FM Screening
What is FM (stochastic) screening, and how does it differ from conventional screening?
Stochastic or FM screening utilizes a micro-dot that is randomly placed throughout the image. As a result, FM screening produces a much higher resolution than the AM screening methods. For comparison, a typical 20 micron FM screen would be roughly similar to a 365 line AM screen, which is more than twice the screen resolution of a standard 175 line AM screen used on most offset presses.
Conventional or AM screening utilizes a variable dot size along a fixed grid. This dot ranges in size from about 10 or 20 microns, to over 200 microns. What’s important to understand is that physical resolution will always be limited by that fixed grid, no matter how small the dot. The resulting technical limitations within this process yields potential flaws in picture quality, like moire patterns, rosette patterns, color loss, and loss of detail.
Some of the clear advantages to stochastic printing are:
- Improved detail and definition
- Reversed text prints cleaner
- Improved highlight and shadow detail
- Wider color gamut
To put this into perspective, AM screening compared to FM screening is like comparing a VHS Tape to a Blu-Ray Disc. Sure, a VHS tape works, but would you buy one today? The printing industry has been very slow to adopt this technology on offset; not because it isn’t better, because it’s a difficult transition internally. The switch requires calibrations, upgrades, and a willingness to learn and keep up with the best technologies available. Eventually AM screening will go the way of the VHS, but until then you can count on us to provide your company with the very best offset technologies of today, so you’ll be here tomorrow.
Ask your printer what line screen their offset presses use. If they give you a number like 175, they aren’t using FM screening.
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