Re: Some general color profiling questions...
Re: Some general color profiling questions...
- Subject: Re: Some general color profiling questions...
- From: Terry Wyse <email@hidden>
- Date: Mon, 22 Nov 2004 12:15:40 -0500
On Nov 22, 2004, at 10:55 AM, Walt wrote:
Recently, I was assisting an organization with their
color management and discovered that they were
converting their images from RGB to CMYK using
two different profiles. They used one profile for
images that were going to be printed on matte stock
and another profile for images to be printed on gloss
stock. Does this make sense?
Yep. If you're talking about matte COATED stock and gloss coated stock,
it might be a bit overkill to have separate profiles (I typically
create a profile that's an average of the two stocks) but it's not
uncommon to do this.
If by "matte" stock, they really mean something like an uncoated offset
or text stock, then a separate profile is almost a requirement.
The pressman has two different ink color sets on the
ImageControl densitometer unit (Heidelberg 10-color
SM102, very new) for the different types of paper.
Wouldn't this be redundant for them to use separate
profiles in prepress when they're already compensating
for different stocks in the pressroom?
They can only control density on the press but virtually nothing else.
Even at the same solid ink densities, these two stocks may perform
significantly different as far as trapping, dot gain, etc. resulting in
the need for two different profiles.
In addition, is there a substantial benefit to having a
custom press profile in use in prepress, as opposed to
using something standard like US Sheetfed Coated v. 2?
Yes and no. If prepress and the pressroom are in-house, then there's a
substantial advantage to having custom press profiles that precisely
model their printing conditions. On the OTHER hand, if they are running
to unique (non-standard) conditions as far as density, dot gain, etc.,
then they are likely going to run into issues with supplied CMYK
images. At the very least, they may have to convert the supplied CMYK
images to their press profile(s) to compensate for the differences,
assuming the the supplied images have either an embedded profile or
they know something about how the images were separated.
The best of both worlds, and what I try to shoot for, is to bring the
pressroom into some sort of standard printing condition such as SWOP or
GRACoL, and then profile that. By conforming to a standard, they have
at least half a chance of being able to deal with supplied images
easily but also having more accurate color for their own RGB-to-CMYK
conversions than simply using a generic profile such as
USWebCoated(SWOP) or USSheetfedCoated.
Lastly, on the first round of profiling a press run of
an EIC target, I ended up with very accurate color on
an HP 5000, except for an extremely light shade of
green in the background of the printed area. Is it
normal to run into oddities like this? What could be
done to avoid it?
Better proofing RIP, better printer, better paper, better calibration,
better profiling, better.....There's a bazillion reasons minus 1 why
you may not be hitting a particular color!
OK, I'll try to be more helpful: Are you using Absolute Colorimetric
rendering? Lighter shades like that can be GREATLY affected by either
the inclusion or exclusion of the paper color cast. What sort of
proofing RIP is driving the HP5000?
Regards,
Terry
_____________________________
WyseConsul
Color Management Consulting
email@hidden
704.843.0858
http://www.colormanagementgroup.com
http://www.wyseconsul.com (coming soon)
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