How many DeltaEs are there in a DeltaD?
by John Seymour, QuadTech
Kind of attacks the ISO 12647-2 standard. There are three reqs:
The first req is that we make a proof and we have to match the target LAB values. Then, the second req is that the OK sheet must meet the LAB values of the proof. Then the press run is the same, having to match the LABs of the OK sheet.
John's thesis is that it is possible to maintain a given DeltaD throughout a press run and n this way maintain DeltaE.
L* and density have an almost linear relationship. You can predict L* based on density when paper is a given.
Another conclusion is that we cannot use density to compare proof and press run, mainly because of the impurity of the inks (plus different pigmentation).
2 comments:
"Kind of attacks"? It was not my intent to put down ISO 12647-2, but rather to build a bridge. We use density today, we will use colorimetry in the future. The standard is a bit short on providing a transition between them.
Thanks for your comments!
John
True... I misjudged what was John's sense of humor to a 'kind of an attack'.
We need criticism, constructive criticism regarding standards, and we need to back it up by similar research!
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