Digital Print Manufacturing: Color Management Workflows and Roles
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Digital Print Manufacturing: Color Management Workflows and Roles Ann McCarthy Xerox Innovation Group ICC Steering Committee ICC Color Management Workflows Digital Smart Factory Forum 24 June, 2003 What do we mean by workflow? 2 The term “color fidelity” refers to the successful interoperability of color data, from color object creation to output across multiple targets, such that color reproduction quality consistent with the user’s intent can be achieved. In this context, a workflow is a sequence of color object manipulations … …that accomplishes a color capture to color production process. ICC Color Management A. McCarthy Digital Smart Factory Forum 24 June, 2003 What are the key ‘color’ questions? 3 • RGB vs. CMYK ? Scanning Design Exchange Archive Re-use • RGB vs. CMYK is not where the color workflow question starts… ICC Color Management A. McCarthy Digital Smart Factory Forum 24 June, 2003 Digital Color Control (ICC) Architecture Elements 4 • Device calibration Color Calibration – Printing Aims Alters the color response of a device to return it to a known state • Capture and visualization characterization Response Measurement Describes the color response of an input or output condition • Profile creation Full Range – Color Response Specification Encodes a characterization and a color aim for use in a transform • Image color encoding Color Source Specification – Digital Capture Unrendered (e.g., capture a scene) vs. color-rendered (targeted) • Profile selection and exchange Color Communication – Virtual Film Profiles can be embedded with an image or document, or can be transmitted as separate files • Profile use Color Transformation – Automated Aid to Pressman Profiles are applied in pairs to transform an image from a current encoding (the source) to another encoding (the destination) • Visualization – the human element Printed Job Color Expectation What does the human expect? ICC Color Management A. McCarthy Digital Smart Factory Forum 24 June, 2003 5 The seven color control architecture elements are threads that interact throughout a color workflow. What is the next step in understanding a color workflow… ICC Color Management A. McCarthy Digital Smart Factory Forum 24 June, 2003 Analyzing workflow workflow primitives 6 • Workflow primitives are the building blocks of every workflow • These 'normalized' workflow building blocks can be used to understand interactions in real world workflows • Four dimensions describe the workflow primitives and differentiate them from each other: Fundamental Imaging Operations • Correction, preference, gamut mapping, appearance mapping Key Color Fidelity Requirements • Process control stability, transformations, metadata persistence Image State Impact • Initialization, transition, preservation Image System Interfaces • Proprietary/standard methods, proprietary/standard output format ICC Color Management A. McCarthy Digital Smart Factory Forum 24 June, 2003 Image State 7 • The degree to which image data has been constrained or purposed to a particular visualization mechanism, as compared to the degree to which the image data has been retained unaltered with respect to its capture condition Concepts of scene- referred, original- referred, and output- referred image state as shown in ISO CD 22028-1-Part 1 ICC workflows include both Actual Output Referred (a particular visualization device) and Reference Output Referred (e.g., SWOP) ICC Color Management A. McCarthy Digital Smart Factory Forum 24 June, 2003 Image State 8 • The degree to which image data has been constrained or purposed to a particular visualization mechanism, as compared to the degree to which the image data has been retained unaltered with respect to its capture condition Image state helps with: 1. Sequencing color transformations Concepts of scene- in your workflow referred, original- referred, and output- 2. Re-purposing and re-targeting referred image state as color jobs while maintaining color fidelityshown in ISO CD 22028-1-Part 1 (minimize the need to estimate colors) ICC workflows include both Actual Output Referred (a particular visualization device) and Reference Output Referred (e.g., SWOP) ICC Color Management A. McCarthy Digital Smart Factory Forum 24 June, 2003 Functional Workflow Primitives 9 • Capture • Adjust image/object What is that proprietary Device correction operations function Apply that image handles preferences Process control stability Preferencedigitization? operations are Digitized format and data are arbitrary & use specific device dependent and • Assemble object/entity manufacturer controlled What is theCombination “primitive” of objects functionality of a CMM? • Color-Render (CMM) Control of job