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Digital Compositing for Film and Video, 4th Edition

Name: Digital Compositing for Film and Video, 4th Edition
Author: Steve Wright
ISBN: 9781315283999

by Steve Wright

November 2017

Intermediate to advanced

576 pages

18h 18m

English

Routledge

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Cover
Title
Copyright
Table of Contents
About the Author
Acknowledgements
Preface
Chapter 1 – Getting Started
1.1 How this Book is Organized1.2 Web Content1.3 What’s New in the 4th Edition1.4 Gold Mines1.5 Tool Conventions1.5.1 The Slice Tool1.5.2 Flowgraphs1.5.3 Color Lookup Tables (LUTs)1.5.4 Nuke1.6 Data Conventions1.6.1 Floating Point Data1.6.1.1 Banding1.6.1.2 Clipping1.6.2 Linear Light Space1.6.3 HDR Images1.6.4 Stops
PART I MAKING A GREAT COMPOSITE
Chapter 2 – Pulling Keys
2.1 Luma Keys2.1.1 How Luma Keys Work2.1.2 Making Your Own Luminance Image2.1.2.1 Variations on the Luminance Equations2.1.2.2 Non-luminance Monochrome Images2.1.3 Making Your Own Luma Keyer2.2 Chroma Keys2.2.1 How Chroma Keys Work2.2.2 Making Your Own Chroma Keyer2.2.3 Making a 3D Chroma Keyer2.3 Difference Mattes2.3.1 How Difference Mattes Work2.3.2 Making Your Own Difference Matte2.3.2.1 Making the Difference Image2.3.2.2 Making the Difference Matte2.4 Bump Mattes2.5 Color Difference Keys2.6 The “Blur and Grow” Technique2.7 Rotoscoping2.7.1 Control Point Coherency2.7.2 Shape Breakdown2.7.2.1 Hierarchical Articulation2.7.2.2 Organization2.7.3 Bezier or B-spline?2.7.4 Keyframe Strategies2.7.4.1 On 2s2.7.4.2 Binary Multiples2.7.4.3 Bifurcation2.7.4.4 Motion Extremes2.7.5 Motion Blur2.7.5.1 Spline Placement2.7.5.2 Edge Decontamination2.7.6 Inspection

