How did wirephoto work?
March 24, 2012 10:04 PM   Subscribe

How did Wirephoto (news wire photo transmission) work ca. 1948 or earlier? Transmission over phone lines of...pixels? Was there error correction? Etc.

Just finished watching Northside 777 and was shocked not only by the early example of an "ENHANCE PHOTO" sequence but by the fact that a newswire photo service existed.

I looked up wirephoto @ Wikipedia but frustratingly there's no information about how the technology worked back then.

Any information would be appreciated. Just wondering how it was different from the dialup modem transmission system I used in the 1980s.
posted by circular to Technology (8 answers total) 18 users marked this as a favorite
Best answer: "In 1918 H. Nyquist began investigating ways to adapt telephone circuits for picture transmission. By 1924 this research bore fruit in "telephotography" - AT&T's fax machine.

The principles used in 1924 were the same as those used today, though the technology was comparatively crude. A photographic transparency was mounted on a spinning drum and scanned. This data, transformed into electrical signals that were proportional in intensity to the shades and tones of the image, were transmitted over phone lines and deposited onto a similarly spinning sheet of photographic negative film, which was then developed in a darkroom. The first fax images were 5x7 photographs sent to Manhattan from Cleveland and took seven minutes each to transmit.
1924: Fax Service". AT&T Labs timeline.

Here are some other really cool accounts of how it worked,

Cook, Charles Emerson. “Pictures by Telegraph,” Pearson’s Magazine. April 1900. HTML transcription. (Retrieved 2010-06-30.) See here for facsimile reprint. (Retrieved 2010-06-30.)

"Photo Sent In Less Than A Minute" Popular Science, September 1929

"Wire That Photo" Popular Mechanics, July 1937, pp 392-395
posted by Blasdelb at 10:27 PM on March 24, 2012 [4 favorites]

Best answer: The Fax was actually invented before the telephone. Some high level info is available on wikipedia
posted by bottlebrushtree at 10:28 PM on March 24, 2012

Best answer: The ever-entertaining Secret Life of Machines has a nice demo of the tech.
posted by pompomtom at 10:36 PM on March 24, 2012 [3 favorites]

Ace question and comments!
posted by carter at 6:04 AM on March 25, 2012

Response by poster: Thanks for those responses! It would indeed make a good MeFi post.
posted by circular at 7:06 AM on March 25, 2012

Best answer: There are still some simple bitmap modes that scan this way used in amateur radio: Hellschreiber (a bitmap mode for sending text on tickertape; a printer demo, an Arduino sketch that can send Hellschreiber), SSTV (sends colour pictures, some examples recently received at stations around the world [potential cheescake warning]), and WEFAX.
posted by scruss at 7:42 AM on March 25, 2012

pompomtom: "The ever-entertaining Secret Life of Machines has a nice demo of the tech."

That was fascinating. I know what I'm doing with my Sunday afternoon now!
posted by Petrot at 8:37 AM on March 25, 2012

Best answer: In short, the original machines (with the rotating drum at each end of the connection) sent the information by analog signal, not using pixels.

Modern machines (no rotating drums) send the information digitally, using pixels.
posted by exphysicist345 at 7:08 PM on March 25, 2012

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