I have read here, in Forum, so many questions and feature requests from Arnold users to have Cryptomatte editing tool in Photoshop, and now it is here.
The free Exr-IO 2 Photoshop plugin can automatically read all your AOVs and Cryptomattes and create masks (or whatever you want) of it.
I have posted also a step-by-step Tutorial about how to utilize Cryptomattes and few base AOVs in the production pipeline.
Hope it helps for the start :)
Exr-IO 2.00 https://www.exr-io.com/exr-io-2-00/
3d-io has released the Exr-IO 2.00, the free OpenEXR plug-in for Adobe Photoshop.
The new version of the popular Exr-IO file format plug-in includes support for additional features like cryptomatte decoding, support for mipmaps and ripmaps, reduced memory consumption and numerous quality, compatibility and stability improvements with better error handling.
Exr-IO 2.00 aims to be as feature complete as possible to allow users to read and write the full scope of EXR image data wherever possible.