optimized workflow in digital printing – part 2
DESCRIPTION
Producers of support-independent printing data can save a lot in terms of work and data. The point at which data needed for the final colorimetric space is converted remains totally under the control of the data creator. The only important thing is that the conversion occurs as late as possible. How to proceed?TRANSCRIPT
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Support-independent production
Optimized workflow in digital printing – Part 2
Producers of support-independent printing data can save a lot in
terms of work and data. The point at which data needed for the final
colorimetric space is converted remains totally under the control of the
data creator. The only important thing is that the conversion occurs as
late as possible. How to proceed?
Digital printing data can be created on the basis of various givens.
On the one hand there is data processed expressly for digital printing;
on the other, you can create data for offset printing and then
reproduce it in digital for other purposes.
At this point, printing-service suppliers have to differentiate, in digital
printing, the way in which data will be finally processed. In general
there is a choice between two procedures.
• Data optimized for offset printing:
Because of the difference, from the color standpoint, between offset
and digital printing (in depth work you can get much better results
in offset than in digital, while in color variety and brightness digital
printing surpasses offset in many fields) in most cases it’s impossible
to get truly 1:1 reproduction because print supports generally have
limitations in regard to depth and chromatic range. The aim must be to
optimize output in order to produce an image as similar as possible to
the one desired.
• Data optimized for digital printing
To take full advantage of the possibilities the color range offers in
digital printing, you cannot limit it in the preliminary stage while
creating printing data. All too often you hear the question “How should
I deliver the data” and the reply: “Create data for ISP Coated v2 and
deliver it in PDF/X-1a or PDF/X-3”. The only correct reply should be
“Create the data independently from the support in RGB (equipped
with profile of course) and generate a support-independent PDF/X-4
document”.
The difference between ISO Coated v2 and
printing material in digital printing.
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The goal determines the route.
So in digital printing do you always have to have the goal clearly in
mind? Do you want to get the best from digital printing where color
quality and variety are concerned? Or simply reproduce the best 1:1
result possible?
One thing should be clear. If, for example, an image is already trimmed
in the colorimetric space (color information having already been lost)
you can optimize the image (i.e., improve color variety) only by analy-
zing the image and automatisms, whose results are only as good as the
technology behind them, and the base image - information that can be
gotten mostly from the image. However, predictability does not exist
because this may work with one image and not another.
Both routes have to be considered separately. In this second part of our
analysis I would like to describe the ideal case: creating from InDesign
CS5 a support-independent PDF/X-4 file as an output base in digital
printing, suitable for any printing material. Although many people
believe that the “ideal case” doesn’t exist, what they should do is try to
“live” the ideal case and not continually limit possibilities.
Preparatory work
Prior to digital production you need to complete some preparatory
stages. You need to:
• Install updated versions of software:
Has an updated version of the software been installed? Here I start
from InDesign CS 5 7.03, Illustrator CS 5 15.02, Photoshop CS 5 12.02
and Acrobat Professional 9.4.1 or Acrobat X Professional.
Download the latest versions from the Adobe website and install the
updates. This will prevent surprises in PDF creation.
• Get current color profiles
Here you have to distinguish between two situations:
1. Print support ICC profiles: for your own production, install the
current ICC profiles for the printing materials used. These are utilized
only for the Proof Simulation of data on the screen. However, up to this
point these profiles are not strictly necessary in producing support-
independent printing data.
2. Standard profiles for offset printing: they are included in the
standard installation of every layout and graphics station because,
when possible, support-independent data are created in the eciRGB v2
colorimetric space.
Load current eci_offset_2009.zip or ecirgbv20.zip profiles in http://
www.eci.org/doku.php?id =de:downloads.
• Install the profiles
Decompress the ZIP files and copy (only) the profiles into the system
directory – Mac OS X: Hard Disc/Library/ColorSync/Profiles or Win-
dows: C:\Windows\System32\spool\driver.
• Define color-management configuration in Photoshop:
Even if we are producing independently from the support, it’s absolu-
tely necessary to have a color-management configuration. This is be-
cause we want to give the support-independent data the right profiles
and on the screen evaluate output simulation. Start with file creation
for Adobe Photoshop CS5 color configuration and open the dialog box
to configure colors with the Bearbeiten • Farbeinstellungen (Process
– Color configuration) command. If you have an output profile for the
printing material you can save the color configuration setting. Saving
the color-configuration setting for a printing material makes sense only
if you have to create files primarily for a given material.
Nevertheless, for offset printing, at least for paper classes 1 and 2,
you should create a color-configuration setting. Enter the values in
the dialog box on the basis of the image and save this configuration
in ISOCoated_v2. This setting will be used to synchronize the colors in
Creative Suite.
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Using the selected settings the assigned profiles aren’t easily
eliminated from CMYK data and the user is led to believe that his/her
CMYK images are found in the same colorimetric space. So a CMYK to
CMYK compensation may occur.
