User manual HP LASERJET 1200 - PCL/PJL REFERENCE (PCL 5 COLOR) - TECHNICAL REFERENCE MANUAL

PCL 5 Color Technical Reference Manual Notice The information contained in this document is subject to change without notice. Copyright and License Copyright © 1999 Hewlett-Packard Company. All rights are reserved. This document contains proprietary information which is protected by copyright. Except as allowed by copyright laws or herein, reproduction, adaptation, or translation without prior written permission is prohibited. Trademarks Adobe, PostScript, and the PostScript logo are trademarks of Adobe Systems Incorporated which may be registered in certain jurisdictions. AppleTalk is a registered trademark of Apple Computer, Inc. PCL and Resolution Enhancement are registered trademarks of Hewlett-Packard Company. IBM is a registered trademark of International Business Machines Corporation. Hewlett-Packard Company 11311 Chinden Boulevard Boise, Idaho 83714 U.S.A. Inside This Manual What You Can Learn From This Manual This manual describes the PCL 5 commands used to print color on the HP Color LaserJet printer family and the other Hewlett-Packard PCL 5 color printers. Some of the main topics include an overview of the color printing process, using palettes, choosing color modes, adjusting output color to meet your requirements, printing color raster graphics, and HP-GL/2 vector graphics. Examples are provided which demonstrate the use of the PCL 5 color commands. Note All commands described in this manual are not necessarily supported by all printers. See the PCL 5 Comparison Guide for feature support information for each printer. This manual is written primarily for users that are already familiar with PCL 5 printer features. For information on using PCL 5, see the PCL 5 Printer Language Technical Reference Manual. iii Manual Organization This manual contains seven chapters and four appendices. Chapters 2 through 4 describe command usage for the HP Color LaserJet 4500 and 8500 printers. Appendices A through D describe how these functions are achieved on the HP Color LaserJet, Color LaserJet 5, 5M, and the DeskJet 1200C and 1600C printers. Chapters 5 through 7 pertain to all the color printers described in this manual. A brief description of each chapter is provided below. Chapter 1. Color Printing Overview This chapter explains background information about printing color documents using PCL 5. Topics include palettes, color selection, pixel encoding, color modes, and color matching. Chapter 2. Using Color Modes Chapter 2 defines the color modes and describes how to use them, including descriptions of sending color raster data using different pixel encoding modes and color spaces. Chapter 3. Using Palettes This chapter describes the palettes associated with the color modes and explains how palettes are created, saved, and modified. Chapter 4. Modifying Output Color This chapter explains the options for modifying the output color: the Render Algorithm command, the Monochrome Print Mode command, Driver Configuration command, and Finish Mode command. Chapter 5. The PCL Print Model Chapter 5 describes the print model and how it determines the printed outcome when various patterns, colors, and images are applied together on a page. This chapter discusses the role that logical operations and transparency modes have on this process. Chapter 6. Raster Graphics This chapter describes the raster graphics commands and also compressing raster graphics images using various compression methods. iv Chapter 7. Color Vector Graphics (HP-GL/2) This chapter discusses printing color pages using HP-GL/2, the vector graphics language included on all PCL 5 printers. The chapter describes new and/or modified HP-GL/2 commands and how they are used to print with HP color printers. Appendix A. Color Printing Overview (Color LaserJet, 5, 5M, DeskJet) Appendix A explains background information about printing color documents using PCL 5. Topics include palettes, device-dependent vs. device-independent color, color selection, pixel encoding, color modes, and color matching. Appendix B. Using Color Modes (Color LaserJet, 5, 5M, DeskJet) Appendix B defines the color modes for the HP Color LaserJet, Color LaserJet 5, 5M, and the DeskJet 1200C and 1600C printers, and describes how to use them. It includes descriptions of sending color raster data using different pixel encoding modes and color spaces. Appendix C. Using Palettes (Color LaserJet, 5, 5M, DeskJet) Appendix C describes the use of palettes for the HP Color LaserJet, 5, and 5M, and DeskJet 1200C and 1600C printers. It explains the palettes associated with the color modes and explains how palettes are created, saved, and modified. Appendix D. Modifying Output Color (Color LaserJet, 5, 5M, DeskJet) Appendix D describes how to modify output color for the HP Color LaserJet, Color LaserJet 5, 5M, and the DeskJet 1200C and 1600C printers. This chapter explains how color can be optimized by compensating for different conditions, such as variations in color due to light sources, limitations of the original artwork and variations in viewing monitors. The chapter details the use of halftone rendering algorithms, color lookup tables, gamma correction, and viewing illuminant commands. These commands are provided so that users can request and receive color output that matches their expectations. Index An index offers quick access to PCL command information. v Related Documents The following documents provide related information about Hewlett-Packard PCL 5 printers. PCL 5 Printer Language Technical Reference Manual The PCL 5 Printer Language Technical Reference Manual provides a description of the printer command language that controls PCL 5 printers. The manual provides explanations of each PCL command, and has examples demonstrating how the commands are used to manipulate the printer. A large portion of the manual is devoted to HP-GL/2, the vector-based graphics language in PCL 5 printers. PCL 5 Comparison Guide This document provides printer-specific information on paper handling, internal fonts, PCL command support, and control panel information. It identifies feature differences between the various PCL 5 printers, and how the printers implement the commands described in the PCL 5 Printer Language Technical Reference Manual. Printer Job Language Technical Reference Manual This manual describes PJL, the HP printer job language used on many of the Hewlett-Packard printers. PJL is used for switching printer languages, requesting status information, changing display messages, inquiring about feature settings, and other job-level functions. PCL/PJL Technical Quick Reference Guide This booklet is designed to provide quick access to the syntax of each PCL and PJL command. The commands are grouped by their function so that those familiar with PCL and/or PJL can find the syntax of a specific command without opening the manual. vi Contents PCL 5 Color Technical Reference Manual Inside This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Manual Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv Related Documents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi Chapter 1 Color Printing Overview Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1 Working with color documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2 PCL 5 Color Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3 Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3 Color Specifications and Color Spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3 Color Management and the Standard Red, Green, Blue Color Space . . . . . . . .1-4 Palettes and Color Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6 PCL 5 Color Graphics Context . