On Effects

Transcript

3rd Edition Volume 2: Advanced Techniques Trish & Chris Meyer San Francisco, CA D E D I C AT E D to the memory of Vera McGrath, who always said I could do anything I put my mind to – Trish and to the memory of Leroy Meyer, who taught me to be curious about how all things worked – Chris Published by CMP Books An imprint of CMP Media LLC CMP Books, 600 Harrison St., San Francisco, California 94107 USA Tel: 415-947-6615; Fax: 415-947-6015 www.cmpbooks.com Email: [email protected] Copyright © 2000, 2003, 2005 by Trish and Chris Meyer. All rights reserved. No part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. Designations used by companies to distinguish their products are often claimed as trademarks. In all instances where CMP is aware of a trademark claim, the product name appears in initial capital letters, in all capital letters, or in accordance with the vendor’s capitalization preference. Readers should contact the appropriate companies for more complete information on trademarks and trademark registrations. All trademarks and registered trademarks in this book are the property of their respective holders. The programs in this book are presented for instructional value. The programs have been carefully tested, but are not guaranteed for any particular purpose. The publisher does not offer any warranties and does not guarantee the accuracy, adequacy, or completeness of any information herein and is not responsible for any errors or omissions. The publisher assumes no liability for damages resulting from the use of the information in this book or for any infringement of the intellectual property rights of third parties that would result from the use of this information. For individual orders, and for information on special discounts for quantity orders, please contact: CMP Books Distribution Center, 6600 Silacci Way, Gilroy, CA 95020 Tel: 1-800-500-6875 or 408-848-3854; Fax: 408-848-5784 Email: [email protected]; Web: www.cmpbooks.com Distributed to the book trade in the U.S. by: Publishers Group West, 1700 Fourth Street, Berkeley, California 94710 Distributed in Canada by: Jaguar Book Group, 100 Armstrong Avenue, Georgetown, Ontario M6K 3E7 Canada Library of Congress Cataloging-in-Publication Data Meyer, Trish Creating motion graphics with after effects / Trish & Chris Meyer. – 3rd ed. p. cm. Includes index. ISBN 1-57820-249-3 (softcover with dvd : alk. paper) 1. Cinematography–Special effects–Data processing. 2. Computer animation. 3. Computer graphics. 4. Adobe After Effects. I. Meyer, Chris II. Title. TR858.M49 2004 778.5'2345'028553–dc22 2004017343 ISBN: 1-57820-269-8 (volume 2) Printed in the United States of America 05 06 07 08 09 5 4 3 2 1 EXPERT SERIES Table of Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Integrating After Effects into a variety of workflows. How to Use This Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x How this book is organized, typographical conventions, and what the icons mean. DVD Roadmap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 The enclosed DVD is an essential companion for getting the most out of this book, including projects for most of the chapters, free plug-ins, and other goodies. PART 1 Type, Draw, Paint 1 All About Alphas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Alphas 101, background color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Antialiased edges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alphas in After Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alphas in Photoshop; Straight versus Premultiplied Alphas . . . . . . . . . . . . . . . . . . . . . Remove Color Matting; Alpha Add mode; Channel Effects . . . . . . . . . . . . . . . . . . . . . . Rendering separate alphas; luminescent premultiplied alpha . . . . . . . . . . . . . . . . . . . 2 4 5 8 15 19 2 Working with Photoshop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Creating transparency in Photoshop; saving layered files . . . . . . . . . . . . . . . . . . . . . . . Importing Photoshop files, including as compositions . . . . . . . . . . . . . . . . . . . . . . . . . Pixel Aspect Ratios (sidebar on Photoshop PAR tags) . . . . . . . . . . . . . . . . . . . . . . . . . . . Layer Sets, Styles, and Effects; Color Management (sidebar) . . . . . . . . . . . . . . . . . . . . . Buttons for Encore DVD (sidebar on exporting files for Encore DVD) . . . . . . . . . . . . . 23 27 30 33 34 2B Dots, Pixels, and Inches (Bonus Chapter PDF on DVD) Scanning artwork at the correct sizes to use in After Effects. 3 Working with Illustrator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Insider Illustrator, creating text, kerning, saving files, creating outlines . . . . . . . . . . Defining the Document Size (setting the crop area, resampling) . . . . . . . . . . . . . . . . . Importing from Illustrator; Merging Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Importing from Illustrator as Composition; Blending Modes . . . . . . . . . . . . . . . . . . . . Continuous Rasterization and render order issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . More Illustrator Tricks; Release to Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 42 43 44 46 50 iii 4 Paint and Clone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Getting started, editing and managing strokes; Paint on Transparent . . . . . . . . . . . . Transforming Brush strokes; Channels; Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eraser tool; erase Paint Only and Erase Last Stroke options . . . . . . . . . . . . . . . . . . . . . Animating strokes; using Write On Mode, replacing strokes . . . . . . . . . . . . . . . . . . . . . Rotoscoping; Brush Tips and tablets; interpolating strokes; Effects and Paint . . . . . Clone Stamp tool; Clone Presets; Clone Source Overlay; Source Time Shift . . . . . . . Using Motion Tracking and Expressions to automate cloning . . . . . . . . . . . . . . . . . . . Random Paint Splatters: painting in a straight line, copy/pasting strokes . . . . . . . . . 52 56 58 60 62 66 70 73 4B Vector Paint (Bonus Chapter PDF on DVD) This legacy paint and rotoscoping plug-in still has its fans. Since it offers some features not supported by Paint, we demonstrate ways to use it in production. PART 2 Animation Assistants 5 Additional Assistants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Exponential Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Wiggler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Keyframe Assistants from Third Parties (3D Assistants, Useful Assistants) . . . . . . . . . Smart Mask Interpolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 76 81 82 6 Express Yourself . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 Creating expressions, including using the pick whip . . . . . . . . . . . . . . . . . . . . . . . . . . . Mixing and matching parameters, ranges, and dimensions . . . . . . . . . . . . . . . . . . . . . Controlling Expressions; Expression Language Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . Building more complex expressions, including wiggle . . . . . . . . . . . . . . . . . . . . . . . . . . Expression examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scripting Overview (sidebar on controlling After Effects with scripts) . . . . . . . . . . . . 6B Deeper Modes of Expression (Bonus Chapter PDF on DVD) Diving deeper into the expression language. Other useful math expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Interpolation methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Deeper into arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Space conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Comp, Footage, and Layer attributes . . . . . . . . . . . . . . . . . . . . . . . . . Managing time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Making decisions, including if/then/else statements . . . . . . . . . . . Expressions for looping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The wiggle expression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Random numbers, including noise . . . . . . . . . . . . . . . . . . . . . . . . . . . Color space conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Text and expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv 3 9 11 16 19 21 29 35 38 42 45 48 90 92 98 101 106 114 PART 3 More on Effects 7 Professional Edition Effects Roundup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Adjust and Channel effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Distort effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Noise & Grain effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Render and Stylize effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A Few of our Favorite Things (sidebar on third party effects) . . . . . . . . . . . . . . . . . . . . Sweet 16 (16 bit per channel mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 119 124 127 129 132 8 Color Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 Levels and Curves to improve contrast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Colorization adjustments and tricks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Adjusting color by channels, brightness, and with keying; “Instant Sex” . . . . . . . . . . Third Party Magic (Digital Film Tools and Magic Bullet) . . . . . . . . . . . . . . . . . . . . . . . . Synthetic Aperture’s Color Finesse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 137 139 143 144 9 Compound Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 How compound effects work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Compound Blur and Texturize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Displacement mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146 148 152 10 The Blue Riders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 Keying approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . An overview of the different keying plug-ins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Keylight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inner/Outer Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Color correction and edge improvements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 160 163 166 168 10B Color Difference Keyer (Bonus Chapter PDF on DVD) How to use the most powerful of the Adobe keyers. PART 4 Working with Audio 11 Audio Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 Reading audio waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . How to spot audio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Controlling audio levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Previewing Audio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 175 176 177 12 Audio Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 Trimming layers; avoiding clipping distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The workhorse Stereo Mixer effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Time-based effects, including Delay, Reverb, and Flange & Chorus . . . . . . . . . . . . . . Pitch-based effects, including equalization and creating tones . . . . . . . . . . . . . . . . . . 180 181 182 184 v PART 5 Time and Tracking 13 Time Remapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 Overview, including creating freeze frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Manipulating the speed of clips to change the action . . . . . . . . . . . . . . . . . . . . . . . . . . Adding handle to a clip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Manipulating keyframed animation, sequenced layers, and frame sequences . . . . 188 192 195 196 14 Time Games . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 Posterize Time versus Preserve Frame Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Step-time tricks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Echo, Time Difference, and Time Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Third party time-based effects, including the bundled Cycore FX . . . . . . . . . . . . . . . . 200 202 204 210 15 On Stable Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 Overview of the motion tracker/stabilizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tracking, and applying a track . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Masking and Motion Stabilization (sidebar on keeping masks stationary) . . . . . . . . Stabilization practice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 217 219 220 16 Motion Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 Tracking Position, including working with the Attach Point . . . . . . . . . . . . . . . . . . . . . Tracking Rotation and Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Corner Pin tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tracking practice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PART 6 224 226 228 229 NLE, 3D, and Web Integration 17 Integration 101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234 An overview of managing the workflow between After Effects and other common production tools. 18 Integration with Nonlinear Editing Systems . . . . . . . . . . . . . . . . . . . . . . . . . . 