Even though, as described below, all the images are saved in RGB,
this modification belongs to standard procedure, because often,
unfortunately, we are not just dealing with the “ideal case”.
Preparation is ended, and the following tips can be correctly put to use.
Now it’s time to create a support-independent file.
And here I want to deal separately with recommended procedures for
pixel fields, vector data and layouts.
The values entered to configure the colors for a given printing material
have to be handled like configurations for class 1 paper. Instead of
ISOCoated_v2, select the ICC profile for the print support.
• Synchronize the color-management configuration:
This configuration must be exported into all Creative Suite programs.
Use Adobe Bridge CS5. Boot the program and select Bearbeiten •
Creative Farbeinstellungen (Process – Creative color configurations).
From the color-configuration list on the screen select the already-
saved setting and click on Anwenden (Use). The dialog box will close. To
check, reopen the dialog box, which should be similar to what follows.
• Adapt the color-management configuration to InDesign:
In order for the structure of a support-independent layout, at times
containing other chromatic definitions (which we do not want in
the ideal case) to work, you have to further modify the standard
configurations, which have been completed through synchronization.
Start up InDesign CS5, select configuration from the dialog box with
the Bearbeiten • Farbeinstellungen (Process – Color configuration)
command and modify the CMYK value in the Farbmanagement-Richt-
linien (Color-management directives) saved in the incorporated profile.
Save the modified setting under another name.
To tag it as a configuration for InDesign, you can simply precede the
name with the letters ID.
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Processing pixel images
For support-independent production, all pixel images have to be
processed, optimized and saved in RGB. Image data is opened in
Photoshop, processed from the color standpoint, retouched and finally
saved with the assigned ICC profile. The ideal “save as” formats are TIFF,
PSD or JPEG. However, depending on the departure situation, different
steps are required before being able to save the image.
Before processing the image, and depending on the situation, image
data should be treated as follows.
• The image is RGB and has an origin profile:
At this point we have to start from the supposition that the origin
profile of the RGB image has been saved, not by error but in a suitable
way by the application that produced it, and that it is correct.
The data have to be processed in their output colorimetric space and
saved with this profile. And if, when opening the file, a dialog box for
colors appears, select Eingebettetes Profil verwenden (anstelle des
Arbeitsfarbraum) (Use incorporated profile) (instead of work
colorimetric space).
• The image is CMYK without an origin profile:
Because when opened the image is assigned the currently set CMYK
profile as standard, you will see the image in the colorimetric space
that is currently set. If in work preparation you have chosen the color
configurations for the print support, you will see the result in output.
If, instead, ISOCoated_v2 was selected, you will see the result gotten
in offset printing on class 1 paper. Since for the structure of
support-independent data we want RGB data, here too you have
to first produce a result satisfactory from the color standpoint by
assigning and afterwards converting the image in an RGB work
colorimetric space.
Upshot: the images not assigned an ICC profile make everyone’s daily
work harder!
So that during image processing you can also see what is expected
from the printed result, select Ansicht • Proof einrichten
• Benutzerdefiniert (Image – Set proof – User-defined) and choose
the destination colorimetric space (printing material) in the dialog box
visualized as an ICC profile. Activate proof simulation with (cmd) + (Y)
or (Strg) + (Y).
Thanks to the larger chromatic range, in image processing you should
no longer have to touch certain chromatic spaces, or, if the ISO-
Coated_2 simulation has been activated, the paler spaces should be
“saturated”.
• The image is RGB without an origin profile:
This data should open with the same option.
From the color standpoint, these images may differ considerably from
the original. So you should check whether another origin profile could
guarantee chromatic neutrality better. Give the image another origin
profile with the command Bearbeiten • Profil zuweisen (Process –
Assign profile) and select one of the four profiles available.
The profile used will depend on the observer’s visual judgment. Choose
the suitable profile from AdobeRGB, sRGB, AppleRGB or ProPhoto.
Assign the profile you think is suitable and never again save an image
without an origin profile! A calibrated monitor and a bit of sensitivity
to colors are undoubtedly other important factors in not leaving
judging capacity to mere chance.
• The image is CMYK and has an origin profile:
Convert the CMYK image to RGB. The simplest thing is to convert the
image in the eciRGB_v2 colorimetric space set in the work colorimetric
space. Converting does not lead to color variations.
Save the image, always with the assigned ICC profile. Choosing another
RGB-origin colorimetric space is possible and correct (unless the image
isn’t converted in the profile used by the monitor).
Print-support simulation ISOCoated_v2 simulation
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In the case of vector data, a distinction has to be made.
• Logos:
Normally, for all types of logo output the numerical values of the
colors must absolutely be maintained. No responsible person would
accept cyan values “mixed” into an originally pure yellow space.
Don’t create this vector data independently from the support! As we
described in part 1 of this analysis, the disadvantages deriving from
possible reproduction errors can be greater than the advantages. In
this case, make sure that the surfaces, gradations or black outlines of
these objects are created correctly as 4c-Schwarz (4c-Black).