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6 PCL 5 Color Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6 PCL 5 Raster Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7 Pixels and Pixel Encoding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7 Well-Behaved Raster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-9 Chapter 2 Using Color Modes Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1 Simple Color Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3 PCL Imaging Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5 Configure Image Data (CID) Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5 HP-GL/2 Imaging Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-13 Chapter 3 Using Palettes Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1 Saving the Palette . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3 Push/Pop Palette Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3 Palette Management by ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5 Select Palette Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-6 Palette Control ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-8 Palette Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-9 Simple Color Palettes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-11 EN Contents vii CID Color Palettes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-13 Device RGB and sRGB Palettes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-13 Device CMY Palettes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-14 HP-GL/2 Palettes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-15 Foreground Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-17 Foreground Color Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-17 Programming Color Palettes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-19 Chapter 4 Modifying Output Color Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1 Halftone Render Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2 Render Algorithm Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2 Monochrome Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3 Monochrome Print Mode Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3 Driver Configuration Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4 Finish Mode Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-6 Chapter 5 The PCL Print Model Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1 Command Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-6 Source Transparency Mode Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-7 Pattern Transparency Mode Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-8 Logical Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-9 Logical Operations and Transparency Interactions. . . . . . . . . . . . . . . . . . . . . .5-12 Logical Operation Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-13 ROPs in the RGB Color Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-14 ROPs in the CMY Color Space. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-15 Using a ROP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-16 Table of Logical Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-18 Pixel Placement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-24 Pixel Placement Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-27 Filling with Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-28 Pattern ID (Area Fill ID) Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-29 Select Current Pattern Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-32 User-Defined Pattern Graphics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-33 Using User-Defined Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-33 How the Printer Tiles a Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-34 Pattern Reference Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-36 Download Pattern Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-38 User-defined Pattern Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-40 Set Pattern Reference Point Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-43 Pattern Control Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-44 Rectangular Area Fills (Rules) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-45 Pattern Transparency for Rectangular Area Fill. . . . . . . . . . . . . . . . . . . . . . . . . . . .5-50 Contents viii EN Rectangular Fill Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-52 Solid Fill (Black/White) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-52 Shaded Fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-54 Chapter 6 Raster Graphics Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1 PCL 5 Color Raster Graphics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-4 Raster Graphics Command Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-6 Raster Graphics Resolution Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-8 Raster Graphics Presentation Mode Command . . . . . . . . . . . . . . . . . . . . . . . . . . .6-10 Source Raster Height Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-13 Source Raster Width Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-15 Start Raster Graphics Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-17 Raster Y Offset Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-19 Set Compression Method Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-20 Unencoded (Method 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-21 Run-length Encoding (Method 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-21 Tagged Image File Format Encoding (Method 2) . . . . . . . . . . . . . . . . . . . . . . .6-21 Delta Row Compression (Method 3). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-24 Adaptive Compression (Method 5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-28 Transfer Raster Data Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-32 Transfer Raster Data by Plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-33 Transfer Raster Data By Row/Block Command . . . . . . . . . . . . . . . . . . . . . . . .6-33 End Raster Graphics Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-35 Raster Scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-36 Raster Graphics Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-38 Color Raster Graphics Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-42 Chapter 7 Color Vector Graphics (HP-GL/2) Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-1 Enter HP-GL/2 Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-2 MC (Merge Control). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-6 PC (Pen Color) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-14 NP (Number of Pens) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-17 CR (Color Range) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-19 PP (Pixel Placement) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-20 EN Contents ix Appendix A Color Printing Overview (Color LaserJet, 5, 5M, DeskJet) Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1 Color Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3 Palettes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3 Raster Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3 Raster Color vs. Non-Raster Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3 Device-Dependent vs. Device-Independent Color . . . . . . . . . . . . . . . . . . . . . . A-4 Black and White References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-4 Color Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-5 Pixel Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-6 Encoding by Plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-6 Color Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-7 Device-Dependent Color Spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-8 Device-Independent Color Spaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-8 Device-Independent Color. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-10 Device-Dependent Color. