Topographic feature extraction using sensor array system

• US 4,590,608 A
• Filed: 05/30/1980
• Issued: 05/20/1986
• Est. Priority Date: 05/30/1980
• Status: Expired due to Term

• Current Assignee: The United States Of America As Represented By The Secretary Of The Army
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Chen, Pi-Fuay, Rohde, Frederick W., Seemuller, William W.
• Primary Examiner(s): Krass, Errol A.
• Application Number:
  US06/154,661
• Time in Patent Office: 2,181 Days
• Field of Search: 364/514, 364/515, 364/521, 364/522, 364/727, 364/498, 358/108, 358/109, 340/146.3 F, 340/146.3 G, 340/146.3 P, 340/17 A, 382/16, 382/43
• US Class Current: 382/281
• CPC Class Codes: G06V 10/431 Frequency domain transformation; Autocorrelation

Abstract

A method and apparatus for topographic feature extraction by masking a video signal representation of an optical image using a two-dimension Walsh function is disclosed. The optical energy of an image is converted into a video signal. A Walsh function signal in accordance with a two-dimension Walsh is generated. The video signal is multiplied with the Walsh function signal to produce a Walsh transform coefficients signal indicative of the decomposed spectral components of the image. The method and apparatus can further include providing selected topographical feature signals in accordance with the Walsh transform coefficients of selected topographic features. A selected topographical feature can be detected by comparing the Walsh transform coefficients signal with the selected topographical feature signals. The Walsh transform coefficients signal is unique to the selected topographical feature being detected.

Claims

1. Apparatus comprising:

a. means for converting optical energy of an image into a video signal;

b. means for generating a Walsh function signal in accordance with the equation;

##EQU2## where;

a(i,j) is said Walsh transform coefficients signal;

i and j indicate the order of said Walsh function signal; and

n and m are integers; and

f(k,1) is said video signal; and

c. means for multiplying said video signal with said Walsh function signal to produce a Walsh transform coefficient signal indicative of the decomposed spectral components of said image.

2. The apparatus as recited in claim 1, wherein said generating means comprises:

control signal means for providing a modified clock signal, an end of line signal, and an end of frame signal under effective control of said converting means;

X Walsh function generator means responsive to said modified clock signal and said end of line signal for providing a first pair of output signals;

X decoder means responsive to said first pair of output signals and said end of frame signal for providing an X Walsh signal;

Y Walsh function generator means responsive to said end of line signal and said end of frame signal for providing a second pair of output signals;

Y decoder means responsive to said second pair of output signals for providing a Y Walsh signal; and

exclusive OR means having inputs responsive to said X Walsh signal and said Y Walsh signal, respectively, for providing at an output said Walsh function signal.

3. The apparatus as recited in claim 1, wherein said multiplying means includes a plurality of electronic gates.

4. The apparatus as recited in claim 1, wherein said multiplying means includes:

modified clock means under control of said converting means for providing a modified clock signal;

first NAND gate means responsive to said modified clock signal, said video signal and said Walsh function signal to provide a first digital signal;

first counter means responsive to said first digital signal for supplying a first counter signal in accordance with a count of said first digital signal;

first digital to analog converter means responsive to said first counter signal for providing an analog version of said first counter signal;

second NAND gate means responsive to said modified clock signal, said video signal and said Walsh function signal to provide a second digital signal;

second counter means responsive to said second digital signal for supplying a second counter signal in accordance with a count of said second digital signal;

second digital to analog converter means responsive to said second counter signal for providing an analog version of said second counter signal; and

differential amplifier means responsive to said first and second counter signals for providing as an output said Walsh transform coefficients signal in accordance with the difference between said first and second counter signals.

5. The apparatus as recited in claim 4, further comprising:

means for providing selected topographical feature signals in accordance with the Walsh transform coefficients of selected topographical features; and

binary to analog converter means responsive to said Walsh transform coefficients signal and said selected topographical features signals to detect a selected topographical feature.

6. The apparatus as recited in claim 1. wherein said converting means comprises:

a. sensor array means having a two-dimension array of pixel detector elements for providing said video signal;

b. illuminating means for providing optical energy;

c. a photo-transparency disposed so that said optical energy passing therethrough generates an optical image; and

d. imaging means for focusing said optical image onto said two-dimension array of pixel detector elements.

