Digital pictures fifty years ago

Automatic translation of the lights and shades of a picture into a digital record tape and its reconversion to a picture were elements of the Bartlane picture transmission system in operation on telegraph circuits fifty years ago. s. Using digital signals on submarine cables, the Bartlane system handled nearly 500 pictures of portant news events prior to the outbreak of war in Europe in 1939. Publication of the first pictures cabled from New York to London in 1920-1921 established the Bartlane method of employing the picture machines off line and using standard printing telegraph apparatus operated by regular telegraph personnel for accurate transmission of the picture signals. With the communication link determined, experimental work was concentrated on improvements in the methods of converting a picture into a telegraph tape and of recovering the picture.