Re: Working with a not Color Managed PrePress (was gamma 1.8 or 2.2)
Re: Working with a not Color Managed PrePress (was gamma 1.8 or 2.2)
- Subject: Re: Working with a not Color Managed PrePress (was gamma 1.8 or 2.2)
- From: Marco Ugolini <email@hidden>
- Date: Sat, 17 Sep 2005 20:18:42 -0700
In a message dated Sat, 17 Sep 2005 13:34:47, Carlo Lavatori wrote:
> So, I suppose, I have no choice but to profile myself my prepress Scanner and
> Chromalin printer?
That's a good way to do it. Just make sure that both testcharts are scanned
or proofed to Cromalin at default values, with no color adjustments or
modifications applied.
For example, the scan testchart should be scanned without any curves,
levels, automatic adjustments, color corrections or even sharpening. All
controls should be "wide open", and you should make sure that, after you
receive the testchart scan, any subsequent scans will be made exactly with
those very same "wide open" defaults. Otherwise you may end up profiling one
set of conditions and applying the profile to a scan made under a set of
conditions different from the ones under which the testchart scan was
produced. And that wouldn't be too good...
As for the Cromalin, make sure that the testchart is also output "as is,"
without color or tonal corrections of any kind.
> I suppose I can supply them, my targets, have them scanned and printed and
> then profile them myself.
Yes. When you receive the digital image produced from the scan, run it
through some software like GretagMacbeth ProfileMaker or Monaco Profiler and
build your scanner profile that way.
But BEWARE: Just make sure that the values in the reference file for your
testchart are accurate, by which I mean, make sure that they match the true
colorimetric values of the physical scanning testchart that you sent to your
prepress shop. Scan testcharts fade and/or shift with time, and their true
color values change, eventually, or are never accurate to begin with. If the
values in the testchart are different from the color values in your actual
scan testchart, your profile will be invalid.
So make sure that your scan testchart is fresh and its colors correspond to
those listed in the reference file. If they do not, either measure the chart
yourself with your spectro, or buy a pre-measured and certified chart from
someone like Don Hutcheson (<http://www.hutchcolor.com/hct.htm>).
As for the digital testchart file for the Cromalin, probably the ECI2002CMYK
is the most appropriate one for the task. (Other people on this forum may
suggest a different CMYK testchart)
Something you should be careful about if you wish to use your Cromalin
profile to create your own CMYK separations, is to create the Cromalin
profile with separation settings that reflect the characteristics of the
printing press on which the work will be printed: max CMYK, max Black, GCR,
UCR, etc. You will need to speak to your prepress house to get these values.
If your separation settings are inappropriate to the printing conditions,
you may cause overinking, clipping, etc.
> At that point I finally will have some profiles to assign to my files in
> Photoshop...
Correct.
> So could this be a correct workflow?
> (since my prepress doesn't use any profiles at all):
>
> 1 - I open the scans I get made from my prepress service assigning them the
> profile I made myself of their scanner
Yes. Assign - not convert.
> 2 - Convert the file into my working space CMYK (next big question: I know
> what RGB working space I like, but in CMYK I wouldn't know which one to
> use...)
I would think it depends on what is the final destination. But I would not
convert to a CMYK space that early on in the game (which would be the
"early-binding" option).
Instead, I would keep my options open and convert to a perceptually uniform
synthetic RGB workspace like AdobeRGB. Only when the editing, color
correction, image retouching, etc, is done, I would convert to Destination
CMYK, the Cromalin profile in your case (which is the "late-binding"
workflow option).
> 3 - Retouch the files as I wish
> 4 - Soft Proof the retouced file (with photoshop proof setup) with the
> cromalin profile assigned to it
Yes: soft-proof the RGB file to the Cromalin profile, that is.
You should activate your Proof Setup this way:
View -> Proof Setup -> Custom: Profile: [Your Cromalin Profile]
Intent: Absolute Colorimetric
Play with the "Paper White" checkbox, and let your eyes adapt to the new
white point.
> but at this point when I have to return the file to the service to have a
> cromalin made, since they will discard any profile assigned to it, (not even a
> working space CMYK)
OK.
> what should I do?
>
> 5a - Send the file when the soft proof seems correct without any profiles
> assigned to it
>
> 5b - Convert the file into the cromalin profile (and then discarding it)
> before sending it to the service...
5b is the correct one: convert the RGB file to the Cromalin profile (using
the "Convert to Profile" menu command with the preview box checked, so that
you can view the results on your profiled monitor with either perceptual or
relative colorimetric intents before you commit your file to CMYK).
Once you convert to CMYK using your Cromalin profile, save the CMYK image
WITHOUT attaching a profile and deliver it that way to your prepress house.
But do NOT trust the prepress house to do the job correctly just yet: if you
have the capability, you should accompany the final digital separated file
with your own paper proof, which you have generated on your profiled inkjet.
You will print the proof differently depending on whether you print to the
inkjet directly through your printer driver or indirectly through a RIP.
Then print your inkjet proof using these settings in Photoshop's "Print With
Preview" dialog box:
Source Space: Proof: [Your Cromalin Profile] (see Proof Setup above) (if you
use a RIP, choose Document: [Your RGB Working Space])
Print Space: [Your Inkjet Printer Profile] (if you use a RIP, choose "Same
As Source")
Intent: Absolute Colorimetric (if you choose "Same As Source", the choice is
unavailable)
And last but not least, don't forget to TALK to the prepress house about
your expectations for the job, and make sure they provide a final set of
Cromalins as legally binding contract proofs to approve and sign.
Buona fortuna!
--------------
Marco Ugolini
Mill Valley, CA
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