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About Channels

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9 Working with Image Channels Mattes and channels not only affect what is retained and discarded in the final composite- Front they allow sophisticated, precise, and artful effects through their changeability. Alpha About Channels When you start a new branch, color channels and an alpha channel are created automatically. Color channels show the amount of the corresponding color present in the clip using a grayscale image with a certain bit depth (for example, 8 bits). For more information, see "Bit Depth Basics" in Chapter 22, "Working with Bit Depth''. Each branch has three color channels, one each for red, green, and blue. The alpha channel uses another grayscale image (with the same bit depth) to determine which pixels are opaque and which are transparent for each frame. The alpha channel is represented by a grayscale image embedded in the file. The grayscale value determines the opacity: white pixels are opaque (100% opacity), black pixels are transparent (0% opacity), and gray pixels represent varying degrees of opacity. Alpha Channels You use alpha channels to determine how much of the front image shows over the back image(s). If you are looking through a keyhole inside a room, the door is the front, the keyhole is the alpha, and the room is the back. Combined together, these layers form a composite. The following illustration shows the function an alpha channel performs when compositing. Back Composite If you render the contents of the alpha channel, you get what is called a matte. A matte can be completely black and white (called a hi-con for high-contrast), or can contain many shades of gray. In video and film, mattes are rarely static, and are rarely pure black and white. Any areas of the front containing transparency (glass, smoke, curly blond hair) or motion blur appear in the matte as gray areas, allowing the transparent (or blurred) areas to partially show through. The process of generating a matte (from blue screen, for example) is also known as pulling a matte. Getting as close as possible to the perfect matte is perhaps the most important part of compositing. Because you are superimposing layers on layers with the aim of creating a reality, any imperfections in the 208

