Digital Compositing for Film and Video Production Workflows and Techniques

Written by senior compositor, technical director and master trainer Steve Wright, this book condenses years of production experience into an easy-to-read and highly-informative guide suitable for both working and aspiring visual effects artists. This expanded and updated edition of Digital Compositing for Film and Video addresses the problems and difficult choices that professional compositors face on a daily basis with an elegant blend of theory, practical production techniques and workflows. It is written to be software-agnostic, so it is applicable to any brand of software. This edition features many step-by-step workflows, powerful new keying techniques and updates on the latest tech in the visual effects industry. Workflow examples for: Grain Management Lens Distortion Management Merging CGI Render Passes Blending Multiple Keys Photorealistic Color Correction Rotoscoping Production Techniques for: Keying Difficult Greenscreens Replicating Optical Lens Effects Advanced Spill Suppression Fixing Discoloured Edges Adding Interactive Lighting Managing Motion Blur With brand new information on: Working in linear ACES Color Management Light Field Cinematography Planar Tracking Creating Color Difference Keys Premultiply vs. Unpremultiply Deep Compositing VR Stitching 3D Compositing from 2D Images How Color Correction ops Effect Images Color Spaces Retiming Clips Working with Digital Cinema Images OpenColorIO A companion website offers images from the examples discussed in the book allowing readers to experiment with the material first-hand.

About the Author Acknowledgements Preface Chapter 1 - Getting Started 1.1 How this Book is Organized 1.2 Web Content 1.3 What’s New in the 4th Edition 1.4 Gold Mines 1.5 Tool Conventions 1.5.1 The Slice Tool 1.5.2 Flowgraphs 1.5.3 Color Lookup Tables (LUTs) 1.5.4 Nuke 1.6 Data Conventions 1.6.1 Floating Point Data 1.6.1.1 Banding 1.6.1.2 Clipping 1.6.2 Linear Light Space 1.6.3 HDR Images 1.6.4 Stops Chapter 2 - Pulling Keys 2.1 Lumakeys 2.1.1 How Lumakeys Work 2.1.2 Making Your Own Luminance Image 2.1.2.1 Variations on the Luminance Equations 2.1.2.2 Non-luminance Monochrome Images 2.1.3 Making Your Own Lumakeyer 2.2 Chromakeys 2.2.1 How Chromakeys Work 2.2.2 Making Your Own Chromakeyer 2.2.3 Making a 3D Chromakeyer 2.3 Difference Mattes 2.3.1 How Difference Mattes Work 2.3.2 Making Your Own Difference Matte 2.3.2.1 Making the Difference Image 2.3.2.2 Making the Difference Matte 2.4 Bump Mattes 2.5 Color Difference Keys 2.6 The Blur and Grow Technique 2.7 Rotoscoping 2.7.1 Control Point Coherency 2.7.2 Shape Breakdown 2.7.2.1 Hierarchical Articulation 2.7.2.2 Organization 2.7.3 Bezier or B-spline? 2.7.4 Keyframe Strategies 2.7.4.1 On 2’s 2.7.4.2 Binary Multiples 2.7.4.3 Bifurcation 2.7.4.4 Motion Extremes 2.7.5 Motion Blur 2.7.5.1 Spline Placement 2.7.5.2 Edge Decontamination 2.7.6 Inspection Chapter 3 - Working with Keyers 3.1 Keyers 3.2 How Keyers Work 3.2.1 Calculating the Color Difference Matte 3.2.1.1 The Theory 3.2.1.2 Pulling the Raw Matte 3.2.1.3 A Simplified Example 3.2.1.4 A Slightly More Realistic Case 3.2.1.5 And Now, The Real World 3.2.1.6 Matte Edge Penetration 3.2.2 Scaling the Raw Matte 3.3 The After Effects Keyer 3.3.1 Step-by-Step Procedure 3.3.2 Flowgraph of the After Effects Keyer 3.4 Typical Greenscreen Problems 3.4.1 Over Exposed 3.4.2 Under Exposed 3.4.3 Impure