In the early 1950s it was recognized that one of the most important sources of information for computers would be from printed documents. Reading or Optical Character Recognition (OCR) machines were the answer, and several techniques were proposed and tested. The approach taken at the NBS Ordnance Laboratory differed from other techniques that analyzed the shape of characters or counted how many "black" areas they contained. A reading machine that employed a novel technique was invented at NBS in the early 1950s. It was called the DOFL (Diamond Ordnance Fuze Laboratory) Reader.
To give an example how this technique worked, consider the case where the unknown character is an "M". In the DOFL First Reading Machine, the comparison of the "M" was made optically to each of a set of negative pictures of the entire alphabet. The comparisons were scanned by a line scanner, the differences between the "M" and each of the others were noted and stored, and at the completion of the entire procedure, the closest match was determined.
In one machine built 10 years later, an unknown character was compared to each of a set of 360 characters, and the best match was determined in less than one microsecond.
The "best match principle" is now universally employed, not only in OCR machines, but in Magnetic Character Recognizers, other pattern recognizers, and in most voice recognizers.
The Reading Machine was done by Jacob Rabinow.
The Diamond Ordnance Fuze Laboratory (DOFL) Reader is shown in a schematic view.
Side and Rear view of the DOFL Reader.
Last Updated on October 24, 2004
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