Section	Page
Table of Contents	5
Chapter 1: Introduction	17
About Combustion	18
What’s New	18
Key Features	19
Workflow	19
Interface	19
Compositing	19
Particles	19
Paint	20
Adobe® Flash® Animations	20
Selections	20
Editing	20
Capturing	20
Animation	21
Expressions	21
Keying	21
Color Correction	21
Tracker	21
Film Tools	21
Audio	21
Rendering	21
File Format Support	22
Using this Documentation	22
Notation Conventions	22
Combustion Documentation	22
Printed Documentation	23
Online Documentation	23
Accessing Online Documentation	23
Combustion Training	23
Autodesk Support	24
Chapter 2: Welcome to Combustion	25
About Combustion	26
Image Data Flows Downstream	27
Overview of the Interface	28
Customizing the Interface	29
Showing or Hiding Interface Elements	29
Resizing Screen Elements	30
Button Conventions	30
Reset Buttons	30
Fields	30
Using the Workspace Panel	31
Navigating in the Workspace Panel	32
Changing What Appears in the Workspace Panel	33
Expanding the Workspace Panel	33
Viewing the Footage Library	33
Using the Operator Controls	34
Using the Schematic View	34
Using the Operators Panel	34
Customizing the Favorites Category	35
Using the Favorites Palette	36
Using the Viewports	37
Displaying Operators in the Viewport	37
Changing the Viewport Layout	38
Zooming and Panning the Viewport	38
Changing View Modes	39
Showing Wireframe Icons	39
Changing Display Quality	40
Changing Composite Views	41
Displaying Lighting and Surface Effects	41
Changing Object Detail	42
Using the Toolbar	42
Using the Compare Tool	43
Using the Timeline	44
Using the Menu Commands	45
File Menu	45
Edit Menu	45
Operators Menu	46
Movie Menu	46
Window Menu	47
Help Menu	48
Using Context Menus	48
Workspace Panel and Timeline Menus	48
Viewport Menus	49
Miscellaneous Context Menus	50
Using the Filmstrip	50
Customizing the Filmstrip	51
Using the Playback Controls	51
Global Time versus Local Time	52
Setting the Play Mode	53
Using the Info Palette	53
Flush Cache	54
Using the File Browser	54
Changing the Browser View	55
Previewing Clips	55
Searching in the Browser	55
Customizing the Browser	56
Browsing a Wiretap Server	56
Using Grids, Guides, and Rulers	57
Snapping Objects to the Grid and Guides	58
Using Guides	58
Using Rulers	59
Using the Pick Color Dialog	60
Using the Color Palette	60
Using the Vectorscope	60
Customizing the Vectorscope Display	61
Setting Preferences	62
Setting General Preferences	62
Setting Monitor Preferences	64
Repositioning Interface Elements	64
Setting Mesh Preferences	65
Setting Capture Preferences	65
Setting Framebuffer Preferences	66
Setting Up a Broadcast Monitor	66
Setting Animation Preferences	66
Setting Caching Preferences	66
Setting Behavior Preferences	67
Setting Interface Color Preferences	67
Setting Grids and Guides Preferences	68
Setting Safe Zone Preferences	69
Setting Vectorscope Preferences	70
Setting Transparency Preferences	70
Setting Footage General Preferences	70
Setting Footage Library Preferences	71
Setting Footage Import Preferences	71
Setting Paint Preferences	71
Other Preferences	72
Chapter 3: Quick Tour	73
Getting Started	74
Capturing Video Footage and Audio	74
Managing Layers and Operators	75
Arranging Layers in the Stack	75
Toggling Layer Visibility	76
Compositing	76
Positioning, Scaling, Rotating, and Shearing	76
Keying and Masking	77
Keying Out a Color	77
Masking Layers	79
Nesting Layers and Composites	80
Creating Nested Layers	81
Applying Operators	81
Applying an Operator to a Layer	82
Editing a Clip	83
Editing in the Timeline	83
Keyframing	85
Animating with Motion Paths	86
Copying and Pasting Keyframes	87
Creating Expressions	87
Using the Paint Tools	87
Creating a Paint Object	88
Adding a Caption	89
Creating the Drop Shadow	90
Playing the Animation	90
Exporting to Flash	91
Working with Audio	91
Using Lights and Cameras	92
Adding Lights to a Composite	93
Viewing the Scene Through a Camera	93
Rendering the Finished Product	94
Rendering to RAM for Real-Time Playback	95
Chapter 4: Building Workspaces	97
File Formats	98
Supported File Formats	98
Adobe Illustrator	99
Adobe Photoshop	99
Cineon	99
RPF	99
Starting a Workspace	99
Planning Your Projects	100
Choosing Media Settings	101
Footage Basics	101
Time and Timecode	102
Duration and Timelines	102
Frame Rate	102
Cross-Platform Considerations	102
Getting Media onto the System	103
Creating Branches in the Workspace	103
Creating Composites	104
Creating Paint Branches	105
Creating Edit Operators	107
Opening Footage into a New Edit Operator	107
Creating an Edit Operator	108
Creating Other Branches	108
Keying and Color Correction Branches	109
Text and Particles Branches	109
Opening Footage and Creating Solid Footage	109
Choosing Format Options	111
Customizing Format Settings	112
Creating Multiple Branches	113
Opening a Workspace	113
Finding or Replacing Missing Footage	113
Importing a Workspace	114
Importing Footage	114
Importing an Image Sequence	115
Importing a Still Image	117
Importing Multilayer Files	117
Importing Adobe Illustrator Files	119
Importing Adobe Illustrator Files as Paint Operators	119
Rasterizing Adobe Illustrator Files on Import	120
Importing Adobe Illustrator Image Sequences	121
Adobe Illustrator Import Limitations	122
Replacing Footage	122
Importing Audio	122
Using Quick Capture	123
Capturing Video and Audio	124
About Composite Settings	125
Editing Composite Settings	125
Specifying Branch Settings	126
Changing Footage Source Settings	126
Changing Channel Settings	127
Setting Field Dominance	127
Changing the Frame Rate	128
Mixing Frame Rates in a Composite	128
Changing the Pixel Aspect Ratio	128
Removing 3:2 Pulldown	129
Specifying Source Layer	129
Changing Footage Output Settings	130
Setting Footage Display Quality	130
Setting Footage Resolution	131
Changing the End Behavior	131
Changing Footage Direction	132
Specifying Frame Holding Duration	132
Using Time Stretch and Frame Blending	132
Cropping Footage	133
Creating Proxy Footage	134
Clearing Proxy Footage	135
Changing Footage Start and End Points	136
Extending Solid Footage Duration	136
Saving a Workspace	137
Reverting to a Saved Workspace	137
Chapter 5: Compositing	139
About Compositing	140
Adding Layers to a Composite	141
Creating a Layer from Footage	141
Creating a Solid Layer	141
Creating a Paint, Text, Particles, or Edit Layer	142
Creating a Layer from an Operator	143
Instances in the Workspace Panel	143
Renaming Layers	144
Turning Layers On or Off	144
Making Layers the Current Object	145
Adding Markers to Operators and Layers	146
Transforming Layers	148
Moving and Rotating Layers	148
Tool Constraint Shortcuts	150
Scaling Layers	150
Shearing Layers	151
Changing the Pivot Point	151
Controlling the Behavior of Layers	152
Parenting Layers	152
Hinging Layers	153
Targeting Layers	153
Creating a Null Object	154
Aligning Layers	154
Reshaping Layers	155
Reordering Layers	155
Locking Layers to the Background	156
Changing the Duration of a Layer	157
Duplicating and Moving Layers	157