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-10 Device-Independent Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-10 Color Matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-11 Processing Color Documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-14 Non-Raster Color vs. Raster Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-14 Color Raster Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-14 Appendix B Using Color Modes (Color LaserJet, 5, 5M, DeskJet) Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2 Simple Color Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4 PCL Imaging Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-6 Configure Image Data (CID) Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-6 Short Form of CID Command (Configure Image Data) . . . . . . . . . . . . . . . . . B-15 Long Form of CID Command (Configure Image Data) . . . . . . . . . . . . . . . . . . B-17 HP-GL/2 Imaging Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-28 Appendix C Using Palettes (Color LaserJet, 5, 5M, DeskJet) Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1 Saving the Palette . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3 Push/Pop Palette Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3 Palette Management by ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-5 Palette Control ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-8 Palette Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-9 Simple Color Palettes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-11 CID Color Palettes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-13 HP-GL/2 Palettes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-16 Foreground Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-18 Contents x EN Programming Color Palettes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Color Component One . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Color Component Two . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Color Component Three . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Assign Color Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-20 C-20 C-20 C-21 C-21 Appendix D Modifying Output Color (Color LaserJet, 5, 5M, DeskJet) Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-1 Halftone Render Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-3 Render Algorithm Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-3 User-Defined Dithers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-6 Download Dither Matrix Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-7 Multiple Dither Matrices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-10 Color Lookup Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-13 Gamma Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-17 Viewing Illuminant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-18 Monochrome Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-20 Driver Configuration Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-21 Index EN Contents xi Contents xii EN 1 Color Printing Overview Introduction This chapter provides an overview of color printing with Hewlett-Packard printers. A primary goal for HP color printers has always been WYSIWYG (What You See Is What You Get) color, where the color displayed on the screen while creating a document is the same as the color in the printed document. However, this goal has been very difficult to realize due to a number of factors such as: · Some colors that can be shown on a computer display cannot be reproduced by a printer. · The Cyan, Magenta, and Yellow colors used to create the colors specified in a document can differ in hue and quality from printer to printer, even printers from the same manufacturer. Furthermore, the colors produced by a given printer can change over time, due to internal changes as well as temperature and humidity. Until recently, these and other problems have led HP to approach color matching by presenting a PCL 5 color command set giving users the ability to make both major and minor color print quality adjustments. However, the emergence of sRGB (standard Red Green Blue) as an international color data standard and the growing sophistication of Hewlett-Packard printers has allowed HP to provide high quality WYSIWYG color documents with a much simpler PCL color command set. Therefore, this manual has two main parts: Chapters 1 through 7 present the latest, simplified PCL 5 color command set, and the appendices describe the command set described in Chapters 1 through 4 as they are supported by the Color LaserJet, Color LaserJet 5, DeskJet 1200C, and DeskJet 1600C printers. Chapters 5 ­ 7 pertain to both sets of printers. EN Color Printing Overview 1-1 Working with color documents A document can be thought of as a series of text characters, vector graphics objects and images. The parts of a document either have color specifications in them, as do color images, or have color specifications applied to them, as do color vectors or text. For color images, the PCL 5 command set provides a way to specify the color format so that the image data can be interpreted correctly. For vector graphics and text, the PCL 5 color commands support the application of a color from a palette of colors. Each color printed is synthesized from a combination of three colors: Cyan, Magenta, and Yellow. The way the three colors are combined to produce the desired color is called a half-tone, and the PCL 5 color command, Render Algorithm, specifies which half-tone to use for a color. Advances in Hewlett-Packard printers have allowed HP to reduce the number of render algorithms to Best, High, and Low. While the actual implementation of each of these algorithms may vary from printer to printer, HP has determined that the three algorithms are sufficient to produce high quality color documents containing text and graphics. The colors that appear on a page also have one of two color treatments applied to them: 1 Screen Match (sRGB), which provides the best WYSIWYG color. This is the default color treatment. The Vivid color treatment, which provides access to the entire device gamut (range of colors the printer can produce). However, these colors are less correlated to those shown on a monitor than colors that have had the Screen Match treatment applied. 2 The following factors form the heart of the PCL color graphics state: · The palette of colors to be used in a document · The render algorithm to print the colors · The color treatment to be applied to each color Palettes of colors can be referenced by an ID, and so can PCL color graphic states. At any given time there is an active palette to apply colors from, along with a render algorithm and color treatment to be applied to the colors. Palettes and their associated render algorithm and color treatment can be stored and retrieved using a palette ID. When a palette is retrieved and made the active palette, the render algorithm and color treatment stored with the palette are set as the current render algorithm and color treatment. 