The first installment of this series showed why offset printing using FM screening cannot completely match proofs based on a conventional AM-based GRACoL proof.
The mismatch can’t be fixed with curves, but it can be resolved with device-link profiles. We will discuss exactly how these profiles will be implemented into the workflow in the next installment; but for the moment let’s examine the challenges of producing a reliable FM press characterization profile.
AM-based GRACoL Proof Offset Press with FM Screening
This isn’t nearly as easy as it may sound. Conducting a proper characterization run is a challenging process, and the stakes are high…all of our future press runs will depend on the data we gather during the press characterization.
Even the best characterization run is simply a snapshot in time that may contain unacceptable irregularities. In order to be truly useful, any proofing profile should be based on multiple press runs, carefully conducted, averaged together, and normalized to eliminate irregularities.
For the very technically-minded, CGATS/IDEAlliance TR015 outlines methods for establishing near-neutral gray-scale aims; however for matching FM offset printing to GRACoL we can take the much more direct approach of following the usual procedures of conducting a GRACoL G7 press run.
I use Bodoni pressSIGN to control the press run and to create the G7 NPDC curves to export directly into the plate rip. Other G7 certified tools are available and can be found on the IDEAlliance website:
Once aims for solids, overprints, and NPDC are achieved, I use a profiling program like i1Profiler to make the press reference profile. Ideally, the process should be repeated several times and normalized and averaged using a profile-editing program such as Color Ant.
With a reliable and accurate FM press characterization profile in hand, we are prepared to match proof and press. We can go either of two directions…match FM press to AM proof or match AM proof to FM press, and we will get into the pros and cons of each approach in the next installment.