238 Adobe Premiere Pro, including AAF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Media 100 i, HD, and 844/X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Avid systems (using Automatic Duck Pro Import AE) . . . . . . . . . . . . . . . . . . . . . . . . . . . Apple Final Cut Pro and Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 241 245 247 19 Integration with 3D Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 3D Channel Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Importing camera moves from different 3D packages . . . . . . . . . . . . . . . . . . . . . . . . . . Creating mattes for 3D objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Multilayer compositing and compositing tricks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi 250 261 276 282 20 Integration with Web Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288 Importing JPEGs, GIFs, and PNGs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flash SWF import issues, including frame rates and alpha channels . . . . . . . . . . . . . Exporting SWF animations from After Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SWFing Textacy (sidebar on exporting text animations as SWF files) . . . . . . . . . . . . . SWF Export Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PART 7 288 288 292 293 294 Format Issues and Rendering 21 Video Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 Fields, Interlacing, and Frame Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Frame sizes and nonsquare pixels; anamorphic widescreen . . . . . . . . . . . . . . . . . . . . . Safe areas and colors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Previewing your work on a real video monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 298 303 306 22 Playing the Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308 Fields and interlacing explained, including deinterlacing sources . . . . . . . . . . . . . . . Rendering with fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Field order problems, and how to fix them . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Managing interlace flicker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308 313 315 319 23 3:2 Pulldown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324 Pulldown explained, including Advanced Pulldown . . . . . . . . . . . . . . . . . . . . . . . . . . . . Removing pulldown from footage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Advantages of removing pulldown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rendering with pulldown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 324 325 327 329 24 Luminance and IRE Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330 The difference between computer and video luminance ranges . . . . . . . . . . . . . . . . . Converting between different luminance ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IRE and Setup issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Superblack (sidebar on keying based on special luminance levels) . . . . . . . . . . . . . . . Making sure your colors are broadcast-safe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330 331 337 337 339 25 Working with D1/DV NTSC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342 Pixel aspect ratio issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dealing with square pixel sources, and working square . . . . . . . . . . . . . . . . . . . . . . . . . Field order and frame rate issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Drop Frame versus Non-Drop timecode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342 345 348 349 26 Working with D1/DV PAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350 Pixel aspect ratio issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dealing with square pixel sources, and working square . . . . . . . . . . . . . . . . . . . . . . . . . Field order issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350 352 355 vii 27 Working with Widescreen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356 Working in high definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anamorphic widescreen standard definition video . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Repurposing 4:3 content into a widescreen format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Making widescreen sources fit into 4:3 video frames . . . . . . . . . . . . . . . . . . . . . . . . . . . Designing for both widescreen and 4:3, plus faking widescreen . . . . . . . . . . . . . . . . . 356 358 361 363 365 28 Working at Film Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368 Film frame sizes and framing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scanning in and recording out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Telling Time (sidebar on feet+frames plus keycode numbers) . . . . . . . . . . . . . . . . . . . The online/offline workflow (applies to hi-def video as well) . . . . . . . . . . . . . . . . . . . . Working with the Cineon file format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368 372 375 377 379 29 Prerendering and Proxies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384 Prerendering to save time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Creating and applying proxies; placeholders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Working with proxies, including rendering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384 385 387 30 Advanced Rendering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390 Consolidating, removing unused footage, and reducing projects . . . . . . . . . . . . . . . . Collect files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Network rendering, including using the Watch Folder . . . . . . . . . . . . . . . . . . . . . . . . . . GridIron X-Factor and Rush Render Queue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390 391 392 396 31 What’s Your Preference? