Overprint preview provides an onscreen simulation that approximates blending and overprinting in the color-separated output. Overprinting effects can also be simulated when you output to a composite printing device. Both of these methods are useful for proofing color-separated documents.
When you print a color-managed RGB or CMYK document, you can specify additional color management options to keep color consistent in the output. For example, suppose the document contains a profile tailored for prepress output, but you want to proof the colors on a desktop printer. In the Color Management panel of the Advanced Print settings dialog box, you can temporarily convert the document’s colors to the color space of the desktop printer—the printer profile is used instead of the current document profile when printing. In addition, you can send color data as RGB values to printers using various RGB profiles.
When you print a color PDF, all of the colors used in the file print on one plate. This process is called composite printing. The options available in the Output panel of the Advanced Print Setup dialog box depend on the selected printer.
Artwork that will be commercially reproduced and that contains more than a single color must be printed on separate master plates, one for each color. This process is called color separation. If you’re creating color separations, you can print a color or grayscale composite proof to check your work.
Consider the following issues when printing composites:
Any overprinting options that you select print correctly only on a printer that supports overprinting. Since most desktop printers don’t support overprinting, you can simulate the effects of overprinting by selecting Simulate Overprinting in the Output panel of the Advanced Print Setup dialog box. Be aware that selecting Simulate Overprinting converts spot colors to process colors for printing. If you intend to use a file for final output, do not select this option.
When you print to a black-and-white printer, a grayscale composite version of the pages is produced (unless you select Print Color As Black in the main Print dialog box; this option prints all nonwhite color as black). If the document contains color, visually correct grays are used to simulate that color. For example, the gray that simulates a 20% tint of yellow is lighter than a 20% tint of black, since yellow is visually lighter than black.
Remember that, like monitors, color printers vary greatly in color reproduction quality; thus, proofs from your service provider are the best way to verify how the finished piece will look.
To produce high-quality separations, it helps to be familiar with the basics of printing, including line screens, resolution, process colors, and spot colors.
If you are using a print service provider to produce separations, you’ll want to work closely with its experts before beginning each job and during the process.
To reproduce color and continuous-tone images, printers usually separate artwork into four plates—one plate for each of the cyan (C), yellow (Y), magenta (M), and black (K) portions of the image. When inked with the appropriate color and printed in register with one another, these colors combine to reproduce the original artwork. The process of dividing the image into two or more colors is called color separating, and the films from which the plates are created are called the separations.
Acrobat supports host-based separations and in-RIP separations. The main difference between them is where the separations are created—at the host computer (the system using Acrobat and the printer driver) or at the output device’s RIP.
For host-based separations, Acrobat creates PostScript information for each of the separations required for the document and sends that information to the output device. For in-RIP separations, the work of separating a file is performed by the RIP. This method often takes less time than creating host-based separations, but it requires a PostScript 3 output device with in-RIP separation capability. To produce in-RIP separations, you need a PPD file that supports in-RIP separations, and any PostScript 3 output device or a PostScript Level 2 device whose RIP supports in-RIP separations.
- Calibrate your monitor. See Calibrate and profile your monitor.
- Specify whether the document contains trapping information, if known. See Declare the presence of trapping information.
- Preview separations and transparency flattening results. See Preview color separations and Preview which areas of artwork will be flattened.
- Run preflight inspections using desired criteria. See Preflight profiles.
If you use a print service provider to produce separations, you’ll want to work closely with its experts before beginning each job and throughout the process.
For more information on high-end PDF printing, see:
Adobe PDF in the Print Production Workflow: www.adobe.com/studio/print/pdfs/PDF_wp_A9_updates_july08.pdf.
If you are sending your PDF files to a print service provider, you can use the Document Properties dialog box to specify whether a PDF contains trapping information. This detail can help prevent the service provider from adding potentially conflicting trapping commands to the file. Trapping information can either be imported with other PostScript information from the authoring application, or it can be created in Acrobat using trapping presets supported by Adobe In-RIP Trapping.
Depending on the prepress software available, a service provider may be able to perform such prepress activities as trapping, imposition, separating, and OPI replacement at the output device’s RIP. Therefore, your service provider may prefer to receive a composite PostScript file of the document optimized for in-RIP separations rather than a preseparated PostScript file.
Saving the file as PostScript preserves the separation settings, the PPD information, and any color conversions you have specified in the Advanced Print Setup dialog box.
For best results when generating PostScript for reuse in a print production workflow, use the Save As command rather than the Print To File option available in the Print dialog box.