1-2 Color Printing Overview EN The PCL language also allows users to use patterns in combination with colors. These patterns and colors can be combined with text, vector graphics, and images to create new, complex graphics objects. The PCL Print Model determines the logical operations (known as ROPs, Raster Operations) used to combine each part of the graphic object. PCL 5 Color Concepts This section describes some of the concepts and terminology of color science related to the PCL 5 color commands. Color Color is a combination of human physiological and psychological responses to a relatively narrow band of frequencies in the electromagnetic spectrum. The frequencies visible to the human eye are called the visible spectrum. It's useful to understand that color comes both from direct light and indirect light that has reflected from a surface. Reflected light absorbs all but the reflected frequency. The colors seen on a color monitor are combinations of different-colored lights traveling directly to the eye. They are called additive colors since the different colors combine to form the resulting color. The colors seen on a printed material such as paper are reflected from the paper surface, which absorbs some of the light. Colors seen under these conditions depend on the viewing conditions, the amount and color of ambient light, as well as the amount and color of the reflected light. Color Specifications and Color Spaces A given color can be described as particular amounts of three light frequencies (red, green, and blue light). For example, equal amounts of red, green, and blue light are perceived as white light. The absence of all three primary light colors is black. EN Color Printing Overview 1-3 Color can be described in ways other than amounts of red, green, and blue light. Generally, these color specification systems are known as color spaces. For example, The Cyan, Magenta, Yellow (CMY) color space is used to describe colors that are printed by depositing varying amounts of these three ink pigments (Cyan, Magenta, Yellow). The absence of pigment is considered to be white, and the presence of all three is black. The CMYK color space is similar to the CMY color space, but black pigment is used in place of 100% C, M, Y since imperfections in the hues of the C, M, Y pigments yield a dark brown rather than black. A color specification, then, depends on the color space as well as the values used to describe a given color. Black in the RGB color space is described using the three numbers (0, 0, 0), but in the CMY color space it is described as (100, 100, 100), where the values are percentages of each color. Color Management and the Standard Red, Green, Blue Color Space For color to be reproduced in a predictable manner across different devices and materials, it has to be described in a way that is independent of the specific mechanisms and materials used to produce it. For instance, color displays and color printers use very different mechanisms for producing color. Traditionally, operating systems have supported color by declaring support for a particular color space (RGB in most cases). However, since the interpretation of RGB values varies between devices, color was not reliably reproduced across different devices. The needs of the very high-end publishing sector could not be met by the traditional means of color support, so the various computer operating systems added support for using International Color Consortium (ICC) profiles to characterize device-dependent colors in a device-independent way. They used the profiles of the input device that created an image, and the output device that displayed or printed the image, to create a transform that moved the image from the color space of the input device to that of the output device. This resulted in very accurate color and access to the entire color gamut of both devices. However, it also involved the overhead of transporting the profile of the input device with the image and running the image through the transform. 1-4 Color Printing Overview EN Note HP's ICC profiles are available through normal HP software distribution channels. For those who want the additional control available through building their own ICC profiles, there are several vendors of profiling tools available. To provide access to the printer's pure primaries and entire available printer gamut, the Vivid mode may be used when profiling the printer, and subsequently when using the ICC workflow. However, there are a broad range of users that do not require this level of flexibility and control in an embedded color profile mechanism. Instead it is possible to define a single, standard default color space for exchange and interpretation of color data. Additionally, most existing file formats do not support color profile embedding, and may never do so. There is also a broad range of uses that actually discourages people from appending any extra data to their files. The sRGB color space addresses these issues. The sRGB color space maintains the advantage of a clear relationship with ICC color management systems while minimizing software processes and support requirements. Since the image is in a known color space and the profile for that color space is included within the operating system and display application, this enables end-users to enjoy the benefits of color management without the overhead of larger files. Application developers and users who do not want the overhead of embedding profiles in documents or images should convert them to sRGB. While it may be that profiles buy slightly higher color accuracy, the benefits of using a standard color space far outweigh the drawbacks for a wide range of users. The migration of devices to support the standard color space (sRGB) natively will further enhance the speed and quality of the user experience. The international standard color space sRGB (IEC 61966-2-1) is designed to complement current color management strategies by enabling a simple, robust method of handling color in the operating systems, device drivers and the Internet. This solution provides good quality and backward compatibility with minimum transmission and system overhead. Based on a calibrated colorimetric RGB color space well suited to cathode ray tube (CRT) displays, flat panel displays, television, scanners, digital cameras, and printing systems, the sRGB color space can be supported with minimum cost to software and hardware vendors. The four major technical components of the sRGB color space are the standard CRT primaries (HDTV P22 phosphors); the simple gamma value of 2.2, a D65 white point, and its well-defined viewing conditions. EN Color Printing Overview 1-5 Palettes and Color Selection The PCL 5 language allows the user to define a palette of colors. Each color is specified by three quantities or values which are interpreted depending on the color space. For example, the color white in an RGB palette is (1, 1, 1) while this set of values in a CMY palette defines the color black. Each color in the palette is accessed using an index number, starting with 0 as the first color in the palette. The largest palette holds 256 colors, which is approximately the largest set of distinct colors the human eye can distinguish under normal viewing conditions. A color from a palette can be applied to either text or vector graphics using the Foreground Color command. Once the command is invoked the selected color will be applied to all text and vector graphics page marking primitives, and to a certain extent to raster images. Palettes can be identified with a Palette ID and then stored and recalled as needed. A palette stack mechanism is also supported for the convenience of applications that work well with a graphics stack. PCL 5 Color Graphics Context The Palette acts as the focal point of the PCL 5 color graphics context. The color space, render algorithm, color treatment, and pixel encoding mode are stored along with the palette. Therefore, selecting or restoring a palette also restores these values. PCL 5 Color Mode The PCL language has four modes or ways of specifying and using color: · Black-and-White (monochrome) mode is the default mode so that backward compatibility with previous printers is maintained. When the printer is turned on it has a 2-entry palette containing the color white at index 0 and black at index 1. When the printer is reset with an ?E it reverts to this mode. · Simple Color mode is entered with the Simple Color command, which creates one of three fixed color palettes: A monochrome, two-entry palette with white at index 0 and black at index 1. 