Color and Mastering for Digital Cinema

Color and Mastering for Digital Cinema

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Color and Mastering for Digital Cinema Glenn Kennel Digital Cinema Industry Handbook Series Charles S. Swartz

First published 2007 This edition published 2013 by Focal Press 70 Blanchard Road, Suite 402, Burlington, MA 01803 Simultaneously published in the UK by Focal Press 2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN Focal Press is an imprint of the Taylor & Francis Group, an informa business Copyright 2007 by Taylor & Francis. All rights reserved. No part of this book may be reprinted or reproduced or utilised in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publishers. Notices Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Library of Congress Cataloging-in-Publication Data Application submitted British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. ISBN 13: 978-0-240-80874-1 (hbk) Cover photograph: Standard Evaluation Material (StEM) picture by permission of the American Society of Cinematographers (ASC) and Digital Cinema Initiatives (DCI). Color Timing Theatre is courtesy of Laser Pacific Media Corporation.

To Sarah and Lucy

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Contents Preface ix Acknowledgments xi About the Author xiii About the Series Editor xv 1 Overview of Color and Mastering for Digital Cinema 1 2 Color in Motion Picture Film 9 3 Color Space for Digital Cinema 33 4 Transfer Function 47 5 Reference Projector and Environment 67 6 Digital Mastering 85 7 Color Encoding for Digital Cinema Distribution 105 8 Color Processing in the Projector 119 9 DLP Cinema Case Study 131 10 Digital Display Technologies 145 11 Digital 3D Presentation 157 12 The Future 169 Index 181 vii

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Preface The standardization of 35 mm film nearly 100 years ago paved the way for the growth of the motion picture industry. From its humble roots in nickelodeons and peep shows, the motion picture business evolved into popular entertainment for the masses. Along the way, the 35 mm film standard was extended to support sound, color, wide screen presentation, and multi-channel digital soundtracks. The film-making process is being revolutionized by the adoption of digital imaging technologies. Digital post production was widely embraced in the 1990s, and digital cinema distribution and exhibition is now taking off with a consensus standard supported by all of the major studios. This book describes the color mastering and encoding methods for digital cinema, looking back at the traditional film process, providing insight into the evolving digital intermediate process, and reviewing the basis for the color encoding standards for digital cinema distribution. One can only hope that these digital cinema standards can be as capable and enduring as 35 mm film. ix

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Acknowledgments I could not have written this book without the help of many people. First, I d like to thank my wife, Sarah Priestnall, for checking my writing and correcting my mistakes, and also for helping me rewrite sections for clarity, particularly the chapter on Digital Intermediate. I also thank her for her support and patience while I was spending many weekends on the writing. I am deeply indebted to Tom Maier of Kodak for his lucid writing on the subject of color processing for digital cinema. In particular, much of Chapters 3, 4, 7, and 8 are based on documents that he wrote as a leading contributor to the SMPTE DC28 Color ad hoc group. I also thank Matt Cowan of Real D for his contributions as a member of the SMPTE DC28 Color ad hoc group, and for his help in reviewing and editing the chapter on Digital 3D. Matt also contributed several illustrations to this book. Brad Walker of Texas Instruments taught me a lot about the color processing that he designed for the DLP Cinema projectors, and much of Chapter 9 is based on a paper that he co-authored with Greg Pettitt, also of Texas Instruments. Brad was also a key contributor to the SMPTE DC28 Color ad hoc group. I d also like to thank the other members of the SMPTE DC28 Color ad hoc group, who dedicated many hours to our discussions and evaluations leading up to the specification of X Y Z color encoding for digital cinema distribution. This group also included Prinyar Boon, Chuck Harrison, Jim Houston, George Joblove, Howard Lukk, Arjun Ramamurthy, Jeremy Selan, John Silva, Kaz Tsujikawa, and Ron Williams. xi

xii Acknowledgments I d like to thank industry consultant Peter Putman for his contributions to Chapter 10 on Digital Display Technologies. Many of the illustrations in this chapter come from his tutorials to HPA and NAB audiences. And finally, I d like to pay a special tribute to Walt Ordway, Howard Lukk, and Jim Whittlesey of Digital Cinema Initiatives, who drafted the DCI System Specifications, and in the process built a technical and political consensus amongst the major studios, enabling the deployment of digital cinema.

