ICCICC colorcolor managementmanagement forfor printprint productionproduction TAGA Annual Technical Conference 2002 W Craig Revie Principal Consultant Fuji Film Electronic Imaging Limited ICC Chair of the Graphic Arts Special Interest Group © FujiFilm 2002 TutorialTutorial outlineoutline • About the ICC • ICC color management concepts • Creating ICC profiles • Using ICC profiles • Defining an ICC-based workflow © FujiFilm 2002 AboutAbout thethe ICCICC • ICC History • ICC Objectives • ICC Membership • Working groups • Details from www.color.org © FujiFilm 2002 ICCICC HistoryHistory -- somesome milestonesmilestones • 1990 PostScript Level 2 released by Adobe • 1993 FOGRA conference - Intercolor consortium formed • 1994 Apple’s ColorSync format adopted • 1994 Version 2 ICC profile format defined • 1995 Windows 95 with ICM • 1999 PDF 1.3 has support for ICCBased colorspaces • 2000 Photoshop 6 released • 2001 Version 4 ICC profile format defined • 2002 PDF/X-1a (and possibly PDF/X-3) standardized © FujiFilm 2002 ICCICC ObjectivesObjectives • Open systems color management – Portable, standard color profile format – Framework independent of device capabilities • ‘Technical’ basis and broad membership – Develop a common understanding of color • Not limited to print production – Basis of profile connection space is a reflection print which may limit areas of application © FujiFilm 2002 ICCICC MembershipMembership andand OrganizationOrganization • Founding members • Regular members • Honorary members •Observers • Steering committee – Founding members + elected members • Chair, vice chair, secretary and technical secretary – Lars Borg [Adobe], Uwe-Jens Krabbenhoeft [Heidelberg], Kip Smythe [NPES], Tony Johnson [London College of Printing] © FujiFilm 2002 WorkingWorking groupsgroups • Focus on specific areas • Examples: – Architecture Working Group – Workflow Working Group – Graphic Arts Special Interest Group • Email discussion groups + 4 meetings per year © FujiFilm 2002 TutorialTutorial outlineoutline • About the ICC • ICC color management concepts • Creating ICC profiles • Using ICC profiles • Defining an ICC-based workflow © FujiFilm 2002 ICCICC colorcolor managementmanagement conceptsconcepts • Basic colorimetry, CIE standard observer • RGB additive and CMY(K) subtractive color models • ‘Device independent’ color • Color transforms © FujiFilm 2002 HowHow wewe seesee colorcolor Rod cells Cone cells Response of cone cells to different The CIE standard observer frequencies of light CIELab and CIEXYZ standards • based on CIE standard observer • describe colors as we see them • used in both PostScript and PDF © FujiFilm 2002 ColorColor illusionsillusions AdditiveAdditive colorcolor SubtractiveSubtractive colorcolor Start with black and add Start with white and subtract red, green and blue red, green and blue Many (but not all) colors can be simulated in this way © FujiFilm 2002 EachEach devicedevice ‘sees’‘sees’ colorcolor differentlydifferently Photographic printer Image display Ink jet printer How can we convert colors from one device to another? Digital camera Printing Scanner press © FujiFilm 2002 DeviceDevice dependentdependent solutionsolution Photographic printer Image display Ink jet printer Colour transform jungle Digital camera Printing M x N transforms press Scanner required © FujiFilm 2002 Device-independentDevice-independent solutionsolution Color transform for Photographic Photographic device to standard printer printer color space and Image from standard color display space to device Ink jet TAG printer TAG Standard TAG colour TAG space TAG TAG Digital camera Printing M + N transforms press Scanner required © FujiFilm 2002 HowHow ICCICC profilesprofiles workwork Given a colour calculate ink percentage required to reproduce that colour ICC Profile BtoA tables AtoB tables Calculate colour produced by Standard color space given ink percentages Ink percentage [CIEXYZ or CIELab] [CMYK] © FujiFilm 2002 BasicBasic colorcolor transformtransform elementselements curve 1-D LUT values stored in profile ‘count’ samples parameters defining one parametric curve of a standard set of functions in profile e1 e2 e3 matrix coefficients e4 e5 e6 matrix stored in profile e7 e8 e9 e1 e2 e3 e10 matrix coefficients e4 e5 e6 e11 matrix with offset stored in profile e7 e8 e9 e12 multi-dimensional values at each node of the 3- or 4-D table LUT stored in profile © FujiFilm 2002 PuttingPutting thethe elementselements togethertogether C L e1 e2 e3 R M e4 e5 e6 a e7 e8 e9 G Y b B K CMYK 1-D tables 4-D LUT Lab 1-D tables matrix parametric curves AToB tag from printer profile tags from monitor profile C L e1 e2 e3 e10 e4 e5 e6 e11 M a e7 e8 e9 e12 Y b Lab 1-D tables Matrix with offset 'M' 1-D tables 3-D LUT CMYK 1-D tables K BToA tag from version 