Adobe 22020737 Acrobat X Pro Manual - Page 418

USING ACROBAT X PRO 412 Printing A B C D Line screens A. 65 lpi: Coarse screen for printing newsletters and grocery coupons B. 85 lpi: Average screen for printing newspapers C. 133 lpi: High-quality screen for printing four-color magazines D. 177 lpi: Very fine screen for printing annual reports and images in art books The PPD files for high-resolution imagesetters offer a wide range of possible screen frequencies, paired with various imagesetter resolutions. The PPD files for low-resolution printers typically have only a few choices for line screens, usually coarser screens of between 53 lpi and 85 lpi. The coarser screens, however, give optimum results on low-resolution printers. Using a finer screen of 100 lpi, for example, actually decreases the quality of your image when you use a low-resolution printer for final output. Specify halftone screen frequency ❖ In the Output panel of the Advanced Print Setup dialog box, do one of the following: • To select one of the preset screen frequencies and printer resolution combinations, choose an option from the Screening menu. • To specify a custom halftone screen frequency, in the ink list, select the plate to be customized, and then enter the lpi value in the Frequency box and a screen angle value in the Angle box. Note: Before creating your own halftone screens, check with your print service provider for the preferred frequencies and angles. Also, be aware that some output devices override the default frequencies and angles. About emulsion and image exposure Depending on the type of printing press used and how information is transferred from the film to the printing plates, you may need to give your service provider film negatives or positives, with emulsion side up or down. Emulsion refers to the photosensitive layer on a piece of film or paper. Typically, print service providers require negative film in the United States and positive film in Europe and Japan. Check with your service provider to determine which emulsion direction they prefer. To tell whether you are looking at the emulsion side or the nonemulsion side (also referred to as the base), examine the final film under a good light. One side appears shinier than the other. The dull side is the emulsion side; the shiny side is the base. Last updated 10/11/2011