1-6 Color Printing Overview EN An RGB, eight-entry palette with the following colors starting at index 0: black, red, green, yellow, blue, magenta, cyan, and white. A CMY, eight-entry palette with the following colors starting at index 0: white, cyan, magenta, blue, yellow, green, red and black. · PCL Imaging mode is entered with the Configure Image Data command that creates a programmable palette of a programmed size. This palette can be programmed using the color component and set index commands. · HP-GL/2 Imaging mode is entered when HP GL/2 mode is entered and the initialize command IN creates a programmable palette that is shared between PCL and HP-GL/2. Any and all of the modes can be used on a page. For example, you could enter the Simple Color mode to print a headline and bar chart, PCL imaging mode to print a photographic image, and Black-and-White mode for the text on the page. Each mode is described in more detail in Chapter 2. "Using Color Modes." PCL 5 Raster Images Monochrome PCL 5 raster images are made up of a series of zeros and ones. A one indicates that a black dot should be deposited, a zero indicates no dot, letting the white background show through. A one-inch wide image with a resolution of 600 dots per inch (DPI) has 600 consecutive zeros and/or ones, which represent a horizontal slice through the image starting at the left edge of the image. This slice is known as a raster row. For an image one inch high and one inch wide, at 600 dpi there are 600 hundred rows of 600 zeros and/or ones. Color raster images follow the same conventions with this major exception: the representation of a dot is changed from a single zero or one to a color specification (a pixel). Pixels and Pixel Encoding Raster images can be thought of as being composed of a series of pixels (picture elements). In the case of monochrome raster images, a pixel is a single bit which takes on a value of zero or one. In color images a pixel is essentially a color specification. However, there are several ways of specifying a color, and how the color is specified is called the Pixel Encoding Mode (PEM). EN Color Printing Overview 1-7 The PCL 5 color command set supports several Pixel Encoding Modes. The PEMs are categorized first by whether the pixel is an index into a palette, or a color specification. The other PEM categorization is whether the pixel data is divided into planes and transferred one plane at a time or is transferred in sequential order. There are four supported Pixel Encoding modes: 1 2 3 4 Indexed by Plane Indexed by Pixel Direct by Plane Direct by Pixel (also known as 24-bit direct). For example, the format known as direct by plane, uses a 3-bit pixel where the first bit indicates the presence or absence of a red dot, the second a green dot and the third a blue dot. The data is still arranged in rows, but all the red data is sent, then the green and finally all the blue. The example below represents the commands to transfer an image with the direct by plane PEM. The underlined bits, while transferred separately, are logically from the same pixel. ?*b#V row 1 ?*b#V ?*b#W ?*b#V row 2 plane 1 (red) plane 2 (green) plane 3 (blue) plane 1 (red) b1 b2 b3 b1 b1 b2 b3 b1 b1 b2 b3 b1 b1 b2 b3 b1 b1 b2 b3 b1 b1... b2... b3... b1... The direct by pixel PEM uses only the row transfer command. Each pixel is composed of three bytes, one byte per component of the color specification. All the bytes of a given pixel are transferred before the next one is transferred. ?*b#W row x b1 b2 b3 b1 b2 b3 b1... The indexed by pixel PEM is similar to the direct pixel PEM but the pixel occupies at most one byte and is an index into the current palette. The indexed by plane PEM is similar to the direct by plane PEM except the pixel's value is an index into the current palette. The use of this mode is discouraged due to the extra processing required to combine the bits from each plane into a single number, which is then used as an index into the current palette. 1-8 Color Printing Overview EN Well-Behaved Raster PCL raster images are processed most efficiently when the height and width of the image are specified before the Raster Start command begins an image data transfer. Furthermore, the entire image should be transferred before using the End Raster command to end the image. If the image is broken into pieces, certain print artifacts such as lines or squares can appear in the image. These can occur when "nearest neighbor operations" are applied to pixels that appear to be at the edge of an image, but are really inside an image that has been artificially broken up into smaller images. EN Color Printing Overview 1-9 1-10 Color Printing Overview EN 2 Using Color Modes Introduction The PCL printer language has four color modes: · Black-and-White · Simple Color · PCL Imaging · HP-GL/2 Imaging PCL allows you to use any mode or combination of modes to accomplish your printing objectives most efficiently. All four of the color modes create a palette. The palette for each mode is discussed in the section describing that mode, and also in Chapter 3 ("Using Palettes"). Black-and-White Mode (Default) Black-and-White Mode is the default color mode. PCL devices power up in this mode and revert back to it whenever the printer receives an ?E reset. Black-and-White mode is also selectable using the Simple Color command (?*r1U). This mode creates an unmodifiable, default 2-pen palette, with white at index 0 and black at index 1 (compatible with existing monochrome PCL 5 printers). Simple Color Mode Simple Color Mode, entered by the Simple Color command (?*r#U), creates a fixed-size, fixed-color, unmodifiable palette. Depending on the value field, ?*r#U can create a 2-pen Black-and-White palette, an 8-pen RGB palette, or an 8-pen CMY palette. When using the Simple Color mode, the pixel encoding mode is always indexed planar. EN Using Color Modes 2-1 PCL Imaging Mode PCL Imaging Mode, enabled by the Configure Image Data command (?*v#W), allows a maximum of 24 bits per pixel for color specification. Therefore, more colors may be specified than are obtainable in Simple Color Mode. In the PCL Imaging Mode, pixel encoding mode, bits per pixel, bits per primary, and the color palette are all programmable. HP-GL/2 Imaging Mode In HP-GL/2, the Initialize (IN) command starts color imaging and performs the following: · Sets the pixel encoding mode to index by plane. · Sets bits per index to 3. · Creates an 8-pen palette that is reprogrammable in either PCL or HP-GL/2 contexts (see Chapter 3, "Using Palettes," for more information). Although default HP-GL/2 palettes are different than default PCL palettes, an HP-GL/2 palette is modifiable in either PCL or HP-GL/2 (using the Assign Color Index [?*v#I] or Pen Color [PC] commands, respectively). Likewise, a PCL palette created by the Configure Image Data command (?*v#W) is modifiable in both PCL and HP-GL/2 using the same commands. The active palette is always transferred between HP-GL/2 and PCL contexts. Since only one palette at a time can be active, a new palette created in either context overwrites the current palette. 2-2 Using Color Modes EN Simple Color Mode The Simple Color command (?*r#U) specifies color selection from a fixed palette. RGB or CMY raster data must be sent by plane (?*b#V) as well as by row (?*b#W). The last plane in each row is sent using the ?*b#W command; all other planes are sent using the ?*b#V command. In Simple Color mode, the pixel encoding mode is always indexed planar. Simple Color Command The Simple Color command creates a fixed-size palette, whose color specification cannot be modified. ?*r#U # = ­3 - 3 planes, device CMY palette 1 - Single plane K (Black) palette 3 - 3 planes, device RGB palette Default = 1 Range = ­3, 1, 3 This command destroys the active palette and creates a new palette, which becomes the active palette. When the Simple Color mode is active, PCL and HP-GL/2 commands that modify the palette are locked out (NP, PC, ?