Cryptomattes in Blender

To achieve this, follow these steps in Blender using the Cycles Render Engine (Version 3.5):

  1. Set your render engine to Cycles.
  2. In the View Layer Properties, locate the Cryptomatte section.
  3. Choose the Cryptomatte option that suits your needs: Object, Material, or Asset.
  4. In the Compositing tab, enable the Use Nodes option.
  5. You'll find a Render Layers node and a File Output node. Press Shift+A to create a new output node.
  6. Connect the File Output node to your Crypto Passes.
  7. Adjust the node options by changing the file output format from PNG to OpenEXR MultiLayer.
  8. Within the node view of the File Output node, click on Add Input.
  9. Add your three Cryptomatte passes and make sure their names match those in your Render Layers.
  10. Render your images, and you're all set for compositing.