PATTERN RECOGNITION SYSTEM

• US 3,846,755 A
• Filed: 08/06/1973
• Issued: 11/05/1974
• Est. Priority Date: 12/15/1969
• Status: Expired due to Term

• Current Assignee: William H. Hart
• Original Assignee: William H. Hart
• Inventors: Hart, William H.
• Primary Examiner(s): Shaw, Gareth D.
• Assistant Examiner(s): Boudreau, Leo H.
• Application Number:
  US05/385,713
• Time in Patent Office: 456 Days
• Field of Search: 340/146.3H,146.3R,146.3AG,146.3G,347AD 356/71 235/183
• US Class Current: 382/206
• CPC Class Codes: G06V 30/144 using a slot moved over the image; using discrete sensing elements at predetermined points; using automatic curve following means
• CPC Class Codes: G06V 30/162 Quantising the image signal
• CPC Class Codes: G06V 30/18 Extraction of features or characteristics of the image

Abstract

A pattern recognition system scans an unknown pattern to detect moments of successive slices or portions of the pattern. Certain of these moment signals are selected in various sections of the pattern to obtain comparison parameters based on characteristics of the sections. These comparison parameters and parameters for reference patterns are compared to identify the unknown pattern.

Claims

1. A method of identifying an unknown pattern comprising the steps of:

A. measuring a plurality of moments about at least one predetermined axis in each of successive portions of the pattern, at least two of the moments being different moments with respect to the same axis, B. generating a moment signal corresponding to the value of each of the measurements, C. selecting certain of the moment signals indicative of predetermined characteristics of the pattern in sections thereof less than the entire pattern, D. generating a plurality of comparison parameter signals including comparison parameter signals for the sections, at least one of the comparison parameter signals for a section being generated by taking a ratio of said moment signals, at least one moment signal for that ratio being a preselected moment signal for that section, and E. comparing the values of the comparison parameter signals with corresponding values of reference patterns to identify the unknown pattern.

2. A method as recited in claim 1 wherein said selecting step includes the selection of moment signals in sections of the pattern which produce maximum and minimum values of a moment signal and said comparison parameter signal generating step additionally generates signals corresponding to the value of a moment signal for those sections.

3. A method as recited in claim 1 wherein said measuring and moment signal generating steps develop signals representing moments of a pattern about a first axis, said moment signal generating step additionally including generating signals representing moments of the pattern about a second axis perpendicular to the first axis.

4. A method as recited in claim 1 wherein said moment signal generating step inclUdes:

i. generating a moment signal proportional to the area of the pattern in each portion, and ii. generating a moment signal proportional to the aggregate distance of the pattern area in each portion from an axis perpendicular to the direction of succession of the portions.

5. A method as recited in claim 4 wherein said moment signal generating step additionally includes generating a moment signal disproportionate to the aggregate distance.

6. A method as recited in claim 1 wherein said selecting step includes the selection of moment signals in sections of the pattern which produce maximum and minimum values of a moment signal and said comparison parameter signal generating step additionally generates signals corresponding to the integrals over sections of moment signals in the sections.

7. A method as recited in claim 6 wherein said selecting step includes the selection of moment signals in other sections of the pattern which produce moment signal values which are other than maximum and minimum values and said comparison parameter signal generating step additionally generates comparion parameter signals corresponding to integrals over sections of moment signals in the other sections.

8. A method as recited in claim 1 wherein at least one comparison parameter signal represents a comparison of moment signals representing moments of different sections of the pattern.

9. A method as recited in claim 6 wherein in one section the selected moment signal is a maximum and in another section a selected moment signal is a minimum.

10. A method as recited in claim 1 wherein said moment signal generating step includes:

i. generating a moment signal proportional to the area of the pattern in each portion, and ii. generating a moment signal proportional to the aggregate distance of the pattern area in each portion from the predetermined axis, the predetermined axis being parallel to the direction of succession of the portions.

11. A method as recited in claim 10 wherein said moment signal generating step additionally includes generating a moment signal disproportionate to aggregate distance from the predetermined axis.

12. A system for identifying a pattern, said system comprising:

A. means for measuring a plurality of moments about at least one predetermined axis in each of successive portions of the pattern, at least two of the moments being different moments with respect to the same axis, B. means connected to said measuring means for generating a moment signal corresponding to the value of each measured moment, C. means for selecting certain of the moment signals indicative of predetermined characteristics of the pattern in sections thereof less than the entire pattern, D. means connected to said moment signal generating means and said selecting means for generating a plurality of comparison parameter signals including comparison parameter signals for the sections, at least one of the comparison parameter signals for a section being generated by taking a ratio of the moment signals, at least one moment signal for that ratio being a preselected signal for that section, and E. means connected to said comparison parameter signal generating means for comparing the values of the comparison parameters with corresponding values of reference patterns to identify the unknown pattern.

13. The system defined in claim 12 in which said comparison parameter signal generating means includes means for generating a signal representing the centroid position of a section of the pattern in which the zero order moment is other than a maximum, the centroid position being obtained from the zero and first order moment signals.

14. The system defined in claim 12 in which the moment signals correspond to the zero, first and second order moments with respect to the axis, said measuring means additionally including i. means for developing time signals representing the elapsed time from commencement of the measurinG of said moments and the square of the elapsed time, and ii. means for multiplying said zero moment by said time signals to provide further moment signals corresponding to the first and second order moments of said portions about a second axis tranverse to said first axis.

15. The system defined in claim 12 A. said selecting means including means for detecting the occurrence of maxima of at least one of said moment signals, and B. said comparison parameter signal generating means including means for counting the number of maxima of each moment for which the maxima are detected, the output of said counting means constituting a comparison parameter signal.

16. The system defined in claim 12 in which said selecting means includes means for selecting moment signals in a section corresponding to the occurrence of the peak value of one of said moment signals and said comparison parameter generating means includes means for integrating over sections a plurality of the moment signals in the sections.

17. The system defined in claim 16 in which said selecting means includes means for selecing moment signals in other sections in which a selected moment signal is at other than the peak value said compison parameter signal generating means includes means for integrating over sections a plurality of the moment signals in the sections corresponding to the other sections.

18. The system defined in claim 12 in which the moment signals represent the zero, first and second order moments, said comparison parameter signal generating means additionally including A. means for obtaining a first ratio of the first moment signal to the zero moment signal, and B. means responding to changes in the value of the first ratio to provide a signal indicating the presence of a single slope signal in said pattern.

19. The system defined in claim 18 wherein said comparison parameter signal generating means further includes A. means for obtaining a second ratio of the second moment signal to the zero moment signal, and B. means responding to changes in the value of the second ratio to provide a double slope signal responsive to a double slope in said pattenr.

20. A system as recited in claim 12 wherein said moment signal generating means includes:

i. means for generating a moment signal proportional to the area of the pattern in each portion, and ii. means for generating a moment signal proportional to the aggregate distance of the pattern area in each portion from the predetermined axis, the predetermined axis being parallel to the direction of succession of the portions.

21. A system as recited in claim 18 wherein said moment signal generating means additionally includes means for generating a moment signal disproportionate to the aggregate distance.

22. A system as recited in claim 12 wherein said moment signal generating means includes i. means for generating a moment signal proportional to the area of the pattern in each portion, and ii. means for generating a moment signal proportional to the aggregate distance of the patern area in each portion from an axis perpendicular to the direction of succession of the portions.

23. A system as recited in claim 22 wherein said moment signal generating means additionally includes means for generating a moment signal disproportionate to the aggregate distance.