*v#A, ?*v#B, ?*v#C, ?*v#I). When a Simple Color palette is popped from the stack (?*p#P), it cannot be modified, and the pixel encoding mode reverts to indexed planar. · A value field of 1 creates a 2-entry Black-and-White default palette. · A value field of 3 creates an 8-entry Device RGB palette (compatible with a PCL Imaging Mode palette, but not an HP-GL/2 default (IN) palette). · A value field of ­3 creates an 8-entry palette in Device CMY color space. EN Using Color Modes 2-3 The Simple Color palettes are structured as follows: Single Plane (value = 1) Index 0 1 Color White Black 3-Plane RGB (value = 3) Index 0 1 2 3 4 5 6 7 Color Black Red Green Yellow Blue Magenta Cyan White 3-Plane CMY (value = ­3) Index 0 1 2 3 4 5 6 7 Color White Cyan Magenta Blue Yellow Green Red Black 2-4 Using Color Modes EN PCL Imaging Mode The PCL Imaging mode, entered using the Configure Image Data (CID) command (?*v#W), creates a variable-sized programmable palette. It provides multiple color spaces, pixel encoding modes, and reprogrammable palettes. Configure Image Data (CID) Command The CID command provides configuration information for creating palettes and transmitting raster data. The CID command performs the following: · Designates the color space for the newly created palette · Designates the size of the palette · Designates the Pixel Encoding Mode, the format of the raster data · Designates, in certain circumstances, the size, in bits, of the three components of the color specifications. However, this information is rarely useful since it applies only to the direct-by-pixel PEM, where the format must be eight bits per component for 24-bit direct color, and the direct-by-plane, where there is one bit per component. ?*v6W b0 b1 b2 b3 b4 b5 Where: 6= b0 = b1 = b2 = b3 = b4 = b5 = The number of bytes following the "W" byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 The color space The Pixel Encoding Mode The number of bits per index which implies the size of the palette The number of bits in color component (primary) #1 The number of bits in color component (primary) #2 The number of bits in color component (primary) #3 EN Using Color Modes 2-5 The bytes are ordered as follows and are unsigned bytes: Byte 0 2 4 15 (MSB) Color space Bits/index Bits/primary #2 8 7 0 (LSB) Byte 1 3 5 Pixel encoding mode Bits/primary #1 Bits/primary #3 Invalid configurations of the CID command are ignored and the data discarded. A minus or a plus sign in the value field (-6 or 6) is ignored The data fields in the command, bytes zero to five, must contain byte-aligned binary data, not ASCII data. Byte 0 (Color Space) This byte specifies the color space. The range of values is 0 through 2. All other values are ignored. Byte Value 0 1 2 Color Space Device Dependent RGB (default) Device Dependent CMY Standard RGB (sRGB) Color space 2, sRGB, was the designation for Colorimetric RGB in the Color LaserJet and Color LaserJet 5 printers. The value 2 is used to represent sRGB since it is analogous to a standardized Colorimetric RGB and the intent of the two color spaces is the same. 2-6 Using Color Modes EN Byte 1 (Pixel Encoding Mode) This byte designates the format of any subsequent raster images. The range of the value is zero to three. All other values for this field are ignored. Value 0 Pixel Encoding Mode Indexed by Plane Restrictions Bits/Index can only be 1, 2, 3, 4, 5, 6, 7, or 8. Bit/Components 1, 2, and 3 are ignored Bits/Index can only be 1, 2, 4, or 8. Bit/Components 1, 2, and 3 are ignored Bits/Components 1, 2, and 3 must be 1 Bits/Components 1, 2, and 3 must be 8 1 Indexed by Pixel 2 3 Direct by Plane Direct by Pixel The number of bits per index determines the size of the palette created by this command. In the case of the Indexed by Plane mode the number of planes needed to represent the index is also determined by the number of bits per index. Therefore, if a 256 entry palette is needed, then the bits per index is set to eight since 28 = 256. If the Indexed by Plane mode is chosen, at most eight planes are needed to represent each row of data. The recommended pixel encoding mode is Direct by Pixel, since this gives the most efficient raster processing. However, using this mode means that delta row compression should be used since it exploits redundancy between rows. Other PCL compression modes exploit redundancy within a row. With Direct by Pixel the redundancy from pixel to pixel in a row is masked by the differences at the byte level within the pixel, that is, the differences between the red, green, and blue bytes within the pixel. Note Raster data in Index by Plane or Direct by Plane modes cannot be compressed using raster compression mode 5. You need one plane or one bit/pixel for each power of two colors in the palette. For example, a 256-color palette requires 8 planes or 8 bits/pixel (28 = 256). EN Using Color Modes 2-7 PEM 0: INDEXED BY PLANE In Pixel Encoding Mode 0, successive planes of data are sent for each raster row. A plane contains one bit for each pixel in a row. A pixel is not fully defined until all the planes for that row have been received, which is signaled by a transfer raster row command. The planes in a row form index numbers into the current palette. For example, assuming three bits per index, the underlined column of bits in the figure below is the palette index for pixel three of the first row (i1 is the least significant bit, i3 is the most significant bit). Note that the Transfer Raster Data by Plane command (?*b#V) is used for all planes except the last plane of each row, which is sent using the Transfer Raster Data by Row command (?*b#W). ?*b#V ?*b#V ?*b#W ?*b#V Example: row 1 plane 1 plane 2 plane 3 i1 i2 i3 i1 i1 i2 i3 i1 i1 i2 i3 i1 i1 i2 i3 i1 i1 i2 i3 i1 i1 i2 i3 i1 row 2 plane 1 In the example below, the row transfer commands are shown in binary for clarity, even though the actual data would be byte-aligned binary data. The example is for an eight-pixel-wide image. ?*v6W 00 00 03 08 08 08 Binary data for CID represented in hex. This command sets the color space to RGB, the PEM to Indexed by Plane, the palette size to 8 (23). The last 3 bytes are ignored. Start raster. Transfer plane 1 (the first bit for each pixel in the first row). Transfer plane 2 (the second bit for each pixel in the row). Transfer plane 3 (the third and final bit for each pixel in the row) and move to the next row. Note that the ?*b#W command is used to send the last plane of each row. ?*r1A ?*b1V10110000 ?*b1V01110000 ?*b1W10101000 2-8 Using Color Modes EN PEM 1: INDEXED BY PIXEL In this mode, each pixel in a row is fully specified before any bits are sent for the next pixel. The bits for each pixel form a palette index number. Assuming four bits per index, the underlined block below is the palette index for pixel two of row one (i1 is the least significant bit). ?*b#W row 1 i4 i3 i2 i1 i4 i3 i2 i1 . . . ?*b#W row 2 i4 i3 i2 i1 i4 i3 i2 i1 . . . ?*b#W row 3 i4 i3 i2 i1 i4 i3 i2 i1 . . . Example: In the example below the data in the row transfer commands are shown as two-digit hexadecimal numbers for clarity, even though the actual data would be byte-aligned binary data. The example is for a two-pixel-wide image. ?*v6W 00 01 04 08 08 08 Binary Data for the CID command represented in hexadecimal. This command sets the color space to RGB, the PEM to Indexed by Pixel, the palette size to 16 (24). The last three bytes are ignored. Start raster The most significant nibble selects palette entry 4 for the first pixel. The second pixel is set to index 5. Move to next row. The first pixel is index 6, the second pixel is index 10. Move to the next row. The first pixel is index 0, the second pixel is index 3. ?*r1A ?*b1W45 ?*b1W6A ?