The Dish on Dots
Industry experts weigh in on AM, FM, and transitional (hybrid) screening methods.
June 2006 by Jean-Marie Hershey
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Most screening technologies work well. Every prepress workflow presents a multitude of screening options. Beyond these simple assumptions, however, questions proliferate. Is AM screening the right choice, or is FM better? Will transitional screening supplant them both? What are the tradeoffs? How tight a process control window can the printer operate within?
The answers to these questions vary from market to market and from one print discipline to another. What is certain is that the right choice of screening method can help printers in their quest for differentiation. It can also have an impact in the pressroom, based on its runnability.
Screening has a long history. Developed long before the advent of digital imaging technologies, conventional Amplitude Modulation (AM) screening places halftone dots in a consistent pattern, varying the size of the individual dots to simulate the tone values of the original. It has proven to be very stable and to produce the most realistic flesh tones.
Frequency Modulated (FM or stochastic) screening randomly places dots of the same size, in different concentrations, to reproduce continuous tone. With the FM method, it is possible to produce very fine detailed print, highlight, and shadow areas, and eliminate the moiré and broken lines associated with AM screening.
More recently, screening technologies designed to compensate for the deficiencies of each method combine the best features of AM and FM screens. These so-called “transitional” screens are said to be easier to print, due to the need for less rigorous process control.
In sorting through the extensive array of screening options available to today’s package printer, we spoke with Steve Musselman, senior manager for the market development of digital solutions and emerging technologies, North America, Agfa; Mark Sanworth, vice president of technology, Artwork Systems; Tyler A. Harrell, flexo implementation quality manager, Esko-Graphics; Bryan Hughes, product manager, elecronic products, Enovation Graphic Systems, Inc.; Mark Tonkovich, product manager, CtP and proofing, Heidelberg USA; and Gordon Pritchard, Value in Print marketing manager, Kodak (Canada). Subject matter experts Socrates Rettos and Gary Russell of Phototype spoke about the company’s proprietary screening technology (see sidebar).
pP: FM screening has been around for more than a decade. What is driving its adoption?
AGFA: With the recent introduction of XM screening technologies from Heidelberg and Harlequin to complement Agfa’s :Sublima XM, along with Esko’s Samba and Kodak’s MaxTone, the writing is on the wall for the future of FM. FM has proven to be difficult to work with in prepress and onpress, with little onpress color adjustment possible, and debate rages on as to whether FM truly offers the benefits it has touted over the years.
The answers to these questions vary from market to market and from one print discipline to another. What is certain is that the right choice of screening method can help printers in their quest for differentiation. It can also have an impact in the pressroom, based on its runnability.
Screening has a long history. Developed long before the advent of digital imaging technologies, conventional Amplitude Modulation (AM) screening places halftone dots in a consistent pattern, varying the size of the individual dots to simulate the tone values of the original. It has proven to be very stable and to produce the most realistic flesh tones.
Frequency Modulated (FM or stochastic) screening randomly places dots of the same size, in different concentrations, to reproduce continuous tone. With the FM method, it is possible to produce very fine detailed print, highlight, and shadow areas, and eliminate the moiré and broken lines associated with AM screening.
More recently, screening technologies designed to compensate for the deficiencies of each method combine the best features of AM and FM screens. These so-called “transitional” screens are said to be easier to print, due to the need for less rigorous process control.
In sorting through the extensive array of screening options available to today’s package printer, we spoke with Steve Musselman, senior manager for the market development of digital solutions and emerging technologies, North America, Agfa; Mark Sanworth, vice president of technology, Artwork Systems; Tyler A. Harrell, flexo implementation quality manager, Esko-Graphics; Bryan Hughes, product manager, elecronic products, Enovation Graphic Systems, Inc.; Mark Tonkovich, product manager, CtP and proofing, Heidelberg USA; and Gordon Pritchard, Value in Print marketing manager, Kodak (Canada). Subject matter experts Socrates Rettos and Gary Russell of Phototype spoke about the company’s proprietary screening technology (see sidebar).
pP: FM screening has been around for more than a decade. What is driving its adoption?
AGFA: With the recent introduction of XM screening technologies from Heidelberg and Harlequin to complement Agfa’s :Sublima XM, along with Esko’s Samba and Kodak’s MaxTone, the writing is on the wall for the future of FM. FM has proven to be difficult to work with in prepress and onpress, with little onpress color adjustment possible, and debate rages on as to whether FM truly offers the benefits it has touted over the years.
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