A photograph in a computer’s memory
On 9 December 1957 Russell Kirsch and three colleagues at the US National Bureau of Standards described a drum scanner attached to the SEAC computer. In 25 seconds it turned a 44 x 44 mm picture into 176 by 176 binary digits, and a program displayed the picture back on an oscilloscope.
Why it matters
Until then a computer received data a person had already described: punched cards, tape, recognised characters. Here a picture became for the first time an array of numbers in memory that a program could read, change and show again - the starting point both for recognition and for everything a machine would later do to make or alter an image.
Paper at the Eastern Joint Computer Conference, pages 221-229. Each binary digit stood for a 0.25 mm square, black or white; one picture took 704 words of SEAC’s 1500-word memory. Grey levels came from several scans at different thresholds, and a halftone in a single scan from a threshold varied as a sawtooth (Fig. 3, "computer halftone reproduction"). That the first picture scanned on SEAC was Kirsch’s baby son is stated by Kirsch himself in his 1998 recollection in IEEE Annals of the History of Computing; the 1957 paper is silent on it. The name Walden and a size of 5 cm come only from NIST in 2007, while the recollection, like the paper, describes 0.25 mm squares in a 176 by 176 grid, that is 44 mm.