CryptoMatte Node IDs

When an EXR file with CryptoMatte information is exported, multiple layers of data will be created. Each of the layers correspond to an object ID and the amount of coverage (opacity) that the object contributes to that layer. Often, the EXR file will also contain a flat composite image along with a variety of layers and channel information.

When the exporting software is creating the EXR, it will generate CryptoMatte channels that provide both an object ID and this object’s overall coverage in that layer. By using the IDs and its coverage, the CryptoMatte Node can identify how much of a final image was created by the object in the original source. Based on its contributing pixels, custom matte passes can then be created for each object via its IDs.