OPTICAL CHARACTER RECOGNITION SYSTEM

• US 3,723,970 A
• Filed: 01/04/1971
• Issued: 03/27/1973
• Est. Priority Date: 01/04/1971
• Status: Expired due to Term

• Current Assignee: Scan-Optics, Incorporated (Scan-Optics LLC)
• Original Assignee: Milton Stoller
• Inventors: Stoller, Milton
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Boudreau, Leo H.
• Application Number:
  US05/103,646
• Time in Patent Office: 813 Days
• Field of Search: 340/146.3MA,146.3AC,146.3AG,146.3F,146.3H,146.3R 356/71
• US Class Current: 382/270
• CPC Class Codes: G06V 10/20 Image preprocessing
• CPC Class Codes: G06V 10/28 Quantising the image, e.g. histogram thresholding for discrimination between background and foreground patterns
• CPC Class Codes: G06V 10/40 Extraction of image or video features
• CPC Class Codes: G06V 10/46 Descriptors for shape, contour or point-related descriptors, e.g. scale invariant feature transform [SIFT] or bags of words [BoW]; Salient regional features colour feature extraction G06V10/56

Abstract

As described herein, a program controlled image dissector tube scans the printed information recorded on a storage medium to provide analog information signals. The analog signals are converted into digital data signals representative of the segmental brightness of the scanned storage medium and thereafter accumulated in an image enhancement network. In the image enhancement network, selected arrays of the signals are scanned to develop directional and threshold digital data bits representative of the character information contained in each of the arrays. These digital data bits are, in turn, accumulated to provide arrays of the digital data bits representative of entire characters. The presence or absence of selected digital data bits in each of the arrays is then detected and the detected digital data bits combined to provide a character representative signal.

Claims

1. Optical character recognition apparatus comprising means for scanning a storage medium having recorded thereon character representative symbols to develop analog information signals representative of the brightness of the storage medium, converter means for converting the analog information signals into digital data signals representative of a range of the segmental brightness of the scannEd storage medium, enhancement network means including means for accumulating the digital data signals into predetermined arrays and means for periodically sampling selected directional sets of digital data signals within said predetermined arrays to develop directional digital data bits and threshold digital data bits, each of the directional digital data bits representing the set of said directional sets having the least brightness and threshold digital data bits characterizing said directional digital data bits as black or white, register means for accumulating the directional and threshold digital data bits in a sequential manner in arrays to provide arrays of such directional and threshold digital data bits representative of entire characters, detection means for detecting the presence and absence of such directional and threshold digital data bits in said arrays and means for combining the detected directional and threshold digital data bits to provide a character representative signal.

2. Optical character recognition apparatus according to claim 1 wherein the enhancement network means comprises register means for sequentially accumulating the digital data signals into sequential arrays corresponding to the scanning of a selected area on the storage medium by the scanning means and means for periodically sampling selected directional sets of the digital data signals accumulated in the arrays for developing each sampling directional digital data bits representative of the set of said directional sets having the least brightness and threshold digital data bits characterizing said directional digital data bits as black or white, said directional and threshold digital data bits representative of the character information contained in each of the arrays.

3. Optical character recognition apparatus according to claim 2 wherein the register means comprises a plurality of storage means for sequentially accumulating the digital data signals into arrays corresponding to the scanning of a selected number of scanning lines on the storage medium by the scanning means and the sampling means comprises means for sampling periodically the digital data signals accumulated in selected storage means extending in a plurality of directions outwardly from a common reference storage means for developing each sampling directional digital data bits representative of the storage means storing the digital data signals representative of the least brightness and threshold digital data bits characterizing said directional digital data bits as black or white.

4. Optical character recognition apparatus according to claim 3 wherein the sampling means comprises means for separately adding the digital data signals stored in the storage means extending in different directions to provide analog sum signals representative of the magnitudes of said digital data signals and comparator means responsive to the sum signals, the comparator means comprising means for generating directional digital data signals representative of the sum signals having the smallest magnitudes and means for detecting sum signals having amplitudes less than a predetermined amplitude to produce threshold digital data signals.

5. Optical character recognition apparatus according to claim 1 wherein the register means comprises first means for sequentially accumulating the directional and threshold digital data bits representative of the character information contained in each array sampled by the sampling means and second means coupled to the first means for accumulating the directional and threshold digital data bits representative of the character information contained in a plurality of sampled arrays to thereby provide directional and threshold digital data bits representative of entire characters.

6. Optical character recognition apparatus according to claim 5 further comprising means for transferring the directional and threshold data bits accumulated in the first means to the second means at a variable frequency.

7. Optical character recognition apparatus according to claim 6 wherein the transfer means comprises a source of timing signals for supplying alternate sets of timing signals to said first means to effect the sequential transfer of the directional and threshold data bits from the first means to the second means at a fast frequency and at a slow frequency.

8. Optical character recognition apparatus according to claim 7 wherein the number of timing signals occurring at the fast frequency corresponds to one-half the number of threshold and directional digital data bits accumulated by the first means and the number of timing signals occurring at the slow frequency corresponds to the other one-half the number of accumulated threshold and directional digital data bits.

9. Optical character recognition apparatus according to claim 8 wherein the second means comprises a plurality of shift registers coupled together in serial fashion, each register designed to accumulate the directional and threshold digital data bits accumulated by the first means, whereby the plurality of shift registers accumulate directional and threshold digital data bits representative of entire characters.

10. Optical character recognition apparatus according to claim 9 wherein the detection means comprises means for scanning a predetermined array of stages in the plurality of shift registers to determine the presence or absence of threshold and directional data bits in such stages by which the microfeatures of characters can be identified.

11. Optical character recognition apparatus according to claim 10 wherein the source of timing signals includes means for generating an enabling signal and supplying such signals to the detection means to enable the detection means to detect threshold and directional data bits in the stages of the shift registers during the occurrence of the slow frequency timing signals.

12. Optical character recognition apparatus according to claim 11 wherein the detection means further comprises feature recognition network means responsive to the detected threshold and directional data bits for generating signals representative of microfeatures by which characters can be identified.

13. Optical character recognition apparatus according to claim 12 wherein the combining means comprises means responsive to the signals representative of microfeatures for combining such signals to produce character representative signals.

14. Optical character recognition apparatus according to claim 12 wherein the combining means comprises means responsive to the signals representative of the positive and negative microfeatures by which a character can be identified for combining such signals to produce character representative signals.

15. Optical character recognition apparatus according to claim 14 further comprising matching circuit means operatively coupled to the combining means for precluding the simultaneous production of more than one character representative signal.

16. Optical character recognition apparatus according to claim 14 further comprising matching circuit means operatively coupled to the combining means for transmitting character representative signals having amplitudes greater than a predetermined amplitude.

17. Optical character recognition apparatus according to claim 16 further comprising encoder circuit means responsive to the transmitted character representative signals for encoding such signals into binary coded signals representative of such characters.

18. Optical character recognition apparatus according to claim 1 wherein the scanning means comprises an image dissector for dissecting the photoelectric image of the storage medium in a line-by-line scanning pattern to develop analog information signals having line-by-line components.

19. Optical character recognition apparatus according to claim 18 further comprising control means coupled to the image dissector for controlling the frequency of the scanning by the dissector and the area of the photoelectric image dissected by the image dissector.