About the Author Glenn Kennel has worked in technology development in the motion picture industry for over 25 years, pioneering the application of digital technology to the filmmaking process He started his career with Eastman Kodak in 1980, and participated in the development of Kodak High Speed Negative Film 5293. In the mid-1980s, Kennel assembled a project team and led the development of a prototype HDTV telecine that later provided the basis for the Philips Spirit Datacine. In 1989, he worked with Industrial Light & Magic (ILM) to build the first linear CCD scanner for motion picture film scanning. Kennel was also the architect of the Cineon digital film system in 1990 and led the development of the Cineon CCD film scanner and film recorder over the next couple of years. He helped launch Kodak s Cinesite Digital Film Center in 1992 and evangelized digital technology with the visual effects industry. He also provided technical support to Cinesite during the digital restoration of Disney s Snow White. In 1993, Glenn Kennel was recognized by SMPTE with the Agfa-Gaevert Gold Medal for outstanding achievement in the field of film/television interface. In 1995, he received the Academy Scientific and Technical Achievement award for the linear CCD film scanner, jointly developed with ILM. He worked with Philips to extend the Spirit Datacine to Cineon-compatible digital file output, first applying it to the film Pleasantville in 1997. He helped establish Cinesite s Digital Mastering department in 1998, providing technical support to the first major feature film to go through the DI process, O Brother, Where Art Thou? in 1999 2000. xiii

xiv About the Author As program manager of Kodak s Digital Cinema effort in 2000 2003, he led a team that developed servers and software for digital cinema and coordinated a joint development program with JVC for a digital cinema projector. In 2003, Kennel left Kodak to work as an industry consultant with DCI on color encoding for digital cinema, including coordinating the digital mastering process for the ASC/DCI StEM test. He chaired the SMPTE DC28 ad hoc group on Color and helped draft several digital cinema standards. He joined Texas Instruments DLP Cinema group in 2004, in a role that combined technology and business development for digital cinema, helping the industry address the practical hurdles to digital cinema deployment. Kennel was elected to the Scientific and Technical Branch of the Academy of Motion Picture Arts and Sciences in 2005. Kennel is now Vice President and General Manager of the Motion Picture division of Laser Pacific Media Corporation, where he is responsible for services including digital dailies, previews, Digital Intermediate, mastering and digital cinema packaging. Kennel is the author of many technical papers on applications of digital technology to filmmaking published in the SMPTE Journal, and co-author of a chapter in Understanding Digital Cinema (2005). He is also a fellow of SMPTE.

About the Series Editor Charles S. Swartz oversees efforts to further the entertainment industry through new technology. He draws from more than two decades of experience in feature film and television production, academic programming and strategic consulting to lead the center in identifying emerging entertainment technology issues and developing projects to study them. Swartz assumed his current position at the Entertainment Technology Center in 2003, where he has refocused and recharged the research center. He serves in two positions for SMPTE/Hollywood: Governor of the Hollywood Region and co-chair of the education committee. In 1996, the Los Angeles Business Journal named him one of 100 technology leaders in Los Angeles. xv

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1 Overview of Color and Mastering for Digital Cinema In June of 1999, George Lucas released his film Star Wars: Episode 1 on two digital cinema screens one in New York and one in Los Angeles. In the five years since this historic debut, over 150 films have been released digitally to over 500 screens in 30 countries around the world. These digital movies have played over 20,000 shows to satisfied audiences. Although digital cinema has not been widely promoted as a new and improved display method, educated audiences have shown a preference for digital over film presentation. This book presents a survey of the development of color encoding and decoding standards for digital cinema distribution and exhibition. It describes the key issues and provides background on decisions that were made in the standardization process. Although the author was a key participant in the development of the SMPTE 1 DC28 documents, it is recommended that the reader refer to the published SMPTE standards 2 for the final word on implementation. 1. Society of Motion Picture and Television Engineers. 2. At the time of this writing, the SMPTE DC28 working group has several digital cinema documents in process. These standards are available to participants, but have not yet been published. 1