For digital printing the special case of “Black” must be dealt with
separately.
• Illustrations:
Create them independently from the support as an RGB vector graphic.
Here, too, use the RGM work colorimetric space set as eciRGB_v2.
Even in programs for vector graphics, such as Illustrator and Corel-
DRAW, color simulation for the selected print support can be visualized
on the screen.
Processing vector data
So adapt color configurations to the document and in each case select
Alle Profile aktivieren (Activate all profiles) in the Platzierter Inhalt
(Positioned content) menu. This re-establishes parity with the
predefined setting, with which it’s once again possible to produce
independently from the support.
How should you create colored surfaces in InDesign? With the same
procedure used for vector graphics. If you are dealing with chromatic
values, which in digital printing have to be maintained, the surfaces
must not be created as support-independent. If the colors in the
InDesign document have to be as close as possible to the colors of the
printing material, then the surfaces must be created independently
from the support.
Black surfaces and text have to be handled separately. Whoever creates
the layout must always bear in mind “deep black” objects.
Creating the file layout.
Were default color-management settings previously modified in
InDesign? You can create a new document and start with the layout.
Now InDesign contains the original chromatic space of all the
positioned files.
However, if a document was created earlier, what regarded color
management is probably incorrect. In this case, when the InDesign
document is opened a color warning pops up.
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The digital printer converts as follows: to follow this route, at printing
time the printer has to know exactly which color conversion is better
and cheaper. In addition, if it uses the latest technology, such as APPE
(Adobe Print Engine 2) the digital printer can guarantee optimized
transparency processing. The errors that can derive from transparency
reduction (whole rows of pixels can be lost) are eliminated once and
for all. In this case, as previously stated, whoever created the data must
produce a PDF/X-4 through PDF-Export from InDesign.
Creating PDF files
After finishing the layout, you still have to create and check the PDF
file. But what PDF file should be created? Which configuration is the
right one? And when does PDF/X come into play?
To answer these questions we have to clarify where the final
transformation of colorimetric space into destination colorimetric
space should occur. The two possibilities are the following:
• Conversion:
In the first case you can convert by means of writing the PDF file in
InDesign or afterwards in Adobe Acrobat Pro.
In the first method, give the document the desired destination profile
through Bearbeiten • Profil zuweisen (Process – Assign profile) (of
the printing material). Then call up PDF-Export (native) and select in
PDF-Export from InDesign the default PDF/X1-a: 2001 setting. Then go
to Register Ausgabe (Output register). The dialog box should look like
what is shown in the figure.
All the RGB data is converted to CMYK but CMYK data is excluded from
the conversion. This also holds true for CMYK image data with another
origin profile. If you want to convert these images too, you have to
activate in Farbkonvertierung (Color conversion) the In Zielprofil
konvertieren (Convert destination profile) option. This way, now even
all the CMYK data with other origin profiles is converted into the
destination colorimetric space.
It is also important to know that InDesign flattens all transparencies, so
that in certain situations it is no longer possible to convert colors into
another colorimetric space! This file is “dead” and can be used solely for
the selected destination chromatic space. Anyone who processes this
file again or compensates colors becomes a digital “profaner”!
- For the second case, in PDF-Export select the default PDF/X-4: 2008
setting. InDesign thus generates a PDF-Export that is stable from the
color standpoint, without reducing transparencies. All the original
chromatic spaces and all the transparencies are maintained in the PDF
file and the origin profile remains assigned to images. On the basis of
this support-independent PDF file, at any time in Acrobat or using a
PDF-appropriate tool like callas pdfToolbox, or the color-conversion
server from various producers, or inside RIP (Caldera) it is possible to
convert colorimetric space into destination colorimetric space. PDF/X-4
data can still be amply processed, and, being support-independent, can
be converted even in later years into any X destination chromatic space
you prefer.
PDF/X-3 is “dead”.
InDesign can generate a support-independent PDF only with PDF/X-4
because PDF/X-3 doesn’t import transparencies and so they flatten.
And right during flattening, all RGB objects are converted into CMYK!
So where does that leave support-independence?
The choice of parameters (compression, text placement, etc,) during
PDF/X file creation plays a secondary role where support-independence
is concerned. However, even for these factors appropriate values must
be used.
Even the way in which special colors are managed has to be treated
separately. The point at which special color compensation occurs in
the printing material’s colorimetric space depends on the possibilities
foreseen by the RIP or instruments available.
Upshot: For the offset or digital printer PDF/X-1a creates “dead” files
with color compensation. PDF/X-4 instead creates “open” PDF files
independent from the support. It’s that simple.
So try to pursue this path for your own production and bring data
suppliers along with you. Only those who constantly follow this road
can take full advantage of the possibilities digital printing offers.
The question, from the print supplier’s standpoint, of how to generally
manage customer data and which colorimetric space transformations
to perform for use in which situations, will be dealt with in upcoming
articles.