PUB: How to Control Lines Per Inch (LPI) From Publisher

MORE INFORMATION

What is Lines Per Inch?

The term, "lines per inch," comes from a photo-mechanical process called halftoning. Halftoning is a method of breaking up shades of gray into dots of different sizes. True halftones are created by photographing continuous tone artwork onto high-contrast film through a halftone screen. Halftone screens were originally created by etching a grid of lines onto optical glass. The number of etched lines per inch is where the term lines per inch comes from.

In a true halftone, all the dots are the same distance apart. You achieve the effect of light and dark by increasing or decreasing the size of the dots. The larger the dots, the smaller the amount of white space around them and the darker that area of the paper appears when you view it at a distance. The higher the lines per inch, the closer together the dots appear.

Electronic printers do not print true halftones. Electronic printers print dots of only a single size (measured in dots per inch or dpi); instead of changing the size of their dots they change the distance between the dots. Many electronic printers simulate true halftones by clustering their tiny fixed-size dots in such a way as to give the appearance of an array of (larger) equidistant dots of different sizes.

Setting Lines Per Inch

You can change the lines per inch setting only if you are printing to a PostScript printer. Use these steps to define lines per inch:

1. On the File menu, click Print Setup.
2. Under Printers, in the Name list, click the PostScript printer you want to use.
3. Click Properties.
4. Click the Graphics tab.
5. Under Halftoning, click to select the Use Settings Below option.
   
   The Screen Frequency box is now available and shows a recommended value.
6. In the Screen Frequency box, select the recommended value and then type a new value that represents the lines per inch you want to use, or click the arrows to select a new value.
7. Click OK.
   
   NOTE: If you type a number which is higher than the recommended value, shades of gray may not print evenly.