device differences and display a scan’s actual colors.
A color management system uses the following kinds of profiles:
Monitor profiles Describe howthe monitoriscurrently reproducingcolor.Thisisthe firstprofile youshouldcreate because it is absolutely essential for managing color. If what you see on your monitor is not representative of the actual colors in your document, you will not be able to maintain color consistency.
Input device profiles Describe what colors an input device is capable of capturing or scanning. If your digital camera offers a choice of profiles, Adobe recommends that you select Adobe RGB. Otherwise, use sRGB (which is the default for most cameras). Advanced users may also consider using different profiles for different light sources. For scanner profiles, some photographers create separate profiles for each type or brand of film scanned on a scanner.
Output device profiles Describe the color space of output devices like desktop printers and a printing press. The colormanagementsystemusesoutputdeviceprofilestoproperlymap thecolorsinandocumenttothe colors within the gamut of an output device’s color space. The output profile should also take into consideration specific printing conditions, such as the type of paper and ink. For example, glossy paper is capable of displaying a different range of colors than a matte paper.
Most printer drivers come with built-in color profiles. It’s a good idea to try these profiles before you invest in custom profiles. For information on how to print using the built-in profiles. For information on how to obtain custom profiles.
Document profiles Define the specific RGB or CMYK color space of a document. By assigning, or tagging, a document with a profile, the application provides a definition of actual color appearances in the document. For example, R=127, G=12, B=107 is just a set of numbers that different devices will display differently. But when tagged with the AdobeRGB color space, these numbers specify an actual color or wavelength of light; in this case, a specific color of purple.
When color management is on, Adobe applications automatically assign new documents a profile based on Working Space options in the Color Settings dialog box. Documents without associated profiles are known as untagged and contain only raw color numbers. When working with untagged documents, Adobe applications use the current working space profile to display and edit colors.
About monitor calibration and characterization
Profiling software such as Adobe Gamma can both calibrate and characterize your monitor. Calibrating your monitor brings it into compliance with a predefined standard; for example, adjusting your monitor so that it displays color using the graphics arts standard white point color temperature of 5000 degrees Kelvin. Characterizing your monitor simply creates a profile that describes how the monitor is currently reproducing color.
Monitor calibration involves adjusting the following video settings, which may be unfamiliar to you.
Brightness and contrast The overall level and range, respectively, of display intensity. These parameters work just as they do on a television. Adobe Gamma helps you set an optimum brightness and contrast range for calibration.
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. Gamma defines the value of that curve halfway between black and white.
Phosphors The substances that CRT monitors use to emit light. Different phosphors have different color characteristics.
White point The color and intensity of the brightest white the monitor can reproduce.
To calibrate and profile your monitor
When you calibrate your monitor, you are adjusting it so it conforms to a known specification. Once your monitor is calibrated, the profiling utility lets you save a color profile. The profile describes the color behavior of the monitor—what colors canorcannotbedisplayed on themonitor andhow thenumeric colorvaluesinanimage must be converted so that colors are displayed accurately.
1. Make sure your monitor has been turned on for at least a half hour. This gives it sufficient time to warm up and produce more consistent output.
2. Make sure your monitor is displaying thousands of colors or more. Ideally, make sure it is displaying millions of colors or 24-bit or higher.
3. Remove colorful background patterns on your monitor desktop and set your desktop to display neutral grays. Busy patterns or bright colors surrounding a document interfere with accurate color perception.
4. Do one of the following to calibrate and profile your monitor:
• In Windows, use the Adobe Gamma utility, located in the Control Panel.
• In Mac OS, use the Calibrate utility, located in the System Preferences/Displays/Color tab.
• For the best results, use third-party software and measuring devices. In general, using a measuring device such as a colorimeter along with software can create more accurate profiles because an instrument can measure the colors displayed on a monitor far more accurately than the human eye.
Note: Monitor performance changes and declines over time; recalibrate and profile your monitor every month or so. If you find it difficult or impossible to calibrate your monitor to a standard, it may be too old and faded.
Most profiling software automatically assigns the new profile as the default monitor profile. For instructions on how to manually assign the monitor profile, refer to the Help system for your operating system.
To install a color profile
Colorprofilesare ofteninstalled when adeviceisaddedtoyoursystem. Theaccuracy of theseprofiles(oftencalled generic profiles or canned profiles) varies from manufacturer to manufacturer. You can also obtain device profiles from your service provider, download profiles from the web, or create custom profiles using professional profiling equipment.
• In Windows, right-click a profile and select Install Profile. Alternatively, copy the profiles into the WINDOWSsystem32spooldriverscolor folder (Windows XP) or the WINNTsystem32spooldriverscolor folder (Windows 2000).
• In Mac OS, copy profiles into the /Library/Application Support/Adobe/Color/Profiles/Recommended folder. You can also copy profiles into the /Users/username/Library/ColorSync/Profiles folder.
After installing color profiles, be sure to restart Adobe applications.
To embed a color profile in a document
In order to embed a color profile in a document you created in Photoshop, Illustrator, or InDesign, you must save or export the document in a format that supports ICC profiles.
1. Save or export the document in one of the following file formats: Adobe PDF, PSD (Photoshop), AI (Illustrator), INDD (InDesign), JPEG, or TIFF.
2. Select the option for embedding ICC profiles. The exact name and location of this option varies between applications.
Search Help in the relevant CS2 application for additional instructions.
Changing the color profile for a document
Thereare very fewsituationsthatrequireyou to change thecolor profilefor adocument. This is becauseyourapplication
automatically assigns the color profile based on the settings you select in the Color Settings dialog box. The only times you should manually change a color profile are when preparing a document for a different output destination
or correcting a policy behavior that you no longer want implemented in the document. Changing the profile is recommended for advanced users only.
You can change the color profile for a document in the following ways:
• Assign anew profile. Thecolor numbersinthe document remain thesame, butthe newprofile maydramatically change the appearance of the colors as displayed on your monitor.
• Remove the profile so that the document in no longer color-managed.
• (Photoshop and InDesign) Convert the colors in the document to the color space of a different profile. The color numbers are shifted in an effort to preserve the original color appearances.
To assign or remove a color profile from a document in Photoshop or Illustrator
1. Choose Edit > Assign Profile.
2. Select an option, and click OK:
Don’t Color Manage This Document Removesthe existing profilefromthe document.Selectthisoptiononlyifyou are sure that you do not want to color-manage the document. After you remove the profile from a document, the appearance of colors is defined by the application’s working space profiles, and you can no longer embed a profile in the document.
Working [color model: working space] Assigns the working space profile to the document.
Profile Lets you select a different profile. The application assigns the new profile to the document without converting colors to the profile space. This may dramatically change the appearance of the colors as displayed on your monitor.
To convert colors in a document to another profile
1. In Photoshop or InDesign, choose Edit > 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
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.