2 1. Overview of Color and Mastering for Digital Cinema This book refers to colorimetric principles that are more rigorously defined in color textbooks 3,4 and assumes that the reader has a working knowledge of basic color principles and motion picture industry practices. However, one does not need to be a color scientist or industry insider to read and understand this book. In late 1999, SMPTE established the DC28 working group to study the standardization requirements for digital cinema distribution, with the goal of establishing a world-wide standard. Since its standardization by SMPTE in 1916, the 35 mm motion picture film format has served as the single worldwide distribution standard for movies. 35 mm motion picture film has weathered the test of time, supporting major exhibition enhancements like sound, color, widescreen presentation and multitrack digital soundtracks, all compatible with 35 mm projection equipment based on the original standard. In today s hyper-competitive and fast-changing digital world, it seemed a tall order to establish a digital cinema distribution standard that would serve the industry for the next century. But the industry set its sights on just that. The goal was to develop a universal standard for digital cinema distribution that could be implemented in a cost effective way today, while also extensible to support future exhibition improvements. The SMPTE DC28 group concluded its study work at the end of 2000 by identifying the need for standards for digital cinema mastering, distribution and exhibition. Working groups were established to address each of these areas. In addition, ad hoc groups of industry experts were formed to address specific issues, including packaging, key management and security, and color. The DC28 color ad hoc group began its work in 2002, focusing its initial discussions on the color encoding for digital cinema. The group was composed of experts from diverse parts of the industry that included studios, post production facilities and equipment manufacturers. While everyone agreed on the goal, there were many opinions on how best to get there. While the SMPTE DC28 work proceeded slowly and steadily as a due process forum with diverse interests, the establishment in 2002 of the Digital Cinema Initiatives, LLC (DCI), a consortium formed by seven major Hollywood studios, provided a focus for the development of the digital cinema standards. A group of technical experts from the member studios met regularly to hammer out a consensus technical specification for digital cinema distribution. In its work, DCI used available and prototypical digital cinema equipment to evaluate requirements for compression, security, content packaging and color encoding. DCI hired several industry experts to supplement its internal expertise. Amongst other things, DCI funded the Contrast Sensitivity Test that verified the bit depth requirement for color encoding (see Chapter 4). Most importantly, DCI provided a venue for the political process of building consensus amongst its members. Its crowning achievement was the delivery of a consensus technical specification for 3. R.W.B. Hunt, The Reproduction of Color, 6th Edition, Wiley, 2004. 4. G. Wyszecki and W.S. Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulae, 2nd Edition, Wiley, 2000.

Overview of Color and Mastering for Digital Cinema 3 a 2 K/4 K scalable solution in July 2005 that was supported in its entirety by all of its members. This consensus specification removed a substantial uncertainty, paving the way for commercial deployment of compliant systems while substantially reducing the risk of technological obsolescence. STUDIO OBJECTIVES CTO Brad Hunt of the Motion Picture Association of America (MPAA) framed the work of DCI with the following ten goals: 1. ENHANCED THEATRICAL EXPERIENCE The introduction of digital cinema must be used by the motion picture industry as an opportunity to significantly enhance the theatrical film experience and thus bring real benefits to theater audiences. 2. QUALITY The picture and sound quality of digital cinema should present as accurately as possible the creative intent of the filmmaker. To that end, its quality must exceed the quality of a projected 35 mm answer print shown under optimum studio screening theater conditions. Any image compression that is used should be visually lossless. 3. WORLDWIDE COMPATIBILITY The system should be based around global standards so that content can be distributed and played anywhere in the world as can be done today with a 35 mm film print. 4. OPEN STANDARDS The components and technologies used should be based on open standards that foster competition amongst multiple vendors of equipment and services. 5. INTEROPERABLE Each of the components of the system should be built around clearly defined standards and interfaces that insure interoperability between different equipment. 6. EXTENSIBLE The hardware used in the system should be easily upgraded as advances in technology are made. This is especially important in evolving to higher quality levels. 7. SINGLE INVENTORY Once a consensus on digital cinema standards is reached and implemented, upgrades to the system should be designed so that a single inventory of content can be distributed and compatibly played on all equipment installations. 8. TRANSPORT The system should accommodate a variety of secure content transport mechanisms, including electronic as well as a physical media delivery. C