Re: Certified InkJet-Proofs
Re: Certified InkJet-Proofs
- Subject: Re: Certified InkJet-Proofs
- From: Henrik Holmegaard <email@hidden>
- Date: Sat, 14 Sep 2002 08:22:18 +0200
email@hidden wrote:
>
The point is not the certification. What we need is a scheme for quality
>
control in inkjet-proofing.
Absolutely.
>
In Germany, we have now an official standard for controlling inkjet proofs.
>
The FOGRA has releases a digital control strip called "mediawedge cmyk" and
>
Lab-values for every cmyk-patch from the control-strip.
>
The printing-house can control the proof
>
by measuring the "mediawedge-cmyk" printed on the proof and compare it to
>
Lab-values.
The abbreviated workflow is in the proof-printing cookbook on the ColorSync
home page, but the media wedge itself is not shown in the cookbook. The copy
was written before it was known that Apple would upgrade the Generic CMYK
Profile to a standard offset color space aka TR001. This is why the copy
does not explain how to use the FOGRA Media Wedge CMYK with TR001 proofs.
Briefly, TR001 and FOGRA3 should give the same results if printed at 53/cm
screen frequency with SWOP dot gains (tone value increase) or with 60/cm
frequency witht he normal tone value increase, and on 65 - 70 g/m2 offset
web paper. The copy also does not explain how to use the i1 with the
KeyWizard software to transfer measurements.
As I understand FOGRA, the historical reason for the coincidence is that
SWOP proofs used to be made with negative plates on sheet offset presses in
very short runs. Under such conditions the tone value increase is very low
approaching that of positive plate production which is usually 7% lower.
The next cookbook update will try to be more helpful. Sorry for the
inconvenience.
>
problems with optical brighteners, etc.
The FOGRA Media Wedge CMYK checks for media dE (among other things). If the
proofing paper is off due to optical brightener, the Excel spreadsheet will
report that the proof has failed. The user does not have to wait until the
press is run to learn that there is a problem.
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