Chapter 3 – Working with Keyers
3.1 Keyers3.2 How Keyers Work3.2.1 Calculating the Color Difference Matte3.2.1.1 The Theory3.2.1.2 Pulling the Raw Matte3.2.1.3 A Simplified Example3.2.1.4 A Slightly More Realistic Case3.2.1.5 And Now, the Real World3.2.1.6 Matte Edge Penetration3.2.2 Scaling the Raw Matte3.3 The After Effects Keyer3.3.1 Step-by-step Procedure3.3.2 Flowgraph of the After Effects Keyer3.4 Typical Greenscreen Problems3.4.1 Overexposed3.4.2 Underexposed3.4.3 Impure Greenscreens3.4.4 Uneven Lighting3.5 Preprocessing the Greenscreen3.5.1 Denoise and Degrain3.5.2 Screen Leveling3.5.3 Local Suppression3.5.4 Channel Clamping3.5.5 Channel Shifting3.5.6 Screen Correction3.5.6.1 Step-by-step Procedure3.5.6.2 Pictographic Flow Chart3.5.6.3 Flowgraph of the Screen Correction Procedure3.5.6.4 How to Create a Clean Greenscreen
Chapter 4 – Refining Mattes
4.1 Gamma Slamming4.2 Garbage Mattes4.2.1 Pre-matting4.2.2 Post-matting4.3 Filtering the Matte4.3.1 Noise Suppression with a Median Filter4.3.2 Softer Edges4.3.3 Controlling the Blur Operation4.3.3.1 The Blur Radius4.3.3.2 The Blur Percentage4.3.3.3 Masking the Blur4.4 Adjusting the Matte Size4.4.1 Eroding a Matte with Blur and Scale4.4.2 Dilating a Matte with Blur and Scale4.4.3 Blurring Out4.4.4 Sculpting Edges4.5 Edge Masks
Chapter 5 – Spill Suppression
5.1 Sources of Spill5.2 The Despill Operation5.3 Despill Algorithms5.3.1 Green Limited by Red5.3.1.1 Implementing the Algorithm5.3.1.2 The Spillmap5.3.2 Green Limited by the Average of Red and Blue5.3.3 An Adjustable Despill5.3.4 What About Blue Spill?5.3.5 Refining the Despill5.3.5.1 Channel Shifting5.3.5.2 Spillmap Scaling5.3.5.3 Mixing Despills5.3.5.4 Matting Despills Together5.4 The Unspill Operation5.4.1 How to Set It Up5.4.2 Grading to the Backing Color5.5 Despill Artifacts5.5.1 Finding the Artifacts5.5.2 Hue Shifts5.5.3 Dark Edges5.5.4 Fixing Despill Artifacts5.6 Edge Grading5.7 Edge Extension
Chapter 6 – The Composite
6.1 Premultiply vs. Unpremultiply6.1.1 Premultiply6.1.2 Unpremultiply6.1.3 The Double Premultiply6.2 The Composite6.2.1 The Over Composite6.2.2 The KeyMix Composite6.2.3 The AddMix Composite6.2.3.1 How It Works6.2.3.2 How to Build It6.2.3.3 How to Use It6.2.4 The Processed Foreground Method6.2.4.1 The Workflow6.2.4.2 What to Watch Out For6.3 Compositing With a Keyer6.3.1 Soft Comp/Hard Comp6.3.2 “Cut and Paste” Keyer Compositing6.4 Compositing Outside the Keyer6.4.1 The Single Key6.4.2 The Uberkey6.4.3 Soft Key/Hard Key6.4.4 The Additive Keyer6.5 Stereo Compositing6.5.1 Anaglyph6.5.2 Stereopsis6.5.3 Stereoscopy6.5.4 The Stereo Conversion Process6.5.5 Depth Grading6.5.5.1 Scene Transition6.5.5.2 The Dashboard Effect6.5.5.3 Window Violation6.5.5.4 Miniaturization6.5.5.5 Divergence6.5.6 Stereo Compositing6.5.6.1 Dual View Display6.5.6.2 Split and Join Views6.5.6.3 Disparity Maps
Chapter 7 – Compositing CGI
7.1 Multi-pass CGI Compositing7.1.1 Process Verification for Your Renderer7.1.2 Render Passes7.1.3 Lighting Passes7.1.3.1 Render Passes Workflow7.1.3.2 Beauty Pass Workflow7.1.4 AOVs7.1.5 ID Passes7.1.6 Normals Relighting7.2 EXR File Format7.2.1 Film Scans7.2.2 Linear Lightspace7.2.3 Arbitrary Image Channels7.3 HDR Images7.4 Deep Compositing7.4.1 Deep Images7.4.2 The Layering Complexity Problem7.4.3 The Depth Compositing Edge Problem7.4.4 The Re-rendering Problem7.4.5 Deep Compositing with Live Action
Chapter 8 – 3D Compositing
8.1 A Short Course in 3D8.1.1 The 3D Coordinate System8.1.2 Vertices8.1.3 Meshes8.1.4 Surface Normals8.1.5 UV Coordinates8.1.6 Map Projection8.1.7 UV Projection8.1.8 3D Geometry8.1.9 Geometric Transformations8.1.10 Geometric Deformations8.1.10.1 Image Displacement8.1.10.2 Noise Displacement8.1.10.3 Deformation Lattice8.1.11 Point Clouds8.1.12 Lights8.1.13 Shaders8.1.14 Reflection Mapping8.1.15 Ray Tracing8.1.16 Image-based Lighting8.1.17 Cameras8.2 3D Compositing8.2.1 3D Compositing from 2D Images8.2.2 Pan and Tile8.2.3 Camera Projection8.2.4 Multiplane Shots8.2.5 Set Extension8.2.6 3D Backgrounds8.3 Alembic Geometry8.3.1 The Simple Case8.3.2 Scenegraphs8.3.3 Advantages Over FBX8.4 Camera Tracking8.4.1 Step 1 – Feature Tracking8.4.2 Step 2 – The Solve8.4.3 Step 3 – Build the Scene8.4.4 Placing the Geometry8.4.5 A Large Outdoor Scene