*b1W03 EN Using Color Modes 2-9 MODE 2: DIRECT BY PLANE In this mode, a pixel is composed of three, one-bit components. The data is transferred a plane at a time, one plane for each component. Therefore, each bit in a plane represents one component of a pixel. The underlined bits below show the components for a pixel. ?*b#V row 1 ?*b#V ?*b#W ?*b#V row 2 Example: plane 1 (red) plane 2 (green) plane 3 (blue) plane 1 (red) b1 b2 b3 b1 b1 b2 b3 b1 b1 b2 b3 b1 b1 b2 b3 b1 b1 b2 b3 b1 b1 b2 b3 b1 In the example below the data in the row transfer commands are shown in binary for clarity, even though the actual data would be byte-aligned binary data. The example is for an eight-pixel-wide image. ?*v6W 00 02 01 01 01 01 Binary Data for the CID command represented in hexadecimal. This command sets the color space to RGB, the PEM to Direct by Plane. The palette size is ignored. The last three bytes are always one for this mode. Start raster Transfer plane 1 (the first bit for each pixel in the first row). Each bit controls the red primary. Transfer plane 2 (the second bit for each pixel in the row). Each bit controls the green primary. Transfer plane 3 (the third and final bit for each pixel in the row) and move to the next row. Each bit controls the blue primary. Note that the ?*b#W command is used to send the last plane of each row. ?*r1A ?*b1V10110000 ?*b1V01110000 ?*b1W10101000 2-10 Using Color Modes EN MODE 3: DIRECT BY PIXEL This mode specifies a pixel as three, eight-bit components, thus the name 24-bit direct color. Assuming the RGB color space with the mandatory eight bits per component, the underlined bytes below define the first pixel of row two. ?*b#W ?*b#W ?*b#W Example: row 1 row 2 row 3 r7­r0 r7­r0 r7­r0 g7­g0 g7­g0 g7­g0 b7­b0 . . . b7­b0 . . . b7­b0 . . . In the example below the data in the row transfer commands are shown as two-digit hexadecimal numbers for clarity, even though the actual data would be byte-aligned binary data. The example is for a one-pixel-wide image. ?*v6W 00 03 00 08 08 08 Binary Data for CID command represented in hexadecimal. This command sets the color space to RGB, the PEM to Direct by Pixel. The palette size is ignored. The last three bytes must be 8. Start raster The three bytes specify a single pixel. The first sets 45 as the red component's value, the second sets the green value to 06, and the third sets the blue value to 30. ?*r1A ?*b3W 45 06 30 Byte 2 (Number of Bits per Index) This command creates a palette regardless of the PEM chosen. This byte determines the size of the created palette. The palette size is two raised to the power of n (2n), where n is the bits per index. · In the Indexed-by-Plane PEM, where the raster data is interpreted as palette indices, this value determines the number of planes required per row. EN Using Color Modes 2-11 · In the Indexed-by-Pixel PEM, where the raster data is interpreted as palette indices, this value determines how to interpret the byte-ordered row transfers. The following list shows how each byte is translated into indices: Bits/Index 1 2 4 8 Indices/Byte 8 4 2 1 · In the Direct-by-Plane and Direct-by-Pixel PEMs, byte 2 does not apply to the raster format. Bytes 3, 4, and 5 (No. of Bits for Components 1, 2, and 3) These bytes are ignored for the Indexed by Plane and Indexed Direct PEMs. For the Direct by Plane PEM they must be set to one bit per component. For the Direct by Pixel PEM, they must be set to eight bits per component. 2-12 Using Color Modes EN HP-GL/2 Imaging Mode The HP-GL/2 Imaging Mode provides a way of using vector commands in printing documents. Although the default PCL and HP-GL/2 palettes are not the same, when transferring from PCL to HP-GL/2, active palette information does stay the same. You can switch between PCL and HP-GL/2 and use the same palette, and you can also modify palettes using either PCL or HP-GL/2. Compared to monochrome printers, the HP Color LaserJet printer family, DeskJet 1200C and 1600C color printers have some commands that are new and/or modified for use with color printers. Chapter 7 describes the new or modified HP-GL/2 commands. If you are not familiar with using HP-GL/2, see the PCL 5 Printer Language Technical Reference Manual. It provides a detailed explanation of using HP-GL/2. EN Using Color Modes 2-13 2-14 Using Color Modes EN 3 Using Palettes Introduction A palette is a collection of color specifications selected using index numbers. The figure below illustrates a palette. Each palette entry associates an index number with three primary color components. For HP-GL/2 purposes only, a pen width is also associated with each palette entry. EN Using Palettes 3-1 In non-raster mode, the current palette contains all the available colors. In raster mode, indexed color selection uses the palette, but direct selection does not. Default palettes are created by all the PCL color modes (Black and White, Simple Color, PCL Imaging, and HP-GL/2 Imaging). The active palette may be modified when in the PCL Imaging or HP-GL/2 imaging modes, but not when in the Simple Color or Black and White modes. When switching between PCL 5 and HP-GL/2 contexts, the active palette is automatically transferred. Multiple palettes can exist in the system via the Palette ID and Palette Stack mechanism. However, only one palette at a time can be active. A palette created in the PCL context remains active and unchanged when switching to the HP-GL/2 context, and a palette created in the HP-GL/2 context remains active and unchanged when switching to the PCL context. Performing a reset or entering PJL overwrites the active palette with the default black and white palette. Whenever a new palette is created, the currently or previously active palette is destroyed. A new palette is created by power-on and also by the following commands: · PCL Reset (?E) · Simple Color (?*r#U) · Configure Image Data (?*v#W) · HP-GL/2 Initialize (IN) The active palette can be saved by pushing it onto the palette stack with the Push/Pop Palette command (?*p#P). Popping a palette from the stack destroys the active palette--the popped palette becomes the active palette. 3-2 Using Palettes EN Saving the Palette The current palette is destroyed when a new palette is created. The Push/Pop Palette command (?*p#P) can save (push) the current palette and then restore (pop) it. Push/Pop Palette Command This command pushes or pops the palette from the palette stack. ?*p#P #= 0 - Push (save) palette 1 - Pop (restore) palette Default = 0 Range = 0, 1 (invalid values are ignored) A value of 0 (?*p0P) pushes a copy of the active palette onto the palette stack. When a palette is pushed, the active palette is not affected. A value of 1 (?*p1P) pops the most recently pushed palette and destroys the active palette; the popped palette becomes the active palette. As with any stack, the last item pushed is the first item popped. Pushing a palette saves the following parameters: · Color definitions for each palette entry · Pen widths (for HP-GL/2 use) · Color space specification · Number of bits per index · Pixel encoding mode · Number of bits per primary · Color treatment · Render algorithm EN Using Palettes 3-3 Pushing a palette does not save the following parameters. · Foreground color · Color components: 1st, 2nd, and 3rd · Finish mode · Monochrome print mode The palette stack depth is limited by printer memory. Attempts to push a palette with insufficient memory cause an out-of-memory error. Attempts to pop from an empty stack are ignored. Macros can push and pop palettes. A palette that was popped in an executed macro remains in effect at the end of the macro (this is not true for "called" or "overlaid" macros). The PCL reset command (?E) or an exit to PJL causes the printer to empty the palette stack and overwrite the active palette with a non-programmable black and white palette. The HP-GL/2 commands IN and DF have no effect on the palette stack, but they do destroy the active palette and replace it with the default HP-GL/2 palette. 