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User Manual: Contents | Guidelines | Blender Version 2.43

Compositing Nodes allow you assemble and enhance an image (or movie) at the same time. Using composition nodes, you can glue two pieces of footage together and colorize the whole sequence all at once. You can enhance the colors of a single image or an entire movie clip in a static manner or in a dynamic way that changes over time (as the clip progresses). In this way, you use composition nodes to both assemble video clips together, and enhance them.

To process your image, you will use nodes to import the image into Blender, change it, merge it with other images, and finally save it. Think of nodes as workers on an assembly line. Each worker performs one basically simple task before passing the product on to the next worker. The assembly line is called a thread, and the image enters and leaves a node by sockets. You connect one node to another by creating a thread that runs from one node's output socket to another node's input socket. A bunch of connected nodes is called a noodle. The example to the right shows the simplest noodle; an input node threads the camera view to an output node so it can be saved.

Compositing nodes are connected by threads into a map that routes an image through a sequence of nodes. Each node performs some operation of the image. You create the map using the Node Editor window type. Before you continue reading, it is elementary that you understand how to use this window type. Read all about the Node Editor by clicking here.

Every node has a similar set of controls and conventions. For more information on working with node controls, click here.

Accessing and Activating Nodes

Select the Node Editor window

Access the Node Editor and enable Composite Nodes by clicking on the correct icon (picturing a Face).

Node Editor Header with Composite Nodes enabled.

To activate nodes for the composition, click the Use Nodes button. Blender creates a default starting noodle, consisting of two nodes threaded together.

Use Composition Nodes

To use this mini-map, you must now tell Blender to use the Compositing Node map that has been created, and to composite the image using composition nodes. To do so, switch to the Scene button area (F10) and activate the Do Composite button located below the Animation button. This tells Blender to composite the final image by running it through the composition node map.

Working with the Composition Map

You now have your first noodle, a RenderLayer input node threaded to an Composite output node. From here, you add and connect nodes in a sort of map layout to your heart's content (or physical memory constraints, whichever comes first). There are many types of compositing nodes that do many different things. The available nodes are discussed in the next section, which you can quickly access by clicking here.

As your map grows, you will need to keep it organized. Try to arrange the 'assembly line' of nodes from left to right, top to bottom. You can also group nodes together into subroutines, as discussed below.

Grouping Composition Nodes

As your map grows, you might find it helpful to organize your nodes by grouping some of them together. Blender allows you to make user-defined groups of nodes.

Node maps can get quite complex. Blender allows you to group a set of nodes together to both save space and help you conceptualize what the net effect of a mini-map does to a material/image. This menu selection shows the names of the groups of nodes that you have defined. Select any one to add that group to the map.

Create a Node Group

A group is created by Shift-clicking all the nodes you want in the group, and then selecting Node -> Make Group (Ctrl G). The group node is shown with a green bar, and the name is shown in an editable field (Shift-click on the name to enter EditMode and change the name to something that represents what that group does. The input sockets to the group is the input sockets of contained nodes, and akin for output(s).

Editing Node Groups

You can select the group and press Tab (or select Node -> Edit Group) to enter/leave the group.

Ungroup Nodes

You can select the group and press Alt G (or select Node -> Ungroup) to convert the grouped nodes back to normal.

A "FadeToBlack" compositing group would be a Time node that feeds the Factor of an RBG Curve node. The curve in the RGB Curve node would be a flat line at zero. Namely, any X that came in results in a zero output (black). The factor starts at zero (no effect on the input image), and cranks up to one (full effect, namely black). The input sequence will fade to black over the frame count set in the timer.

Some Examples of Using Compositing Nodes

You can do just about anything with images using nodes. The "Fade to Black" noodle group above is a simple example of what you can do using compositing nodes.

Raw footage from a foreground actor in front of a blue screen, or a rendered object doing something can be layered on top of a background. Composite both together, and you have composited footage.

You can change the mood of an image:

• To make an image 'feel' colder, a blue tinge is added to the pic.
• To convey a flashback or memory, the image may be softened.
• To convey hatred and frustration, add a red tinge or enhance the red. The film 'Sin City' is the most extreme example of this I have ever seen.
• A startling event may be sharpened and contrast enhanced.
• A happy feeling - you guessed it - yellow (equal parts red and green no blue) for bright and sunny.
• Dust and airborne dirt is often added as a cloud texture over the image to give a little more realism.