7. The apparatus as recited in claim 6, wherein said pixel detector elements have substantially the same area.

8. The apparatus as recited in claim 6, wherein said illuminating means is a source providing substantially white

22. The method as recited in claim 1, wherein said selected topographical features are substantially linear.

9. Apparatus, which comprises:

a. means for converting optical energy of an image into a video signal;

b. means for generating a Walsh function signal in accordance with a two-dimension Walsh function;

c. means for multiplying said video signal with said Walsh function signal to produce a Walsh transform coefficients signal indicative of the decomposed spectral components of said image;

d. means for providing selected topographical feature signals in accordance with the Walsh transform coefficients of selected topographical features; and

e. means for detecting a selected topographical feature by comparing said Walsh transform coefficients signal with said selected topographical feature signals.

10. The apparatus as recited in claim 9, wherein said generating means, said multiplying means, said providing means, and said detecting means are provided by a computer under stored program control.

11. The apparatus as recited in claim 9, wherein said converting means supplies said video signal in accordance with a two dimension analog array of pixels.

12. The apparatus as recited in claim 11, wherein said converting means includes means for digitizing said video signal to produce a corresponding two-dimension digital array of pixels.

13. The apparatus as recited in claim 12, wherein said converting means further includes means for thresholding said video signal to produce a corresponding two-dimension binary array of pixels.

14. The apparatus as recited in claim 13, further comprising means responsive to said video signal for outputting said two-dimension binary array of pixels.

15. The apparatus as recited in claim 9, wherein said detecting means is a binary to analog correlator having inputs responsive to said Walsh transform coefficients signal and said selected topographical feature signals.

16. A method comprising the steps of:

a. converting optical energy of an image into a video signal using a sensor array with a two-dimensional analog array of pixels;

b. generating a Walsh function signal in accordance with a two-dimension Walsh function;

c. multiplying said video signal with said Walsh function signal to produce a Walsh transform coefficients signal indicative of the decomposed spectral components of said image.

17. The method as recited in claim 16, wherein said video signal is digitized to produce a corresponding two-dimension digital array of pixels.

18. The method as recited in claim 17, wherein said video signal corresponding to said two-dimension digital array of pixels is thresholded to produce a corresponding two-dimension binary array of pixels.

19. Themethod as recited in claim 18, further comprising the step of outputting said video signal corresponding to said two-dimension binary array of pixels.

20. The method as recited in claim 19, further comprising the step of storing said video signal corresponding to said two-dimensional binary array of pixels.

21. The method as recited in claim 20, wherein said step of storing utilizes an electronic memory.

23. The method as recited in claim 18, wherein said tresholding is performed at a selected signal value to reduce image background noise.

24. The method as recited in claim 23, wherein said video signal of step c is in accordance with said two-dimension binary array of pixels.

25. The method as recited in claim 24, wherein said two-dimension Walsh function of step b has at least two orders.

26. The method as recited in claim 25, wherein said multiplying of step c is performed by multiplying said video signal in accordance with said two-dimension binary array pixels by said Walsh function signal in accordance with each of said orders of said two-dimension Walsh function to provide said Walsh transform coefficients signal having a Walsh transform coefficients signal having a Walsh transform coefficient for each of said orders.

27. The method as recited in claim 26, further comprising the step of normalizing each of said Walsh transform coefficients of said Walsh transform coefficients signal.

28. The method as recited in claim 26, further comprising the step of outputting said Walsh transform coefficients signal.

29. The method as recited in claim 26, wherein said Walsh transform coefficients of said Walsh transform coefficients signal are arranged in a two-dimension array format.

30. A method comprising the steps of:

a. converting an optical image into a video signal;

b. generating a Walsh function signal in accordance with a two-dimension Walsh function;

c. multiplying said video signal with said Walsh function signal to produce a Walsh transform coefficients signal indicative of the decomposed spectral components of said image;

d. providing selected topographical feature signals in accordance with the Walsh transform coefficients of selected topographical features; and

e. detecting a selected topographical feature by comparing said Walsh transform coefficients signal with said selected topographical feature signals.

31. The method as recited in claim 30, wherein step a is performed by using an area sensor array having optical energy of an image from an illuminated transparency focused on the detecting surface thereof.

