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Prinect
Color and Quality
Multicolor Workflow
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Contents
1 Introduction
1.1 Get closer to the original with the multicolor workflow 5
1.2 Developments aiming at expanding the press color space 6
1.3 Definition of the multicolor workflow 6
1.4 The advantages of the multicolor workflow opposed to the
CMYK workflow 6
1.5 Prinect workflow components
1 – Prinect Signa Station•
2 – Prinect Prepress Manager •
3 – Prinect MetaDimension•
4 – ColorProof Pro•
5 – Prinect Pressroom Manager/Prinect Prepress Interface•
6 – Platesetters•
7 – Speedmaster with Prinect Press Center/ •
Prinect CP2000 Center
8 – Prinect Image Control•
9 – Prinect Color Toolbox 3.5•
10 – Calibration Tool•
11 – Profile Tool and Quality Monitor•
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1.6 What you need for the beginning
Knowledge•
Prepress equipment•
Equipment and conditions in the press room•
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1.7 The “multicolor strategy from Heidelberg”
The central points of the “multicolor strategie from •
Heidelberg”:
FM screening is not always the ultimate choice •
Screening with Prinect IS Classic or Prinect Hybrid Screening •
and multicolor profiles from Heidelberg
Color usage and screen angle•
Selection of inks •
Flexibility with spot colors•
Matching rheological properties•
Which colors are not suited for the multicolor workflow?•
5, 6 or 7 colors?•
5-color process•
6-color process •
7-color process•
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2 Preparations for a 7c job
2.1 Determine the optimum density of the spot color 16
2.2 Define process curve set for spot colors 17
2.3 Create multicolor process standard 19
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2.4
2.5
2.6
Create multicolor test form
Linear imaging of test chart plates
Printing to the desired multicolor process standard
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2.7 Measuring the dot gain charts for process calibration 23
2.8 Analysis and mean value calculation of measured data 23
2.9 Create process calibration 24
2.10 Generate a multicolor ICC profile 26
3 Workflow – step by step
3.1 Input data 29
3.1.1 Color space of input data
3.1.2 Color space expansion by “inverse Gamut Mapping”
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3.2 Create PDF document in the DTP application 30
3.3 Job processing in Prinect Prepress Manager
3.3.1 Create job and assign sequences
3.3.2 Configure Prepare sequence
3.3.3 Configure the Imposition Output sequence
3.3.4 Configure Sheetfed Printing sequence
3.3.5 Configure job settings
3.3.6 Edit the job settings
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3.4 Create the layout 40
3.5 Platemaking and generation of CIP4 data 43
3.6 Check the CIP4 data in Prinect Pressroom Manager 43
3.7 Prinect Press Center/Prinect CP2000 Center 44
3.8 Measure the multicolor control elements in
Prinect Image Control 47
3.9 Stand-alone Quality Monitor: analysis of multicolor
measurement results 53
3.10 Create color proof
3.10.1 Configure the Imposition Proof (Page Proof) sequence
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1.1 Get closer to the original with the multicolor workflow
Conventional color printing using the four yellow, magenta, cyan and black
inks is a compromise between profitability and reproducible color space.
The standardization according to the process standard offset lets you obtain
the (restricted) color space in a stable and safe process and to provide a
color quality regarded as sufficient for many jobs at justifiable costs.
But the brilliance of the original is seldom reached with 4-color printing.
Because pigments of different inks are blended, the obtainable color
saturation of mixed colors, e.g. green or orange/red is by nature less
than the color saturation of a homogeneous green or red ink pigment.
But more brilliant colors and a color reproduction closer to the original are
the distinctive features that make you stand out from conventional 4-color
quality. Typical areas of application for Prinect® Multicolor are high-quality
job printing products and art printing where special uncoated paper is used
frequently.
During the last decades, attempts to expand the color space limits posed by
printing technology were made in two directions.
1 Introduction
Left picture: 6-color process with orange and green, right picture: 4-color CMYK process.
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1.2 Developments aiming at expanding the press color space
Improved ink pigments and ink composition. Development of high-pigment
inks.
Development of color systems with more than the four standard colors. •
Use of additional process colors (orange/red, green, blue/purple) in
5- to 7-color printing.
1.3 Definition of the multicolor workflow
In this document, we regard the following as part of the multicolor
workflow:
Expansion of the press color space by additional chromatic process •
colors.
Separation of image data and line art (HiFi Color, Hexachrome, •
5- to 7-color printing).
The following is not regarded as part of the multicolor workflow in this
document:
Printing of any number of separate spot colors without separation of •
image data and line art. Today, this is possible without restrictions and
does not require any special process.
Replacing one process color with a spot color (e.g. cyan, red, yellow, •
black instead of cyan, magenta, yellow, black). Application of the Prinect
products for process calibration and profile generation does not pose any
special demands on the process.
Use of high-pigment inks. With the Prinect products this does not pose •
any special demands on the process either.
1.4 The advantages of the multicolor workflow as opposed to the
CMYK workflow
The advantages of the multicolor workflow:
Extended gamut (closer to the original)•
Better definition and contrast even in pastel hues•
Better reproduction of saturated colors•
Exact colorimetric reproduction even of extreme product colors•
Better reproduction of separated spot colors•
The Prinect multicolor workflow and printing with five to seven process
colors offers your customer better differentiated products and stresses
the quality in contrast to competitors’ products.
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1.5 Prinect workflow components
1 – Prinect Signa Station
Prinect® Signa Station® is used to combine files to signatures ready to
be printed. During this process, you position color control bars – the
Mini Spots® in our case – on the press sheet. Prinect Signa Station relays
the control bar positions, allowing Prinect Image Control to automatically
detect the color control bar positions. You should use color control bars of
the current Dipco package only.
2 – Prinect Prepress Manager
In the Prinect environment, Prinect Prepress Manager™ provides the
Prepress workflow that allows for an automation of all prepress production
steps from data input via preflighting of PDF files to imposition and proof,
acceptance cycles and platemaking with this flexible digital workflow.
The multicolor option is available for the Classic or Integrated workflow
variants. Using the multicolor option you extend the capabilities of Prinect
Prepress Manager by processing of multicolor input data and multicolor
profiles.
