The depicted fax technology is analogue. It works really well on a quiet wire line, but even cross-country landline amplification in the USA in the 1920s or 1930s was pushing the limits of noise and distortion. You can always scan more slowly, of course. But you can also quantize. Digital signals are wonderfully robust. Heck, you can send an unamplified binary telegraph signal under an ocean.
One could imagine the photograph having a grid superimposed over it. And one could measure the intensity of light for each spot on the grid. Record those intensity values as numbers, perhaps automatically, to paper tape. Send that list over a telegraphic wire at high speed. Use the same size grid over a photographic plate. Read the tape, perhaps automatically, and expose the plate to light in proportion to the value of each recorded number.
Yes, it was actually done. The technique was invented in the 1920s, originally to send photographs over transatlantic telegraph cables before radio could reliably bridge the ocean. Sending a photograph of people leaving on a ship in London for New York, days before they arrived, meant a lot of money for newspapers. Definitely a market for it.
Can't find it freely online but some more info about the system is available: "Digital pictures 50 years ago", Proceedings of the IEEE ( Volume: 60, Issue: 7, July 1972) https://ieeexplore.ieee.org/document/1450705
1930s How Photographs Were Transmitted by Wire (1937) · HackerTrans
The depicted fax technology is analogue. It works really well on a quiet wire line, but even cross-country landline amplification in the USA in the 1920s or 1930s was pushing the limits of noise and distortion. You can always scan more slowly, of course. But you can also quantize. Digital signals are wonderfully robust. Heck, you can send an unamplified binary telegraph signal under an ocean.
One could imagine the photograph having a grid superimposed over it. And one could measure the intensity of light for each spot on the grid. Record those intensity values as numbers, perhaps automatically, to paper tape. Send that list over a telegraphic wire at high speed. Use the same size grid over a photographic plate. Read the tape, perhaps automatically, and expose the plate to light in proportion to the value of each recorded number.
Yes, it was actually done. The technique was invented in the 1920s, originally to send photographs over transatlantic telegraph cables before radio could reliably bridge the ocean. Sending a photograph of people leaving on a ship in London for New York, days before they arrived, meant a lot of money for newspapers. Definitely a market for it.
https://en.wikipedia.org/wiki/Bartlane_cable_picture_transmi...
Can't find it freely online but some more info about the system is available: "Digital pictures 50 years ago", Proceedings of the IEEE ( Volume: 60, Issue: 7, July 1972) https://ieeexplore.ieee.org/document/1450705