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From the author of How Does This Apply to Acrobat?

How Does This Apply to Acrobat?

The Macintosh and Windows have long had built-in support for CIE-based color management. On the Mac, you can go to the Displays preferences (among the System Preferences) and select a Display profile, which lets the Mac adjust all colors so they look correct on your screen (Figure 4). Windows has a similar mechanism in its Control Panel.

Figure 4 The Mac and Windows use a system-wide color profile to adjust document RGB values for the computer display.

Acrobat uses these system-wide profiles when it displays a PDF document on the screen or sends it to your printer. (Printer color profiles are installed as part of the printer driver.)

Say you design a brochure on your iMac; you design by eye, selecting colors for your artwork so that it looks beautifuliscious on your iMac display. When you export the brochure to a PDF file, the design software stores in the file the RGB values for your graphics together with the color profile for your display device; the final PDF file contains your RGB colors and, in effect, the instructions for converting those colors to XYZ.

When somebody opens your PDF file on his computer system (a Toshiba laptop, perhaps), his copy of Acrobat uses the color profile in the PDF file to convert your original color values to the corresponding XYZ and then, using the Toshiba display’s color profile, converts those XYZ values to RGB values appropriate to the laptop’s monitor (Figure 5). The Toshiba will display RGB values that look just like the Macintosh RGB values you chose when you created the document.

Figure 5 Colors in your original design are stored in a PDF file together with the color profile for the design computer’s monitor. When the file is opened on another computer, Acrobat uses the profile to convert the RGB values to XYZ and then uses the new computer’s display profile to convert the XYZ values to RGB appropriate to that display.

What you saw is what they get.

If a PDF document contains colors that don’t have associated profiles, Acrobat will apply a default color profile. Acrobat has separate default profiles for RGB, CMYK, and Gray values, and it applies the appropriate profile to any uncalibrated colors it finds in a PDF file. You can set these default profiles in the Acrobat preferences (Figure 6), but I counsel against it unless you have a good reason (and know what you’re doing); the default defaults are perfectly reasonable.

Figure 6 Acrobat maintains a set of default color profiles it can apply to uncalibrated colors within a PDF file.

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