3 – Prinect MetaDimension
Prinect® MetaDimension® lets you drive proofers and image film and offset
plates on Heidelberg CtF and CtP devices. Processing of multicolor process
calibrations and multicolor separations are additional features of the
multicolor workflow. Control of Prinect MetaDimension occurs via Prinect
Prepress Manager.
4 – ColorProof Pro
ColorProof Pro is the Proof Engine Manager of Prinect MetaDimension and
lets you print layout, color and concept proofs. Checking the register and
the color reproduction using a layout and color proof is a necessary help,
especially for computer-to-plate. The color management system developed
by Heidelberg is used in conjunction with ICC profiles. This technology
Overview of Prinect multicolor workflow (with reference points 1 thru 10).
Prinect Prepress InterfacePrinect Pressroom Manager
Prinect Signa Station
Prinect Prepress Manager
Prinect MetaDimension
Platesetter
SpeedmasterPrinect Press CenterCP 2000 Center
Prinect Image Control
Prinect Color Toolbox with:– Profile Tool– Quality Monitor
Calibration Tool
Color Proof ProProofer
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guarantees true to color reproduction and correct print simulation on the
respective proof system. Apart from an inkjet-based proof system with
paper output you can also use the monitor softproof function to check the
sheet and the individual pages.
In the multicolor workflow, a true color proof is more difficult to obtain
than in the four-color workflow: Many currently available proof systems
have more than four color inks but process CMYK input data “only” or per-
form an internal conversion to CMYK first. For this reason, the multicolor
color space cannot always be fully reproduced on the proofer.
5 – Prinect Pressroom Manager/Prinect Prepress Interface
Prinect Pressroom Manager is the connecting link between RIP and Prinect
Press Center® as well as Prinect Image Control. Using the low-resolution
previews it calculates the zonal ink coverage values needed by Prinect
Press Center/Prinect® CP2000 Center® for ink fountain presetting. Prinect
Pressroom Manager® also processes the parameters for workflow successors
Prinect Press Center/Prinect CP2000 Center and Prinect Image Control
received from the RIP.
6 – Platesetters
The platesetter functions in the multicolor workflow just like in a
conventional workflow. Heidelberg uses all screening systems in the
multicolor workflow: Stochastic Screening, IS-Classic and Prinect
Hybrid Screening.
7 – Speedmaster with Prinect Press Center/Prinect CP2000 Center
Multicolor printing is only feasible with regard to costs and technology if
printing can be done in a single pass. For this reason you must match your
multicolor strategy with the configuration of your presses. A 5- to 7-color
press offers ideal conditions to enter into the multicolor workflow. Prinect
Press Center lets you incorporate the press into the integrated Prinect
workflow management system. With Prinect Prepress Interface you import
presettings from prepress.
8 – Prinect Image Control
Prinect Image Control is a color measurement system for quality control
outside the printing press and an ideal measuring equipment for the
multicolor workflow. It is the only system worldwide that lets you perform
a spectrophotometric measurement of the entire print image. Based on the
calculated offsets to predefined reference values, the operator is automatically
given correction recommendations. These are submitted to the press
online, which then adjusts the ink fountains in all press units simultaneously.
The integrated Quality Monitor lets you carry out a broad range of quality
assessments. Prinect Image Control thus warrants a reliable quality check
making it easier for the print shop to continuously print at a constantly high
quality level.
The multicolor workflow places higher demands on the colorimetric system
than the 4-color workflow. In this context Prinect Image Control offers an
enormous speed advantage over other colorimetric systems. On one hand,
there is the automatic detection of control elements based on the positioning
data provided by Prinect Signa Station. On the other hand, there is the
online provision of measured data in Prinect Workflow, likewise for quality
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control of ongoing production but also for calculating and correcting profiles
in Profile Tool and process calibrations in Calibration Tool.
9 – Prinect Color Toolbox 3.5
Prinect Color Toolbox comprises two components that can be licensed
separately: Calibration Tool (further development of Calibration Manager),
Color Tool (further development of Print Open and Quality Monitor).
10 – Calibration Tool
Calibration Tool is the “stand-alone” version of Calibration Manager
integrated in Prinect MetaDimension. It is used to create and correct
process calibrations. You can use the measurement data of the Mini Spots
for correction.
Calibration Tool can be operated as stand-alone version or fully integrated
in the Prinect workflow with online data connection to Prinect Image
Control and as central calibration server for the Prinect MetaDimension
Rips connected to the network.
In the multicolor workflow, the Calibration Tool has the same task as in the
4-color workflow. It provides the calibration curves for Prinect
MetaDimension.
11 – Profile Tool and Quality Monitor
Color Tool is a further development of the former Prinect Profile
Toolbox (i.e. Print Open and Quality Monitor). Both applications now run
in a common user interface. You can license any of the two separate
functions:
Profile creation
Creation and editing of DeviceLink profiles and ICC output profiles for color
printers, color copiers, proofers and presses. You can use the measurement
data of the Mini Spots to correct profiles. When the multicolor option has
been licensed, the Profile Tool can also calculate Multicolor profiles. In the
multicolor workflow the Prinect Color Toolbox has the same task as in the
4-color workflow. It provides the profiles for Prinect Prepress Manager.
Process and quality control
With the Quality Monitor function you can monitor the measurement data
for compliance with printing standards, visualize offsets and make quick
decisions whether or not a correction of process calibrations or ICC profiles is
necessary. You can use the measurement data of the Mini Spots for quality
checking. The quality check is identical to the 4-color workflow.
Color space comparison between a 7c multicolor process and the
ISOcoated_v2 process. The color space in the blue, green and orange/red
areas expanded by the additional inks blue, green and orange is clearly
visible (the red border indicates the ISOcoated color space, the blue border
the multicolor color space).
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1.6 What you need for the beginning
Knowledge
Knowledge and expertise in process calibration and profile generation in •
4-color printing.
Knowledge and expertise in printing according to the process standard •
offset. The multicolor strategy from Heidelberg is based on these
foundations.
Knowledge of the Heidelberg workflow. •
These three prerequisites must be met before you launch into the multicolor
workflow.