Greenscreens 3.4.4 Uneven Lighting 3.5 Preprocessing the Greenscreen 3.5.1 Denoise and Degrain 3.5.2 Screen Leveling 3.5.3 Local Suppression 3.5.4 Channel Clamping 3.5.5 Channel Shifting 3.5.6 Screen Correction 3.5.6.1 Step-by-Step Procedure 3.5.6.2 Pictographic Flow Chart 3.5.6.3 Flowgraph of the Screen Correction Procedure 3.5.6.4 How to Create a Clean Greenscreen Chapter 4 - Refining Mattes 4.1 Gamma Slamming 4.2 Garbage Mattes 4.2.1 Pre-matting 4.2.2 Post-matting 4.3 Filtering the Matte 4.3.1 Noise Suppression with a Median Filter 4.3.2 Softer Edges 4.3.3 Controlling the Blur Operation 4.3.3.1 The Blur Radius 4.3.3.2 The Blur Percentage 4.3.3.3 Masking the Blur 4.4 Adjusting the Matte Size 4.4.1 Eroding a Matte with Blur and Scale 4.4.2 Dilating a Matte with Blur and Scale 4.4.3 Blurring Out 4.4.4 Sculpting Edges 4.5 Edge Masks Chapter 5 - Spill Suppression 5.1 Sources of Spill 5.2 The Despill Operation 5.3 Despill Algorithms 5.3.1 Green Limited by Red 5.3.1.1 Implementing the Algorithm 5.3.1.2 The Spillmap 5.3.2 Green Limited by the Average of Red and Blue 5.3.3 An Adjustable Despill 5.3.4 What About Blue Spill? 5.3.5 Refining the Despill 5.3.5.1 Channel shifting 5.3.5.2 Spillmap Scaling 5.3.5.3 Mixing Despills 5.3.5.4 Matting Despills Together 5.4 The Unspill Operation 5.4.1 How to Set It Up 5.4.2 Grading to the Backing Color 5.5 Despill Artifacts 5.5.1 Finding the Artifacts 5.5.2 Hue Shifts 5.5.3 Dark Edges 5.5.4 Fixing Despill Artifacts 5.6 Edge Grading 5.7 Edge Extension Chapter 6 - the Composite 6.1 Premultiply vs. Unpremultiply 6.1.1 Premultiply 6.1.2 Unpremultiply 6.1.3 The Double Premultiply 6.2 The Composite 6.2.1 The Over Composite 6.2.2 The KeyMix Composite 6.2.3 The AddMix Composite 6.2.3.1 How it Works 6.2.3.2 How to Build It 6.2.3.3 How to Use It 6.2.4 The Processed Foreground Method 6.2.4.1 The Workflow 6.2.4.2 What to Watch Out For 6.3 Compositing With a Keyer 6.3.1 Soft Comp/Hard Comp 6.3.2 "Cut and Paste" Keyer Compositing 6.4 Compositing Outside the Keyer 6.4.1 The Single Key 6.4.2 The Uberkey 6.4.3 Soft Key/Hard Key 6.4.4 The Additive Keyer 6.5 Stereo Compositing 6.5.1 Anaglyph 6.5.2 Stereopsis 6.5.3 Stereoscopy 6.5.4 The Stereo Conversion Process 6.5.5 Depth Grading 6.5.5.1 Scene Transition 6.5.5.2 The Dashboard Effect 6.5.5.3 Window Violation 6.5.5.4 Miniaturization 6.5.5.5 Divergence 6.5.6 Stereo Compositing 6.5.6.1 Dual View Display 6.5.6.2 Split and Join Views 6.5.6.3 Disparity Maps Chapter 7 - Compositing CGI 7.1 Multi-Pass CGI Compositing 7.1.1 Process Verification for Your Renderer 7.1.2 Render Passes 7.1.3 Lighting Passes 7.1.3.1 Render Passes Workflow 7.1.3.2 Beauty Pass Workflow 7.1.4 AOVs 7.1.5 ID Passes 7.1.6 Normals Relighting 7.2 EXR File Format 7.2.1 Film Scans 7.2.2 Linear Lightspace 7.2.3 Arbitrary Image Channels 7.3 HDR Images 7.4 Deep Compositing 7.4.1 Deep Images 7.4.2 The Layering Complexity Problem 7.4.3 The Depth Compositing Edge Problem 7.4.4 The Re-rendering Problem 7.4.5 Deep Compositing with Live Action Chapter 8 - 3D Compositing 8.1 A Short Course in 3D 8.1.1 the 3D Coordinate System 8.1.2 Vertices 8.1.3 Meshes 8.1.4 Surface Normals 8.1.5 UV Coordinates 8.1.6 Map Projection 8.1.7 UV Projection 8.1.8 3D Geometry 8.1.9 Geometric Transformations 8.1.10 Geometric Deformations 8.1.10.1 Image Displacement 8.1.10.2 Noise Displacement 8.1.10.3 Deformation Lattice 8.1.11 Point Clouds 8.1.12 Lights 8.1.13 Shaders 8.1.14 Reflection Mapping 8.1.15 