What is line ruling?

What is line ruling?

Line ruling refers to resolution or lpi (lines per inch). It relates to the amount of halftone dots printed based on the specified measurement. The example in the lecture states, “100 lpi means 100 lines of dots per linear inch and 10,000 halftone dots per square inch. Similarly, a 150 lpi screen ruling will have 22,500 halftone dots per square inch.” (Foundations of Electronic Production G322 UG, 2).

The different resolutions are necessary for printing for a few different reasons. A newspaper for example has a rather low resolution ranging from 85lpi to 150lpi. Printing a newspaper at this lower resolution compared to a magazine, which ranges from 135lpi to 175lpi, the print will be a lower quality. With larger dots used the print will not be as accurate in the reproduction as it would be at a higher lpi. Using a lower resolution will also increase the processing speed in production by reducing the size of the file, but keep in mind a lower resolution will limit the number of grays available.

The resolution on a monitor is different as the standard resolution is at 72 pixels per inch (ppi). In print the resolution needs to be higher to not appear fuzzy or pixilated.

Work cited:
Foundations of Electronic Production G322 UG . Week Two Online Lecture :Resolution 4 2010

Resources
AIO Lecture Week 2
Pocket Guide to Digital Prepress