exrTrader Pro - Cryptomatte
In addition to the other features, exrTrader Pro allows you to write Cryptomattes.
Cryptomattes - originally devised by Jonah Friedman and Andy Jones from psyop - allow you to store automatically generated mattes for all items or surfaces in a single OpenEXR image.
These can then be extracted in a compositing application using freely available plugins.
The levels determine how many different mattes may be stored per single pixel. 6 is usually a sufficient number.
You can also decide if the manifest - the file containing the names of the mattes - is stored embedded in the EXR image or as a separate file.
exrTrader Pro also allows you to select any of the OpenEXR compression types that are compatible with Cryptomatte.
Current Limitations: Volumes are not selectable via Crpytomattes. Reconstruction filters other than Box and a Filter Radius other than 0.0 will produce results differing from the LightWave 3D renders. We are working with the LightWave 3D developers to remove these limitations.