Prepress equipment
When you want to work with Mini Spots and automatic position detection:
Prinect Signa Station with enabled Presetting Data for Press and Post-•
press option. Software version 4.0 is used in this example.
Prinect Prepress Manager Classic/Integrated. As of version 4, Color Carver •
Plus is enabled by default. It contains the MultiColor option.
Software version 4.0 is used in this example.
Prinect MetaDimension. Software version 7.0 is used in this example.•
Proofer and platesetter that can be controlled with Prinect MetaDimension.•
Prinect Color Toolbox 3.5 (ProfileTool, QualityMonitor, CalibrationTool) •
with enabled MultiColor option or the Prinect ProfileTool.
Equipment and conditions in the press room
Press with Prinect PressCenter/Prinect CP2000 Center, equipped with •
five, six or seven offset print units. Multicolor printing is only feasible with
regard to costs and technology if printing can be done in a single pass.
Prinect ImageControl with software version 5 and the Color Interface •
option.
Flawless press conditions (machine check).•
1.7 The “multicolor strategy from Heidelberg”
There is no such things as the only correct strategy. There are different
approaches and recommendations how to reach a stable and predictable
production process. And for each strategy you can find a proof that it is
successful. Quite a number of companies have been applying multicolor
printing and selling their products successfully for years.
The multicolor strategy from Heidelberg presented below is based on stan-
dardized 4-color printing and offers a comparably easy start.
The central points of the “multicolor strategy from Heidelberg”
Screening with AM and FM screens (Prinect IS Classic, Prinect Hybrid •
Screening, Prinect Stochastic Screening).
Use of classical CMYK process colors in process standard offset and one, •
two, or three additional colors.
Gray balance: as with 4-color offset printing using a GCR of 50%.•
FM screening is not always the ultimate choice
Many multicolor strategies provide for the usage of FM screens in order to
avoid the moiré issue. But the FM screening process is more difficult to
handle than AM screening. There is no equivalent for the process standard
offset with multicolor printing either. The combination of FM screening and
additional colors places great demands on the production process. You
must gather a lot of experience first unless you are familiar with one of
these factors. This is one of the reasons why multicolor printing has not yet
become widely popular.
Screening with Prinect IS Classic or Prinect Hybrid Screening and multicolor
profiles from Heidelberg
The separation procedure shown here lets you use AM screening. The basis
is Prinect IS Classic/Prinect Hybrid Screening and Heidelberg multicolor
profiles.
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The chart shows the structure of the separation with multicolor profiles from Heidelberg.
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The inner area of the color space coarsely identified by the bright triangle
(Fig. 1/1) can be obtained with conventional inks black, cyan, magenta and
yellow.
In the dark sectors (Fig. 1/2) one spot color each is used to fully utilize the
gamut of the sector.
The color composition of multicolor profiles from Heidelberg is always
restrictive: every color within the dark sectors is mainly made up of not
more than four “optimal” inks. The complementary color of the respective
color sector is widely suppressed in the color composition. This prevents
the moiré issue.
Color usage and screen angle
The table below shows the color usage in the sectors and the recommended
screen angle for the spot colors. For orange and green the screen angle
prevents the formation of moirés. For blue it is more feasible to use the
same screen angle as for magenta or black.
Selection of inks
Continue using standard CMYK process colors
The multicolor strategy from Heidelberg is based on the assumption that you
continue using the familiar standard process colors. Depending on the
sujet and the desired gamut, one, two or three spot colors are added, to be
included into the color separation, making them additional process colors.
Flexibility with spot colors
In contrast to other multicolor strategies you are not bound to the hue of
these spot colors. You obtain the largest gamut with colors opposing the
respective colors magenta, cyan and yellow in the chromatic circle.
Since there is no restriction to exactly defined hues, you save on licensing
fees and have more freedom in selecting an ink supplier and an ink series.
Well suited for a maximum sized color space are: orange red or bright to
medium red, medium green and blue or violet. The major requirement is
to use as lightproof colors as possible, decide on a printing order and
then generate your own multicolor profiles. With multicolor printing you
can reach the same process safety as in 4-color printing provided the
parameters are kept constant.
Matching rheological properties
Spot colors matching the used standard process colors cyan, magenta,
yellow and black with regard to their rheological and printing properties
are optimal. These spot colors normally belong to the same ink series as
standard process colors. You should ask your ink supplier for advice.
During process calibration you will find out that most spot colors print finer
than the CMYK standard colors. Ink manufacturers usually adjust their
standard inks so that the optimum desired inking is reached with a layer
thickness of 0.8 to 1.0 µm. Spot colors are usually adjusted so that the
desired inking is reached with a greater layer thickness (approx. 1.4 to
1.8 µm). Careful process calibration and profile generation is therefore
essential.
Which colors are not suited for the multicolor workflow?
Achromatic secondary colors (e.g. gray, brown, beige, etc.)•
Metallic colors, bronze colors, glimmer•
Fluorescent colors•
Replacement of CMYK with other colors•
5, 6 or 7 colors?
The number of used colors depends on the sujet to be printed, the machine
configuration and the profit that can be made in contrast to a 4-color
product. Recommended printing order: black, cyan, magenta, yellow, spot
colors in the downstream print units. The rheological sequence of standard
colors has been chosen so that they can be printed optimally in the usual
order.
Please note that the printing order greatly influences the process calibration
and the profile generation. When you change the printing order you will in
most cases have to repeat the process calibration and the profile generation.
5-color process
Depending on the sujet to be printed, one spot color orange (red), green
or blue (violet) is added. 5-color printing is also ideal for gathering initial
experience in multicolor printing because compared to 4-color printing the
effort is not much higher.
Print order black, cyan, magenta, yellow, spot color in print unit 5.
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6-color process
In most cases, the two spot colors orange (red) and green (or a palette of
six matched colors, e.g for Hexachrome) are added to the 4 process colors.
Although 6-color printing does not quite reach the gamut of 7-color
printing, it is by far less complex.
Print order black, cyan, magenta, yellow, orange, green. (As an alternative,
you can also swap the order of orange and green.)
7-color process
Here, the spot colors orange (red) and green and blue (or a palette of
seven matched colors) are added to the 4 process colors.
