0Harlequin RIP. Named Color Databases. Technical Note Hqn039 June 2001

Transcription

1 0Harlequin RIP Named Color Databases Technical Note Hqn039 June 2001

2 1 Introduction The Harlequin RIP uses named color databases for various purposes including recombination, or interception and color management, of named colors. This document describes the use of these databases with recombination. Note: A description of the use of named color databases for interception and color management may be added in a revised version of this document. The Harlequin RIP supports recombination of preseparated jobs where it can identify the separations as being for different colors and obtain a process equivalent in the color space of the output device. 2 When is a database necessary? When the RIP encounters a separation name, it looks first for an equivalent defined in the job. This is for reasons of both accuracy and convenience. Colors defined in the job should be self-consistent and they are always available. The RIP is able to recover such information from the incoming job where: the job is well-structured the job comes from some well-known applications If the job contains both a spot name and a process-color equivalent, then the RIP can start recombination immediately and does not refer to the named color databases. The RIP processes jobs that supply only a name, provided that there is some accessible reference linking spot colors and their process equivalent. As with the device-independent PANTONE values already shipped with the Harlequin RIP for other uses, this reference can be a file local to the RIP, or a sequence of files. An OEM or an end-user can provide a custom reference file, perhaps building it by measuring actual values of spot inks. The process equivalent can be defined in any convenient color space: XYZ, L*a*b*, and calibrated RGB. (These are implemented as specific CIEBasedABC colorspaces.) CMYK RGB 1 Commercial in Confidence Technical Note Hqn039: v101 June 2001

3 3 Order of database search The RIP reads these reference files as required by the incoming job, so there is an opportunity for a suitable OEM-written workflow system to create a dynamic resource, such as a local file refreshed from a centrally maintained database. If all these files fail to provide a match, the RIP fails to image the job and displays an appropriate message. 3 Order of database search The order of search for recombine is defined in the file: SW/NamedColorOrder/Recombine Note: The similar Intercept file is used to define the order of search for interception and color management. Normally, custom OEM or user files produced to match a specific job or type of job should be first, or at least early, in the search order. If the custom files do not exist, or fail to find a match, the RIP can proceed to another stage where it uses some standard local files. The inclusion of these files and the search order among the files are both easily definable. See Appendix A, Example of ordering file. There is also scope here for an OEM to create or purchase other large databases of color equivalents and add the databases to these standard files. 4 Definition of equivalents The Harlequin RIP is shipped with example files that show how to define colors with XYZ, CMYK, and RGB equivalents. These come from sources including the PANTONE equivalents already mentioned, and applications such as Adobe Illustrator. As an example of file format only, there is a file based on RGB colors from the X Windows system on the UNIX operating system. Definitions intended for use with color management must be made in a CIEBasedABC colorspace: XYZ, L*a*b*, or calibrated RGB. Note: Harlequin suggests that each database file should define equivalents in only one colorspace. While it is currently possible to combine definitions from Technical Note Hqn039: v101 June 2001 Commercial in Confidence 2

4 different colorspaces in one file, using this ability may complicate use of such a file in future. The handling of different languages is important. Unlike a user interface, which can be switched into the preferred language for a site, the database may need to recognize the names of the same process colors given in several languages. A simple solution is repeat the definitions for names in each language of interest, for example, giving the same equivalent for Red, Rot, Rosso, Rojo, Rouge, and so on. Another consideration is case sensitivity and the use of mixed case in color names. The supplied KnownColors file maps all color names to uppercase, to provide a case-insensitive search. See Appendix B, Example of database file. Appendix A Example of ordering file Each ordering file defines a resource named the same as the file. The resource must be of type /NamedColorOrder. This listing shows how the Recombine file shipped with the RIP defines a search order of the referenced files: KnownColors, IllustratorColors, PantoneU, PantoneV. These referenced files should be in the SW/NamedColor folder. KnownColors defines the common alternate process colors: Red, Green, and Blue. IllustratorColors defines different values for these same colors and defines some additional shades such as Gold and Grass Green. The search order shown in the example Recombine ordering file means that the definition of Red will always be taken from KnownColors. Any files added by an OEM can be added to the search order before or after these files. Both supplied files are small and the decision should be made on the desired search order rather than search time. 3 Commercial in Confidence Technical Note Hqn039: v101 June 2001

5 Appendix B Example of database file This file is called SW/NamedColorOrder/Recombine. %!PS-Adobe-3.0 %%Title: Recombine %%Creator: Harlequin %%CreationDate: February 1999 %%For: Harlequin % Copyright (c) Harlequin Limited, 1999 All Rights Reserved. %%EndComments % This resource defines the order in which NamedColor resource % databases should be searched during recombine when % looking for CMYK equivalents. /Recombine [ /KnownColors /IllustratorColors % /Sample %uncomment this line to include Sample /PantoneU /PantoneV ] /NamedColorOrder defineresource %%EOF Appendix B Example of database file Each database file defines a resource named the same as the file. The resource must be of type /NamedColor. A database file can be made suitable for use with both recombination and color management by defining colors in a CIEBasedABC colorspace and defining the Lookup procedure suitably. A database file intended for use with recombination only can define the RCLookup procedure and a very simple Lookup procedure, as shown in the following listing. (If there is no RCLookup procedure, recombination uses the Lookup procedure.) This listing shows what a simple file able to hold equivalents defined in CMYK, and thus suitable for recombination only, looks like. This file is supplied as: SW/NamedColor/KnownColors Technical Note Hqn039: v101 June 2001 Commercial in Confidence 4

