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Sunil Ketty
Digital Compositing Tutorial
Masters of Education in Art Education
Spring 2010
Digital Compositing Tutorial Overview
In today’s cinema special FX’s and computer generated images are revolutionizing the way
people experience movies. With such blockbusters as Transformers, Iron Man, Disney
Pixar's Up and an endless amount of other hits being view by millions, the popularity of CGI
has never been so in demand. Besides the effects and stunning graphics bringing the
masses to the theaters, the creation of never before seen worlds and characters being
seamlessly blended with live action footage or static digital images are blurring the line
between what is real and what is not.
Objectives
• The students will explore different techniques used to seamlessly composite a
computer generated image with a static digital photograph using modeling, lighting and rendering methods.
• The students separate essential material elements and scene properties like
reflections and shadows for use in digital compositing software to seamlessly
combine the GCI with the photograph.
Prerequisites
• This tutorial will build on previous knowledge of 3d application, modeling, texturing
and lighting.
• We will use tools, techniques and principles that have been established in many of your courses leading up to digital compositing.
Tutorial Content
• The tutorial is separated into 3
distinct sections o Tutorial Page 1
Getting Started
Software/Hardware requirements
Digital photography and Plates
General modeling information o Tutorial Page 2
2D Camera Matching in 3ds Max o Tutorial Page 3
Setting up for rendering
Feedback
• A weekly question and answer session will lead off weekly classes
• Weekly postings, including websites and example, will be posted to be view and
discuss.
• A final critique will be held at the completion of the tutorial
Student Evaluation/Methods of Assessment:
• Projects are graded and based on the criteria listed below.
• Points may vary based on the assignment.
• Points will not be given to projects turned in after the predefined due date and
time.
• Not turning in the project can result in an F for the class.
1. Comprehension Did you use the techniques discussed in class and or experiment with new techniques?
2. Objectives Did you meet/exceed the project objectives?
3. Work Ethic Did you work well in class?
4. Quality Does your project reflect strong effort and attention to detail?
A – A- ( 100 %– 90%) The student has EXCEEDED the expectations of ALL criteria, and with high quality
B+ - B- (89% – 80%) Has met ALL objectives competently and with quality
C+ - C- (79%-70%) The student has met the requirements within their simplest definition
D+ - D (69%-60%) The student has met all requirements but at a very low level
F (59% - Below) The student has not fulfilled requirements or has done so very poorly
Conclusion
• Upon conclusion of this tutorial you should have a better understanding of Render
Elements, 2d Camera Matching and seamlessly compositing a computer generated
image onto a static digital photograph.
• This will allow for future exploration in digital compositing techniques and principles
when dealing with compositing CG elements with static photographic.
These processes can also be a useful tool when developing your final senior demo reel.
Tutorial Page 1 (From
Website) Objective: To seamlessly composite a computer generated 3d model into a static digital photograph.
For this project we will concentrate on creating a CG (computer generated) 3d model that
can exist in the digital photograph to deceive the audience and make them believe all
objects are real. To accomplish this we will be creating a 3d model of a college keychain
and digitally compositing that onto a computer desk.
Software Requirements: Autodesk 3ds Max 2009 Adobe Photoshop CS4 Adobe After Effects CS4 Hardware Requirements: Digital Camera Tripod Camera Matching object w/accurate measurements Render Settings: Aspect Ratio – 720x480
Getting Started Note: this is a compositing tutorial and will not include how to model and texture your computer generated 3d
model. Previous knowledge of modeling, lighting, and texturing techniques are required in order to complete this
tutorial.
Note: Making sure to save often and to create incremental project file is a good workflow to help when files fail to
open, files get corrupted or if you need to revert to an older version of a scene.
Step 1: Folder Setup
It is always important when working on a computer or with computer software that you stay organized and establish a folder structure that you maintain throughout the process.
- Always establish a root folder or project folder
- Name all folder and files as if you were working with a team and so that anyone at any given time can easily make sense of you project and files.