Print order black, cyan, magenta, yellow, orange, green, blue.
The sections to follow describe all necessary workflow steps.
Required and recommended workflow settings•
Multicolor test documents, test charts•
Process calibration procedure•
Creation of multicolor profiles•
Quality check and corrections in the multicolor workflow•
Prerequisites: full expertise in standardized 4-color printing with CMYK.
You also need to know how to operate the workflow components in
4-color printing. The present document supplements the operating
instructions of the each of the components but cannot replace them.
2 Preparations for a 7c job
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2.1 Determine the optimum density of the spot color
First you must determine the optimum desired inking for all used spot colors.
The best way to do this is to determine the relative print contrast. For this
purpose, you print an ink series using a suitable test chart (containing three
quarter and solid density patches). This ink series ranges from slightly
under-inking to over-inking of the press sheets.
A printed product should have as much contrast as possible. To this end, the
solids must have a high color density whereas the screen should be printed
with as much definition as possible (optimum difference of dot gain). When
the inking and consequently the screen dot density increase, the contrast
rises. But this can be done up to a certain level only; beyond this point, the
screen dots tend to grow and consequently – in particular in shadow areas –
to fill in. This in turn reduces the portion of paper white – and the contrast
decreases again.
The relative print contrast is calculated from the measured values of density
of solids and the density of the screen. The screen density value is mostly
measured in the three quarter tint patch.
Mathematic formula for calculation of the relative print contrast.
Graphical representation of the “relative print contrast”.
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2.2 Define process curve set for spot colors
In Calibration Tool 3.5 you first create a process curve set. You do this in
Administration/Process Curve Sets
The screenshot above shows a list of different process curve sets: The status
“identical” indicates that the version in the local database corresponds to
the database of the Master Data Server (MDS).
First copy an existing process curve set, e.g. HD ISO 60 Papiertypen 1+2
positiv and rename the copy, e.g. Multicolor-7c.
Then click CMY on the left, type the name of a new spot color on the right
– e.g. Orange – and click “Copy”. This will transfer the dot gains from CMY
(graph A) to the new spot color.
Process curve “Any (other) Spotcolor” should always be contained in the
process curve set. This ensures a process calibration is also present for
spot colors not or incorrectly defined and the RIP process will not abort.
For dot gains of spot colors you would normally use curve A.
When the established densities exceed D log 1.7, you should use curve B.
Information
Density curves according to ISO 12647-2: The dot gain for a density of 40
percent is: curve A = 13 percent, curve B = 16 percent, curve C = 19 percent,
curve D = 22 percent, curve E = 25 percent, curve F = 28 percent.
The screenshot below indicates the dot gains of curve A for orange because
the orange curve was created by copying the CMY curve.
Note
A great number of tests have shown that this procedure is a feasible
approach.
By enabling the Master Data Server (MDS), the new process curve set is
made available to all workflow components.
In the next step you will create a new multicolor process standard in Prinect
Color Toolbox 3.5. Here we will use our new Multicolor-7c process curve
set.
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Prinect Color Toolbox 3.5 presettings: In the MDS section, the Use tonal
values from Calibration Manager option is enabled.
2.3 Create multicolor process standard
In Prinect Color Toolbox 3.5 you have three options to create a new process
standard in the Process Standard section: CMYK, Spot Color and Multicolor.
Choose Multicolor here. In addition to the name of the standard you can
type a detailed description for this process standard in a comment box.
Selected process curve set and dot gain table.
To select the dot gains you choose the process curve set created beforehand.
You can specify the paper white and the CIELab values of all colors as
follows:
by manual input•
by importing test data of the 7c multicolor print job (OK sheet) •
Paper white, CIELab values and printing order.
Now migrate the new multicolor process standard you created in Prinect
Color Toolbox 3.5 into the Master Data Server (MDS).
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2.4 Create multicolor test form
Use Prinect Signa Station to create test form in dependence of the format .
The following control elements are used (present example: 50 × 70 format):
Color control bar for process control and press control
7S_i_F74 for 7c process•
6S_i_F74• for 6c process
FOGRA_6_F74 for 6c process•
FOGRA_5_F74• for 5c process
Control elements for color constancy and color decrease
7c_ColConst•
7c_ColDecrease•
For gray balance checking
ECI_GrayConL_FOGRA39 (or S, M variants)•
Prinect Mini Spots for checking color location and dot gain
MB_100_80_40_7C (all colors are on one control bar)•
Single color Mini Spots (measuring blocks)
MB_100_0_80_40_X•
MB_100_0_80_40_Z•
MB_100_0_80_40_U•
MB_100_0_80_40_S1•
MB_100_0_80_40_S2•
MB_100_0_80_40_S3•
MB_100_0_80_40_S4•
To generate the process calibration you should place as many dot gain
charts as possible on the sheet.
TWZ_7C •
For generating the multicolor ICC profile:
The test forms come in two parts because there is a greater number of
color patches. To minimize the influence of the ink zones you should
arrange the test form twice diagonally if possible.
7c_PO1•
7c_PO2•
The screenshot below shows the layout of a test chart (here: 70 × 100
format). The four small color patches on the edge of the test chart (with red
frame) make it easier to distinguish between the two test charts 1 and 2.
2.5 Linear imaging of test chart plates
Heed the correct angle when imaging the printing plates:
CMYK according to the selected screen system•
Map orange on the cyan angle•
Map green on the magenta angle•
Map blue on the magenta or black angle•
Note
In future versions you will be able to use custom screen systems with mixed
AM and FM screens in the multicolor workflow by way of the Screening
Editor. In this case you need to match the linearizations to the respective
process. This will be possible as of version 2.6 of the Calibration Tool.
Application of CIP3/CIP4 data will optimize the overall workflow. In Prinect
Press Center you generate optimized ink zone apertures by way of prepress
data and ink zone default settings. In Prinect Image Control you can
use position data of all control elements and test charts for automatic
measurement by way of the CIP3/CIP4 data.
You make all necessary settings in Prinect Prepress Manager or in Prinect
MetaDimension. Check all separate modules for correct settings. This
applies to: Prinect Pressroom Manager, Prinect Prepress Interface, Prinect
Press Center, Prinect Image Control.