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 General preferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Previews and Display preferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Import and Output preferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Grids, Guides, and Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Memory, Cache, and Video Previews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . User Interface Colors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398 400 401 402 402 403 31B The Secret Preferences (Bonus Chapter PDF on DVD) Editing the After Effects text-based preference file. The Road Home Bonus DVD Tutorials Overview A number of tutorial projects are also included on this book’s DVD. See summary on page Afterword: CoSA Lives (Bonus Chapter PDF on DVD) David Simons – one of the original creators of After Effects – takes us back in time to learn how this program we love came into being. viii 404. INTRODUCTION Learning to Play with Others A fter Effects can be applied to a dizzying variety of tasks. However, not all jobs begin and end inside After Effects – indeed, very few do. This book focuses on integrating with the rest of the world. Imagery may be scanned, captured with digital still image cameras, created in Adobe Photoshop or Illustrator, rendered from a 3D program, or originally created as an animation for the web. Of course, a large amount of content will be recorded on videotape or film, in a variety of formats, pixel aspect ratios, frame sizes, even frame rates. Much of this footage may be used roughly as is (after a bit of color correction or enhancement, of course). However, some of it will be shot against green or blue screens, and you will need to extract the action from this background and composite it into a new scene. Some footage has objects you need to track so other objects can follow their motion; some will contain an unacceptable amount of motion or shake that you need to stabilize or remove. And not all content is visual – audio is a major portion of the motion graphics experience, as well. Then there’s output! Few of your animations will be played back only on your computer screen. Most of them will go back out to video, film, or the web, again with a large number of technical issues and workflow practices that must be observed. Of course, there are always ways to work smarter. After Effects features a number of Keyframe Assistants plus the Expression language to help perform complex animation tasks for you. There are ways to manipulate the fabric of time itself, plus a whole host of additional plug-in effects that come with the Professional edition – and other useful ones to download or purchase. Preferences can be customized, compositions can be prerendered to save time, and renders can be split across multiple computers to meet tight deadlines. All of this and more is what Creating Motion Graphics, Volume 2: Advanced Techniques is about. After you have read Volume 1: The Essentials and mastered the core of After Effects, we want to help you take your skills further, and enable you to tackle a wider variety of tasks – while expressing your individual creativity along the way. Trish and Chris Meyer CyberMotion By Trish and Chris Meyer As a companion book to the Creating Motion Graphics series, we have also created After Effects in Production, which puts many of the features of After Effects to work in a series of intermediate-toadvanced tutorials. It also includes a set of six broadcast case studies from award-winning studios including ATTIK, Belief, Curious Pictures, The Diecks Group, and Fido, and well as our own studio, CyberMotion. Look in the Goodies folder on the DVD for more information. As a set, we hope these books empower and inspire you to realize your own creativity with this wonderful program. April 2005 ix GETTING STARTED How to Use This Book This book explores the more specialized portions of Adobe After Effects 6.5 – from audio to painting to keying to motion tracking and stabilization to advanced animation techniques including Expressions. We will assume you already know your way around After Effects – or at least have access to a good reference, such as Creating Motion Graphics, Volume 1: The Essentials. This book also discusses how to use other programs with After Effects, including the still image applications Adobe Photoshop and Illustrator, most of the leading 3D animation packages and nonlinear editing systems, and the web animation tool Macromedia Flash MX. We also explore many of the additional features available in the Professional edition version of After Effects. You don’t need to have all of these programs to use this book, but you will no doubt encounter one or more of them during your creative life – and we want to prepare you to deal with them. This book will also serve as a technical reference on video and film issues. We suggest reading Chapter 1 on alpha channels to ensure a grounding in this core concept that touches on everything you do in After Effects. After that, you can skip around and read chapters that pertain to a particular job. In addition to the printed pages of this book, Bonus Chapters on subjects including scanning, Expressions, Vector Paint, Preferences, and the creation of After Effects are included on the accompanying DVD. Additionally, there is a selection of Bonus Tutorials on the DVD that explore specific techniques or plug-ins, such as using expressions or enhancing 3D renders. These tutorials consist of a PDF file with instructions, a corresponding After Effects project, and a movie of the finished piece. (A summary of these tutorials starts on page 404.) x You will find that a good portion of this book is technical in nature. Like you, we’re more interested in being artists than engineers, but understanding the underlying technical details of some challenges – such as dealing with film or high-definition video – makes problems go away faster, so you can get back to being an artist. What’s in a Name? There are many elements in an After Effects project. We’ve tried to establish a set of typographical conventions to make it easier to understand what we are talking about and when:
Words in bold refer to the specific names of folders, files, or layers you are using.
[Words in bold and in brackets] are the names of compositions, as opposed to layers in a composition.
“Words in bold and in quotes” are text you should enter.
Words and symbols in this alternate bold font represent pieces of the Expression language.