- Since we are using 3ds Max 2009 and to isolate specific techniques, I will be using multiple 3ds Max files and renders.
- An R&D (Research & Design) folder can always be useful to store references images, concept art or any other miscellaneous files.
Sample folder structure Root Folder: Digital Compositing Project
Sub Folders: 3ds Max Files and Renders
Step 2: Shot Location and CG Element
- Making sure you have planned out what you will model and where you will be compositing that model will help the project move along smoothly.
- Always focus on your strengths as a computer artist so that you can challenge yourself, but be successful in the creation of the 3d mesh.
- Having concept art, reference images and images planes to use as background
images to model from.
CG Element Make sure when modeling you consider the following:
- Objects measurements to ensure accurate and proper scaling to the other objects in the digital photograph
In 3ds Max go to Customize/Unit Setup, check US Standard and use Feet w/Decimal Inches, this can help make sure you model is modeled to scale.
- Material & Surface makeup of the object
- Any special characteristics that are important to making the CG model appear real
Shot Location Make sure when shooting the digital photograph you consider the following:
- Lighting
- Composition
- Shot angle
Picture Taking
You will need three digital photographs known as plates for this step. All three images have
to be shot from the same location, so a tripod is necessary in making sure they are.
Shot location set and the camera locked onto the tripod ready to take the digital
pictures. Plates
- Clean Plate
This digital photograph will be use to composite the CG element on to
Will be use in the final render
Can be used as reference in 3ds Max to make sure the 3d model is placed in
the correct location.
- Matching Plate
This digital photograph will be use in a 3D application to match the images perspective with a virtual camera in the 3D application.
You will need an object that has been measured and placed so it is visible in
the photograph.
The Matching object – For this tutorial I will be using a VHS Tape as my matching.
• Must have distinct corners, no bevels or misshapen edges
• Must have the accurate height, width and length to be used during the matching process in 3ds Max.
• Objects such as shoe boxes, VHS tape boxes, cereal boxes etc. The
distance your digital pictures are being taken from will affect the
object that can be used. For tight shots or close-ups, smaller object
will suffice and for long shots larger object will be necessary.
Sample Matching Object – 7 useable points (Red Dots) and visible height, length and width
• When placing the matching object into the shot, you should see a
minimum of 5 points and no more than 7. This will ensure that
when plotting the camera point, 3ds Mac can calculate and create the virtual camera.
- Shadow Plate
This digital photograph will be use as reference for the shadow direction
created by the lighting in the digital photograph. Computer generated
lights will be used to match the light direction, shadows, and material properties (specularity, reflectivity etc.)
Depending on the distance and shot angle, different objects can be placed
into this plate to clearly see the shadow direction.
An object placed in this plate can help align virtual lights to recreate the light direction
- Make sure to upload the digital picture and name those plates to identify
their purpose. The Plates
These are the plates that will be used in this tutorial
The CG Model
Since this tutorial is specifically geared towards the digital compositing of a CG model, prior
knowledge of proper modeling techniques will help and allow for a more successful project.
You will also need to be proficient in materials, assigning materials and creating mapping
coordinates if necessary. Computer based lighting is another aspect of this process that
needs to be understood prior to completing this digital compositing tutorial. You can refer
to the 3ds Max help file or other book/tutorials to help with any of the areas referred to above.
- These topics or key terms can assist you:
Poly modeling & Editable Poly/Editable Mesh
UVW Mapping Coordinates and Unwrap UVW modifier
Lighting, specifically Standard Light or Photometric Lights for
advanced users - Destination
Tutorial Page 2 (From Website)
2d Camera Matching Step 1: Placing the matching plate
- In order to create a virtual camera that matches the perspective of the clean plate,
you will place the matching plate as a background image in the perspective view.
With the perspective view active, either use the shortcut Atl+B or got to Views/Viewport Background.
Click Files under Background Source and load in the matching plate.