3-4 Using Palettes EN Palette Management by ID All palettes have a unique ID (identification number). The default black and white palette created on power-up or ?E has an ID of 0. Palette management by ID lets applications have multiple palettes. As shown below, multiple palettes can exist in two areas: the palette stack and the palette store. The stack holds palettes that are pushed via a Push/Pop Palette command; the store holds palettes having palette IDs. Palettes on the stack may not be selected by ID, since only a copy of a palette is pushed onto the stack; the original palette and ID remain in the palette store. A palette popped from the stack goes into the palette store, becomes the new active palette, and assumes the ID of the previously active palette, which is overwritten. Only one palette at a time may be active. Using Palettes 3-5 EN Management by ID allows applications to tag data, have multiple raster configurations, and have palettes for different color spaces--all without reconfiguring the active palette. For example, one palette can be created for PCL text, one for HP-GL/2 primitives, one for simple raster, and one for 24-bit raster. The application can then switch between palettes according to what is being sent to the printer. Selecting a new active palette changes the PCL graphics state. Besides the color entries, a palette also has the graphics state which contains the color space, color treatment, and render algorithm. This ensures that the same color specification in a given palette will always produce the same printed color. As described below, the Select Palette (?&p#S), Palette Control (?&p#C), and Palette Control ID (?&p#I) commands implement the three basic operations of management by ID. · Selection of the active palette · Deletion of palettes · Copying of palettes Select Palette Command The Select Palette command selects a new active palette by specifying an ID number. The previously active palette is unchanged. ?&p#S # = Palette ID number Default = 0 Range = 0 to 32767 (command is ignored for out- of-range values) This command activates the designated palette in the palette store. The command is ignored if the specified ID matches the active palette's ID, or if no palette with that ID exists. The designated ID is saved as the palette select ID for the duration of the print job, or until another Select Palette command is received. This command can be used to de-select the active palette and select as the new active palette a palette created by the Palette Control command (?&p#C). For example, to copy the active palette to an ID of 44 and select the new palette to use or modify, send ?&p44i6c44S. 3-6 Using Palettes EN When a palette creation command is received such as Configure Image Data (?*v#W), Simple Color (?*r#U), or an HP-GL/2 IN, the created palette overwrites the active palette and is assigned the current palette select ID. A palette popped from the stack overwrites the active palette, and is assigned the current palette select ID. ?E resets the palette select ID value to 0 and deletes all palettes in the palette stack and palette store, including the active palette, which is replaced by a default PCL fixed black and white palette with a palette ID of 0. Macros affect the palette select ID value as follows: · Calling or Overlaying a macro--saves the ID value and a copy of the active palette. Upon macro exit, the restored palette again becomes the active palette with the restored ID. An existing palette with this ID is deleted. · Executing a macro--does not save the ID value or the active palette; changes remain in effect. EN Using Palettes 3-7 Palette Control ID The Palette Control ID command specifies the ID number to be used by the Palette Control Command. ?&p#I # = Palette ID number Default = 0 Range = 0 to 32767 (command is ignored for out-of-range values) The ID number specified by this command is saved as the palette control ID and is used by the Palette Control command (?&p#C). ?E or power-up resets the palette control ID to 0, which is then the default black and white palette ID. Macros affect the palette control ID value as follows: · Calling a macro--saves the value and restores the value at exit. · Executing a macro--does not save the value; changes remain in effect at exit. · Overlaying a macro--copies the value before resetting to 0, and restores at exit. 3-8 Using Palettes EN Palette Control The Palette Control command provides a mechanism for making and deleting palettes. ?&p#C #= 0 - Delete all palettes except those in the stack (active palette deleted) 1 - Delete all palettes in the stack (active palette is not affected) 2 - Delete palette (specified by Palette Control ID) 6 - Copy active palette to ID specified by Palette Control ID Default = 0 Range = 0, 1, 2, 6 (command is ignored for unsupported values) · A value of 0 deletes all palettes except those on the palette stack. The active palette is replaced by the default black and white palette (ID 0). The palette control ID is not used. · A value of 1 clears the palette stack. The active palette is unaffected, and the palette control ID is not used. · A value of 2 deletes the palette with the specified palette control ID if it exists; otherwise the command is ignored. For example, to delete palette 53, send ?&p53i2C. If the active palette's ID is specified the active palette is replaced by the default black and white palette. This option does not change the palette control ID value. Note When the active palette is replaced by the default black and white palette, the graphics state associated with the previous palette is also replaced. · A value of 6 creates a copy of the active palette. The copy receives the ID specified by the last Palette Control ID command. For example, to copy the active palette to a palette with an ID of 14, send ?&p14i6C. The copied palette overwrites any palette that already has an ID equal to the palette control ID. The copied palette does not become the active palette. The command is ignored if a palette is to be copied to its own ID. EN Using Palettes 3-9 The Palette Control command provides a way of managing system memory by deleting palettes in either the stack or store that are no longer in use. Palette Control that is exercised during macros can have significant impact on palettes that exist within the system. Deleting all palettes, or those on the stack, or the current palette, or all those except on the stack can have adverse effects when the macro is exited. The adverse effect could be the deletion of the desired palette, and replacement with a black and white non-programmable palette. 3-10 Using Palettes EN Simple Color Palettes The Simple Color command (?*r#U) provides a quick way to select colors from a fixed, non-programmable palette. The Simple Color command overwrites the current palette with one of the fixed palettes below. When the Simple Color command is in effect, the PCL and HP-GL/2 commands that modify a palette entry (NP, PC, ?*v#A, ?*v#B, ?*v#C, ?*v*I, ?*t*I) are locked out. A popped simple color palette cannot be modified and the pixel encoding mode reverts to "index by plane". Only the IN or the CID (?*v#W) commands can create a modifiable palette. As shown below, a value field of 1 (?*r1U) creates a black and white palette. A value of 3 creates an 8-pen palette in Device RGB color space. A value of ­3 creates an 8-pen palette in Device CMY color space. All of these Simple Color palettes are fixed and non-programmable. Single Plane (value = 1) Index 0 1 Color White Black 3-Plane RGB (value = 3) Index 0 1 2 3 4 5 6 7 Color Black Red Green Yellow Blue Magenta Cyan White EN Using Palettes 3-11 3-Plane CMY (value = ­3) Index 0 1 2 3 4 5 6 7 Color White Cyan Magenta Blue Yellow Green Red Black 3-12 Using Palettes EN