This article describes how journalists sent photographs across the Atlantic “instantly” in 1926. The most amazing thing to me is that the image is literally digitized into “pixels” along a helical scanline, quantized into 5 levels of gray—all through analog means.
So utterly fascinating.
An enterprising person could have used the 5 hole punches to encode 32 levels of gray, or used maybe 3 holes to encode 8 levels of gray, saving 40% of the transmission cost at the expense of making the machines more complicated…
@drahardja They also sent faxes over radio, not just telephone lines. Some radio stations would end their programming at midnight but stay on the air overnight for facsimile service. So there were wireless digital photos being sent in the '20s and '30s!
@drahardja
That's fascinating. I remember a project in one of the electronics magazines (1970s/early 80s), but might have been a much older mag as I had a lot of second-hand mags) that involved taping a picture to a revolving drum, and reading it in columns using (probably) an LDR. I forget how it was to be reproduced, now. I did think, later, on using it as an input device for my 8-bit home micro, but I never did manage to build a working version.
@robert The ThunderScan was basically exactly that. It was an attachment for the Apple ImageWriter dot matrix printer that takes the place of the ink cartridge. It had a single red LED and an LDR behind a lens, and used the printer’s motors to scan a document one line at a time.
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