Under the Aspect Ratio check Match Rendering Output
Display Background – Checked on
Lock Zoom/Pan – Check on
Hit OK
Step 2: Model the Matching Object
- By recreating the object to its exact dimension you give yourself a reference object
that will be used to plot the camera points then assign them to the matching object in the digital image.
- Using a Primitive Box create the VHS Tape (keep in mind that if you are using a different
object, have the exact dimensions) - VHS Tape Dimensions
Length – 1.065”
Width – 4.25”
Height – 7.5”
Computer Generator Tape
Step 3: Camera Match Helper
- Helpers Tab
The Helpers tab is recognized by the tape measure icon
- Change from Standard to Camera Match
Note: have vertex snap on will ensure that when creating the CamPoints that the snap to the corners or vertices.
- Rotate your modeled reference object so it is close to the same perspective as the
object in the digital image. Remember the Matching Plate is your background
image in your perspective viewport.
CamPoints placed and model rotated to resemble the position of the matching object in the digital
picture
- Click CamPoints
When CamPoints are active you are ready to assign them to the corners of
the reference object you modeled. Keep in mind that 5-7 points can help
with a more accurate and successful match. With vertex snap on you will
know that the CamPoints are placed directly over the corners of the reference model (CG VHS Tape).
- Once the CamPoints have been placed they can be identified by the yellow x located over the corners of the modeled reference object.
Note: It is VERY important to make sure you remember the order you assign the CamPoints. You will need to
use that information when assigning the position of those CamPoints. As you create each CamPoint, there is an
option that allows you to name each CamPoint once they have been placed.
*Make sure to save often and name all objects in a scene*
Assigning Positions
Step 1: Assigning the Camera Points
- Now you will take the CamPoints that were assigned to the 3d generated reference
object and plot them onto the reference object in the matching plate.
- Go to the Utilities Tab and click the Camera Match utility
- In the CamPoints Info section, click Assign Position
The CamPoints will now be visible and displayed with the default name unless you have changed them.
In the options, select the CamPointand and assign that position to the
corresponding position in the digital image that is you background.
*IMPORTANT – Select and assign the CamPoints in the exact order that you created them.
- Once all the points have been assigned, in the Camera Match options click Create Camera
(If something was done incorrectly, this is where you would run into errors.)
Once the camera has been created, hit “C” to view the created camera in any of the
viewports.
Tutorial Page 3 (From Website)
Set Up for Rendering Keeping in mind that the CG element has already been created, you will set up your scene
to render out some key passes that will be used in post production to seamlessly match the
CG model to the Clean Plate. We will not cover all the different render passes that are
available, but focus on some of the main ones that will give you a good understanding on
why this is such a useful process. Some of the passes that I cover might not be need for your composite, but will demonstrate
some of the possibilities when isolating specific elements of a final render. Once you have
an understanding of some of the basic passes, you can use that to build on and problem
solve for future composites.
Render Elements help the workflow of rendering out specific passes, so once the render
elements have been setup you can quickly and easily render out a pass and save that file to
a specific location you have established. Utilizing Render Elements whenever possible will
allow for a better workflow. Rendering/Render Setup/Render Elements Tab
- Add a Render Element by clicking the Add icon to browse a list of available render
elements. Select the element you want 3ds max to separate out for the render.
- In this tutorial I will use render elements to separate out the light direction based
on color information with a diffuse element. I will also use this method to separate
out the specularity (highlights), reflections and shadows.
- In the Selected Element Parameters, you can predefine a folder and name to save
the element every time you render. Just be cautious of this because you might
overwrite a render that you do not wish to. To protect you for doing this you and
enable and disable any elements you choose to. Some of the passes we will cover in this tutorial:
- Global Illumination
- Ambient Occlusion
- Diffuse For light Direction
- Shadow
- Specular
- Reflection
- Holdout Matte
Global Illumination, GI Pass
Will not contain Specularity, Reflectivity, but is a full color rendering of the CG Element.
- This pass can be used to get a generally lit model
Has some depth, but no direct light source causing
any distinct shadowing - One method to get this look is to use
a 3ds Max Skylight with Light Tracer.
Rendering/Render Settings/Advanced Lighting – select
Light Tracer
Sample Render GI Pass
NOTE: The look of using a Skylight is very nice with little setup, but comes with a price, render time. Render time
will increase significantly and when rendering out a sequence of images or an animation, this can become very time
consuming. For a still render, this method is useful and can give you some nice results in the aesthetics of this
pass. An option for a sequence or animation is to create a light array with standard or photometric light sources.
Ambient Occlusion, AO Pass
- This pass is used to give depth to you render and to generate self-shadowing and
contact shadowing with other objects.
Some of the “other objects” may only be visible in the Clean Plate. If this is
the case, then references objects might have to be modeled to receive a shadow or cast a shadow onto the CG element.
- There are different methods to achieve an AO pass and for this tutorial I will use a Mental Ray material and assign that to the object.
Make sure assign the Mental Ray Renderer in the render settings
In the Material Editor select a blank(standard) material and change Standard to Mental Ray
Assign an Ambient/Reflective Occlusion map to the Surface slot by clicking none.
Adjust the Samples (default 16) to acquire a more detailed render. The higher the samples are the more defined the shadows will render.
Apply material to all object that need this specific information. NOTE: The higher the samples the more you increase render time.
Sample Render AO Pass
TIP: If you have objects that need to cast shadows or receive shadows, but do not want them in
the final render, you can turn off Visible to Camera in the Object Properties of a mesh under
Rendering Controls. This will calculate the shadows, but not render the mesh.
This example shows a sphere onto of the main mesh, but all we want is the shadow being created from the contact
between the two. Shot two has the object properties adjusted to calculate the objects shadow, but not to render the
actual mesh.
Object Properties w/Visible to Camera turned off
NOTE: If the environments background is visible in the render, in the Rendering/Environments, you can change the
background color to white. This will benefit the way this pass is composited with the rest in post production.
Diffuse Pass for Light Direction
- When rendering out elements, diffuse refers to the color pass and sometimes as a
beauty pass. This pass consists of the objects colors or textures and does not contain any highlights, shadows or reflectivity.
- The reason I have added light direction to the title of this section is because I will be
using the RGB information of a render to isolate the different directions of the lights
used in this render. Each light in the scene will be colored red, green or blue and that information can be used in post production to isolate the light sources.
- This is just a technique that can assist in the compositing aspect of this tutorial, but
might not be used as a key pass in all situations.
- Once the lights have been placed in the scene to match the lighting in the clean
plate, you will just adjust the light color to a pure red, green or blue.
Shadow Pass
- For this render I will set up a shadow Render Element to separate out the shadows
generated from the lighting in your scene.
- The shadows have to match the direction of the Plates so that when the CG element is composited, it seamlessly fits.
- The density, blur and other aesthetics of the shadow can be manipulated in post.
- I will have 3 lights in my scene keylight from my main lamp, secondary lamp light
and any indirect light for outside sources.
- As you become more comfortable with these techniques you can separate each
shadow into its own render to have more control in post. This would be a more
effective way of rendering most of your passes, separating them as much as
possible.
NOTE: When the shadow elements are separated for the render, you will notice that you
cannot see the shadows. Do not let this confuse you, check the Alpha Channel of the
render to ensure that the shadows have indeed been separated into its own element.
Specular/Reflection Pass
- Since these 2 elements share many of the same techniques, I will combine them in this tutorial.
- Like most passes there are multiple ways to accomplish this, but using 3ds Max’s
Render Elements to automatically separate the passes will be the most proficient way.
- It is important that the lighting has been established for the highlights and
reflections.
- Also making sure that the objects in the digital picture are reflecting into the CG
element and the CG element reflects in to objects in the digital image. This will help the realism of the final render and is a major factor in the seamless look.