4 printer profile © FujiFilm 2002 ExampleExample ICCICC ProfileProfile Header Private Public ICC Profile Inspector.lnk A2B0 B2A0 A2B1 B2a1 A2B2 B2A2 A2B3 B2A3 © FujiFilm 2002 ICCICC colorcolor managementmanagement conceptsconcepts (2)(2) • Rendering Intent • Profile connection space (PCS) • Color Management Module (CMM) © FujiFilm 2002 ColorColor gamutgamut comparisoncomparison Solid shape indicates gamut of print process Wire frame indicates gamut of monitor When printing colors viewed on screen some kind of trade-off must be made to determine how we should map one color gamut to the other © FujiFilm 2002 GamutGamut mappingmapping dependsdepends onon pagepage elementelement Company logo Tinted Areas Illustrations Photographs Text © FujiFilm 2002 ICCICC RenderingRendering IntentsIntents • Four ICC Rendering Intents define gamut mapping – Absolute Colorimetric: measurement (relative to illuminant) of output color should match that of input color if possible – Relative Colorimetric: measurement (relative to paper) of output color should match that of input – Perceptual: color images should be transformed to produce desired appearance on the output – Saturation: color transforms should maintain saturation in colors where possible © FujiFilm 2002 PerceptualPerceptual IntentIntent Color images should be transformed to produce desired appearance on the output - but how? Input ? profile 1 Output PCS profile Input profile 1 We need to agree a means to Images and input determine 'desired appearance' profiles are created with respect to the PCS independently of the output profile © FujiFilm 2002 ProfileProfile connectionconnection spacespace definitiondefinition (Perceptual(Perceptual Intent)Intent) Ah yes, not a D50, 500 lux light bad looking source virtual print Media White Point has neutral reflectance of 89% (Dmin 0.0506) Media Black point has neutral reflectance of 0,30911% (Dmax 2.51) CIE 1931 standard colorimetric observer adapted to viewing environment 20% surround © FujiFilm 2002 NowNow wewe cancan useuse PerceptualPerceptual IntentIntent Color images should be transformed to produce desired appearance on the output Input profile 1 Output PCS profile Input profile 1 Output profile creators can assume On input images and/or profiles that images have been adjusted to can be adjusted to achieve achieve desired appearance and desired result on (virtual) can perform necessary gamut reference medium mapping for printer © FujiFilm 2002 OpenOpen question:question: HowHow bigbig // whatwhat shapeshape isis thethe PCSPCS gamut?gamut? • This is at present undefined • Given the density range that has been defined gives us an idea of size • ICC is studying the advantages and disadvantages of defining the PCS gamut more precisely • Perceptual gamut mapping is vendor specific - "beauty is in the eye of the profile creator" © FujiFilm 2002 ColorColor ManagementManagement ModuleModule (CMM)(CMM) Rendering Intent Profile from Header Header Private Private Profile from document Public Public A2B0 B2A0 A2B0 B2A0 printer A2B1 B2a1 A2B1 B2a1 A2B2 B2A2 A2B2 B2A2 A2B3 B2A3 A2B3 B2A3 Input Output transform transform Combined transform CMM - often part of OS usually more than one option © FujiFilm 2002 ColorColor ManagementManagement ModuleModule (CMM)(CMM) • Applies transforms implied by profile data • No formal ICC definition • Why multiple CMMs? – Handling TRC profiles – Chromatic adaptation – Interpolation algorithms – Private tags – Some minor differences of interpretation © FujiFilm 2002 TutorialTutorial outlineoutline • About the ICC • ICC color management concepts • Creating ICC profiles • Using ICC profiles • Defining an ICC-based workflow © FujiFilm 2002 CreatingCreating ICCICC profilesprofiles • Creating a scanner profile • Creating a monitor profile • Creating a printer or proofer profile • Creating a profile for a printing press • Profile testing © FujiFilm 2002 ClassesClasses ofof profileprofile (1)(1) Input Display Output May be Matrix+TRC Usually Matrix+TRC type Must be LUT- based type but is more but may be LUT-based Must contain PCS- usually LUT-based Must contain both Device- Device and Device- Must contain at least PCS and PCS-Device PCS intents for all Device-PCS table for tables for Perceptual Rendering Intents Perceptual Intent Intent © FujiFilm 2002 ScannerScanner profileprofile creationcreation Color target patch colors ICC Profile valid for measured selected media Color target for when scanned media to be L*a*b* using reference profiled scanner settings Header Private Public A2B0 B2A0 A2B1 B2a1 A2B2 B2A2 A2B3 B2A3 RGB Profiling package constructs profile Reference scanner Note the media, scanner model and settings selected scanner settings - the profile isn't worth as much without them © FujiFilm 2002 DigitalDigital