information Appearance and gamut mapping • Visualize operations - input to output Device correction operations Apply capture specific Manufacturer controlled characterization transform Process control stability Apply ‘reference’ color space Includes halftoning, trapping encoding transforms Can include black channel Apply visualization condition specific transforms UCR/GCR, black-only • Scum dot elimination Overprint/knockout • Separation⇔gamut interactions • Display the assembled entity ICC Color Management A. McCarthy Digital Smart Factory Forum 24 June, 2003 Functional Workflow Primitives 10 • Capture • Adjust image/object Device correctionHow do we factoroperations in to the Apply image preferences workflow the image edits Process controlthat people stability want to do to Preference operations are Digitized formatimprove andtheir dataimages? are arbitrary & use specific device dependent and • Assemble object/entity manufacturer controlled In many workflows, Combination of objects • Color-Renderprobably all (CMM)workflows in Control of job information Appearancethe commercial and world, gamut we mapping • Visualize operationsneed to combine - input images, to output text, and vector… Device correction operations Apply…and capture we need specific to keep Manufacturer controlled characterizationtrack of all of the transformdata and metadata in a “job.” Process control stability Apply ‘reference’ color space Includes halftoning, trapping encoding transformsWhat is the proprietary Can include black channel Apply visualization condition function that UCR/GCR, black-only specific transformshandles display? • Scum dot elimination Overprint/knockout • Separation⇔gamut interactions • Display the assembled entity ICC Color Management A. McCarthy Digital Smart Factory Forum 24 June, 2003 11 What are the roles of printer, prepress, and creator in shaping a workflow… ICC Color Management A. McCarthy Digital Smart Factory Forum 24 June, 2003 Printer Responsibilities in a Distributed Color Managed Workflow 12 • Identify your print shop PRINT CONDITION A Print Condition is capabilities defined by • Establish color calibration – process 1. The Digital Front optimization and process control for each End (DFE) and print engine combination PRINT CONDITION 2. The opacity, white • Characterize and provide clients with an point, and gloss of the paper stock Actual-Output-Referred ICC profile for each 3. The screening preferred PRINT CONDITION method • Provide clients with a submission guideline 4. The selected calibration Look-Up defining your capabilities and workflow Table (LUT) in the expectations DFE 5. Any selectable • Determine the capabilities of the data calibration parameters exchange methods available to clients and 6. Any selectable color-rendering provide recommendations (TIFF, EPS, PDF, options in the DFE PDF/X, fttp to job folder, JDF, etc…) ICC Color Management A. McCarthy Digital Smart Factory Forum 24 June, 2003 Printer Responsibilities in a Distributed Color Managed Workflow 13 • Identify your print shop PRINT CONDITION A Print Condition is capabilities defined by • Establish color calibration – process 1. The Digital Front optimization and process control for each End (DFE) and print engine combination PRINT CONDITIONIf a print condition conforms 2. The opacity, white • Characterize and provide clients with an point, and gloss of the to a Reference Print Condition:paper stock Actual-Output-Referred1. Identify ICCthe standardprofile forcharacterization each 3. The screening preferred PRINTvia CONDITIONthe ICC Characterization Registry method • Provide clients2. with Pre-press a submission and creator guideline may use the 4. The selected calibration Look-Up defining your capabilitiesReference-Output-Referred and workflow ICC profile Table (LUT) in the expectations DFE 5. Any selectable • Determine the capabilities of the data calibration parameters exchange methods available to clients and 6. Any selectable color-rendering provide recommendations (TIFF, EPS, PDF, options in the DFE PDF/X, fttp to job folder, JDF, etc…) ICC Color Management A. McCarthy Digital Smart Factory Forum 24 June, 2003 Prepress Responsibilities in a Distributed Color Managed Workflow 14 • Identify client print shop PRINT CONDITION Re-targeting capabilities and submission requirements (proofing) Maintaining image • Obtain a Ref/Actual-Output-Referred ICC colorimetry while profile for each preferred PRINT CONDITION changing device code values to customize to • Calibrate and characterize each proofing a particular device of device (soft/hard) the same or larger gamut. • Establish a calibrated re-targeting color •Need for preserving workflow – stabilize the proof to production black in hard proof? •Acceptable viewing relationship soft proof in RGB? • Provide creative clients