To accomplish this you will have to either create temporary 3d models so
the main 3d element can reflect into them. The use of HDRI, High Dynamic
Range Images and gazing ball to help match the environment are some
advanced techniques you can look into. Holdout or Geometry Matte
- This pass can be use to isolate multiple objects that are visible in the same render.
- By utilizing the RGB channels of a render, we can make use of that information in post to select and isolate particular objects.
- Using the material editor
Make sure the Ambient and Diffuse are black
Check Self-Illumination Color and change the color to either Red,
Green, or Blue Apply to the objects in the scene
Material Editor
Same technique applies to all 3 colors
Holdout or Geometry Matte Render
Tutorial Page 3 (From Website)
Compositing the Image
Introduction
- The Compositing portion of this tutorial will use Adobe After Effects CS4.
- This tutorial is designed for students that are already familiar with After Effects and the
interface.
- Please refer to the Documentation link for information on Blend Modes.
Importing Images into After Effects
Ignore
- This will ignore any alpha channel information in the imported image.
Straight (or unmatted)
- Transparency information is only stored in the alpha channel, not in any of the visible
color channels. With straight channels, the effects of transparency are not visible until
the image is displayed in an application that supports straight channels.
Premultiplied (or matted)
- Transparency information is stored in the alpha channel and also in the visible RGB
channels, which are multiplied with a background color. The colors of semitransparent
areas, such as feathered edges, are shifted toward the background color in proportion
to their degree of transparency.
The Layers
- Use premultiplied when importing images (better edges)
- When deciding what Blend Modes to use, please refer to the Blend modes PDF for detailed description of each mode.
Rendered Passes GI Pass
- The global illumination pass is the base layer in the composition. - This is the layer with general lighting and includes textures.
Effects to add:
- You can adjust the gamma (levels Effect) of this layer to darken or brighten the composition.
After the GI you can build with any of the other layers Diffuse Layer Effect to add: - Channel Combiner
- Adjust Hue/Saturation (effects/color corrections/levels)
- Can use a set matte
Blend Mode:
- Screen
Channels:
If you rendered the image by separating light direction into the Red, Blue and Green
Channels, you can separate the image into each.
Separate RGB into the R/G/B channel unless you have separated it in the render process. - The second process is to create a solid color for the light source and then
use a set matte Pick the layer you want, DIFFUSE And then select the color
channel
Hmatte
- Use this layer to matte out certain areas of the
composition. - Use Set Matte and use the
Hmatte as its masking
Shadow
- This layer will use the alpha channel to place the shadows into the comp. o No Blend
Mode necessary
o Remember, you will not see the shadow pass unless you view the passes alpha
channel. If you do not see distinct shadows make sure to check the pass in 3ds Max.
- Depending on how you rendered the layers you might have to use a set matte. o If 3d elements were not separated in the rendering phase, a set matte effect and HMatte
layer can help place information in specific locations.
Ambient Occlusion(AO)
Effect to add:
- Use Levels to expand or contract the shadow spread
- Gaussian blur to soften the edge
- Might have to use a set matte depending on how the passes were rendered.
Blend Mode:
- Multiply
AO (Option 2)
Render Settings: - Common Tab o Use Mental Ray Renderer
- Indirect Illumination Tab o Make sure Final Gather under
- Processing Tab o Change the override material to use the Metal Ray Material with the
Ambient/Reflective Occlusive map assigned to the Surface slot.
o Make sure to check the samples of the surface map. The higher the samples the
more detailed the self/contact shadowing. That will affect render time
Reflection
Effects to add:
- Use Channel Combiner if you want to isolate the R/G or B
- Hue/Saturation to change the color
Blend Modes
- Use Add as the blend mode
Specular
Effects to add:
- Use Channel Combiner if you want to isolate
the R/G or B - Hue/Saturation to change the
color
Blend Modes
- Use Add as the blend mode
The example of each pass may vary and as always using your own artistic license to make sure the CG element is seamlessly composited is crucial.
