About the CryptoMatte Node
The CryptoMatte Node is a node that facilitates the compositing and manipulating of a fully rendered image or image sequence that has been imported. The CryptoMatte Node is a special kind of node that can identify individually tagged layers contained in a single EXR file.
These individually tagged layers are referenced by a custom name and ID in the rendered image. Using this custom name with the CryptoMatte node, a compositor is able to isolate, separate and apply effects to targeted areas of the rendered image.
The CryptoMatte Node is practical for the compositing workflow as the compositor only needs to import and export a single file sequence. This single file sequence retains access to separate layers and passes within that single image. The CryptoMatte format provides the same information as multiple output passes and can significantly reduce the amount of rendered passes needed for a composited image. This workflow can significantly improve the approach an artist takes in compositing by reducing the overall files needed. This keeps the overall files cleaner, manageable and efficient.
When exporting, the software is also capable of authoring EXRs with an included CryptoMatte. This can be done by using a CryptoMatte-Write Node and Port Names.
For more information about Port Filtering, see Port Filtering.