Xerox DOCUTECH 6155, DOCUTECH 6180, DOCUTECH 6115 User Manual
Xerox Document Services
Platform
Color Management Guide
701P40210 Version 3.7 May, 2003
Xerox Corporation
Global Knowledge and Language Services
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Building 845-17S
Webster, New York 14580
USA
Copyright 2003
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Copywright by Xerox Corporation. All rights reserved.
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This product includes software developed by the Apache Software Foundation (http://www.apache.org/).” SWOP® is a registered trademark of SWOP, Inc.
While the information in this Guide is correct at the time of this publication, Xerox reserves the right at any time to change the information without notice. Changes are made periodically to this document. Changes and technical updates will be added in subsequent editions.
Table of contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Multiple print engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
About this guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Related documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
Customer Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2. DocuSP color management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Queue overrides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Color workflows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Color path charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
ICC standard path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Xerox enhanced path . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 CMYK Native path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
Fast Reprint path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
PANTONE® path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 Color Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Associations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
New Stock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Assign profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
New color group (stock group) . . . . . . . . . . . . . . . . . . . . . 2-6 Color profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
User TRCs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7
Color tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 Print engine specific mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 Xerox consistent color mode . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 Custom color mode (default) . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 Color adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 Image quality tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 Expert color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11 Print as grayscale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
Spot color editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12
OPI (Open PrePress Interface) . . . . . . . . . . . . . . . . . . . . . . . . 2-13 DRIs (Display Resolution Images) . . . . . . . . . . . . . . . . . . . . . . 2-13
3. Stock Management and Calibration . . . . . . . . . . . . . . . . . . . . . . . . 3-1
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Table of contents
Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
Tips for use of Xerox Qualified Stocks . . . . . . . . . . . . . . . . . . . . 3-3
Calibration process overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 Calibrating the DocuColor 2045/2060/6060 family . . . . . . . . . . . 3-4
Calibrating the DocuColor iGen3 . . . . . . . . . . . . . . . . . . . . . . . . 3-4
Calibration target tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 Stock Management hints and tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
General Stock Workflow Setups . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
Unspecified Stock Name Model Setup . . . . . . . . . . . . . . 3-7 Three Stock Model Setup . . . . . . . . . . . . . . . . . . . . . . . . 3-8
Custom and Colored Stock hints . . . . . . . . . . . . . . . . . . . . . . . 3-11
4. Using color tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Using Custom color mode (default) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Basic color tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Image quality tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
User Tonal Reproduction Curves (TRCs) . . . . . . . . . . . . . . . . . . 4-4
Expert color tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 Spot Color Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10
Understanding the Spot Color Editor window . . . . . . . . 4-10
Open PrePress Interface (OPI) . . . . . . . . . . . . . . . . . . . . . . . . 4-11 Using Print Engine Specific mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13
Using XCC (Xerox Consistent Color) mode . . . . . . . . . . . . . . . . . . . . 4-13
5. Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Image paths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Things to remember . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
A. System Specified defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-1 B. Glossary Of Color Management Terms . . . . . . . . . . . . . . . . . . . . .B-1
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Color Management Guide |
1.Introduction
This guide is a reference to the DocuSP controller color management features. The DocuSP controller serves as the digital front end for preparing and processing jobs to print on Xerox color print engines.
The DocuSP operator uses the information in this guide to enhance the use of the color management tools to achieve quality color output.
Assumptions
This guide assumes that the DocuSP operator is familiar with the DocuSP controller and the attached print engine, and is also familiar with color printing.
Refer to the DocuSP on-line help system for procedures on how to use the DocuSP color tools.
Multiple print engines
The DocuSP controller includes color management tools for the
DocuColor 2045/2060/6060 and iGen3 Digital Production
Presses.
This guide provides general color management information for the DocuSP controller; also, printer-specific information is noted where necessary.
About this guide
Before you read in this guide, become familiar with its contents and conventions.
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Introduction
Conventions
This guide includes the following conventions:
•Angle brackets: Variable information that is displayed on your window or that can be entered as part of a command line is enclosed within angle brackets. Examples include "Unable to copy <filename>;" “set –p <printer>.”