Documentation Media Arts and Animation Curriculum
The Mission of the Media Arts & Animation Bachelor of Science degree program is to
prepare students for entry-level positions creating 2D and 3D imagery for employers
that produce traditional and digital illustration, modeling, animation and motion
graphics.
AIP Homepage
Educational Philosophy
• Student Success
• Project Based Education – Real work situations
• Adapting to various learning styles
• Problem Solving •
Work Ethic
The
Instructor
• Use of project samples and real industry examples that pertain to the
competencies of each course
• Maintaining knowledge of updated software and staying ahead of the curve.
• Keep the lines of communication open. Allow student to ask questions and
make yourself available outside of class
• Use of office hours, website and email to keep the students updated with
the course
• Allow for tutors MAA Objectives
• BFA, Bachelor of Science
• To offer an education that will allow our graduates entry opportunities o
Entry-level opportunities available to Media Arts & Animation include
computergenerated lighting, compositing and rendering artist; 3D modeling
and texturing artist for the video game and film industries; computer-
generated special effects and broadcast graphics artist for video post-
production; and forensic artist. In addition, the need for 2D and Flash
animators continues to grow to support webbased corporate
communications, e-commerce and marketing. All courses in the Media Arts
& Animation program are also available online.
• Create courses that help students to explore and problem solve with a
variety of individual and team oriented projects or assignments.
• Create an environment that assist in the learning process
• Opportunities for in-depth discussions and conversations about the industry
and core competencies.
• Critiques
Rubric
• The rubrics will be bases on individual instructor, course and project(s).
• Refer to course syllabus
• Samples
Assessment
Student Evaluation/Methods of Assessment:
• All projects must meet the 4 sections of grading criteria listed below.
• Projects are graded and based on the criteria listed below.
• Points may vary based on the assignment.
• Points will not be give to projects turned in after the predefined due date
and time.
1. Comprehension 5 Points
Did you use the techniques discussed in class and or experiment with new
techniques?
2. Objectives 5 Points
Did you meet/exceed the project objectives?
3. Work Ethic 5 Points Did you work well in class?
4. Quality 5 Points
Does your project reflect strong effort and attention to detail?
A – A- ( 100 %– 90%)
The student has EXCEEDED the expectations of ALL criteria, and with high quality.
B+ - B- (89% – 80%)
Has met ALL objectives competently and with quality.
C+ - C- (79%-70%)
The student has met the requirements within their simplest definition.
D+ - D (69%-60%)
The student has met all requirements but at a very low level.
F (59% - Below)
The student has not fulfilled requirements or has done so very poorly.
A 100 to 92
A- 91.9 to 90
B+ 89.9 to 88
B 87.9 to 82
B- 81.9 to 80
C+ 79.9 to 78
C 77.9 to 72
C- 71.9 to 70
D+ 69.9 to 67
D 66.9 to 60
F 59.9 and below
Software Requirements
The Art Institute of Pittsburgh is very good at making sure our labs and students
have access to all the up to date, industry standard software.
- Autodesk
- Adobe
- Pixelogic
After Effects Blend Modes A Screen shot from Adobe After Effects CS4
Normal
The result color is the source color. This mode ignores the underlying color.
Normal is the default mode.
Dissolve
The result color for each pixel is either the source color or the underlying
color. The probability that the result color is the source color depends on the
opacity of the source. If opacity of the source is 100%, then the result color is
the source color. If opacity of the source is 0%, then the result color is the
underlying color. Dissolve and Dancing Dissolve do not work on 3D layers.
Dancing Dissolve
Same as Dissolve, except that the probability function is recalculated for
each frame, so the result varies over time.
Darken
Each result color channel value is the lower (darker) of the source color
channel value and the corresponding underlying color channel value.