32. The method as recited in claim 31, wherein said optical energy of step a is substantially in the visible range.

33. The method as recited in claim 31, wherein said area sensor array supplies said video signal in accordance with a two dimensional analog array of pixels.

34. The method as recited in claim 33, wherein said two-dimensions of said two-dimension Walsh function are substantially equal in number to the two-dimensions of said two-dimension binary array of pixels.

35. The method as recited in claim 33, wherein said video signal is digitized to produce a corresponding two-dimension digital array of pixels.

36. The method as recited in claim 35, wherein said video signal corresponding to said two-dimension digital array of pixels is thresholded to produce a corresponding two-dimension binary array of pixels.

37. The method as recited in claim 36, wherein said thresholding is performed at a selected signal level to reduce image background noise.

38. The method as recited in claim 36, wherein said video signal of step c is in accordance with said two-dimension binary array of pixels.

39. The method as recited in claim 38, wherein step c provudes said Walsh transform coefficients signal in accordance with ##EQU3## where:

a(i,j) is said Walsh transform coefficients signal;

i and j indicate the order of said two-dimension Walsh function;

n and m are integers; and

f(k,1) is said two-dimension binary array of pixels.

40. The method as recited in claim 38, wherein said two-dimension Walsh function has at least two orders;

and

wherein said multiplying of step c is performed by multiplying said video signal in accordance with said two-dimension binary array of pixels by said Walsh function signal in accordance with each of said orders of said two-dimension Walsh function to provide said Walsh transform coefficients signal having a Walsh transform coefficient for each of said orders.

41. The method as recited in claim 36, wherein said two-dimension Walsh function has at least two orders.

42. The method as recited in claim 30 further comprising the step of normalizing said Walsh transform coefficients signal.

43. The method as recited in claim 30, further comprising the step of storing in an electronic memory said video signal.

44. The method as recited in claim 30, further comprising the step of outputting said Walsh transform coefficients signal.

45. The method as recited in claim 30, wherein step e is performed by a binary-analog correlator.

46. The method as recited in claim 30, wherein steps b and e are performed by a computer under stored program control.

47. The method as recited in claim 46, wherein said computer is digital.

53. The apparatus as recited in claim 46, wherein said Walsh transform coefficients signal is in accordance with the equation:

##EQU4## where;

a(i,j) is said Walsh transform coefficients signal;

i and j indicate the order of said Walsh function signal; and

n and m are integers; and

k(f,1) is said video signal.

48. Apparatus, which comprises:

a. means for converting optical energy of an image into a video signal including

(1) sensor array means having a two-dimension array of pixel detector elements for providing said video signal,

(2) illuminating means for providing optical energy,

(3) a photo-transparency disposed so that said optical energy passsing therethrough generates an optical image, and

(4) imaging means for focusing said optical image onto said two-dimension array of pixel detector elements;

b. means for generating a Walsh function signal in accordance with a two-dimension Walsh function; and

c. means for multiplying said video signal with said Walsh function signal to produce a Walsh transform coefficients signal indicative of the decomposed spectral components of said image.

49. The apparatus as recited in claim 48, wherein said pixel detector elements have substantially the same area.

50. The apparatus as recited in claim 48, wherein said illuminating means is a source providing substantially white light.

51. The apparatus as recited in claim 48, wherein said generating means and said multiplying means are provided by a computer under stored program control.

52. The apparatus as recited in claim 61, wherein said computer is digital.

54. The apparatus as recited in claim 48, wherein said generating means comprises:

control signal means for providing a modified clock signal, an end of line signal, and an end of frame signal under effective control of said converting means;

X Walsh function generator means responsive to said modified clock signal and said end of line signal for providing a first pair of output signals;

X decoder means responsive to said first pair of output signals and said end of frame signal for providing an X Walsh signal;

Y Walsh function generator means responsive to said end of line signal and said end of frame signal for providing a second pair of output signals;

Y decoder means responsive to said second pair of output signals for providing a Y Walsh signal; and

exclusive OR means having inputs responsive to said X Walsh signal and said Y Walsh signal, respectively, for providing at an output said Walsh function signal.