Editing Layers in the Timeline	157
Moving Layers	158
Trimming Layers	158
Slipping Layers	159
Splitting Layers	159
Working with 2D Composites	160
Creating a 2D Composite	160
Comparing 3D and 2D Options	161
Switching 3D Composites to 2D Composites	161
Working with Nested Composites	162
Creating a Nested Composite	162
Organizing Layers	163
Organizing Composites	165
Transforming Nested Layers	166
Applying Operators	166
Applying an Operator to a Layer	168
Applying an Operator to a Composite	168
Applying an Operator to a Nested Layer	168
Applying an Operator to a Branch	169
Using Operators with Selections	170
Modifying Operators	170
Animating Operators	171
Copying or Moving Operators	171
Deleting Operators	172
Turning Operators On or Off	172
Storing Operator Settings	172
Moving between Stored Settings	173
Emptying Storage	173
Exporting and Importing Setups	173
Using OpenGL	174
Previewing with OpenGL	174
OpenGL Diagnostics	175
Rendering with OpenGL	175
Setting OpenGL Preferences	176
Global Settings	176
Background Images	177
Composite OpenGL Settings	177
Spotlight Rendering	177
Chapter 6: Using Schematic View	179
About the Schematic View	180
Showing the Schematic View	180
Working with Nodes	181
Selecting Nodes	181
Using Node Commands	181
Schematic Context Menus	181
Setting the View Context	182
Showing an Operator in the Viewport	182
Node Connection Points	183
Node Input and Output Examples	183
Connecting Nodes	184
Connecting Nodes to Secondary Inputs	185
Disconnecting Nodes	185
Repositioning Nodes	185
Previewing Nodes	186
Organizing Nodes	186
Moving Nodes	186
Copying and Pasting Nodes	186
Guidelines for Copying and Pasting Nodes	187
Duplicating Layer Nodes	188
Grouping Nodes	189
Naming Nodes	190
Adding Nodes	190
Using the Operators Panel	191
Deleting Nodes	192
Deleting Composite Operators	192
Customizing the Schematic View	192
Panning and Zooming the Schematic	193
Using the Schematic Overview	193
Resizing the Schematic View	194
Displaying Thumbnails	194
Displaying Footage Information	195
Arranging Nodes	195
Using Auto Layout	195
Changing Schematic Flow Direction	195
Using the Schematic Grid	196
Changing Connection Types	196
Using Emphasis	196
Making Emphasis Follow the Selection	197
Emphasizing Nodes Manually	197
Output and Connection Nodes	198
Adding Output Nodes	198
Displaying Connection and Layer Nodes	198
Displaying Round Nodes	199
Using Footage Library View	200
Previewing Footage Nodes	200
Footage Library View Commands	200
Displaying Footage Information	201
Using the Footage Overview	201
Chapter 7: Committing Frames to Disk	203
About Committing to Disk	204
Committing an Operator to Disk	204
Updating and Managing Committed Footage	206
Appending Committed Footage to the Switcher	206
Updating Committed Footage	207
Switching Between Inputs	208
Using the Switcher Operator	208
Chapter 8: Using Surface Properties	211
About Surface Properties	212
Surface Properties Interface	212
Layer Controls	212
Surface Controls	214
Settings Controls	216
Using Transfer Modes	216
Using Preserve Alpha	218
Using Reflectivity	219
Creating Shadows	219
Setting Specular Level and Glossiness	221
Creating a Double-Sided Layer	222
Chapter 9: Working with Image Channels	223
About Channels	224
Alpha Channels	224
Supported File Formats	225
Using View Modes	225
Creating an Alpha Channel	226
Creating Alpha Channels with Masks	226
Creating Alpha Channels with Keyers	226
Using the Linear Keyer	227
Using the Difference Keyer	228
Difference Keyer Controls	229
Using Matte Controls Operator	230
Matte Controls	230
Creating Alpha Channels with Paint	231
Importing Files with Alpha Channels	232
Interpreting Alpha Channels	232
Using Stencils	234
Animating Stencils	236
Applying a Matte to a Layer	236
Using Channel Effects	237
Using Alpha Arithmetic	237
Using Blend	237
Using Compound Alpha Arithmetic	238
Using Compound HSV Arithmetic	238
Using Compound RGB Arithmetic	239
Using HSV Arithmetic	240
Using Invert	240
Using Merge	240
Using Minimax	241
Using RGB Arithmetic	242
Using Set Matte	242
Using Switcher	243
Operator List Options	244
Example of Using Channel Effects	244
Create a Workspace	245
Create the Red Channel	245
Make the Green and Blue Channels	246
Use Transfer Modes to Combine the Layers	247
Animate the Layers	247
Rendering Alpha Channels	248
Chapter 10: Using Masks	249
About Masks	250
About Mask Objects	251
Creating Masks	251
Mask Tool Interface	253
Mask Toolbar	253
Freehand Mask	253
Rectangular Mask	254
Elliptical Mask	254
Polygon Mask	254
Magnify Tool	254
Grab Tool	255
Arrow Tool	255
Modes Controls	255
Color	256
Opacity	256
Combine Mode	256
Feather	256
Invert	256
Anti-Alias	256
Edge Gradient	256
Global Apply Mode	256
Background	257
Transform Controls	257
Settings Controls	258
Default Object Duration	258
Spline and Edge Color	258
Mask Setups	259
Using the Mask Tools	259
Polygon Masks	260
Freehand Masks	260
Elliptical Masks	261
Rectangular Masks	262
Editing Masks	262
Working with the Control Points of a Mask	263
Using Active Control Points	264
Rotoscoping	265
Active Channel in Timeline	267
Drawing Order of Mask Control Points	268
Editing Control Points in the Timeline	268
Using Mask Edge Gradients	268
Offset Edge Gradient	269
In/Out Edge Gradient	270
Splines Edge Gradient	270
Changing the Mask Outline Colors	271
Animating Masks	271
Tracking Masks	271
Modifying Mask Opacity	272
Modifying Mask Color	272
Mask Transparency and Color	273
Example: Using Mask Transparency and Color	274
Feathering Masks	275
Combining Masks	275
Inverting Masks	276
Inverting the Global Apply Mode	277
Using Masks with Keys	278
Viewing Mask Outlines	279
Using Mask Setup Files	279
Mask Setup File Guidelines	280
Exporting Paint Masks Outputs as .swf Files	280
Chapter 11: Timewarping	281
About Timewarps	282
Constant and Variable Timewarps	282
Interpolation	282
Timewarp vs. Time Stretch	282
The Timewarp Controls	283
The Curve Editor	283
Timing, Speed, and Interpolation Controls	284
Reset Button	285
Working in the Curve Editor	285
Using the Timewarp Operator	286
Creating a Constant Speed Timewarp	286
Chapter 12: Creating Animations	287
About Animating	288
Keyframing in Paint	288
Enabling Keyframing	288
Creating Animations	289
Creating a Motion Path	289
Editing a Motion Path	291
Timeline Overview	292
Resizing the Timeline	292
Navigating in the Timeline Hierarchy	293
Navigating to a Specific Level	293
Navigating One Level at a Time	293
Filtering the Timeline	293
Showing only Animated Channels	294
Showing only Channels with Expressions	294
Creating Channel Filter Presets	294
Object-Specific Channel Filters	295
Timeline List	295
Timeline Categories	296
Using the Timeline Modes	296
Graph Mode	296
Overview Mode	297
Current Time Indicator	298
Zooming and Scrolling the Timeline View	298
Timeline Controls	299
Playback Controls	300
Navigating in a Workspace	300
Changing Display Units	301
Setting In and Out Points	301
Working with the Timeline	301
Navigating in the Timeline	301