•Square brackets: Square brackets are used for the following:
–Names of menu options that you select; for example, [Printer Default]
–Names of buttons that you select; for example, [OK] and [Cancel]
–Names of text boxes, list boxes, and fields; for example, "the [From] text box," "the [Directories] list box," “the
[Color Source] field”
•Bold: Boldface type is used for the following:
–Directory paths; for example, “Browse to the Color profiles directory.”
–Text that you enter; for example, "Enter purple or Xerox."
–Calling attention to text that is particularly important; for example, “Select [Stop] on the user interface window. Do not press the red stop button on the controller.”
–Introductory words or phrases that begin items in a list; for example,
[Hold job]: The document is held at the printer...
[Cancel job]: The document is not printed...
•Note: Notes are hints that help you perform a task or understand the text. Notes are presented in italics, in separate paragraphs. Example:
NOTE: You cannot submit a job unless the printer is connected to your workstation.
Related documentation
Further information on the specific Xerox print engines or the
DocuSP controller may be obtained by referring to the documentation that was delivered with the elements of the system.
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Introduction
Customer Support
For service and software support, dial 1-800-821-2797. This number is enabled for TTY bridges. To reach Xerox Documentation and Software Services, dial 1-800-327-9753.
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Introduction
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2.DocuSP color management
Color management is a process of attempting to match colors across input (scanners, digital cameras), display (computer monitors), and output devices (color printers).
Hardware devices such as Spectrophotometers for calibration and software tools such as color profiles, tone reproduction curves (TRCs) and color tools are used to match or adjust color to achieve a quality color image.
Spectrophotometers are used to calibrate data for the print engine. Calibration data is used to adjust color balance for stock by halftone.
Color management software converts RGB and CMYK input color profiles to the color gamut of a specific output device.
DocuSP supports the traditional CMYK workflow as well as the ICC Profile workflow.
TRCs and other color tools allow you to make custom color adjustments, fine tuning the color image.
DocuSP provides the software color management tools you can use to produce quality color output.
Refer to the DocuSP on-line help system for detailed information and step-by-step usage procedures for all tools and processes presented in this guide.
Queue overrides
An override can be set for many of the queue properties in Queue Manager. A selected override property is applied to all jobs submitted to that queue, regardless of job or job ticket settings.
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DocuSP color management
Color workflows
A color image follows a path as it is converted from an input color profile to the output CMYK of the print engine. Factors that determine the path are:
•the characteristics and type of the input profile
•conversions needed for the output profile of the print engine
•enhancements made by you, the user
Color path charts
Jobs take one of five paths through the DocuSP controller. Whenever possible, you should use the Xerox Enhanced Path which provides the highest quality color for incoming SWOP™
CMYK color and faster RIP speed.
The color path chart (see Figure 2-1. Simplified DocuSP Color Workflow) displays the paths different documents take as they move through the DocuSP color management system and are processed for print.
The paths are:
•ICC Standard Path
•Xerox Enhanced Path
•CMYK Native Path
•Fast Reprint Path
•PANTONE® Path
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DocuSP color management
Figure 2-1. Simplified DocuSP Color Workflow
ICC standard path
Jobs undergo a color transformation to an independent color space before color transformation to the DocuSP print engine
CMYK color space. This path requires more RIP time as the color is transformed from Input (such as RGB or input CMYK) to Profile Connection Space (PCS) to output CMYK or SWOP™ CMYK. The K channel will not be preserved for incoming CMYK data.
The chief benefit of using this path is its ease of use.
The following conditions guarantee a job follows the ICC standard path:
•A user output profile has been assigned to the job.
•A color adjustment (lightness, contrast, saturation, color cast, trapping, black overprint, or anti-aliasing) has been set for the job.
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DocuSP color management
•The incoming job contains embedded profiles that result in the printer driver creating a Color Space Array (CSA) for the color data. These PDL instructions are honored by the system.
Xerox enhanced path
Incoming RGB or CMYK data uses the DocuSP Xerox Enhanced
Path Look Up Table (LUT) or Emulation LUT when performing the SWOP™ CMYK to DocuSP print engine CMYK transformation.
Benefits of using this path include:
•Faster RIP time via use of the LUTs as contrasted with the
ICC Path.
•This path preserves the Black (K) channel and Black darkness.
