Re: rgb to cmyk conversions
Re: rgb to cmyk conversions
- Subject: Re: rgb to cmyk conversions
- From: Busher Jr Richard C <email@hidden>
- Date: Tue, 28 Feb 2006 23:04:11 -0800
Rich Apollo wrote:
It would be a gross generalization to say that most printers do or do
not "use color profiles". You need to speak to the printers you work
with. However, it doesn't cost anybody a "plug nickel" to
appropriately tag the files. If the printer doesn't utilize the
profiles, fine. If the printer is color managed then you have
communicated important information.
Mr. Apollo is correct (as usual), but I'd like to add a few points to
his points, plus a few personal observations.
In my experience, many printers who provide prepress services (i.e.
scanning>cmyk) have an internally consistent workflow that does not
rely on color management in the sense that most of us think of that
term. However, they are "managing" their color. The output from their
scanners is a cmyk file. They drop this file into your page layout
application, feed it into their RIP and generate a proof, film, or
plates. These image files have, in a real sense, already been
"separated" via their "system profile" when they do the scan, and
everything is internally consistent. If you are not happy with their
proof they will either rescan the image (changing settings), or edit
the cmyk file based on your instructions, and then provide a new proof
(for a price, of course). Their internal cmyk files are not tagged with
a "profile" in most cases. Their RIP does not recognize profiles, as a
rule.
If YOU supply them with a cmyk file the results are: 1) excellent if
you have separated your file with a profile that is a profile for their
proofing/printing conditions (and if you have not done editing in cmyk
that moves the file very far away from the conversion), 2) close if you
have separated your file using a SWOP profile and their printing
conditions are close to SWOP conditions, or 3) off the mark if 1 or 2
do not apply. Again, the RIP does not recognize profiles (at least that
is what I have been told). And the printer is not checking your layout
and image files for compatibility with their system, unless you ask
them to do so. When they accept your files they are assuming that you
are supplying files compatible with their system.
Many sheet fed printers have printing conditions that are quite
different from SWOP conditions, but they do excellent work because they
have created a unique, internally consistent workflow. A SWOP generated
separation might print reasonably well on their presses, but would fall
far short of taking advantage of their true capabilities.
To be successful supplying cmyk files you must either use SWOP profiles
(or EURO profiles) for printers trying to adhere to SWOP conditions, or
somehow obtain custom profiles that are appropriate to your printer's
printing conditions. To do truly fine work with a truly fine sheet fed
printer you may need several custom profiles, to account for different
image types, paper types, etc. The printer must supply you with these
profiles, or you must create them.
On the other hand, if a printer is up to speed with color management,
and if you supply a tagged cmyk file, then they "should" be able to
convert your image to a file that will work within their system,
assuming you have communicated with them on the need to do so. "Work
within their system", however, is not the same as starting with a
profile that matches their system, i.e. matches their printing
conditions. "Should" implies that you have not edited the cmyk file in
any major way after conversion. Doing so may throw the image out of
spec.
In summation: Providing cmyk makes you a Color House. Your
responsibility then becomes Color Integrity. Can you deliver? If the
job goes bad, and if it is your fault, are you in a position to make
corrections and pay for reprinting the job? If not, then consider
handing the job off to some company that can.
An aside! I've seen the color departments shrinking at several printers
I work with. I've been told the reason is that many customers are now
supplying cmyk, and there is less of a demand for their
scanning/prepress services. I conducted a completely unscientific
survey a couple of years ago. My unscientific results? According to
the heads of the Prepress departments of the printing companies
surveyed, 80 % of the printing done by their shops was done with files
supplied by their clients. Based on their "standards" no more than 20%
of the files supplied by their clients where of acceptable quality
based on their in-house standards. Translation: At least 64% of the
printing produced by these companies is below the quality level that
they would produced if everything was dropped in their lap. Printing
quality is being dumbed down by the fact that prepress (cmyk file
preparation) is being provided by people pushing the "cmyk button" in
PhotoShop!!! Yes, you can create a cmyk file. Will it print with the
feeling of your rgb file? Maybe! Will it be a as good as it should be?
Possibly, but don't count on it.
Anyone on the "creative side" of the print industry, designer,
photographer, illustrator, has the potential to become a skilled
prepress provider if they are willing to take the time to learn.
However, it will take at least as long to do so as the time you spent
to develop your skills as a designer, photographer, or illustrator. My
degrees are in Math and Physics. I've been a commercial photographer
for 30 years. I'm a self starter. I've been doing my own prepress for
15 years, and providing prepress services for more than 10 years. I
feel that I'm just scratching the surface of this field. I happily
learn something new every day! That is what keeps me out of retirement!
Some day the software engineers will make this prepress business as
simple as pushing a button. Hopefully dandelions will be growing out of
my chest at that time.
My .02 for the moment.
Cheers,
Dick Busher
Cosgrove Editions
888-507-7375
email@hidden
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