WE can use almost any image format for the Skybox under visual settings. EXR is missing and is getting more common and it is a quality upgrade to the HDR files created by ILM. I know WE can export EXR to HDR with open source software like Gimp but takes a lot of time in case you have large libraries for EXR. Cheers
Submitted on AHA Ideas (ENSCAPE-I-1718).