In 1904, Arthur Korn succeeded in transmitting a photograph by telegraph. His "selenium machine" illuminated a transparent image foil with a bundled beam of light. Using a prism, it fell onto a selenium cell, which changed its electrical resistance according to the changing brightness values. The template was divided into a line grid, transferred step-by-step, and recomposed into a photographic copy into the receiver. The first official transmission took place in 1907.
At that time, it took 24 minutes to send a photograph measuring 12 x 18 cm using the "selenium machine." When the image was rastered, the transmission time was reduced to 12 minutes, but this lowered the quality of the image. Korn sent this photograph of the Bavarian Prince-Regent from Munich to Nuremberg as a test in 1904. After further improvement of the method, the first official transmissions within Germany and Europe followed, starting in 1907. In 1922, the first photograph was sent to the US.
Details