When there is a chain of submenus or subfolders you have to navigate, we separate links in the chain with a > symbol: for example, Effect>Adjust>Levels. We use keyboard shortcuts extensively throughout this book. The Macintosh shortcut is presented first (followed by the Windows keystrokes in parentheses). Context-click means hold down the Control key while clicking on the Macintosh, and right-mouse click on Windows. After Effects makes a distinction between similar keys on the normal keyboard and the numeric keypad. If we do not explicitly say to use the keypad, we’re talking about the numbers and How To Use This Book // symbols in the normal portion of the keyboard. When we say the Enter key, we mean the one in the extended keypad; when we say the Return key, we mean the normal carriage return key (which also happens to be labeled Enter on many keyboards). Iconography The content inside each chapter is usually presented in a linear fashion. However, you will find numerous asides throughout. In addition to sidebars which focus on specific ideas or techniques, you will also see: Tips: Useful tricks and shortcuts, or info on optional third party products we recommend. Factoids: Tweaky bits of specific information that might help demystify some subjects. Gotchas: Important rocks you might trip over, such as special cases in which a feature might not work. Connects: Mini-indexes at the end of most chapters – these point out additional chapters in this book and Volume 1 that contain information related to what you just learned. Professional edition: After Effects comes in two flavors: the Standard and Professional editions. Subjects that rely on the Professional edition’s features are identified with this icon. Disc Access This book and its DVD go hand in hand: Virtually every chapter has its own project file which encourages you to practice the concepts presented in these pages. Look for the Example Project box on the first page of each chapter to verify which project you are to load, and whether you also need to install any of the free third party plug-ins included on the DVD. We recommend you copy the DVD, or at least the Chapter Example Projects and Sources folders, to your hard drive. This will speed up file access and allow you to save your own versions of the projects as you work (it will also serve as a backup if the DVD should accidentally break…you know who you are). If files become “unlinked” for some reason, they will appear in italics in the Project window. Simply double-click the first missing item: This will bring up a standard file navigation dialog where you can locate that item. Select the missing file from its corresponding Sources subfolder and click OK. Provided the folder relationship between the project and the other sources has not changed, After Effects will now search for the other missing items and link them in as well. Installation We assume you already have a copy of After Effects 6.5 or later installed – preferably the Professional edition. To be safe, we have included a fullyfunctional time-limited tryout version of After Effects Professional on the DVD. You may also download the most recent version from Adobe (www.adobe.com). If you don’t already have QuickTime installed, you can download it from Apple’s web site (www.apple.com/quicktime). We assume you also have a copy of Adobe Reader on your computer. An installer is included on your After Effects CD and may also be downloaded from www.adobe.com. There are numerous free and trial version plugins on your DVD. Some of these have their own installers, or must be decompressed either by double-clicking them or using StuffIt Expander (www.stuffit.com). Most of the Mac versions may be dragged directly into your After Effects>Plug-ins folder. On the Windows platform, if a plug-in ends in .aex, you may drag it directly into After Effects> Plug-ins; if it ends in .exe, it is either an installer or self-extracting archive. Copy the .exe file to your hard drive and double-click it to run it. If it is a selfextracting archive, drag the resulting .aex file into your Plug-ins folder. A Read Me summary of all these with a guide to their installation is included in the Free Plug-ins folder on the DVD as a PDF. Contact the individual vendors directly for any tech support issues. If there is a problem with your DVD, contact [email protected] (with a clear subject line) for a replacement. xi // How To Use This Book System Requirements Our system requirements are similar to those Adobe recommends for After Effects. Most of the examples in this book and corresponding content on the DVD are based on 320×240 pixel images, so they take up less memory and screen real estate. The exceptions are Chapters 27 and 28, which contain large high definition video and film content which will require more RAM. In general, we recommend at least 512 Meg for After Effects; installing a gigabyte or more in your computer is considered normal in the production world. We also recommend an extended keyboard, as many shortcuts take advantage of the function keys and numeric keypad. You don’t need a multibutton mouse to use After Effects, but as many keyboard shortcuts use context-clicking, the modifier keys, and even the scroll wheel, it’s not a bad idea. If you are a Mac user, Exposé takes over some of the function keys; open it in System Preferences and reassign any shortcuts that use them. For Instructors If you are an instructor, we hope that you will adapt this book to your specific needs and find it useful in teaching After Effects. Much of this series is modeled on the advanced After Effects classes Trish teaches, as well as sessions we’ve both delivered at numerous conferences and trade shows. Recognizing the budgets and time constraints of most instructional situations, we’ve built 95% of the example projects using 320×240 comps and similar low-resolution sources. This requires less memory all around and results in faster demonstrations and previewing. However, the concepts are certainly from the real world, and should adapt directly to full-frame video projects. For copyright reasons, each student must own their own copy of this book. This also allows them to review the material covered after class – without wasting valuable class time writing reams of notes. Students can open the Chapter Example project from the DVD, make changes to it as they practice, and save the edited project to their own folders on a hard disk or removable media. At the next class, if they mount the DVD before opening their modified projects, the sources should relink properly. If your school has the available disk space, students may copy contents from the DVD to xii their computers, or you may place the files on a server, but again only as long as each student owns their own copy of this book. Provided each student owns the book, you are free to modify the tutorials and adapt them to your specific teaching situation without infringing copyright. As an instructor, you no doubt appreciate how much time and effort it takes to prepare examples and class materials that both teach and inspire. If a school, company, or instructor distributes copies of the sources, plug-ins, projects, or PDFs to any person who has not purchased the book, that constitutes copyright infringement. Also, reproducing pages of this book, or any material included on the DVD (including derivative works), is also a copyright no-no. Thank you for protecting our copyrights, and those of the many vendors and studios who contributed sources – your cooperation enables us to write new books and obtain great source materials for your students to learn with. Qualified teaching professionals can acquire evaluation copies of this book as well as our companion volume, After Effects in Production, by submitting the request form provided on the CMP Books web site (www.cmpbooks.com) – look under Order Info>Classroom Resources. How To Use This Book // DVD ROADMAP The enclosed DVD contains many useful resources for you to explore while you’re reading this book. We suggest you copy its entire contents to your drive for reference and faster access. Here’s what is in each folder:  Bonus Chapters Extended information on scanning, Expressions, Vector Paint, Keying, and the text Preferences. Also includes the story of how After Effects was created and has evolved over the years: CoSA Lives.  