Ray Tracing 8.1.16 Image Based Lighting 8.1.17 Cameras 8.2 3D Compositing 8.2.1 3D compositing from 2D images 8.2.2 Pan and Tile 8.2.3 Camera Projection 8.2.4 Multiplane Shots 8.2.5 Set Extension 8.2.6 3D Backgrounds 8.3 Alembic Geometry 8.3.1 The Simple Case 8.3.2 Scenegraphs 8.3.3 Advantages Over FBX 8.4 Camera Tracking 8.4.1 Step 1 - Feature Tracking 8.4.2 Step 2 - The Solve 8.4.3 Step 3 – Build the Scene 8.4.4 Placing the Geometry 8.4.5 A Large Outdoor Scene Chapter 9 - Color Correction 9.1 The Behavior of Light 9.1.1 The Inverse Square Law 9.1.2 Diffuse Reflections 9.1.3 Specular Reflections 9.1.4 Bounce Light 9.1.5 Scattering 9.2 Gamma 9.2.1 The Math 9.2.2 Why Do We Need Gamma? 9.3 The Affect of Color Operations 9.3.1 Lift 9.3.2 Gamma 9.3.3 Gain 9.3.4 Offset 9.3.5 Saturation 9.3.6 Color Grading vs. Color Correcting 9.3.7 Increasing Contrast with the "S" Curve 9.3.8 Histograms 9.3.9 Channel Swapping 9.3.10 Premultiply vs. Unpremultiply - again 9.4 Matching the Light Space 9.4.1 Brightness and Contrast 9.4.1.1 Matching the Black and White Points 9.4.1.2 Matching the Midtones 9.4.1.3 Gamma Slamming 9.4.2 Matching Color 9.4.2.1 Grayscale Balancing 9.4.2.2 Flesh Tones 9.4.2.3 The "Constant Green" Method of Color Correction 9.4.2.4 Daylight 9.4.2.5 Specular Highlights 9.4.3 Lighting Direction 9.4.4 Quality of Light Sources 9.4.4.1 Creating Softer Lighting 9.4.4.2 Creating Harsher Lighting 9.4.5 Non-linear Gradients for Color Correction 9.4.6 The DI Process 9.4.7 A Checklist Chapter 10 - Sweetening the Comp 10.1 Layer Integration 10.2 Interactive Lighting 10.3 Edge Blending 10.4 Light Wrap 10.5 Creating Shadows 10.5.1 Edge Characteristics 10.5.2 Density 10.5.3 Color 10.5.4 Faux Shadows 10.5.5 Shadow Warping 10.5.6 Contact Shadows 10.6 Atmospheric Haze 10.7 Adding a Glow 10.8 Grain Management 10.8.1 Grain Characteristics 10.8.2 Regraining Techniques 10.8.2.1 Regrain Tool 10.8.2.2 Lifted Grain 10.8.2.3 Grain Rescue 10.8.3 Grain Management Workflows 10.8.3.1 Live Over Live 10.8.3.2 Live Over CGI 10.8.3.3 CGI Over Live 10.8.3.4 CGI Over CGI 10.8.3.5 Still Photos 10.9 Managing Clipping Chapter 11 - Camera Effects 11.1 Lens Effects 11.1.1 Lens Distortion 11.1.2 Depth of Field 11.1.3 Vignetting 11.1.4 Lens Defects 11.1.4.1 Spherical Aberration 11.1.4.2 Astigmatism 11.1.4.3 Chromatic Aberration 11.1.5 Glows and Flares 11.1.5.1 Lens Flare 11.1.5.2 Lens Filter Flare 11.1.5.3 Diffraction Glows 11.1.5.4 Veiling Glare 11.1.6 Grain 11.2 Lens Distortion Workflows 11.2.1 CGI Over Live Action 11.2.2 Live Action Over CGI 11.2.3 CGI Over CGI 11.2.4 Live Action Over Live Action 11.3 Matching the Focus 11.3.1 Using a Blur for Defocus 11.3.2 How to Simulate a Defocus 11.3.3 Sharpening 11.3.3.1 Sharpening Op

Steve Wright is a visual effects pioneer and a 20-year veteran of visual effects compositing on over 70 feature films and many broadcast television commercials. With extensive production experience and a knack for the math and science of visual effects he is a world-recognized expert on visual effects compositing. Since 2005 he has been a master trainer in compositing visual effects, providing staff training to over 25 visual effects studios around the world including Pixar Animation Studios, Disney Feature Animation, Troublemaker Studios, New Deal Studios, and Reliance MediaWorks, along with many others. He has also trained over 1,000 artists in compositing. Visit Steve’s training website at www.fxecademy.com