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2.6 Printing to the desired multicolor process standard
The individual penetration behavior of inks requires to set up wet color sets
for all used inks. This applies to CMYK colors and also to spot colors. For
this purpose, a test print is made where differently thick ink layers are
printed across the entire sheet width.
You start with under-inking on the left side of the sheet and increase the
layer thickness for two to three ink zones each until an over-inking is
obtained on the right side of the sheet. Then allow the sheet to dry. Finally
compare the measured dry sheet with the desired target values. For CMYK
this is usually the process standard offset (PSO always refers to “dry values”).
To create the wet ink set, identify the wet values for CMYK and spot colors
across all ink zones that match the target values when measured in a dry
state. The best wet value for magenta could be in ink zone eight whereas
the value for black is in zone 16.
Proceed in the same manner for spot colors. When a CMYK wet ink set is
already present, it is now supplemented by orange, green and blue.
Control and monitoring of the print process occurs with multicolor control
bars and multicolor Mini Spots.
2.7 Measuring the dot gain charts for process calibration
For further assessment, sample three to ten OK sheets and measure them
with Prinect Image Control. All control elements will be automatically
detected if CIP3/CIP4 data is available here. Otherwise, you must manually
position the measuring masks for measuring the first sheet (for further
information refer to the Mini Spot Workflow documentation).
Then save the data of the dot gain charts locally.
Note
If Prinect Image Control is not available, measurement with a
spectrophotometer will be much more complex (e.g. measurement with
X-Rite Eye-One iSis).
2.8 Analysis and mean value calculation of measured data
The data must now be analyzed with Quality Monitor 3.5. This is best done
in the long-term analysis area. Here you can view all data in one array and
choose CIE, Dot gain or Density reports.
Any outliers will be deactivated before the mean data calculation of
measured data. In this way you obtain consistent data ideal for generating
a process calibration.
Mean data calculation is done in the Analysis tab using the menu item Test
chart -> Calculate mean data.
Another way is to open all data separately one after the other and then
to analyze it in Measure/Open measurement data. Here you must also
eliminate outliers. Final mean value calculation is again done in Test
chart -> Calculate mean data.
2.9 Create process calibration
Use the stand-alone Calibration Tool 3.5. to create the multicolor process
calibration.
Proceed as follows (example):
Create a calibration group Multicolor-7c•
Create a process calibration for CMYK•
Create a process calibration for orange•
Create a process calibration for green•
Create a process calibration for blue•
Import the data for each of these process calibrations and smooth them •
if necessary. For spot colors you can either choose the Spot colors:
Filter (RGB) with maximal density or Spectral density at wavelength with
maximum absorption option.
Note
Import via the spectral density gives more exact, higher density values.
24
Analysis and mean value calculation of dot gain data
Parameter set for: cyan, magenta, yellow and black
25
Parameter set for orange. Set up the other spot colors in the same manner.
Note
To measure the density of spot colors you can choose the filter (RGB)
that provides the respective maximum density. The filter colors of
spectrophotometers are normally designed for process inks cyan (red filter),
magenta (green filter), yellow (blue filter) and black (visual filter) only. But
there are spot colors whose absorption behavior cannot be sufficiently
characterized by these three filters. It is better to use spectral density for
measuring spot colors. Here the density values are calculated from the
wavelength of maximum absorption.
Further steps of generating a process calibration:
After generation, enable the process calibrations (green dot).•
Synchronize Prinect MetaDimension Calibration Server (when the •
stand-alone Calibration Tool 3.5 is used).
Image the multicolor test chart as calibrated plate set.•
Generate CIP3/CIP4 data for Prinect Press Center and for Prinect Image •
Control.
Print to the desired multicolor process standard.•
Again sample three to ten OK sheets and measure the dot gain charts •
and ICC profile test charts (consists of two parts).
Save the data. •
If necessary, you will have to correct the process calibration after this •
step, image new plates and reprint. Corrections that might be necessary
are done manually or using the iterative correction method.
2.10 Generate a multicolor ICC profile
Like with an analysis of test data prior to generation of the multicolor
process calibration, you must analyze the test data of the ICC test charts.
The data must now be analyzed with Quality Monitor 3.5. In Measure open
both pages of the ICC test chart and save them to one file with a new name.
Note
We recommend that you capture all parameters involved in the process and
to save them in Process Parameters.
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Example of remission spectrum for orange
You can perform analysis directly in the Measure or in the Long-term
analysis area. Any outliers will be deleted before the mean data calculation
of measurement data. Final mean value calculation is again done in Test
chart -> Calculate mean data.
After mean value calculation we recommend that you smooth the
measurement data. This will result in a more harmonic dot gain spread
across the entire gradation and eliminate any measurement errors that
may still exist.
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Smooth profile measurement data
In the Create tab you define the profile parameters prior to calculation of
the ICC profile. We recommend the following settings, derived from a great
number of test prints:
Total ink coverage = 340 percent•
Maximum black = 95 percent•
Black generation = GCR 50 percent •
After having set the profile parameters you can save this parameter set for
future use. Now calculate and save the multicolor ICC profile. A normal
4-color profile has a maximum size of up to 2 MB, a Multicolor ICC profile
up to 7 MB. This is why calculating the extended tables takes much longer
(up to five minutes).
Finally, store the new multicolor ICC profile in the respective system folders
and integrate it in the workflow:
\\PrepressManager_Address\PTConfig\SysConfig\Resources\ICC-Profiles\
Multicolor
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Profile settings in the Profile Tool
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Color space diagram
3 Workflow: step by step
3.1 Input data
3.1.1 Color space of input data
The input data can be in the CMYK, RGB, or Lab color space. By selecting
a profile you determine, which profiles are to be used as basis for the
separation.
Lab color space (device-independent)
Input data in the Lab color space have a large gamut and are optimally
suited for making full use of the multicolor color palette.
RGB color space (device-independent when ICC profile is embedded)
Input data in the ECI-RGB or Adobe® RGB color space also have a
sufficiently large gamut allowing the multicolor color palette to be fully
utilized.
Input data in the sRGB color space are suited with restrictions only
because the sRGB color space has too small a gamut to make full use
of the multicolor color palette.