Bonus Tutorials Contains six bonus tutorials in PDF form that explore a variety of techniques, including using paint and expressions. All come with an After Effects project plus QuickTime movie of the final result; some contain additional source material.  Chapter Example Projects Virtually every chapter has a corresponding example project. This way, you can practice concepts as they come up in each chapter. These projects all point to the shared Sources folder on this DVD; some contain folders of additional content.  Credits and Info Information about the numerous stock footage houses and individual artists who contributed content for this book – we encourage you to contact them directly and see what they have to offer. Also contains the End User License Agreements that you agree to when you’re using their content provided on the DVD.  Free Footage & Plug-ins Digital Film Tools, Jens Enqvist, Fnord Software, and Walker Effects have contributed useful free plug-ins for you to add to your collection. Install them; they will be used throughout this book. You’ll find documentation and further information in their respective folders. Additionally, Artbeats and 12 Inch Design have donated 1.5 gigabytes of royalty-free fullsize NTSC and PAL stock footage for you to use!  Goodies A grab bag of additional content and information, including useful articles, white papers, and sample chapters, Animation Presets, Photoshop Styles, video and film safe area templates, plus information on other books, video, and music from Trish and Chris Meyer as well as CMP Books.  Sources Contains movies, music, mattes, objects, stills, and text elements used by the projects and tutorials in this book. Each file has a two-letter prefix that identifies its creator; a key is provided in the Credits and Info folder as well as on page 408. Make sure you read their respective End User License Agreements in the Credits and Info folder – many may also be used in your own commercial projects. DVD Technical Support Each third party is responsible for providing technical support for the products provided free on this DVD. If your DVD becomes damaged or won’t load, contact CMP Books ([email protected]) to arrange a replacement. 1 PART 1 CHAPTER 1 All About Alphas Understanding alpha channels is fundamental to understanding how After Effects works. A lpha channels are central to working in After Effects. Every layer and every composition either has or is given an alpha, and manipulating these alphas is how After Effects combines layers. Many features and techniques – such as masking, using track mattes, stencils, and keying – create alpha channels so you can blend images together in interesting ways. This chapter will explore how After Effects manages alpha channels internally, how to properly import sources with alpha, and the choices you have for rendering with an alpha channel. We’ll spend some time demystifying Straight and Premultiplied alpha, showing you how to identify and handle footage with premultiplied alpha so you can avoid ugly fringes and halos around the edges of objects. We’ll also cover a more unusual alpha channel type, Luminescent Premultiply. Some of the features and techniques that manipulate alpha channels (such as masking) have entire chapters devoted to them elsewhere in this series, so in these cases we’ll refer you to the relevant chapters in the Connect box at the end of this chapter. Alphas 101 Example Project Explore the 01-Example Project.aep file as you read this chapter; references to [Ex.##] refer to specific compositions within the project file. Be sure to install the free plug-ins from the Free Plug-ins folder on the DVD. (This project uses the Walker Effects Premultiply plug-in.) 2 An image’s alpha channel is a fourth channel of information that decides the transparency of every pixel built by the normal RGB color channels. In an 8-bit per channel (bpc) file, it has 8-bit resolution for 256 possible shades of gray, which when combined with the 24-bit RGB color channels results in a 32-bit image. (16 bpc provides a far wider range of values; for the sake of simplicity, we’ll stick with describing 8 bpc images in this chapter – all of the principles remain the same.) You can think of the alpha channel as a grayscale image that acts as a stencil mask for the corresponding color image: A value of 0 – black in the alpha – means the corresponding pixel is totally transparent; 255 – white in the alpha – means totally opaque. Values between these numbers mean the corresponding pixels are partially transparent. Open the project file 01-Example Project.aep from the Chapter Example Projects>01-Alpha Channels folder on the DVD, and open comp [Ex.01-Alpha 101]. The goldfish object is the only layer. Click on the Red, Green, Blue, and Alpha (white) channel icons along the bottom of the Comp window. Notice that the Alpha channel is white where the All About Alphas // 1 fish should be opaque, and black where background pixels should drop out. This allows for the fish to be composited against any color or other image (without this alpha, the fish would exist on a white background, as it appears in Photoshop). Background Color and Alpha It is important to distinguish between the comp’s Background Color, which shows through whenever a comp’s alpha channel is transparent, and filling a comp with a colored solid, which also fills the alpha As viewed in Photoshop, the combination of RGB channels channel. To see this in action, turn off any Comp creates the color for each pixel, window channel icons, and change the background while the corresponding alpha color of the comp (Composition>Background Color) channel determines the pixel’s from