Re: DTP41 White Backing
Re: DTP41 White Backing
- Subject: Re: DTP41 White Backing
- From: Henrik Holmegaard <email@hidden>
- Date: Thu, 28 Feb 2002 03:48:15 +0100
Tom Beckenham <email@hidden> wrote:
In fact there is some debate from a standards point of view whether
anything but very thin substrates should be measured against white at all.
This is woven into the thread 'White and black in color' with Robin
Myers arguing for black and me reporting what the user and developer
communities here in Europe have been saying in favour of white. I
don't argue any scientific point because I am not sure the science
whether right or wrong is always relevant to the here and now
concerns of users ... including this user -:).
You need to be aware that the ECI has the same thread over white and
black in color, and that the ECI guidelines have recommendations on
the choice of backing. This is also true of the manuals that come
with Heidelberg and GretagMacbeth ICC print profiling software.
Finally, you need to be aware that the old ICC ABCs had the same
recommendations on the choice of backing as the print profiling
software, and that ICC ABC Characterizing included a recommendation
on how to obtain the same L* measurements from the DTP 41 as from the
Digital Swatchbook which was sourced from and preread by X-Rite.
There are two levels in this discussion, (a) how do I get the same L*
value from an instrument with a built-in white backing as from an
instrument that uses multiple sheets of blank similar paper as
backing (: DTP 41 and Digital Swatchbook) and (b) how do I apply
colorimetric process control to offset printed sheets when the sheets
are printed both sides and my test chart is printed one side only.
FOGRA is right that if the goal is to apply colorimetric process
control in scenario (b) say using the FOGRA ISO control strip, then
you also need to measure the test chart on black backing. Similarly,
if you build profiles from the ISO 12647-2 data on
http://www.fogra.org or
http://www.color.org, then as the data itself
states the backing used was black, and it follows that it makes sense
to measure the test chart of the proof printer with black backing. If
you don't then you are liable to get a rather high dE between the
offset printing media and the media for your digital contone proofer,
even though you hunted around and actually found media without
optical brightener and with the right look and feel. If you don't use
black backing for the offset test chart (and you don't have to if you
bought the test charts themselves), then you will see that the offset
paper is considerably brighter than the ISO 12647 reference data. So
it's a trade-off: Do you want the extra lightness steps or do you
want colorimetric process control and the ability to keep the print
shop strapped to tolerances? I'd be interested to know what you feel
about this: Bigger gamut or bigger control?
The instrument manufacturers are in a tough spot because they must
cater to both the D50 prepress and printing, the D65 paint and
plastics and photographic, the black backing press and the white
backing photographic and prepress markets. But again I think it's
best to skip the politics and just look at what's needed to make all
this work. If it's another backing then use another backing which is
now available ... there's nothing whatsoever wrong with the
instrument, I've used one since '97 (or was it '98, I forget) and
written a heap of posts and articles about it. Also I might add that
I've never once used a Spectrolino/Spectroscan, never had one in the
house, either. I'm kind of curious how it works, though -:).
_______________________________________________
colorsync-users mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/colorsync-users
Do not post admin requests to the list. They will be ignored.