Is “variable line screen” something I need to request from my printer?

Is “variable line screen” something I need to request the printer to do to reduce moiré and improve flesh tones in my printed work? Or does the graphic designer who creates the art do that? Does each printer have their own formula or do the press manufacturers provide the guidelines?

K. N.

It may surprise you to learn that many output screening systems today use variable line screenings as a matter of course. The concept of variable line screening is this: In the analog days, screens were made in common sets of four. Each screen was created at a different angle to prevent patterns from appearing. If there were only 3 colors to contend with, you would probably never see a pattern, but since there are four colors, the screen angle with the highest potential for being visible is given to the yellow printer. That way the most likely source of screen patterning is assigned to the color least visible to the human eye. Although a "perfect rosette" was considered an ideal screen pattern for printing, this pattern does not look "natural", and with coarse screens a "perfect rosette" can be quite undesirable.

Skin tones are particularly vulnerable to screen patterns both because they have a high percentage of yellow ink and because they are relatively smooth areas of color and any patterning is easily seen by the human eye.

In the digital age, there still isn't a perfect system. The manufacturers of screening devices have tried all kinds of ploys to get rid of the potential for visible screen patterns. By using variable screen rulings, slightly changing angles and by printing on paper that can handle finer screen rulings, it is possible to minimize, but not altogether eliminate objectionable patterns. Herringbone suits and corduroy fabrics can still be problematic for example.

Stochastic (or FM) screening and Hybrid (combining stochastic and conventional) screening are also methods to help eliminate patterns. Some companies that print a large number of images of fabrics or fashion photography have opted for these methods. Stochastic screening is also useful when an increased color gamut is required because it is possible to print a color image with six inks. In the process most commonly called "HI-Fi" printing, fluorescent orange and green inks are added to the mix. The number of printers using this technology is limited. Because Stochastic screening uses what are essentially random dot patterns, there isn’t a screen pattern to worry about, though there can be some other unwanted dithering effects.

For most printing applications, current screening technology offers great results. It's something much better left to the printer because the press, paper and output device all help determine the proper screen angles and frequency. If you have particularly troublesome images, talk to your printer about your options for achieving the best finished results.

Stephen Beals is a digital pre-press manager and has been writing for major print publications for many years. He is the author of A Practical Primer for Painless Print Production. He can be reached at
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