It was called "extended dynamic range" by ILM when they published the OpenEXR spec (2003):
> OpenEXR (www.openexr.net), its previously proprietary extended dynamic range image file format, to the open source community
https://web.archive.org/web/20170721234341/http://www.openex...
And "larger dynamic range" by Rea & Jeffrey (1990):
> With γ = 1 there is equal brightness resolution over the entire unsaturated image at the expense of a larger dynamic range within a given image. Finally, the automatic gain control, AGC, was disabled so that the input/output relation would be constant over the full range of scene luminances.
https://doi.org/10.1080/00994480.1990.10747942
I'm not sure when everyone settled on "high" rather than "large" or "extended", but certainly 'adjective dynamic range' is near-universal.
As I remember it, Paul Debevec had borrowed Greg Ward’s RGBE file format at some point in the late 90s and rebranded it “.hdr” for his image viewer tool (hdrView) and code to convert a stack of LDR exposures into HDR. I can see presentations online from Greg Ward in 2001 that have slides with “HDR” and “HDRI” all over the place. So yeah the term definitely must have started in the late 90s if not earlier. I’m not sure it was as there in the early 90s though.
Oo, interesting! That led me to this pair of sentences:
"Making global illumination user-friendly" (Ward, 1995) https://radsite.lbl.gov/radiance/papers/erw95.1/paper.html
> Variability is a qualitative setting that indicates how much light levels vary in the zone, i.e. the dynamic range of light landing on surfaces.
> By the nature of the situation being modeled, the user knows whether to expect a high degree of variability in the lighting or a low one.
Given those two phrases, 'a high or low degree of variability in the lighting' translates as 'a high or low degree of dynamic range' — or would be likely to, given human abbreviation tendencies, in successive works and conversations.