55. The apparatus as recited in claim 48, wherein said multiplying means includes a plurality of electronic gates.

56. The apparatus as recited in claim 48, wherein said multiplying means includes:

modified clock means under control of said converting means for providing a modified clock signal;

first NAND gate means responsive to said modified clock signal, said video signal and said Walsh function signal to provide a first digital signal;

first counter means responsive to said first digital signal for supplying a first counter signal in accordance with a count of said first digital signal;

first digital to analog converter means responsive to said first counter signal for providing an analog version of said first counter signal;

second NAND gate means responsive to said modified clock signal, said video signal and said Walsh function signal to provide a second digital signal;

second counter means responsive to said second digital signal for supplying a second counter signal in accordance with a count of said second digital signal;

second digital to analog converter means responsive to said second counter signal for providing an analog version of said second counter signal; and

differential amplifier means responsive to said first and second counter signals for providing as an output said Walsh transform coefficients signal in accordance with the difference between said first and second counter signals.

57. The apparatus as recited in claim 56, further comprising:

means for providing selected topographical feature signals in accordance with the Walsh transform coefficients of selected topographical features; and

binary to analog converter means responsive to said Walsh transform coefficients signal and said selected topographical features signal to detect a selected topographical feature.

58. The apparatus as recited in claim 48, further comprising means responsive to said video signal for storing said video signal.

59. The apparatus as recited in claim 58, wherein storing means is an electronic memory.

60. The apparatus of claim 48 further comprising

a. means for providing selected topographical feature signals in accordance with the Walsh transform coefficients of selected topographical features;

and

b. means for detecting a selected topographical feature by comparing said Walsh transform coefficients signal with said selected topographical feature signals.

61. The apparatus as recited in claim 60, wherein said generating means, said multiplying means, said providing means, and said detecting means are providing by a computer under stored program control.

62. The apparatus as recited in claim 60, wherein said converting means supplies said video signal in accordance with a two dimension analog array of pixels.

63. The apparatus as recited in claim 62, wherein said converting means includes means for digitizing said video signal to produce a corresponding two-dimension digital array of pixels.

64. The apparatus as recited in claim 63, wherein said converting means further includes means for thresholding said video signal to produce a corresponding two-dimension binary array of pixels.

65. The apparatus as recited in claim 64, further comprising means responsive to said video signal for outputting said two-dimension binary array of pixels.

66. The apparatus as recited in claim 60, wherein said detecting means is a binary to analog correlator having inputs responsive to said Walsh transform coefficients signal and said selected topographical feature signals.

67. Apparatus, which comprises:

a. means for converting optical energy of an image into a video signal;

b. means for generating a Walsh function signal in accordance with a two-dimension Walsh function;

c. means for multiplying said video signal with said Walsh function signal to produce a Walsh transform coefficients signal indicative of the decomposed spectral components of said image;

d. means for providing selected topographical feature signals in accordance with Walsh transform coefficients of selected topographical features; and

e. means for detecting a selected topographical feature by comparing said Walsh transform coefficients signal with said selected topographical feature signals including a binary to analog correlator having inputs responsive to said Walsh transform coefficents signal and said selected topographical feature signals.

68. The apparatus as recited in claim 67, wherein said generating means, said multiplying means, said providing means, and said detecting means are provided by a computer under stored program control.

69. The apparatus as recited in claim 67, wherein said converting means supplies said video signal in accordance with a two dimension analog array of pixels.

70. The apparatus as recited in claim 69, wherein said converting means includes means for digitizing said video signal to produce a corresponding two-dimension digital array of pixels.

71. The apparatus as recited in claim 70, wherein said converting means further includes means for thresholding said video signal to produce a corresponding two-dimension binary array of pixels.

72. The apparatus as recited in claim 71, further comprising means responsive to said video signal for outputting said two-dimension binary array of pixels.

73. A method comprising the steps of:

a. converting optical energy of an image into a video signal using a sensor array, said sensor providing said video signal in accordance with a two-dimension analog array of pixels

b. generating a Walsh function signal in accordance with a two-dimension Walsh function;

c. multiplying said video signal with said Walsh function signal to produce a Walsh transform coefficient signal indicative of the decomposed spectral components of said image.

74. The method as recited in claim 73, wherein said optical energy of step a is substantially in the visible light range.

