alt Hacker NewsThere were different degrees of quality with holograms. To my recollection, a hologram on glass, that you illuminated with a laser, were stunning in clarity and sense of three dimensionality.
All other variants were degrees of magnitude worse.
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They're also useful for analytical purposes.
It's possible to do this with digital methods, too, but the lower spatial resolution of most digital LCDs and most digital camera sensors (compared to film) limits it somewhat. But I think it'd be more practical than the analog film based analytical holograms.
You are describing transmission holograms, the best visual fidelity but it had to be illuminated by laser light. Reflection holograms had a small field of depth before getting blurry but we're visible in white light. Dichromate Gelating (DCG) holograms were also white-light visible, had a smaller depth field than reflection holograms, but we're very sharp and bright. A lot of novelties were made using the DCG process, like novelty glasses that had alien eyeballs in the lenses.
The Science Museum in London used to have a life-sized holoportrait of Denis Gabor. It looked like a milky plate until you pushed the button that turned on the laser, and... there he was. Stunning.
There was a short-lived flurry of art establishment interest in high quality glass holograms, but the process is just too expensive and fragile to create non-niche art.
I always expected that at some point we'd have dynamic holographic displays, but the processing and resolution requirements are insane.
Holographic film has a resolution in the region of 100,000 to 250,000 ppi, which is quite a bit more than 300dpi for print or a few thousand PPI for plain old film. If you could build a 27" display with that resolution you'd need maybe 1TB per frame at a minimum.
You could probably apply quite a bit of compression to get that down on input, but that's still the order of a workable frame store memory.
Multiply by three for colour.