Match case Limit results 1 per page

Working with Image Channels

208

Mattes and channels not only affect what is

retained and discarded in the final composite—

they allow sophisticated, precise, and artful

effects through their changeability.

About Channels

When you start a new branch, color channels and an

alpha channel are created automatically.

Color channels

show the amount of the

corresponding color present in the clip using a

grayscale image with a certain bit depth (for

example, 8 bits). For more information, see

“Bit

Depth Basics” in Chapter 22, “Working with Bit

Depth’’

. Each branch has three color

channels, one

each for red, green, and blue.

The

alpha channel

uses another grayscale image

(with the same bit depth) to determine which pixels

are opaque and which are transparent for each

frame. The alpha channel is represented by a

grayscale image embedded in the file. The grayscale

value determines the opacity: white pixels are

opaque (100% opacity), black pixels are transparent

(0% opacity), and gray pixels represent varying

degrees of opacity.

Alpha Channels

You use alpha channels to determine how much of

the front image shows over the back image(s).

If you are looking through a keyhole inside a room,

the door is the

front

, the keyhole is the

alpha

, and the

room is the

back

. Combined together, these layers

form a composite. The following illustration shows

the function an alpha channel performs when

compositing.

If you render the contents of the alpha channel, you

get what is called a

matte

A matte can be completely black and white (called a

hi-con

for high-contrast), or can contain many

shades of gray. In video and film, mattes are rarely

static, and are rarely pure black and white. Any areas

of the front containing transparency (glass, smoke,

curly blond hair) or motion blur appear in the matte

as gray areas, allowing the transparent (or blurred)

areas to partially show through.

The process of generating a matte (from blue screen,

for example) is also known as

pulling

a matte.

Getting as close as possible to the perfect matte is

perhaps the most important part of compositing.

Because you are superimposing layers on layers with

the aim of creating a

reality

, any imperfections in the

Front

Alpha

Back

Composite