CMYK color space (device-independent when ICC profile is embedded)
Input data in the CMYK color space are suited with restrictions because the
gamut is smaller than that of the multicolor color space. The device-
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dependent CMYK data is mapped to device-independent Lab data using the
selected profile.
3.1.2 Color space expansion by “inverse Gamut Mapping”
When the profiles of the input data contain the required information,
mapping of the CMYK color space to the larger Lab color space is possible.
This calculation is called inverse Gamut Mapping because the CMYK color
space is inversely mapped to the original Lab color space. You can thus
utilize the multicolor color space and obtain a better color reproduction.
Inverse Gamut Mapping is enabled with the Perceptual Rendering Intent.
For this reason you should use the Perceptual Rendering Intent.
Note
Check whether or not the profiles of the input data contain the necessary
information for inverse Gamut Mapping. The profiles generated by
Heidelberg products contain the necessary information for inverse Gamut
Mapping. For other profiles contact the manufacturer of the product in
question.
3 .2 Create PDF document in the DTP application
The MultiColor test job shown on the next page was created in Adobe
InDesign CS3. Elements and special features of this job:
The headers on pages 1–3 were created in three different Pantone spot •
colors. These differ from the three multicolor process colors orange,
green and blue and only serve to illustrate how spot colors are handled
in the multicolor workflow.
The header on page 4 is in CMY.•
The images on the first three pages are RGB images in the ECI-RGB v2 •
color space.
The image at the bottom of page 4 is in the ISOcoated_v2 -CMYK color •
space.
The technical screen patches are in Pantone colors and equivalent CMYK •
colors.
In the three Pantone colors, gradients were created in order to check the •
gradation shading.
On page 4, two vertical RGB gradients were added. •
Important
Pantone spot colors should always be mapped to Multicolor with the LAB
color space because the large multicolor gamut can thus reproduce the
spot colors better.
4-up document of the multicolor workflow description
The 4-up document was created in Adobe InDesign CS3. Heed the
following:
Check whether ICC profiles were embedded prior to image import. Do not •
use special characters for spot color names
Enable color management in the InDesign color settings for PDF export of •
the InDesign document
No color conversion must be enabled•
Include destination profiles must be enabled•
Make appropriate settings in other DTP applications. QuarkXPress has
the following restriction: LAB and RGB objects are incorrectly handled in
the color management. In this multicolor workflow description the PDF
generation occurs via the Export function in Adobe InDesign. You can also
generate such a PDF by writing a Postscript file and then convert it with
Adobe Distiller later.
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After having created the PDF document you must check whether all color
settings have been adopted correctly. You can do this with Prinect Color
Editor in conjunction with the Acrobat Output Preview.
Example: Adobe Acrobat Output Preview: CMYK is disabled, all spot colors
are enabled. The shown page comprises the spot color orange only.
Example: Prinect Color Editor: This Acrobat plug-in provides information on
the color spaces of images and line art objects, embedded profiles, and the
percentage of the colors (image or line art) in the separations.
The checked production PDF serves as input for the production workflow.
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3.3 Job processing in Prinect Prepress Manager
3.3.1 Create job and assign sequences
First create a new job.
Then select the right Multicolor profile in Job Settings, section Printing
Process. In this example: Multicolor-7c.
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Finally assign the required sequences for the Qualify, Prepare, Imposition
Proof, Imposition Output and Sheetfed Printing operations.
By default, the Qualify sequence can be used without special configuration
for the multicolor workflow.
3.3.2 Configure Prepare sequence
Configure the Prepare sequence as follows:
The Document tab
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The option Ignore embedded non-CMYK profiles is disabled for two
reasons:
The supplied images with RGB profiles could be right.•
If the profiles should prove to be wrong (e.g. Adobe default sRGB), the •
resulting damage is limited. The damage in case of CMYK would be much
greater.
The option Ignore embedded CMYK profiles must be enabled to automatically
remove incorrectly embedded profiles. The damage caused by a wrong
CMYK profile and the resulting mapping is very severe and must therefore
be prevented. For this reason it is better to remove the profile here and to
replace it with a custom profile in the Device Independent Colors section.
Info
These settings are vital because ICC profiles are seldom embedded in the
images in daily production. It happens frequently that wrong profiles are
embedded because the operator is not familiar with the Adobe settings and
applies the default settings only. As a consequence, the images often
contain SWOP profiles, which causes inacceptable results. Embedding ICC
profiles in images is possible in Adobe InDesign and Adobe Acrobat but
takes much time and is avoided by users.
35
The Color Management tab
Enable use press profile from job settings, if available
To correctly map the supplied RGB images to the Multicolor color space,
the RGB options must be enabled in the Device Dependent Colors section.
You do this by selecting the Perceptual Rendering Intent.
Choose an RGB ICC profile matching the used data.
The CMYK options must also be enabled to ensure the CMYK images
are also correctly mapped to the multicolor color space. You do this by
selecting the Perceptual Rendering Intent.
For CMYK you will in most cases choose the ISOcoated_v2 profile in the
Presettings.
For Overprint and Advanced use the default settings also applicable to
CMYK production jobs.
36
The section Device Colors/Device Link
3.3.3 Configure the Imposition Output sequence
Choose the correct curve set for the used screening system here when a
linearization is applied.
In the Calibration section select the Multicolor-7c calibration group you
created earlier. This calibration group comprises curve sets for CMYK and
the spot colors orange, green and blue.
Required settings
Select the multicolor process curve set, here: Multicolor-7c.•
Match, else error is necessary for transmission of all print-related •
parameters (paper class, ink series) to the Prinect Press Center or the
Prinect CP2000 Center.
Selection of press and ink series according to the process calibration.•
Application of the default ink series for the spot colors. This option is •
decisive for an automatic selection of the respective color transfer curves
for spot colors in Prinect Press Center or Prinect CP2000 Center later.
Set the parameters of the screening system according to the process •
calibration.