black to blue so that the fish appears against a opacity. Fish object from Getty colored background. If you click the Alpha icon Images/Design Essentials. again, nothing will have changed. The background color is a display color only and doesn’t affect the comp’s alpha channel. Now create a new solid (Layer>New>Solid). Click the Make Comp Size button, and color it anything but blue (we made ours black). When you click OK, the solid layer will be on top of the fish, so in the Timeline window, drag the solid below the fish layer. Now click on the Alpha icon again: The alpha channel is now fully white, as the solid exists in RGB colorspace, and its alpha is all opaque. With the Alpha icon still on, move the solid layer off-center in the comp, and you’ll see the shape of the fish appear along with the solid’s alpha. In other words, the alpha channel for the fish and the solid are merged together to create a single grayscale image that serves as the Comp’s alpha channel. You’ll see later how you can render a movie with this alpha channel embedded in it, or even render the Comp’s alpha To see a comp’s alpha channel in After channel as a separate movie. Effects, click on the white icon at the On a related note, when you nest one comp into another comp, the bottom of the Composition window. alpha channel of the nested comp is honored. Any background color in Comp 1 is ignored, and treated as transparency in Comp 2. If you need the background color to be visible, create a solid layer using that color. When the solid layer is moved, you can see that the alpha channel for the fish and the solid layer are combined. (The color of the comp’s background is irrelevant where the alpha channel is concerned, but a colored solid layer adds its alpha to the comp’s alpha.) 3 1 // All About Alphas Big picture time: If you’re trying to create an animation that will be rendered with an alpha channel for further compositing in a video editing suite, you need to be sure that there is something interesting in the comp’s alpha channel! If the alpha channel is fully white throughout the animation, there is nothing to be gained from rendering with an alpha – except a larger file. Shades of Gray In the case of our fish image, the shape of the fish in the alpha channel is solid white, making the fish fully opaque. In reality, the various fins of the fish would be semitransparent. If white in the alpha channel is opaque, and black is transparent, it stands to reason that shades of gray will be more or less transparent. The original fish was fully opaque (left). By painting some gray into the alpha channel (center), the fins become semitransparent when they’re composited against a background (right). Water courtesy Artbeats/Water Textures. Open comp [Ex.02], where a modified version of the same fish image is composited over a water movie. Scrub the timeline and notice that the highlights from the water in the background play through the fish’s fins. Double-click layer 2 to open the Layer window (this is the original source to the layer, and the Layer window also has RGB+Alpha channel icons). Click on the Alpha icon; the fins were modified in Photoshop by adding some gray paint to the white areas in the alpha channel, rendering the fins partially transparent in After Effects. (To compare this against the original image, turn off layer 2 and turn on layer 1 instead, and see how the water doesn’t show through the fins in the original fish image. We think you’ll agree that the composite is more believable when the layers appear to interact.) Select Window>Close All when you’re done, to reduce clutter. Life on the Edge Without infinite resolution, a diagonal edge to an alpha channel mask resembles a staircase (left). This is aliasing. Mixing in intermediate gray values to form an edge, based on a percentage of how much of a pixel a theoretically perfect line would intersect (right), smoothes the edge. This is known as antialiasing and is another reason grayscale values in alpha channels are important. 4 Having gray values in the alpha channel serves another important purpose: to help smooth out diagonal edges. Video and multimedia do not have enough resolution to render edges at an angle without visible staircasing being the result, as the edge tries to decide which pixel to land on. This goes for alpha channel edges as well as any color information in a frame. This is called aliasing. Short of resorting to near-infinite resolution, these edges can be made to appear smoother by antialiasing them. In the case of alpha channels, this means mixing in intermediate shades of gray. Virtually all good alpha channels for objects that do not cover the entire frame have antialiased edges. All About Alphas // 1 After Effects and Alphas After Effects uses alpha channels to composite layers together. In fact, if footage doesn’t have an alpha channel, After Effects will assign it one, as it needs to know how opaque to make each pixel. In the Project window, select the movie DV_Pulse.mov from the Sources>Movies folder. Along the top of the Project window, it will report that the movie is Millions of Colors (which means it is 24-bit, with no alpha channel). Option+doubleclick on Mac (Alt+double-click on Windows) the movie to open it in the After Effects Footage window. Click the Alpha icon and you’ll see that the alpha channel is a simple white rectangle; it was assigned by After Effects so that it would know how to composite the movie in a composition. (Why use white and not black? Think about it…) Close the Footage window when you’re done. So every piece of footage that is added to a comp exists as an RGB+Alpha layer, even if the source didn’t start out with an alpha. Once it’s placed in a comp, there are many ways to modify this alpha channel further. Explore the following example compositions: This movie on disk has no alpha channel embedded in it. The After Effects Footage window shows the alpha channel as fully white, so it will be fully opaque when it’s added to a comp. [Ex.03a-Opacity]: Okay, so this is an easy one… Select layer 1; if its Opacity parameter isn’t visible in the Timeline window, press T to reveal it. Scrub the Opacity value and watch the layer get more or less transparent. Now turn on the Alpha icon and scrub Opacity again. When you change Opacity, you’re changing the brightness of the layer’s alpha, not the values of the RGB channels. [Ex.03b-Alpha Mix]: In this example, we have a solid that is 100% blue, sitting on top of another solid that is 100% red. The Opacity for both solids is currently 50%. Click on the Alpha icon and notice that where