PART II THE QUEST FOR REALISM
Chapter 9 – Color Correction
9.1 The Behavior of Light9.1.1 The Inverse Square Law9.1.2 Diffuse Reflections9.1.3 Specular Reflections9.1.4 Bounce Light9.1.5 Scattering9.2 Gamma9.2.1 The Math9.2.2 Why Do We Need Gamma?9.3 The Affect of Color Operations9.3.1 Lift9.3.2 Gamma9.3.3 Gain9.3.4 Offset9.3.5 Saturation9.3.6 Color Grading vs. Color Correcting9.3.7 Increasing Contrast with the “S” Curve9.3.8 Histograms9.3.9 Channel Swapping9.3.10 Premultiply vs. Unpremultiply – Again9.4 Matching the Light Space9.4.1 Brightness and Contrast9.4.1.1 Matching the Black and White Points9.4.1.2 Matching the Midtones9.4.1.3 Gamma Slamming9.4.2 Matching Color9.4.2.1 Grayscale Balancing9.4.2.2 Flesh Tones9.4.2.3 The “Constant Green” Method of Color Correction9.4.2.4 Daylight9.4.2.5 Specular Highlights9.4.3 Lighting Direction9.4.4 Quality of Light Sources9.4.4.1 Creating Softer Lighting9.4.4.2 Creating Harsher Lighting9.4.5 Non-linear Gradients for Color Correction9.4.6 The DI Process9.4.7 A Checklist
Chapter 10 – Sweetening the Comp
10.1 Layer Integration10.2 Interactive Lighting10.3 Edge Blending10.4 Light Wrap10.5 Creating Shadows10.5.1 Edge Characteristics10.5.2 Density10.5.3 Color10.5.4 Faux Shadows10.5.5 Shadow Warping10.5.6 Contact Shadows10.6 Atmospheric Haze10.7 Adding a Glow10.8 Grain Management10.8.1 Grain Characteristics10.8.2 Regraining Techniques10.8.2.1 Regrain Tool10.8.2.2 Lifted Grain10.8.2.3 Grain Rescue10.8.3 Grain Management Workflows10.8.3.1 Live Over Live10.8.3.2 Live Over CGI10.8.3.3 CGI Over Live10.8.3.4 CGI Over CGI10.8.3.5 Still Photos10.9 Managing Clipping
Chapter 11 – Camera Effects
11.1 Lens Effects11.1.1 Lens Distortion11.1.2 Depth of Field11.1.3 Vignetting11.1.4 Lens Defects11.1.4.1 Spherical Aberration11.1.4.2 Astigmatism11.1.4.3 Chromatic Aberration11.1.5 Glows and Flares11.1.5.1 Lens Flare11.1.5.2 Lens Filter Flare11.1.5.3 Diffraction Glows11.1.5.4 Veiling Glare11.1.6 Grain11.2 Lens Distortion Workflows11.2.1 CGI Over Live Action11.2.2 Live Action Over CGI11.2.3 CGI Over CGI11.2.4 Live Action Over Live Action11.3 Matching the Focus11.3.1 Using a Blur for Defocus11.3.2 How to Simulate a Defocus11.3.3 Sharpening11.3.3.1 Sharpening Operations11.3.3.2 Unsharp Masks11.3.3.3 Making Your Own Unsharp Mask11.4 Rolling Shutter
PART III THINGS YOU SHOULD KNOW
Chapter 12 – Digital Color
12.1 Color Spaces12.1.1 Primary Chromaticities12.1.2 Units of Measure12.1.3 Transfer Function12.1.4 Gamut12.1.5 HSV and HSL12.1.6 Log and Linear12.2 Working in Linear12.2.1 What Exactly Is Linear?12.2.2 Color Operations12.2.3 Transformations and Filtering12.2.4 CGI12.3 Metadata12.4 OpenColorIO12.5 ACES Color Management12.5.1 The ACES Workflow12.5.2 The ACES Gamut12.5.3 What About Video Productions?
Chapter 13 – Image Blending
13.1 Image Blending in Linear Light Space13.1.1 Image-blending Operations13.1.2 Compositing Operations13.1.3 Matching the Look of sRGB in Linear13.1.3.1 All sRGB Color Space13.1.3.2 sRGB Within Linear13.2 Alpha Compositing Operations13.3 Image-blending Operations13.3.1 The Screen Operation13.3.1.1 Adjusting the Appearance13.3.2 The Weighted Screen Operation13.3.3 Multiply13.3.3.1 Adjusting the Appearance13.3.4 Maximum13.3.5 Minimum13.3.6 Absolute Difference13.4 Adobe Photoshop Blending Modes13.4.1 Simple Blending Modes13.4.2 Complex Blending Modes13.5 Slot Gags13.6 Retiming Clips13.6.1 Constant Speed Changes13.6.2 Variable Speed Changes13.6.3 Interpolation Methods13.6.3.1 Nearest Neighbor13.6.3.2 Frame Average13.6.3.3 Motion Estimation13.7 VR Stitching13.7.1 Workflow Overview13.7.2 Removing Lens Distortion13.7.3 Building a Matching Computer Rig13.7.4 Projecting Onto the Panosphere13.7.5 The Stitching Process13.7.6 Coping with Parallax13.7.7 Exposure Correction13.7.8 Visual Effects
