Browse Prior Art Database

Narrow Gap Detection for Optical Scanners

IP.com Disclosure Number: IPCOM000081217D
Original Publication Date: 1974-Apr-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Atrubin, AJ: AUTHOR [+3]

Abstract

Linear-array scanners in character recognition systems are sampled at discrete time intervals for quantizing the analog video signals into a digital image. Such sampling, however, may destroy narrow gaps between characters, so that adjacent characters cannot be properly segmented from each other.

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Narrow Gap Detection for Optical Scanners

Linear-array scanners in character recognition systems are sampled at discrete time intervals for quantizing the analog video signals into a digital image. Such sampling, however, may destroy narrow gaps between characters, so that adjacent characters cannot be properly segmented from each other.

Fig. 1 shows a representation of time-sampled signals 10. Each time slot is conventionally quantized into a bit whose value indicates that the cell is black (B) or white (W). Black bars such as 12 and 13 are separated by a gap 14 comparable to the sample spacing, and it is properly quantized at time slot 15. But the same size gap 16, between bars 13 and 17, is destroyed at slots 18 and
19.

Fig. 2 shows a system 20 for overcoming the effects of sample phasing on character segmentation. Blocks 21-24, respectively, represent a conventional linear array of photodetectors and timing circuits for sampling the video signals, a threshold generator for producing digital signals for each time slot, and character- segmentation logic of any conventional type.

Detector 25 is also coupled to the analog video signals from array 21. It produces a continuous output signal proportional to the maximum (blackest) signal seen by any detector in the array. A second threshold generator 26 produces a continuous signal which can be specifically optimized for the sensing of narrow white areas. Comparator 27 produces an output signal on line 28 whenever th...