Tuesday, May 02, 2006

Designing Tips

Designing Tips
More blathering on about line screen.
Sorry about the trend, here just trying to nail down a flexible range for my shading, so I'm not forced to re-ink half of all my pages in a month. Maybe this will help someone else too?

The line screen of a press or negatives produced on an image setter determines the resolution or the amount of detail that will appear on the printed piece. If your printed piece has only solid colors and line art - no screens or photos - then line screen is not an issue. If there are photos or screens present then line screen becomes a very important issue. Different types of presses are capable of printing at different line screens. For example web presses print well at 133 to 150-line screen while sheet fed presses have an optimum range of 150 to 200-line screen. Any press can produce a lower line screen well but a press cannot go above its optimum line screen without a loss of quality. The image will appear muddy because there is more detail than the press is designed to handle. Another factor that affects line screen is the paper that a job will be printed on. Printing at 200 lines per inch on very soft porous paper will produce a disaster. Even at 150 lpi the quality may suffer whereas at 133-lpi, the image may appear crisper even if it technically has less detail. For example, let's look at newsprint, which is one of the softest most porous papers there is. Its optimum line screen is 80 to 100-lpi. If we tried to print a 150-lpi image on newsprint it would look muddy and blurry because of the excessive dot gain. But the same image screened to 85 lpi would appear crisp and in focus. On denser glossy paper higher line screens can be used to achieve extremely detailed images, this is because the ink is less likely to spread out. It is important to talk to your printer about line screen before printing if in doubt, the line screen resolution will determine the resolution of your scanned photos and graphics. Examples of typical products and their line screens: Comic Books: 70 – 85-lpi,Newspapers: 80 – 100-lpi, Color Flyers, Coupons: 133 – 150-lpi, Color Magazines: 150 – 175-lpi, Fine Art Books & Magazines: 175 – 250-lpi.

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