Specifying the printer resolution (the halftone screen ruling)The Printer Resolution menu displays one or more sets of line screens (lines per inch, or lpi) and resolutions (dots per inch, or dpi) available on the printer or imagesetter that prints the color separations. A high line-screen ruling (for example, 150 lpi) spaces the dots used to create an image close together to create a finely rendered image on the press; a low screen ruling (60 lpi to 85 lpi) spaces the dots farther apart to create a coarser image. The size of the dots is also determined by the line screen. A high line-screen ruling uses small dots; a low screen ruling uses large dots. The most important factor in choosing a line-screen ruling is the type of printing press your job uses. Ask your print shop how fine a line screen its press can hold, and make your choices accordingly. The PPD files for high-resolution imagesetters offer a wide range of possible line-screen rulings paired with various imagesetter resolutions. The PPD files for lower-resolution printers typically have only a few choices for line screens, and they are coarser screens of between 53 lpi and 85 lpi. The coarser screens, however, give optimum results on lower-resolution printers. Using a finer screen of 100 lpi, for example, actually decreases the quality of your image when a low-resolution printer is used for final output. That's because increasing the lpi for a given resolution decreases the number of colors that can be reproduced. Adobe Illustrator prints fastest and best by using the default printer resolution. However, in some cases, you might want to decrease the printer resolution--for example, if you draw a very long curved path that won't print due to a limit-check error, if printing is slow, or if objects are not being printed at an adequate resolution. To avoid or correct the limit-check error, you can also split long paths, as described in "Splitting paths to print large, complex shapes" on page 386 and you can change the flatness settings as described in Approximating curved paths. You can set the following Output option in the Print dialog box: Printer Resolution Displays preset halftone screen ruling and printer resolution combinations you can choose from. |