Working with Color Pictures


Working with Color Pictures

When you work with imported graphics, whether they are illustrations or scanned photographs, color is part of the graphic file. So the responsibility for color controls lies primarily with the creator of the picture. It is best to use color files in CMYK EPS or DCS format (for illustrations) or CMYK TIFF format (for scans and bitmaps). These standards are de facto for color publishing, so InDesign is particularly adept at working with them. (See Chapter 22 for details on preparing graphics files for import.)

Note ‚  

RGB is the standard color model used by scanners and graphics software because monitors use red, green, and blue electron guns to display images. The dilemma most designers face is that an RGB image displays properly on-screen but may appear with slightly adjusted hues in print, while a CMYK image may print correctly but appear incorrectly on-screen. Most designers get good at mentally shifting the colors from one model to another, as they see the results of their work in print over time. Until that happens, rely on color proofs from your printer to see what your images actually look like when printed.

Caution ‚  

Color files pasted via the clipboard should print properly after they're pasted into an InDesign picture box. But problems do sometimes occur, such as dropped colors or altered colors, depending on the applications involved and the amount of memory available. If you drag files from Photoshop or Illustrator directly into InDesign, rather than use copy and paste, you should have no such problems.

Working with EPS files

InDesign automatically imports color definitions from EPS files, so you'll see any spot colors in them show up in your Color pane and in menus and dialog boxes that display color lists.

Note ‚  

If you create files in EPS format, do any required color trapping in the source application ‚ InDesign offers only basic trapping capabilities (see Chapter 29).

Not all programs encode color information the same way. If you create EPS files in some illustration programs, colors may not print as expected. One of three things can happen:

  • Each color prints on its own plate (as if it were a spot color), even if you defined it as a process color.

  • A spot color is color-separated into CMYK even when you define it as a spot color in both the source program and in InDesign.

  • A color prints as black.

There is no easy solution, since the problem is in how the illustration program manages color internally. The only safe bet is to use a program that uses standard color-definition methods ; these include the latest versions of Adobe Illustrator, CorelDraw, and Macromedia FreeHand.

Working with TIFF files

Color TIFF files do not cause such peculiarities , since they don't use spot colors ‚ by their very nature, they are broken down into RGB or CMYK when they are created.

InDesign can color-separate RGB TIFF files, as well as CMYK TIFF files. You may notice a color shift for color-separated RGB images, or for RGB images printed on a CMYK proofing printer. The degree of shift will depend on the device and whether any color-management system (CMS) plug-ins were used in creating the image, and whether the same one is active in InDesign for printing. Chapter 29 covers this in more detail.

Working with PDF files

InDesign will accurately import any colors used in a PDF file.

Caution ‚  

Even though InDesign doesn't support Hexachrome colors, it does retain any Hexachrome colors in the PDF file and will retain them for output only if you export the InDesign file to PDF format. Otherwise, the Hexachrome colors are converted to CMYK when you print or generate a PostScript file from InDesign. Many Hexachrome colors do not print properly when converted to CMYK, so you should always export InDesign files using Hexachrome PDF images to PDF for output. If that's not possible, edit the original image in the program that generated the PDF, or in a program like Illustrator that can edit PDF files, and choose CMYK colors instead, and then reexport the PDF image.




Adobe InDesign CS Bible
Adobe InDesign CS3 Bible
ISBN: 0470119381
EAN: 2147483647
Year: 2003
Pages: 344
Authors: Galen Gruman

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net