Enable CIP3/CIP4 data generation.•
CIP3/CIP4 setting at the bottom of the Imposition Output sequence
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3.3.4 Configure Sheetfed Printing sequence
Required settings
Sheet Preview Generation with 50.8 dpi•
Ink Zone Calculation (number of ink zones according to the press)•
Ink Consumption Calculation (for later evaluation in MIS)•
Optional settings
HDM Image Control (for automatic detection of color control elements) •
This setting will optimize the procedure of measurements in Prinect Image
Control. Without forwarding of PPF data from prepress to Prinect Image
Control you must place all color control bars, Mini Spots and test charts by
hand after measuring. The application of PPF data automates this process.
The PPF data (Print Production Format) contain the positions and names of
all used control elements generated by Prinect Signa Station.
3.3.5 Configure job settings
In the Job Settings you define the angles of orange, green and blue.
This controls the multicolor angles and screens.
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The following angle settings are used in this production job
Orange is given the angle of cyan•
Green is given the angle of magenta•
Blue is given the angle of black (magenta is also possible here)•
Important
To convert the PDF documents into the multicolor color space the multicolor
profile must have been selected in the Job Settings even before processing
in Prepare.
3.3.6 Edit the job settings
It may be necessary to edit the Job Settings and to start a second Prepare
step depending on the job.
Example
Our sample document contains three additional Pantone® colors. These
must be mapped with the multicolor profile to the multicolor process.
Ideally this is done via the LAB color space. In case there are only CMYK
definitions of the Pantone colors, you can use these as well.
Note
The three Pantone colors Pantone 165 C, Pantone 286 C and Pantone 354 C
contained in the PDF document are taken from the Pantone solid coated
table. Make sure this color table is as close to the top of the list of all custom
and default color tables as possible.
Job Settings screenshot: This job contains another three Pantone colors in
addition to the multicolor process colors orange, green and blue.
39
40
Required changes in the job settings (screenshot on the previous page)
The colors orange, green and blue are output as single printing plates
(Imposition Output). The Pantone colors were set to Process in the Job
Settings of Output. This means the three Pantone colors will be mapped
with the multicolor profile to the multicolor process. In other words, the
Pantone colors are created by blends of cyan, magenta, yellow, black,
orange, green and blue.
3.4 Create the layout
Start the interactive Prinect Signa Station in Prinect Prepress Manager
and generate a new layout. Administrative data is imported from Prinect
Prepress Manager. An existing layout can be imported.
Follow the Job Assistant step by step and make all necessary settings.
Finally, place the color control bars and Mini Spots suitable for the
multicolor process on the plate template. These control elements will be
detected automatically during the measurement because the JDF data is
transferred to Prinect Image Control.
Important
The Heidelberg workflow uses so-called combination marks. In Prinect
Signa Station you define several color control bars or Mini Spots combined
in a combination mark. For example, the color control bars 4GS, Fogra5,
6S and 7S are defined as a combination mark. By cooperation between
Prinect Signa Station, Prinect MetaDimension and Prinect Prepress Manager,
the number of document colors is used to determine the optimum mark in
the marks pool. This mark is then selected automatically. In our example it
would be Mark 7S.
41
The Mini Spots are likewise defined as combination mark:
MB_100_80_40_CMYK, MB_100_80_40_5C, MB_100_80_40_6C,
MB_100_80_40_7C. The selection of the optimum Mini Spot occurs
automatically here as well.
Screenshot: Example for a combination mark
Template with color control elements in place
There are the following color control elements on the template:
7S_i_F74 (color control bar for 7-color process)•
ECI_GrayConL_FOGRA39 (special Mini Spot for gray balance control)•
MB_100_80_40_7C (Mini Spot for 7-color process)•
When you have saved the job in Prinect Signa Station, Prinect Prepress
Manager will import the data automatically. Then the page assignment of
the page list is performed and the layout completed.
Page lists and page assignment in
Prinect Prepress Manager
Page assignment in Prinect Prepress
Manager
42
Separation list in Prinect Prepress Manager for a fast overview of the colors
that will be printed on the press sheets.
3.5 Platemaking and generation of CIP4 data
When the layout is complete, platemaking and CIP4 data generation can
be started. To do so, place the layout with drag & drop on the configured
Imposition Output and Imposition Proof sequences. The Imposition Proof
sequence will be explained from page 58 onwards.
Note
Platemaking for a multicolor process with a platesetter is nothing special.
The additional colors orange, green and blue are treated and output like
ordinary spot colors.
3.6 Check the CIP4 data in Prinect Pressroom Manager
After the Tiff-B data for platemaking are calculated and the CIP4 data for
the optimized workflow up to the press are generated, you can check the
calculated ink coverage zones in Prinect Pressroom Manager. You can also
check whether or not the area for this calculation was set correctly (green
frame).
43
Both screenshots show the ink coverage zones, the first for all seven colors
and the second for orange only. The correct position of the green frame is
vital.
3.7 Prinect Press Center/Prinect CP2000 Center
In Prinect Press Center you load the job from Prinect Pressroom Manager (or
Prinect Prepress Interface). Apart from administrative data you see the
sheet size (here 50 × 70 centimeter) and a small preview.
44
The parameters ink series and paper class are vital for an automatic
selection of inking unit settings from the Prinect Press Center database.
In our example, these are paper class 1 and ink series OekoSpeed.
In Inking unit settings you can check whether or not the correct values were
submitted by Prepress. The screenshot below shows that the inking unit
settings OekoSpeed was selected for black, cyan, magenta and yellow.
There is a separate inking unit setting of the same name for the three spot
colors orange, green and blue.
45
The color allocation is also read from the CIP4 data.
Before printing begins you must assign the reference values for all seven
inks. You do this directly at the Prinect Press Center (Prinect CP2000
Center) when Prinect® Axis Control® used for color measurement. When
you operate Prinect Image Control, you select the reference values here.
The reference values are saved in ink series.
46
3.8 Measure the multicolor control elements in Prinect Image Control
The use of Prinect Image Control greatly facilitates the multicolor process.
This applies in particular to measuring the two ICC test charts where you
can save a lot of time in contrast to measurements with other
spectrophotometers.
Before starting the first measurement you must load the correct ink series
in Prinect Image Control that contains the reference values of all seven inks.
This ink series was generated during a test print beforehand.
By way of the online connection to the control console of the press (Prinect
Press Center, Prinect CP2000 Center) the color allocation is automatically
submitted to Prinect Image Control.