Multiply
For each color channel, multiplies source color channel value with underlying
color channel value and divides by maximum value for 8-bpc, 16-bpc, or 32-
bpc pixels, depending on the color depth of the project. The result color is
never brighter than the original. If either input color is black, the result color
is black. If either input color is white, the result color is the other input color.
This blending mode simulates drawing with multiple marking pens on paper
or placing multiple gels in front of a light. When blending with a color other
than black or white, each layer or paint stroke with this blending mode
results in a darker color.
Color Burn
The result color is a darkening of the source color to reflect the underlying
layer color by increasing the contrast. Pure white in the original layer does
not change the underlying color.
Classic Color Burn
The Color Burn mode from After Effects 5.0 and earlier, renamed Classic
Color Burn. Use it to preserve compatibility with older projects; otherwise,
use Color Burn.
Linear Burn
The result color is a darkening of the source color to reflect the underlying
color. Pure white produces no change.
Darker Color
Each result pixel is the color of darker of the source color value and the
corresponding underlying color value. Darker Color is similar to Darken, but
Darker Color does not operate on individual color channels.
Add
Each result color channel value is the sum of the corresponding color
channel values of the source color and underlying color. The result color is never
darker than either input color. Lighten
Each result color channel value is the higher (lighter) of the source color
channel value and the corresponding underlying color channel value.
Screen
Multiplies the complements of the channel values, and then takes the
complement of the result. The result color is never darker than either input
color. Using the Screen mode is similar to projecting multiple photographic
slides simultaneously onto a single screen.
Color Dodge
The result color is a lightening of the source color to reflect the underlying
layer color by decreasing the contrast. If the source color is pure black, the
result color is the underlying color.
Classic Color Dodge
The Color Dodge mode from After Effects 5.0 and earlier, renamed Classic
Color Dodge.
Use it to preserve compatibility with older projects; otherwise, use Color
Dodge.
Linear Dodge
The result color is a lightening of the source color to reflect the underlying color by increasing the brightness. If the source color is pure black, the result color is the underlying color.
Lighter Color
Each result pixel is the color of lighter of the source color value and the
corresponding underlying color value. Lighter Color is similar to Lighten, but
Lighter Color does not operate on individual color channels.
Overlay
Multiplies or screens the input color channel values, depending on whether
or not the underlying color is lighter than 50% gray. The result preserves
highlights and shadows in the underlying layer.
Soft Light
Darkens or lightens the color channel values of the underlying layer,
depending on the source color. The result is similar to shining a diffused spotlight
on the underlying layer. For each color channel value, if the source color is lighter
than 50% gray, the result color is lighter than the underlying color, as if dodged. If
the source color is darker than 50% gray, the result color is darker than the
underlying color, as if burned. A layer with pure black or white becomes markedly
darker or lighter, but does not become pure black or white. Hard Light
Multiplies or screens the input color channel value, depending on the
original source color. The result is similar to shining a harsh spotlight on the
layer. For each color channel value, if the underlying color is lighter than 50%
gray, the layer lightens as if it were screened. If the underlying color is darker
than 50% gray, the layer darkens as if it were multiplied. This mode is useful
for creating the appearance of shadows on a layer.
Linear Light
Burns or dodges the colors by decreasing or increasing the brightness,
depending on the underlying color. If the underlying color is lighter than 50%
gray, the layer is lightened because the brightness is increased. If the
underlying color is darker than 50% gray, the layer is darkened because the
brightness is decreased.
Vivid Light
Burns or dodges the colors by increasing or decreasing the contrast,
depending on the underlying color. If the underlying color is lighter than 50%
gray, the layer is lightened because the contrast is decreased. If the
underlying color is darker than 50% gray, the layer is darkened because the
contrast is increased.
Pin Light
Replaces the colors, depending on the underlying color. If the underlying
color is lighter than 50% gray, pixels darker than the underlying color are
replaced, and pixels lighter than the underlying color do not change. If the
underlying color is darker than 50% gray, pixels lighter than the underlying
color are replaced, and pixels darker than the underlying color do not
change.
