Apparatus for recognizing graphic symbols

Claim 2

Apparatus for recognizing graphic symbols comprising means for scanning each of the symbols with a succession of substantially parallel scans along a plurality of parallel lines to derive an analog electrical signal which is a function of the symbol density, and means for establishing a correspondence between each symbol examined and one of a set of predetermined graphic symbols and supplying a recognition-effected signal at the end of the examination and recognition of a symbol, the apparatus further comprising first means for quantizing the analogue signal derived from a first symbol with at least two thresholds of different values to produce corresponding digital signals, second means for indicating by the digital signal corresponding to the threshold for each symbol examined one or more best of said different valued thresholds corresponding to a maximum number of portions of the lines forming the symbol having a thickness approximating the average thickness for the type of symbols examined, said second means comprising at least two counting circuits, one of said counting circuits operating on each of the digital signals, each of said circuits counting the line portions of the symbol having a thickness approximating the average thickness for the type of symbols examined, and means responsive to the counting circuits to indicate the digital signal or signals having a maximum number of portions of a thickness approximating to the average thickness; third means for selecting for recognition one of the digital signals derived by said first means from said first symbol in correspondence with a best threshold indicated for a previously recognized symbol; and fourth means controlled by the means for supplying the recognition-effected signal for commanding a re-examination of an unrecognized symbol by selecting one of the digital signals corresponding to said best different valued thresholds indicated during the scan of said first symbol.

Claim 3

Apparatus for recognizing graphic symbols comprising means for scanning each of the symbols with a succession of substantially parallel scans along a plurality of parallel lines to derive an analog electrical signal which is a function of the symbol density, and means for establishing a correspondence between each symbol examined and one of a set of predetermined graphic symbols and supplying a recognition-effected signal at the end of the examination and recognition of a symbol, the apparatus further comprising first means for quantizing the analogue signal derived from a first symbol with at least two thresholds of different values to produce corresponding digital signals, second means for indicating by the digital signal corresponding to the threshold for each symbol examined one or more best of said different valued thresholds corresponding to a maximum number of portions of the lines forming the symbol having a thickness approximating the average thickness for the type of symbols examined, said second means comprising at least two counting circuits, one of said counting circuits operating on each of the digital signals, each of said circuits counting the line portions of the symbol having a thickness approximating the average thickness for the type of symbols examined, and means responsive to the counting circuits to indicate the digital signal or signals having a maximum number of portions of a thickness approximating to the average thickness; third means for selecting for recognition one of the digital signals derived by said first means from said first symbol in correspondence with a best threshold indicated for a previously recognized symbol; and fourth means controlled by the means for supplying the recognition-effected signal for commanding a re-examination of an unrecognized symbol by selecting one of the digital signals corresponding to said best different valued thresholds indicated during the scan of said first symbol.

Claim 4

Apparatus for recognizing graphic symbols comprising means for scanning each of the symbols with a succession of substantially parallel scans along a plurality of parallel lines to derive an analog electrical signal which is a function of the symbol density, and means for establishing a correspondence between each symbol examined and one of a set of predetermined graphic symbols and supplying a recognition-effected signal at the end of the examination and recognition of a symbol, the apparatus further comprising first means for quantizing the analogue signal derived from a first symbol with at least two thresholds of different values to produce corresponding digital signals, second means for indicating by the digital signal corresponding to the threshold for each symbol examined one or more best of said different valued thresholds corresponding to a maximum number of portions of the lines forming the symbol having a thickness approximating the average thickness for the type of symbols examined, said second means comprising at least two counting circuits, one of said counting circuits operating on each of the digital signals, each of said circuits counting the line portions of the symbol having a thickness approximating the average thickness for the type of symbols examined, and means responsive to the counting circuits to indicate the digital signal or signals having a maximum number of portions of a thickness approximating to the average thickness; third means for selecting for recognition one of the digital signals derived by said first means from said first symbol in correspondence with a best threshold indicated for a previously recognized symbol; and fourth means controlled by the means for supplying the recognition-effected signal for commanding a re-examination of an unrecognized symbol by selecting one of the digital signals corresponding to said best different valued thresholds indicated during the scan of said first symbol.

