Standards-based inkjet proofing ABC_3
Standards-based inkjet proofing ABC_3
- Subject: Standards-based inkjet proofing ABC_3
- From: Henrik Holmegaard <email@hidden>
- Date: Sat, 3 Nov 2001 10:36:11 +0100
Postscript on proof printing:
The spectrophotometer reports deltaE differences in decimals, and
that level of precision goes beyond what the paper manufacturer is
able to meet across the same sheet, long before any ink is applied by
a real world printing mechanism. So what is a relevant level of color
tolerance in a proof print?
One way to answer this is to look at the tolerances in laboratory and
studio workflows, and set aside the tolerances in the printing room
floor. Depending on the state of the equipment and the education of
those operating it, they can be wide, but that also holds true for
the studio -:).
When creating the TR001 characterization data, spot-reading
spectrophotometers of different makes were used to read the same
patch on the same test chart prints, and tolerances of less than dE 1
were found.
When you print the same CMYK test chart across the format of the
studio printer and compare the measurement sets, you can check the
color consistency colorimetrically in the MeasureTool module of
ProfileMaker. Using the same spectrophotometer for readings, the HP
5000PS has an average dE for +300 patches printed four times across
the format of dE 0.5 with outliers at dE 1.5.
Usually, the first thing you do when troubleshooting a color is ask,
What does it look like on the studio monitor? If you save the
ProfileMaker measurement sets for the four corners of your monitor to
disc, and then compare the diagonals in the MeasureTool module of
ProfileMaker, the average dE will as a rule be 2.5 with outliers at
dE +5. The MeasureTool window has a Reference and Sample readout at
the bottom, and if you select outliers marked in red or yellow, the
differences are shown. Even though the monitor is the instinctive
first reference for color, it is not a very consistent reference, as
the color comparisons show. This point has been made many times in
the past.
As better ICC enabled publishing software appears through the next
two quarters, it will (hopefully ....) become simple and easy to do
both symmetric and asymmetric color conversions on the fly to a
printer, and the printed colors can be displayed for discussion in
much more flexible ways than colors displayed on a monitor. The
monitor is still a handy color reference, but the monitor is not the
best color reference. Especially not if on the fly RGB - CMYK - CMYK
proof printing becomes as easy as on the fly RGB - CMYK - RGB
softproofing.
It is quite true that the ultimate proof is the wet press proof, but
we can't have that as we generally don't know what press will be
used. The next best thing is IMO a correctly set up standards-based
inkjet proof. The thing to be avoided, however, is handing the press
operator a full gamut inkjet print which she can't hope to bring the
press up to. And one way of avoiding this is to use the FOGRA Media
Wedge CMYK workflow.
Hope this helps those of you who are confused about proofing basics.