Look Up Tables provide a quick, effective translation from the source space to the specific printer’s CMYK space. These tables are faster because the CMYK values are translated directly to output space, instead of first being translated to deviceindependent space and then to the print-engine-specific space.
RGB data is converted using 3 x 4 LUTs.
4 x 4 LUTs provide direct CMYK to CMYK mapping, preserving black. When pure black is passed through a source profile (ICC profile path), it is converted to XYZ. Once in XYZ, there is no way for the color management system to know that the color was originally pure black. Thus, pure K is converted to a CMYK combination (Gray Component Removal, or GCR, is involved in this process). In contrast, the 4 x 4 tables recognize pure K and output the appropriate K for the source-to-destination mapping.
The following conditions guarantee a job follows the Xerox enhanced path:
•The incoming job is untagged and using a pre-installed output profile.
•A Xerox stock is programmed for the job
•A non-Xerox stock that is a member of an unaltered Xerox color group is programmed for the job
•A Xerox output color profile, included with the system, has been assigned to the job
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DocuSP color management
CMYK Native path
Color management is performed within the application using DocuSP output color ICC profiles to create jobs composed with the DocuSP print engine CMYK color profile. These jobs are sent directly to the RIP with no color transformations, assuming you have not programmed any color adjustments.
Documents destined for this path MUST be designed using the appropriate CMYK color space for the DocuSP destination print engine. This is usually achieved by using the CMYK destination profile for the destination media/engine combination.
Benefits of using this path include:
•Fastest RIP performance of any of the paths
•Color will be consistent throughout, since the job is created and submitted expressly for the specific print engine
Fast Reprint path
Fast Reprint jobs, accessed through Reprint Manager, are saved using “Print and Save” or “Save” commands when processing the job. Fast Reprint jobs do not require re-RIPping. Color management properties are set prior to saving the job.
The only color change that can be applied to a job on the Fast Reprint path is a User TRC.
Benefits of using this path include:
•No need to re-submit jobs
•Fast print times (achieving engine-rated speed) since the RIP is bypassed on reprint
•No need to reset Color Management properties
NOTE: Calibration TRCs and User TRCs may be applied to the reprint job, since TRC processing is done in the hardware.
PANTONE® path
An incoming job is scanned by the controller and, if the job contains PANTONE® calls, the PANTONE® path is invoked. The job’s color information is processed using a pair of Look Up
Tables (one for Coated and one for Uncoated) and then passes directly to the printer output, bypassing all other color processing except for User TRCs.
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DocuSP color management
Color Manager
Color Manager provides access to color management tools for calibration, characterization, assigning color profiles, managing color groups, creating and applying TRCs, and importing or exporting ICC profiles.
Associations
The Associations tab provides a list of stocks, their properties, date last calibrated, and the assigned profile.
Calibration
Calibration is used to return the print engine to a standard condition insuring color consistency for each stock or color group. For more in-depth information regarding calibration, see chapter 3.
New Stock
Destination color profiles are required for each stock or color group.
Stocks added from the catalog (Xerox Qualified Stocks) will automatically be placed in the proper color group.
New custom stocks will automatically be placed in the default color group.
Assign profile
Each stock is automatically assigned to a profile based on its color group.
Color profiles can be assigned to any stock or color group, including pre-defined stocks.
New color group (stock group)
Stocks are assigned groups based upon their whitepoint. Any stock in the group can be calibrated, and the resulting TRCs are assigned to all stocks in the color group.
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DocuSP color management
NOTE: You should calibrate a stock that best represents the other stock in the group; therefore, you should calibrate using a stock that has a whitepoint at about the median of the stocks in the group.
It is recommended that most users confine their use of color groups to the 3 pre-installed groups. This method provides excellent color results with relatively little user intervention.
For a more in-depth discussion of color groups, see chapter 3:
Calibration.
Color profiles
The Color Profiles tab provides a list of color profiles (both source and destination) with their descriptions.
User TRCs
User Tone Reproduction Curves (TRCs) provide the skilled user with a tool for adjusting the individual CMYK color separations in an image and saving those adjustments for use on other images.
The User TRCs tab provides a list of user-created TRCs and allows you to create new TRCs.
Color tools
Color tools allow you to make adjustments that impact the color characteristics of a print job. Color tools can affect jobs or queues, if assigned at the controller, or can be assigned by an application at the client workstation.
