RE: File Preparation for 4 color Grayscale offset printing
RE: File Preparation for 4 color Grayscale offset printing
- Subject: RE: File Preparation for 4 color Grayscale offset printing
- From: "Mike Eddington" <email@hidden>
- Date: Thu, 8 Nov 2007 08:54:42 -0500
- Thread-topic: File Preparation for 4 color Grayscale offset printing
IMO, there are still some things that ICC color management doesn't do
quite well enough (or at least intuitively), and nice 4/c black
separations is one of them. In the case of 4-color "grayscales", we
usually generate a quadtone from a gray scale image with CMYK builds
similar to what Richard Booth suggested...keeping the gray balance
percentages as defined by Gracol and introducing CMY when black reaches
30% or so, maxing at 260TAC.
The benefit here over what I'm interpretting from Richard suggestion
(which is requiring a bit of manual channel manipulation of each image?)
is that once you define your quadtone curves and save the settings, all
you have to do is optimize your grayscale images for highlight/shadow,
then load you quadtone settings via Image-Mode-Duotone. One catch is
that the quadtone build is specific for the grayscale profile you use,
so if you deal with grayscale images tagged with various grayscale
profiles, you'll have to convert them all to the grayscale profile you
used when generating the quadtone curves...converting to common
grayscale "working space" if you wil, prior to applying your settings.
We've had very nice results on some high-end books with this method.
This isn't really ICC "color management" so you'd want to hang on to the
original grayscales for repurposing for say a lower TAC.
You can get decent results using Monaco profiler by manipulating the
black generation , but much more tricky to define where CMY starts
(manipulating black via a curve based on L*), neutral rendering/curves
are not as smooth as you could manually define, and the CMY tends to
want to play more of a role in tonality than I'd like. Max K in
ProfileMaker allows for to much CMY and control over black generation is
too restricted for this purpose.
As others have suggested, simple grayscales for a publication might be
sufficient, but if the process allows fot it, that extra density of a
4/c black quadtone can really add a lot of punch
_______________________________________
Michael Eddington | North American Color, Inc.
QA Manager | Gracol G7 Certified Expert
5960 S. Sprinkle Road | Portage, MI 49002
P. (269) 323-0552 | F. (269) 323-0190
email@hidden | www.nac-mi.com
>>-----Original Message-----
>>From: Vanita Cyril [mailto:email@hidden]
>>Sent: Tuesday, November 06, 2007 2:15 PM
>>To: Richard Booth
>>Cc: email@hidden
>>Subject: Re: File Preparation for 4 color Grayscale offset printing
>>
>>Richard, thank you.
>>
>>
>>On Nov 6, 2007, at 2:11 PM, Richard Booth wrote:
>>
>>> To minimize the possibility of casting on press due to the CM and Y
>>> inking variations, this is the approach we have used, based on
>>> recommendations from both our magazine and book printers. It has
>>> worked well.
>>>
>>> 1. Convert the image to greyscale if it isn't already.
>>> 2. Correct for full tone range- highlight, shadow and midtones
>>> (2%-3% highlight to 96%-97% shadow).
>>> 3.Build a new 4/c starting with the greyscale file being used for
>>> the K channel.
>>> 4. Dupe the K channel for the C, M and Y channels and apply the
>>> range limitations. Come in with the three color when black values
>>> hit 35% and run them to 60% in the shadows. You may want to run a
>>> little higher than 60% if you think the press and paper can handle
>>> a higher max total ink. Check with your printer. To keep the black
>>> neutral, the Cyan should have a little higher density than the M &
>>> Y. Some thing like 4C 2M 2Y or 48C 40M 40Y depending what tone
>>> range you are in.
>>> The idea here is make the K do the heavy lifting - especially in
>>> the lighter areas where variations in the press inking of CM and Y
>>> would be more visible.
>>>
>>> Hope this helps
>>>
>>> Richard Booth
>>>
>>> -----Original Message-----
>>> From: Vanita Cyril [mailto:email@hidden]
>>> Sent: Tue 11/6/2007 11:58 AM
>>> To: Vanita Cyril
>>> Cc: Richard Booth; email@hidden
>>> Subject: Re: File Preparation for 4 color Grayscale offset printing
>>>
>>> Afterthought:
>>> Would a higher total ink be of any help in avoiding the image going
>>> flat?
>>>
>>>
>>>
>>> Vanita Cyril
>>> ....................................
>>>
>>>
>>>
>>>
>>
>>
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