A hdri file extension is related to the High-dynamic-range imaging format.
HDRI file extension - HDRI image
What is hdri file? How to open hdri files?
File type specification:
The hdri file extension is associated with the HDRI (High-dynamic-range imaging), a picture image file format used to reproduce a greater dynamic range of luminosity than is possible with standard digital imaging or photographic techniques.
MIME types:
image/hdri
This hdri file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.