they overlap, the alpha channel is brighter. Make sure the Info palette is visible – if not, press Command+2 (Control+2) to open it. The Info palette defaults to displaying values in RGB 8 bpc (0–255); change this to Percent (0–100) by clicking once on the palette or by selecting it from its Options menu. Now run your cursor around the solids in the Comp window while you’re looking at the Info palette. The alpha channel for each solid is 50%, which makes sense. But where the two solids overlap reads Alpha 75%, not 100% as you might expect. Alpha channel values don’t add – they multiply (so 50% × 50% = 25% transparent, which is 75% opaque). The only way to have 100% opacity is for one layer to be 100% opaque (or to have so many overlapping semitransparent layers that no one will notice the tiny amount of transparency remaining). Return the Info palette to Auto Color Display when done. The Info palette has been set to display values in Percent (0–100). Here, two squares, both at 50% Opacity, report an alpha value of 75% in the area where they overlap. [Ex.03c-Masking]: In this comp, an oval mask is applied to a movie, making the pixels outside the mask edge transparent. When you apply a mask, 5 1 // All About Alphas Masks create transparency on a layer by rendering pixels outside the mask shape with an alpha channel value of 0 (black). Image courtesy Digital Vision/Pulse. The water movie plays inside the fish’s alpha channel by using it as an Alpha Matte. the original RGB image is not changed, only the layer’s alpha channel. (To see the layer and its alpha before the mask is applied, double-click the movie to open it in the Layer window and set the View popup to None.) In Best Quality (the default), the edge of the mask is smoothly antialiased. In Draft Quality, the edge is stairstepped. Click on the Alpha swatch icon to view the alpha channel, then toggle the Quality switch between Best and Draft to compare results. Zoom in if you need to get a closer look. Mask Feather should be twirled down in the Timeline window (if not, select layer 1 and press F). Scrub the Feather amount to around 80; this adds a large falloff to the edge of the mask. The appearance of this feathered edge renders differently depending on whether the layer is in Best or Draft Quality (toggle the Quality switch again if you’re curious). To see how the feathered edge composites on top of another layer, turn off the Alpha icon and add a background movie from the Project window’s Sources>Movies folder, such as AB_DigitalMoods.mov. Scrub the feather amount for the masked layer – the more transparent the feathered edge, the more of the background layer shows through. [Ex.03d-Track Matte]: In this example, the alpha channel of the fish image is “borrowed” by the water texture movie so that the water shows only where the fish’s alpha channel is opaque. Click the Alpha icon to see the Comp’s alpha channel. Change the Track Matte popup for layer 2 to Alpha Inverted – the fish shape cuts out a hole in the movie layer instead. [Ex.03e-Keying]: There are various effects available to key footage, but in all cases the idea is to make a certain color transparent. This could be black or white in the case of a Luma Key, or blue or green when you’re using keying effects like Keylight, Linear Key or the Color Difference Key (see Chapter 10). For instance, in this comp, the Luma Key creates an alpha channel for the AB_FloralTwist movie in layer 1 – it does this by making black transparent. Turn off layer 2, and click the Alpha icon to see The Luma Key effect layer 1’s new alpha. Select layer 1 creates transparency for and press F3 to open the Effect dark areas in this movie. Controls window and check out Footage courtesy Artbeats/Floral Twist. the settings. 6 All About Alphas // 1 [Ex.03f-Unmultiply]: Free on this book’s DVD is a handy plug-in from Walker Effects called Premultiply. When its Mode popup is set to Unmultiply Black, it will drop out a black background. However, it will also take dark values throughout the layer and make them semitransparent, so results are different from a Luma Key. Open [Ex.03f] and compare the alpha channel created (and how it composites against the background layer) with the alpha channel created with the Luma Key effect in [Ex.03e]. The Premultiply effect from Walker Effects (free on the DVD) can render black values in a layer as transparent. [Ex.03g-Blending Modes]: There is yet another method for dropping out black backgrounds when compositing, and that is to use a blending mode for the top layer. Modes such as Add, Screen, Linear Dodge, and Color Dodge are lightening modes that work by adding pixel values from the top layer to the layers below. Black has a value of 0,0,0 RGB, so it is essentially ignored when using these modes. However, blending modes do not create transparency! Turn off layer 2 in this comp and check out layer 1’s alpha channel – it’s completely white, or fully opaque. To summarize, the Luma Key effect is better at creating an alpha for hard-edged solid objects, but it tends to leave black edges that are difficult to clean up correctly. The Walker Effects Premultiply effect is more suited to creating an alpha channel from a black background for footage such as fire and explosions, or when you need to create an alpha channel for a lens flare effect that will be composited in another application. Blending modes are great for compositing inside After Effects, but they don’t create alpha channels – with one exception: [Ex.03h-Stencils]: Stencils and Silhouettes are listed under Modes, but they are capable of creating transparency. In this example, the fish’s alpha channel acts as a stencil for all layers below. Also, the Comp is set to display transparency as a checkerboard pattern (see sidebar, Checkmate). [Ex.03i-Preserve Transparency]: The “T” switch in the Modes panel forces the layer to which it’s applied to render only inside the Comp’s alpha channel (because After Effects renders from the bottom up, this means the sum of the alpha channels from all layers below – layers above the “T” switch are not included). Blending modes offer different formulas for combining images together based on their RGB values – they do not affect the transparency of the alpha channel. Background courtesy Artbeats/Digital Moods. In [Ex.03h], the alpha channel of the fish image is used as a stencil to cut out all layers below. Select Window>Close All before moving on. In [Ex.03i], the movie layer has its Preserve Transparency switch set, so it appears only inside the comp’s alpha channel. Footage courtesy Artbeats/Digital Microcosm. 7