Hard Mix
Enhances the contrast of the underlying layer that is visible beneath a mask
on the source layer. The mask size determines the contrasted area; the
inverted source layer determines the center of the contrasted area.
Difference
For each color channel, subtracts the darker of the input values from the
lighter. Painting with white inverts the backdrop color; painting with black
produces no change.
If you have two layers with an identical visual element that you want to
align, place one layer on top of the other and set the blending mode of the
top layer to Difference. Then, you can move one layer or the other until the
pixels of the visual element that you want to line up are all black—meaning
that the differences between the pixels are zero and therefore the elements
are stacked exactly on top of one another.
Classic Difference
The Difference mode from After Effects 5.0 and earlier, renamed Classic
Difference. Use it to preserve compatibility with older projects; otherwise,
use Difference.
Exclusion
Creates a result similar to but lower in contrast than the Difference mode. If
the source color is white, the result color is the complement of the
underlying color. If the source color is black, the result color is the underlying
color.
Hue
Result color has luminosity and saturation of the underlying color, and the hue of the source color. Saturation
Result color has luminosity and hue of the underlying color, and the saturation of the source color. Color
Result color has luminosity of the underlying color, and hue and saturation of
the source color. This blending mode preserves the gray levels in the
underlying color. This blending mode is useful for coloring grayscale images
and for tinting color images.
Luminosity
Result color has hue and saturation of the underlying color, and luminosity of
the source color. This mode is the opposite of the Color mode.
Stencil Alpha
Creates a stencil using the alpha channel of the layer.
Stencil Luma
Creates a stencil using the luma values of the layer. The lighter pixels of the
layer are more opaque than the darker pixels.
Silhouette Alpha
Creates a silhouette using the alpha channel of the layer.
Silhouette Luma
Creates a silhouette using the luma values of the layer. Creates transparency
in painted areas of the layer, allowing you to see underlying layers or
background. The luminance value of the blend color determines opacity in
the result color. The lighter pixels of the source cause more transparency
than the darker pixels. Painting with pure white creates 0% opacity. Painting
with pure black produces no change.
Alpha Add
Composites layers normally, but adds complementary alpha channels to
create a seamless area of transparency. Useful for removing visible edges
from two alpha channels that are inverted relative to each other or from the
alpha channel edges of two touching layers that are being animated.
Note: Sometimes, when layers are aligned edge-to-edge, seams can appear
between the layers. This is especially an issue with 3D layers that are joined
to one another at the edges to build a 3D object. When the edges of a layer
are anti-aliased, there's some partial transparency at the edges. When two
areas of 50% transparency overlap, the result is not 100% opacity but 75%
opacity, because the default operation is multiplication. (50% of the light
gets through one layer, and then 50% of the remainder gets through the
next layer, so 25% gets through the system.) This is like partial transparency
in the real world. But, in some cases, you don't want this default blending.
You want the two 50% opacity areas to combine to make a seamless, opaque
join. You want the alpha values to be added. In these cases, use the Alpha
Add blending mode.
Luminescent Premul
Prevents clipping of color values that exceed the alpha channel value after
compositing by adding them to the composition. Useful for compositing
rendered lens or light effects (such as lens flare) from footage with
premultiplied alpha channels. May also improve results when compositing
footage from matting software from other manufacturers. When applying
this mode, you may get the best results by changing interpretation of the
premultiplied-alpha source footage to straight alpha.
Blend Modes descriptions from Adobe After Effects CS4 help page
http://help.adobe.com/en_US/AfterEffects/9.0/WSFB0FE760-71F3-4616-AE88275D718E7125a.html
Video Tutorial Page - This is a sample of a video tutorial of how to place the clean plate into the viewport background. To view the video tutorial visit the tutorial site.
Student Sample – To view the breakdown videos of the sudents work please visit the
tutorial site.