DETAIL BOUNDARY DETECTION SYSTEMS

• US 3,696,249 A
• Filed: 09/14/1970
• Issued: 10/03/1972
• Est. Priority Date: 09/14/1970
• Status: Expired due to Term

• Current Assignee: John Kent Bowker
• Original Assignee: John Kent Bowker
• Inventors: Bowker, John Kent
• Primary Examiner(s): Lawrence, James W.
• Assistant Examiner(s): Nelms, D. C.
• Application Number:
  US05/071,816
• Time in Patent Office: 750 Days
• Field of Search: 250/202,23R,23CT,206,208,209,220,219FR 309/311 178/6,6.8,7.5,5.2R,5.2A,DIG.2,DIG.3
• US Class Current: 250/559.44
• CPC Class Codes: G01N 21/5907 Densitometers
• CPC Class Codes: G01N 21/5911 of the scanning type scanning per se G02B
• CPC Class Codes: G06F 3/002 Specific input/output arrangements not covered by G06F3/01 - G06F3/16 other optical apparatus G02B27/00
• CPC Class Codes: G06V 10/10 Image acquisition document image scanning and transmission H04N1/00; control of digital cameras H04N23/60
• CPC Class Codes: G06V 10/12 Details of acquisition arrangements; Constructional details thereof
• 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: G07C 5/002 Analysing tachograph charts arrangements for graph-reading in general G06K11/00
• CPC Class Codes: H04N 1/40093 Modification of content of picture, e.g. retouching geometric modifications H04N1/387

Abstract

Disclosed are detection systems that systematically scan given areas of an object to locate detail boundaries therein. The systems compare radiant energy levels emanating from twodimensionally spaced apart sub-divisions of each scanned area so as to produce an output signal that represents energy level gradients but is independent of gradient orientation with respect to the direction of scan.

Claims

1. A system for detecting significant detail boundaries contained on an object and for producing lines representative of said detail boundaries comprising:

a. means for systematically scanning said object;

b. means for sequentially examining a large plurality of separate two-dimensional areas of said object during the scanning thereof, said examining means including;

1. means for receiving the radiant energy emanating from a plurality of area sub-divisions of each of said twodimensional areas and for producing a plurality of output signal values each of which are a function of the level of radiant energy emanating from a different one of said plurality of area sub-divisions; and

2. means for analyzing said plurality of output signal values and for producing a gradient detection signal dependent upon differences between said plurality of output signal values, which differences result from and indicate the presence of one or more significant detail boundaries within each of said twodimensional areas, said analyzing means further including gradient orientation detection means for detecting the orientation of said indicated detail boundaries within each of said two-dimensional areas independent of the direction of scan of said scanning means; and

c. output means coupled to said analyzing means for producing lines representative of said significant detail boundaries.

2. A system according to claim 1 wherein said energy receiving means comprises radiant energy detection means for producing a plurality of output signals each having a value representing the level of radiant energy emanating from a different one of said area sub-divisions.

3. A system according to claim 2 wherein said analyzing means comprises difference circuit means for producing said gradient detection signal dependent upon differences between the values of said plurality of output signals.

4. A system according to claim 3 wherein said analyzing means further comprises polarity control circuit means for establishing a constant polarity for said gradient detection siGnal.

5. A system according to claim 4 wherein said analyzing means comprises logarithmic circuit means for providing said gradient detection signal with a logarithmic response characteristic.

6. A system according to claim 4 wherein said analyzing comprises threshold means for producing said gradient detection signal in response to the signal value differences detected by said difference circuit means.

7. A system according to claim 2 wherein said radiant energy detection means comprises individual radiant energy detectors receiving energy emanating from each of said area sub-divisions and for producing said plurality of output signals.

8. A system according to claim 7 wherein said energy receiving means comprises a plurality of separate radiant energy transmission paths for isolating the radiant energy emanating from each of the plurality of area sub-divisions and for transmitting said isolated radiant energy to a different one of said individual radiant energy detectors.

9. A system according to claim 7 wherein said analyzing means comprises logarithmic circuit means for providing said gradient detection signal with a logarithmic response characteristic.

