Color Management Policies Intent Working Spaces Device-Dependent Data By their very natures, a monitor and printer reproduce color in completely different ways. A color management system (CMS) is a collection of software tools designed to reconcile the different color capabilities of scanners, monitors, and printers to ensure consistent color throughout the creation, display, and print process. Ideally, this means that the colors displayed on your monitor accurately represent the colors of the final output. It also means that different applications, monitors, and operating systems will display colors consistently. Color Management Policies Leave Color Unchanged. This option leaves device-dependent colors unchanged and preserves device-independent colors as the nearest possible equivalent in PDF. It is a useful option for print shops that have calibrated all their devices, used that information to specify color in the file, and are only outputting to those devices. Tag (or Convert) Everything for Color Management. With Acrobat 4.0 or 5.0 compatibility selected in the General job options, the Tag Everything for Color Management option lets you embed an ICC profile when distilling files and calibrates color in the images, making colors in the resulting PDF files device-independent. With Acrobat 3.0 compatibility selected, Convert Everything for Color Management does not embed ICC profiles in the files. However, device-dependent color spaces in files (RGB, Grayscale, and CMYK) are converted to device-independent color spaces (CalRGB, CalGray, and LAB). Tag (or Convert) Only Images for Color Management. With Acrobat 4.0 compatibility selected in the General dialog box, the Tag Only Images for Color Management option only embeds ICC profiles in images, not text or graphics, when distilling files. This prevents black text from undergoing any color shift. With Acrobat 3.0 compatibility selected, the Convert Only Images for Color Management option does not embed ICC profiles in the files. However, device-dependent color spaces in images (RGB, Grayscale, and CMYK) are converted to device-independent color spaces (CalRGB, CalGray, and LAB). Text and graphics are not converted. Convert All Colors to sRGB (or Convert Everything to CalRGB). As with the Tag (or Convert) Everything for Color Management option, this option calibrates color in the file, making the color device-independent. With Acrobat 4.0 or 5.0 compatibility selected in the General dialog box, CMYK and RGB images are converted to sRGB. With Acrobat 3.0 compatibility selected, CMYK and RGB images are converted to calibrated RGB (CalRGB). Regardless of the compatibility option you select, grayscale images are left unchanged. This option usually reduces the size and increases the display speed of PDF files because less information is needed to describe RGB images than CMYK images. Because RGB is the native color space used on monitors, no color conversion is necessary during display, which contributes to fast online viewing. This option is recommended if the PDF file will be used online or with low-end printers. Intent The Intent menu allows you to specify how to map colors between color spaces. The result of any particular method depends on the profiles of the color spaces. For example, some profiles produce identical results with different methods: Default means that the intent is specified in the output device rather than in the PDF file. In many output devices, Relative Colorimetric is the default intent. Perceptual maintains the relative color values among the original pixels as they are mapped to the destination gamut. This method preserves the visual relationship between colors, although the color values themselves may change. Saturation maintains the relative saturation values of the original pixels. This method is suitable for business graphics, where the exact relationship between colors is not as important as having bright saturated colors. Relative Colorimetric remaps the white point of the source space to the white point of the destination space. Absolute Colorimetric disables the matching of white and black points when converting colors. This method is not generally recommended unless you must preserve signature colors such as those used in trademarks or logos. Note: In all cases intents may be ignored or overridden by color management operations that occur subsequently to the creation of the PDF file. Working Spaces For Gray, choose a profile to define the color space of all grayscale images in files. This option is available only if you chose Tag Everything for Color Management or Tag Only Images For Color Management. The default ICC profile for gray images is Adobe Gray -20% Dot Gain. You can also choose None to prevent grayscale images from being converted. For RGB, choose a profile to define the color space of all RGB images in files. The default, sRGB IEC61966-2.1, is generally a good choice because it is becoming an industry standard and is recognized by many output devices. You can also choose None to prevent RGB images from being converted. For CMYK, choose a profile to define the color space of all CMYK images in files. The default is U.S. Web Coated (SWOP) v2. You can also choose None to prevent CMYK images from being converted. Note: Choosing None for all three working spaces has the same effect as selecting the option Leave Color Unchanged. Device-Dependent Data Preserve Overprint Settings retains any overprint settings in files being converted to PDF. Overprint colors are two or more inks printed on top of each other. For example, when a cyan ink prints over a yellow ink, the resulting overprint is a green color. Without overprinting, the underlying yellow would not be printed, resulting in a cyan color. Preserve Under Color Removal and Black Generation Settings retains these settings if they exist in the PostScript file. Black generation calculates the amount of black to be used when trying to reproduce a particular color. Undercolor removal (UCR) reduces the amount of cyan, magenta, and yellow components to compensate for the amount of black that was added by the black generation. Because it uses less ink, UCR is generally used for newsprint and uncoated stock. Preserve Halftone Information retains any halftone information in files. Halftone information consists of dots that control how much ink is deposited by halftone devices at a specic location on the paper. Varying the dot size and density creates the illusion of variations of gray or continuous color. For a CMYK image, four halftone screens are used: one for each ink used in the printing process. In traditional print production, a halftone is produced by placing a halftone screen between a piece of film and the image and then exposing the film. Electronic equivalents, such as in Adobe Photoshop, let users specify the halftone screen attributes before producing the film or paper output. As with transfer functions, halftone information is intended for use with a particular output device. Preserve Transfer Functions retains the transfer functions traditionally used to compensate for dot gain or dot loss that may occur when an image is transferred to film. Dot gain occurs when the ink dots that make up a printed image are larger (for example, due to spreading on paper) than in the halftone screen; dot loss occurs when the dots print smaller. With this option, the transfer functions are kept as part of the file, and are applied to the file when the file is output. Transfer functions are used for artistic effect and to correct for the characteristics of a specific output device. For example, a file that is intended for output on a particular imagesetter may contain transfer functions that compensate for the dot gain inherent with that printer. Apply Transfer Functions does not keep the transfer function, but applies it to the file, changing the colors in the file. This is useful for creating color effects in a file. Remove Transfer Functions removes any applied transfer functions. Applied transfer functions should be removed unless the PDF file is to be output to the same device that the source PostScript file was created for.