75. The method as recited in claim 74, wherein said video signal is digitized to produce a corresponding two-dimension digital array of pixels.

76. The method as recited in claim 75, wherein said video signal corresponding to said two-dimension digital array of pixels is thresholded to produce a corresponding two-dimension binary array of pixels.

77. The method as recited in claim 76, further comoprising the step of outputting said video signal corresponding to said twp-dimension binary array of pixels.

78. The method as recited in claim 77, further comprising the step of storing said video signal corresponding to said two-dimensional binary array of pixels.

79. The method as recited in claim 78, wherein said step of storing utilizes an electronic memory.

80. The method as recited in claim 76, wherein said thresholding is performed at a selected signal value to reduce image background noise.

81. The method as recited in claim 80, wherein said video signal of step c is in accordance with said two-dimension binary array of pixels.

82. The method as recited in claim 81, wherein said two-dimension Walsh function of step b has at least two orders.

83. the method as recited in claim 82, wherein said multiplying of step c is performed by multiplying said video signal in accordance with said two-dimension binary array pixels by said Walsh function signal in accordance with each of said orders of said two-dimension Walsh function to provide said Walsh transform coefficients signal having a Walsh transform coefficients signal having a Walsh transform coefficient for each of said orders.

84. The method as recited in claim 83, further comprising the step of normalizing each of said Walsh transform coefficients of said Walsh transform coefficients signal.

85. The method as recited in claim 83, further comprising the step of outputting said Walsh transform coefficients signal.

86. The method as recited in claim 83, wherein said Walsh transform coefficients of said Walsh transform coefficients signal are arranged in a two-dimension array format.

87. The method of claim 73 further comprising the steps of:

a. providing selected topographical feature signals in accordance with the Walsh transform coefficients of selected topographical features; and

b. detecting a selected topographical feature by comparing said Walsh transform coefficients signal with said selected topographical feature signals.

88. The method as recited in claim 87, wherein step a is performed by using an area sensor array having optical energy of an image from an illuminated transparency focused on the detecting surface thereof.

89. The method as recited in claim 88, wherein said optical energy of step a is substantially in the visible range.

90. The method as recited in claim 88, wherein said area sensor array supplies said video signal in accordance with a two dimensional analog array of pixels.

91. The method as recited in claim 90, wherein said two-dimensions of said two-dimension Walsh function are substantially equal in number to the two-dimensions of said two-dimension binary array of pixels.

92. The method as recited in claim 90, wherein said video signal is digitized to produce a corresponding two-dimension digital array of pixels.

93. The method as recited in claim 92, wherein said video signal corresponding to said two-dimension digital array of pixels is thresholded to produce a corresponding two-dimension binary array of pixels.

94. The method as recited in claim 93, wherein said thresholding is performed at a selected signal level to reduce image background noise.

95. The method as recited in claim 93, wherein said video signal of step c is in accordance with said two-dimension binary array of pixels.

96. The method as recited in claim 95, wherein step c provides said Walsh transform coefficients signal in accordance with ##EQU5## where:

a(i,j) is said Walsh transform coefficients signal;

i and j indicate the order of said two-dimension Walsh function;

n and m are integers; and

f(k,1) is said two-dimension binary array of pixels.

97. The method as recited in claim 95, wherein said two-dimension Walsh function has at least two orders;

and

wherein said multiplying of step c is performed by multiplying said video signal in accordance with said two-dimension binary array of pixels by said Walsh function signal in accordance with each of said orders of said two-dimension Walsh function to provide said Walsh transform coefficients signal having a Walsh transform coefficient for each of said orders.

98. The method as recited in claim 93, wherein said two-dimension Walsh function has at least two orders.

99. The method as recited in claim 87 further comprising the step of normalizing said Walsh transform coefficients signal.

100. The method as recited in claim 87, further comprising the step of storing in an electronic memory said video signal.

101. The method as recited in claim 87, further comprising the step of outputting said Walsh transform coefficients signal.

102. The method as recited in claim 87, wherein step e is performed by a binary-analog correlator.

103. The method as recited in claim 87, wherein steps b and e are performed by a computer under stored program control.

104. The method as recited in claim 103, wherein said computer is digital.

105. The method as recited in claim:

87, wherein said selected topographical features are substantially linear.