Claim 5

Apparatus according to claim 1, wherein each of said counting circuits comprises a reversible counter.

Claim 6

Apparatus according to claim 2, wherein said second means includes comparison means coupled to said counters to compare with one another bits comprising each of said digital signals contained in the counters starting from the most significant place, the result of the comparison being stored in the indicator means

Claim 7

Apparatus according to claim 3, wherein the comparison of the bits in the counters is effected at a fixed significant place in each of the counters, and including means for causing the bits contained in the other places to shift in turn into the fixed place.

Claim 8

Apparatus according to claim 3, wherein the comparison of the bits in the counters is only effected on a given number of most significant places of said other places.

Claim 9

Apparatus according to claim 1, wherein the indication corresponding to the best threshold is cancelled at each re-examination of the character effected with this threshold as ordered by said fourth means.

Claim 10

Apparatus according to claim 1, wherein the indication corresponding to the best threshold is cancelled after a predetermined number of rE-examinations of the character effected with this threshold as ordered by said fourth means.

Claim 11

Apparatus for recognizing graphic symbols comprising means for scanning each of the symbols with a succession of substantially parallel scans along a plurality of parallel lines to derive an analog electrical signal which is a function of the symbol density, and means for establishing a correspondence between each symbol examined and one of a set of predetermined graphic symbols and supplying a recognition-effected signal at the end of the examination and recognition of a symbol, the apparatus further comprising first means for quantizing the analogue signal derived from a first symbol with at least two thresholds of different values to produce corresponding digital signals; second means for indicating by the digital signal corresponding to the threshold for each symbol examined one or more best of said different valued thresholds corresponding to a maximum number of portions of the lines forming the symbol having a thickness approximating the average thickness for the type of symbols examined said second means comprising, with respect to each of said digital signals, a register to staticize a group of electrical pulses obtained by sampling the digital signal, said electrical pulses corresponding to an area including a predetermined point, means for generating timing signals to shift the contents of the register so as to contain therein successively the signals for a plurality of areas encompassing all points of the symbol, and a logic circuit responsive to the register to indicate the line thickness associated with the predetermined point of each of said areas; third means for selecting for recognition one of the digital signals derived by said first means from said first symbol in correspondence with a best threshold indicated for a previously recognized symbol; and fourth means controlled by the means for supplying the recognition-effected signal for commanding a re-examination of an unrecognized symbol by selecting one of the digital signals corresponding to said best different valued thresholds indicated during the scan of said first symbol.

Claim 12

Apparatus for recognizing graphic symbols comprising means for scanning each of the symbols with a succession of substantially parallel scans along a plurality of parallel lines to derive an analog electrical signal which is a function of the symbol density, and means for establishing a correspondence between each symbol examined and one of a set of predetermined graphic symbols and supplying a recognition-effected signal at the end of the examination and recognition of a symbol, the apparatus further comprising first means for quantizing the analogue signal derived from a first symbol with at least two thresholds of different values to produce corresponding digital signals; second means for indicating by the digital signal corresponding to the threshold for each symbol examined one or more best of said different valued thresholds corresponding to a maximum number of portions of the lines forming the symbol having a thickness approximating the average thickness for the type of symbols examined said second means comprising, with respect to each of said digital signals, a register to staticize a group of electrical pulses obtained by sampling the digital signal, said electrical pulses corresponding to an area including a predetermined point, means for generating timing signals to shift the contents of the register so as to contain therein successively the signals for a plurality of areas encompassing all points of the symbol, and a logic circuit responsive to the register to indicate the line thickness associated with the predetermined point of each of said areas; third means for selecting for recognition one of the digital signals derived by said first means from said first symbol in correspondence with a best threshold indicated for a previously recognized symbol; and fourth means controlled by the means for supplying the recognition-effected signal for commanding a re-examination of an unrecognized symbol by selecting one of the digital signals corresponding to said best different valued thresholds indicated during the scan of said first symbol.

Claim 13

Apparatus according to claim 8, wherein the logic circuit includes means responsive to each of said digital signals for assigning to each predetermined point an integer indicating the line thickness, which integer is the number of points in the side of the largest square which has the predetermined point as a predetermined vertex thereof and which is completely filled with points indicated as being denser than the threshold by the digital signal.