47
Now the PPF data along with details on the positions of color control
elements (information from Prinect Signa Station) generated in Prinect
MetaDimension and forwarded by Prinect Pressroom Manager will open.
A job preview appears. This optional function makes manual positioning
of any color control elements unnecessary and increases productivity.
When you confirm this screen, the next window appears where you see
the loaded prepress data and the active color set.
48
Now measure the first pull sheet in the makeready phase of the current
print job. When you press the Color control strips button, you see all
automatically detected color control elements at he bottom left of the
window (with red frame). This applies when the PPF data was loaded
during job set-up.
The Save Quality Data button lets you save the color control elements
shown. You will receive a message when saving was successful. By default,
the data is written to the folder structure of Prinect Image Control.
C:\cpc24\QualityMonitor\Results
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In the overview (Overview button) you can verify the inking of zonal
deviations to the selected color set (e.g. Delta-E, dEo, dF, S/D, dot gain).
You can analyze the CMYK test data either with the internal Quality Monitor
of Prinect Image Control or with the stand-alone Quality Monitor of Prinect
Color Toolbox 3.5. The stand-alone Quality Monitor of Prinect Color Toolbox
3.5 offers enhanced analysis options.
Here you can also perform long-term and trend analyses for multicolor
data. Thus you are given information on the stability of production processes
during a certain period of time. In case of deviations you can use the Mini
Spots control elements to correct process calibrations and ICC profiles.
You can have Quality Monitor opened automatically after every measurement
or you can open it manually as shown above.
50
In the service area of Prinect Image Control you can specify different
tolerances in section Quality Monitor Setup.
Before starting the analysis, you must select the desired process standard.
In the internal Quality Monitor of Prinect Image Control this only applies
to the CMYK portion of the measurement data. The stand-alone Quality
Monitor of Prinect Color Toolbox 3.5 lets you also analyze multicolor data.
51
You can define filters for opening the measurement data such as press, job
number, date or control element type.
The screenshot below shows the analysis of CIELab color values.
52
In the example below the dot gain in the ECI_GrayConL_Fogra39 control bar
is checked.
3.9 Stand-alone Quality Monitor: analysis of multicolor
measurement results
All measurement data generated with Prinect Image Control can be made
available via the network for in-depth analysis and logging. As mentioned
before, you can analyze multicolor measurement data with the stand-alone
Prinect ColorToolbox 3.5 software only because the multicolor process
standards are available only here. The same applies to the necessary
long-term analyses. First select the multicolor process standard for the
analyses:
53
Prinect Image Control can import or directly capture measurement data
with a spectrophotometer.
For measurement data import you can set up a a maximum of four hotfolders
in the Preferences.
When measuring with a connected spectrophotometer you must first select
the correct test chart type. Make sure an appropriate test chart layout is
present for the existing spectrophotometer.
54
Note
To differentiate between Prinect Image Control Quality Monitor and
stand-alone Quality Monitor of Prinect Color Toolbox 3.5 we are going to
describe the advanced functions of the stand-alone version only.
The first screenshot shows a single imported 7S control bar to be compared
with the selected multicolor process standard. The CIELab color values are
shown numerically and graphically.
The screenshot below shows the dot gain curve for spot color blue
measured with mini spot MB_100_80_40_7C.
55
The screenshot below illustrates the possibilities offered by the long-term
analysis. It shows several measurement data records of the 7S color control
bar as density report.
The following example shows a dot gain report of all seven colors (data re-
cords Mini Spot MB_100_80_40_7C). The tolerance range for orange is also
enabled. At the 80 percent reference point the relative (not the absolute)
dot gain is shown.
56
The screenshot below illustrates another possibility offered by the long-term
analysis. It shows several measurement data records of the 7S color control
bar as CIE report.
There is the option to select two data records in the long-term analysis
and to automatically submit these to the Compare section. Here you obtain
additional, more detailed information.
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3.10 Create color proof
To complete this documentation, we are going to describe how to create a
color proof.
In Prinect Prepress Manager you can configure the Imposition Proof or Page
Proof sequences for this purpose. The present section will close with an
example of how to configure the Imposition Proof sequence.
Information
The screenshot below shows a color space comparison between 7c
multicolor and an Epson 9800 color proofer. It is clearly visible that several
areas of the multicolor color space – the extremely chromatic colors –
exceed the proofer’s color space. This prevents the use of today’s color
proofers such as those made by Canon, Epson, HP as contact proofers for
multicolor.
The quality of the proof also depends on the number of proofer colors
the RIP process can control. There is no use in having a proofer with eight
colors if the RIP process can control four channels (CMYK) only.
As of today, only a proof print can be true to color.
Except for extreme CMY and RGB colors, the proof process nevertheless
provides a very good reproduction of all other color ranges. To sum up:
Although you cannot print a contact proof contact proof with currently
available color proofers, you will obtain results very well suited for an
assessment prior to proof printing.
Comparison of a 7c multicolor color space with the color space of an Epson
9800 color proofer (red = Epson 9800, blue = 7c multicolor color space)
58
3.10.1 Configure the Imposition Proof (Page Proof) sequence
Select the new Multicolor ICC profile you created as press profile. As
Rendering intent select absolute colorimetric .
Proof generation can either occur by way of single pages (Pageproof) or
imposed pages (Imposition Proof).
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Heidelberger Druckmaschinen AGKurfuersten-Anlage 52–60 69115 Heidelberg Germany Phone +49 6221 92-00 Fax +49 6221 92-6999 www.heidelberg.com
Publishing InformationPrinted in: 10/09Photographs: Heidelberger Druckmaschinen AGFonts: Heidelberg Gothic MIPrinted in Germany
Trademarks Heidelberg, the Heidelberg Logo, Prinect, Axis Control, CP2000 Center, MetaDimension, Mini Spots, Prinect Prepress Manager, Prinect Press Center, Prinect Pressroom Manager, Signa Station and Speedmaster are registered trademarks of Heidelberger Druckmaschinen AG in the U.S. and other countries. Adobe, PostScript and Acrobat registered trademarks of Adobe Systems Inc. All other trademarks are property of their respective owners.
Subject to technical modifications and other changes.
