@eriksandblom
It is complicated story and most of the news are from 2008 about re-processing of lost tapes by amateur enthusiasts, etc.
I found at least this mention:
http://astronautix.com/l/lunarorbiter.html
"The lunar orbiter used a film scanning process taken from a classified program and returned high-resolution images of the surface back to Earth."
Keeping the scanning process used by surveillance satellites secret would make perfect sense. But now I really feel bad, that I cannot find the original source of the story. I really don't want to seed misinformation.
https://www.kcra.com/article/60-years-before-artemis-ii-mcmoon-history/70945079
The tapes contained the data that would be decoded by what was called a de-modulator. That technology, however, had been classified during the cold war.
The spy satellite system was called SAMOS. I am really not sure, if NASA had access to better resolution internally and just could not publish tem, or if the better resolution would be available only to intelligence agencies. But the story of classified technology made available to civilian space agency is real, and the pressure to keep the existence of the technology classified seems real. There seems to exist book written about it.
@pomarede