10. A system according to claim 7 wherein said area sub-divisions lie in quadrant portions of each of said two-dimensional areas and wherein said analyzing means comprises difference circuit means for producing a first signal dependent on the difference between the values of said output signals representing radiant energy levels from one diagonal set of said quadrant portions and a second signal dependent on the difference between the values of said output signals representing radiant energy levels from the other diagonal set of said quadrant portions.

11. A system according to claim 10 wherein said analyzing means comprises a polarity control circuit means for establishing a constant polarity for said first and second signals.

12. A system according to claim 11 wherein said polarity control circuit means comprises squaring circuit means for squaring said first and second signals.

13. A system according to claim 12 wherein said analyzing means comprises summing circuit means for adding the values of said first and second signals to produce said gradient detection signal.

14. A system according to claim 1 wherein said energy receiving means includes sweep control means for sequentially changing said area sub-division of each of said two-dimensional areas from which emanating radiant energy is received by said energy receiving means, said energy receiving means further including means for producing an alternating signal output with an amplitude varying in response to varying energy levels emanating from said sequentially changing area sub-divisions.

15. A system according to claim 14 wherein said analyzing means comprises logarithmic circuit means for providing said gradient detection signal with a logarithmic response characteristic.

16. A system according to claim 14 wherein said sweep control means comprises a frequency control means for providing a constant frequency for said sequential changes in the area sub-divisions from which radiant energy is received by said energy receiving means.

17. A system according to claim 16 wherein said analyzing comprises band-pass filter means for isolating a given frequency band component of said alternating signal output.

18. A system according to claim 17 wherein said sweep control means comprises an energy beam that selects said sequentially changing area sub-divisions, and cyclical means for moving said beam in a path that selects annularly distributed area sub-divisions in said given areas.

19. A system according to claim 18 wherein said analyzing comprises a threshold means that receives the output of said band-pass filter means and produces said gradient detection signal.

20. A system according to claim 18 wherein said sweep control means comprises cyclical means for moving said beam in a substantially circular path on said object.

21. A system according to claim 20 wherein said sweep control means comprises a cathode ray tube, said energy beam comprises a light beam produced by said cathode ray tube and directed onto said object so as to generate said radiant energy emanating therefrom, said cyclical means comprise deflection control circuit means coupled to deflection coils of said cathode ray tube and adapted to produce said substantially circular motion of said light beam on said object, and said scanning control means comprise raster generator means coupled to said deflection coils of said cathode ray tube.

22. A system according to claim 20 wherein said sweep control means comprises:

a. lamp means for directing a focussed beam of radiation onto said object;

b. a tilt plate positioned between said lamp means and said object through which said beam passes; and

c. means for rotating said tilt plate for moving said beam in a substantially circular path on said object.

23. A system according to claim 17 including a camera tube and wherein said energy receiving means comprises the anode of said camera tube, and optical means for producing an optical image of said object on the cathode of said camera tube, said sweep control means comprises deflection means of said camera tube, said cyclical means comprise deflection control circuit means coupled to said deflection electrodes and adapted to deflect electrons from circularly distributed area sub-divisions of given areas on said cathode, and said scanning control means comprise raster generator means coupled to said deflection electrodes.

24. A system according to claim 23 wherein said frequency control means produces a reference phase signal of said constant frequency, and said gradient orientation detection means comprises phase comparison means for comparing the phases of said reference phase signal and said given frequency band component.

25. A system according to claim 1 wherein said area sub-divisions lie in quadrant portions of said two-dimensional area, said radiant energy receiving means comprises radiant energy detectors receiving energy emanating from each of said quadrant portions and producing output signals each having a value representing the level of radiant energy emanating from a different one of said quadrant portions and said analyzing means comprises difference circuit means for producing a first signal dependent on the difference between the values of said output signals representing radiant energy levels from one diagonal set of said quadrant portions and a second signal dependent on the difference between the values of said output signals representing radiant energy levels from the other diagonal set of said quadrant portions.

26. A system according to claim 25 wherein said gradient orientation detection means comprises means for determining the value ratios between said first and second signals.