Print engine specific mode
Selected at the queue level, the print engine or product specific mode is unique to each Xerox color print engine and optimizes performance for that print engine. Print engine specific mode provides the best possible default color interpretation and rendering values for the widest range of images.
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DocuSP color management
Table 2-1. DocuColor iGen3 Digital Production Press mode default property settings
Queue Property |
Queue Setting |
|
|
|
|
Rendering Intent |
Relative Colorimetric |
|
|
RGB Source |
sRGB |
|
|
CMYK Source |
SWOP™ |
|
|
CMY Source |
System Specified |
Gray Source |
|
|
|
Destination ICC Profile Front/ |
System Specified (pre-installed |
Back |
and optimized for the iGen3) |
|
|
Lightness |
0 |
|
|
Contrast |
0 |
|
|
Saturation |
0 |
|
|
Color Cast (all) |
0 |
|
|
TRCs |
None |
|
|
Press Color Emulation |
None |
|
|
Table 2-2. DocuColor 2045/2060/6060 mode default property settings
Queue Property |
Queue Setting |
|
|
|
|
Rendering Intent |
Relative Colorimetric |
|
|
RGB Source |
sRGB |
|
|
CMYK Source |
SWOP™ |
|
|
CMY Source |
System Specified |
Gray Source |
|
|
|
Destination ICC Profile Front/ |
System Specified (pre-installed |
Back |
and optimized for theDC20xx/ |
|
60xx) |
|
|
Lightness |
0 |
|
|
Contrast |
0 |
|
|
Saturation |
0 |
|
|
Color Cast (all) |
0 |
|
|
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DocuSP color management
Table 2-2. DocuColor 2045/2060/6060 mode default property settings
Queue Property |
Queue Setting |
|
|
|
|
TRCs |
None |
|
|
Press Color Emulation |
None |
|
|
Xerox consistent color mode
Selected at the queue level, Xerox consistent color mode standardizes the print engine response to undefined color spaces by assigning them default source files. Default Source files provide output that looks similar when submitted from the DocuSP to a compatible Xerox color print engine, currently the DocuColor 2045/2060/6060 and the DocuColor iGen3.
Table 2-3. XCC mode default and override settings
Queue Property |
Queue Setting |
Applicability |
|
|
|
|
|
|
Rendering Intent - |
Relative Colorimetric |
Default |
Images |
|
|
|
|
|
Rendering Intent - |
Pure |
Default |
Text |
|
|
|
|
|
Rendering Intent - |
Saturation |
Default |
Graphics |
|
|
|
|
|
RGB Source |
XCC Mode RGB |
Default |
|
|
|
CMYK Source |
SWOP™ Coated |
Default |
|
|
|
CMY Source |
System Specified |
Default |
Gray Source |
|
|
|
|
|
Destination ICC |
System Specified |
Override |
Profile Front/Back |
|
|
|
|
|
Lightness |
0 |
Override |
|
|
|
Contrast |
0 |
Override |
|
|
|
Saturation |
0 |
Override |
|
|
|
Color cast (all) |
0 |
Override |
|
|
|
TRCs |
None |
Override |
|
|
|
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DocuSP color management
Table 2-3. XCC mode default and override settings
Queue Property |
Queue Setting |
Applicability |
|
|
|
|
|
|
Press Color |
None |
Override |
Emulation |
|
|
|
|
|
Custom color mode (default)
Selected at the queue level, Custom Color mode allows users with a high level of color management skills to make specific color adjustments using industry standard color tools.
Skilled users create queues with specific color properties, defaults and overrides. Jobs sent to these queues are assigned the queue properties automatically, improving the flow of jobs through the DocuSP controller and reducing the adjustments required on a standard set of color jobs.
Color adjustments
Color tools provide a means for you to make adjustments in color images.
•Lightness controls the relative brightness or darkness of the color image.
•Contrast is the ratio between the light tones and dark tones in an image.
•Saturation controls the strength or purity of the color image.
•Color Cast adjustments provide you with the ability to increase or decrease the amount of a single color in an image.
•User TRCs are created to provide a consistent color rendering based upon a given set of properties. TRCs are saved and applied to jobs.
Image quality tools
Image quality tools provide you a means to improve image quality.
•Trapping compensates for misregistration that creates white gaps and shifted hues.
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