Chapter 14 – Transforms and Tracking
14.1 Geometric Transforms14.1.1 2D Transforms14.1.1.1 Translation14.1.1.2 Rotation14.1.1.3 Resize vs. Scale14.1.1.4 Skew14.1.1.5 Corner Pinning14.1.2 Managing Motion Blur14.1.2.1 Transform Motion Blur14.1.2.2 Motion UV Motion Blur14.1.2.3 Speed Changes14.1.3 3D Transforms14.1.4 Filtering14.1.4.1 The Effects of Filtering14.1.4.2 Twinkling Starfields14.1.4.3 Choosing a Filter14.1.5 Lining Up Images14.1.5.1 Offset Mask Lineup Display14.1.5.2 Edge-detection Lineup Display14.1.5.3 The Pivot Point Lineup Procedure14.2 Image Displacement14.3 Warps and Morphs14.3.1 Mesh Warps14.3.2 Spline Warps14.3.3 Morphs14.3.4 Tips, Tricks, and Techniques14.4 Point Tracking14.4.1 The Tracking Operation14.4.1.1 Selecting Good Tracking Targets14.4.1.2 Bad Tracking Targets14.4.1.3 Tracker Enable/Disable14.4.1.4 Offset Tracking14.4.1.5 Keep Shape and Follow Shape14.4.1.6 Pre-processing the Clip14.4.1.7 Coping with Grain14.4.1.8 Tracking Workflow14.4.1.9 Cleaning up Tracking Data14.4.1.10 The Stability Test14.4.1.11 Reasons for Failure14.4.2 Match Move14.4.2.1 2D Transforms14.4.2.2 Corner Pinning14.4.3 Stabilizing14.4.3.1 The Repo Problem14.4.3.2 Motion Smoothing14.4.3.3 Stabilizing For Rotoscoping14.5 Planar Tracking14.5.1 The Planar Grid14.5.2 Drift Correction14.5.3 Exporting Data14.5.4 Roto Assist
Chapter 15 – Digital Images
15.1 HD Video15.1.1 Frame Formats15.1.2 Anamorphic Video15.1.3 Scan Modes15.1.4 Working with Interlaced Video15.1.4.1 De-interlacing15.1.4.2 Scan Line Interpolation15.1.4.3 Field Averaging15.1.5 Color Subsampling15.1.6 Keying with 4:2:2 Video15.1.7 Frame Rates15.1.7.1 24, 25, 30, 60fps15.1.7.2 23.98, 29.97, 59.94fps15.1.8 Timecodes15.1.9 Video File Formats15.1.10 Telecine15.1.10.1 The 3:2 Pull-down15.1.10.2 The 3:2 Pull-up15.2 Digital Cinema Images15.2.1 Digital Camera Advantages15.2.2 The Bayer Array15.2.3 Sensor Crop15.2.4 HFR – High Frame Rate15.2.5 The DCI15.3 Film Scans15.3.1 Grain15.3.2 The “Safe-to” Window15.3.3 Apertures15.3.4 Aspect Ratios15.3.5 Film Formats15.3.5.1 Full Aperture15.3.5.2 Academy Aperture15.3.5.3 Super 35 Formats15.3.5.4 Cinemascope15.3.5.5 Working with Cscope15.3.5.6 “3-perf” Film15.3.5.7 VistaVision15.3.5.8 65mm/70mm15.3.5.9 IMAX15.4 Log Images15.4.1 What Are Log Images?15.4.2 Why We Need Log Images15.4.2.1 Human Vision15.4.2.2 Data Compression15.4.2.3 Working with Log Images15.5 Light Field Cinematography15.5.1 How It Works15.5.2 The Impact on Visual Effects15.5.2.1 Deep Images15.5.2.2 Arbitrary Depth of Field15.5.2.3 Depth Maps15.5.2.4 Stereo Through a Single Lens15.5.2.5 Volumetric Optical Flow15.5.2.6 Position Pass15.5.2.7 Point Clouds15.5.2.8 Mattes15.5.2.9 Normals and Normal Relighting15.5.2.10 Camera Tracking15.5.3 When, and How Much?
Glossary
Index

Content preview from Digital Compositing for Film and Video, 4th Edition

9Color Correction

WWW To download the web content for this chapter go to the website www.routledge.com/cw/wright, select this book then click on Chapter 9.

The objective of this chapter is to help you to make photo-realistic color corrections for your composites. You have pulled your best key, done a great spill suppression, and executed a fine composite, but if the color correction is not photorealistic you do not have a shot. Color correction is probably the most critical aspect of producing a photorealistic composite. It is also the thing that eludes most beginning visual effects artists.

Photorealistic color correction begins by understanding the behavior of light – how it falls off with distance, reacts to diffuse or specular surfaces, ...

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Digital Compositing for Film and Video, 4th Edition

by Steve Wright

9Color Correction

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