6 The contents of this file are: %!PS-Adobe-3.0 %%Title: KnownColors %%Creator: Harlequin %%CreationDate: February 1999 %%For: Harlequin % Copyright (c) Harlequin Limited, 1999 All Rights Reserved. %%EndComments % This header will create a dictionary containing all the named % colors in this file, along with their CMYK values. % Done this way to minimise VM use. currentglobal false setglobal 12 dict begin % scratch, will close off after using with // % array with lower -> upper case /a (a) 0 get def /z (z) 0 get def /A (A) 0 get def /NCcasemap 256 string def { NCcasemap exch dup put } for //a 1 //z { NCcasemap exch dup //a sub //A add put } for /NCstr 256 string def % converts a string to upper case; % converts name to string too, if necessary /NCupcase { //NCstr cvs dup length 1 sub roll { 2 copy get //NCcasemap exch get 2 index 3 1 roll put } for } bind def /linebuff 100 string def { << % Do nothing if asked for named color intercepts /Lookup { pop pop false } bind 5 Commercial in Confidence Technical Note Hqn039: v101 June 2001

7 Appendix B Example of database file /RCLookup { % database name //NCupcase exec % convert name to uppercase exch % name database /Colors get % name colors exch 2 copy % colors name colors name known { % colors name get % color true % color true } { % colors name pop pop false % false } ifelse % color true ; or : false } bind /ColorSpace /DeviceCMYK % Note this tinttransform _always_ returns the values % for a solid tint. /TintTransform { exch pop aload pop } bind /Colors << { % Read in the colorname currentfile //linebuff readline not { pop exit } if cvn [ % And read in the 4 CMYK values currentfile token pop currentfile token pop currentfile token pop currentfile token pop ] >> >> end } loop /KnownColors exch /NamedColor defineresource pop setglobal } exec RED GREEN BLUE Technical Note Hqn039: v101 June 2001 Commercial in Confidence 6

8 Note: The file must end as shown, with the last portion being the color definitions. Because of the way that the code reads the definitions, there cannot be trailing comments. Change history v First issue, for ScriptWorks 5.1 v Updated cover page and copyright page. Removed references to ScriptWorks 5.1 and replaced with Harlequin RIP. No other changes made to text. 7 Commercial in Confidence Technical Note Hqn039: v101 June 2001

9 Appendix B Example of database file Technical Note Hqn039: v101 June 2001 Commercial in Confidence 8

10 Copyright Global Graphics Software Limited. All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of Global Graphics Software Limited. The information in this publication is provided for information only and is subject to change without notice. Global Graphics Software Limited and its affiliates assume no responsibility or liability for any loss or damage that may arise from the use of any information in this publication. The software described in this book is furnished under license and may only be used or copied in accordance with the terms of that license. ScriptWorks is a registered trademark and Harlequin, the Global Graphics Software logo, EasyTrap, FireWorks, FlatOut, Harlequin Color Management System, HCMS, Harlequin RIP, Harlequin Color Production Solutions, HCPS, Harlequin Color Proofing, HCP, Harlequin Full Color System, HFCS, Harlequin ICC Profile Processor, HIPP, Harlequin Standard Color System, HSCS, Harlequin Chain Screening, HCS, Harlequin Dispersed Screening, HDS, Harlequin Micro Screening, HMS, Harlequin Precision Screening, HPS, Harlequin Screening Library, HSL, Harpoon, RipFlow, ScriptWorks MicroRIP, ScriptProof, ProofReady, SetGold, Scalable Open Architecture RIP, SOAR, TrapMaster, TrapWorks, PDF Creator and RIPFlow are all trademarks of Global Graphics Software Limited. Portions licensed under U.S. Patents: Nos. 4,500,919, 4,941,038 and 5,212,546. EasyTrap is licensed under one or more of the following U.S. Patents: Nos. 5,113,249, 5,323,248, 5,420,702, 5,481,379. Adobe, Adobe Photoshop, Adobe Type Manager, Acrobat, Display PostScript, Adobe Illustrator, PostScript, Distiller and PostScript 3 are either registered trademarks or trademarks of Adobe Systems Incorporated in the United States and/or other countries which may be registered in certain jurisdictions. Global Graphics Software Limited is a licensee of Pantone, Inc. PANTONE Colors generated by ScriptWorks are four-color process simulations and may not match PANTONE-identified solid color standards. Consult current PANTONE Color Publications for accurate color. PANTONE, Hexachrome, and PANTONE CALIBRATED are trademarks of Pantone, Inc. Pantone, Inc., Other brand or product names are the registered trademarks or trademarks of their respective holders. US Government Use The ScriptWorks software is a computer software program developed at private expense and is subject to the following Restricted Rights Legend: Use, duplication, or disclosure by the United States Government is subject to restrictions as set forth in (i) FAR Alt III or (ii) FAR , as applicable. Use by agencies of the Department of Defense (DOD) is subject to Global Graphics Software s customary commercial license as contained in the accompanying license agreement, in accordance with DFAR (a). For purposes of the FAR, the Software shall be deemed to be `unpublished and licensed with disclosure prohibitions, rights reserved under the copyright laws of the United States. Global Graphics Software Incorporated, 95 Sawyer Road, Waltham, Massachusetts Commercial in Confidence Technical Note Hqn039: v101 June 2001