Cryptomatte is an open-source standard used to encode accurate mattes to use later on for compositing. This technique isolates a rendered scene's pixel coverage according to properties such as materials, object names, and others for the purpose of adjusting these properties separately in post (figure 1).

The Cryptomatte AOV works with the Direct Light, Path Tracing, and Photon Tracing kernels to render Cryptomattes for use in compositing. They are rendered one at a time, and they contain the masks for all object layers or materials in a scene. The masks also have correct anti-aliasing, and they take into account other features such as motion blur, transparency, and depth-of-field. The Cryptomatte feature is exposed as an AOV under the Auxillary category (figure 2).

Figure 1: Main Beauty pass (left) and a Cryptomatte pass (right)



Figure 2: Accessing the Cryptomatte AOV in the Nodegraph Editor window


The Cryptomatte AOV has the following options and IDs available: