What Are Halftones and Linecreens?

ow can a printer print a grayscale photograph with black ink? A mystery of the universe? No, but I do think whoever came up with this one should've gotten a big bonus in their paychecks. Think how different our world would be if we couldn't print photographs in our books and magazines! Okay, on to the explanation...

A printing press is able to produce only clear, defined images in the color of the ink on the press. To reproduce a wide range of continuous and intermediate tones of gray in a black and white photograph, the photograph must first be converted to an image that conforms to this limitation. This conversion is done by the use of halftone screens.

By shooting a photograph through a screen of dots with a stat camera, the image is converted to rows of tiny black dots. The size and intensity of these dots is relevant to the darkness of the gray areas. These days, photographs are usually scanned into a computer system and output with the halftone screens. The photo can be printed at whatever screen frequency you desire.

The resulting dots create an optical illusion. Because the dots are so small and are of varying proximity to each other, our eyes are fooled into seeing shades of gray when there's only black dots. Halftone screens are measured by the number of lines of dots in an inch of the screen.

The halftone screen frequency, or linescreen, that one uses is dependent on the capabilities of the press and the paper that will be used to print a project. Presses that print newspapers are only capable of handling a low linescreen like 85 lines per inch (lpi). Quality magazines use linescreens of 150lpi and up. The finer the linescreen (the more dots per inch), the better the reproduction quality and detail you'll see in the image.

However, a word of caution: a linescreen that is too high for a paper or press' capabilities, will not look very good at all. The dot pattern will start to fill in and the images will look blotchy and muddy. Ask your printer what linescreen they prefer. You or your designer will need to know this before printing film can be ordered. Your designer will also need to know this before images can be scanned so he/she knows what resolution is required.

VistaPrint.com
Get 250 premium quality, color business cards FREE! Order today! One of the great leaders of online printing. One of the most popular printers on the Internet. Check them out for great deals on the full color printing of brochures, postcards, business cards, newsletters and other customized printing projects.

Mailer's Club
One-stop online printing and mailing resource. On top of doing a great job with their printing (postcards, brochures, business cards, newsletters, catalogs, etc.), Mailer's Club will also find a mailing list to fit your needs and will mail your project pieces — at great savings to you!

ITC Fonts
Professional fonts at reasonable prices from one of the font giants in the business for 30 years; the International Typeface Corporation.