Re: profile targets in trim area
Re: profile targets in trim area
- Subject: Re: profile targets in trim area
- From: Henrik Holmegaard <email@hidden>
- Date: Tue, 30 Jan 2001 01:09:01 +0100
Bernard Furnival <email@hidden> wrote:
I would like to make profiles from targets printed in the trim area of
books. Is this doable yet?
An offset press has ink zones. Each ink zone controls the density
across a certain width of the press. There may be 30 or more ink
zones. Vertically down the press sheet the deltaE may be minute, but
across the press sheet it may be quite large, unless advanced press
control is used.
This means you should as a rule apply randomization and averaging. If
your testchart prints in the trim area, it will depict only a subset
of ink zones.
When you profile a press, choose a testchart with scrambled patches
rather than patches layed out systematically. Printopen 4 has an 'IT8
Rearranged' testchart and equally non-systematic Extended and
Standard charts.
Place the testchart across the format of the sheet, and rotate it by
90% for each time it is placed.
Finally, run the press, cut, measure, and average.
--
Henrik Holmegaard
TechWrite, Denmark