Device and method for analyzing an electronic image signal

• US 5,999,634 A
• Filed: 05/23/1997
• Issued: 12/07/1999
• Est. Priority Date: 09/12/1991
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Electronic Data Systems Corporation (Perspecta, Inc.)
• Inventors: Thomas, William G., Abbott, James P., Stubbington, Brian D., Sermon, Gerald, Gent, Christopher Robert
• Primary Examiner(s): Kelley, Christopher S.
• Application Number:
  US08/862,521
• Time in Patent Office: 928 Days
• Field of Search: 382/100, 382/103, 382/107, 382/133, 382/236, 382/155, 382/156, 382/159, 382/218, 348/77, 348/135, 348/140, 348/143-161, 348/169-172
• US Class Current: 382/103
• CPC Class Codes: G06V 20/52 Surveillance or monitoring of activities, e.g. for recognising suspicious objects recognising microscopic objects G06V20/69
• CPC Class Codes: G08B 13/19602 Image analysis to detect motion of the intruder, e.g. by frame subtraction
• CPC Class Codes: G08B 13/19608 Tracking movement of a target, e.g. by detecting an object predefined as a target, using target direction and or velocity to predict its new position
• CPC Class Codes: G08B 13/19673 Addition of time stamp, i.e. time metadata, to video stream

Abstract

A number of systems and methods for analyzing electronic image signals are provided which include processing the image signal as one or more cells, each comprising a plurality of pixels. For consecutive frames of the monitored image, a set of pointers are generated, each containing a value related to the detail contents of the image. The pointers are used to address a memory array, each pointer corresponding to a row in the memory array and the content of each pointer pointing to a memory element in the corresponding row. For successive frames, the value of each memory element addressed by a pointer is updated.

Claims

1. A method of analyzing an electronic image signal associated with an image that is being monitored, the method comprising:

(a) processing the image signal as one or more cells each comprising a plurality of pixels;

(b) for each consecutive frame of the monitored image, generating a set of pointers by randomly or pseudo-randomly selecting pairs of pixels within a frame and for each pair comparing a light intensity of one pixel against a light intensity of the other pixel, each pointer corresponding to a predefined subset of said plurality of pixels for a cell and each containing a value related to the detailed content of the portion of the frame of the monitored image corresponding to said predefined subset of said plurality of pixels;

(c) using the pointers to address a memory array, each pointer corresponding to a row of the memory array, and the content of each pointer pointing to a memory element in the corresponding row, each cell having its own memory array; and

(d) for successive frames, updating the value of each memory element addressed by a pointer during monitoring of the image.

2. A method according to claim 1, wherein the set of pointers comprises pointers al. ...., am, each of n binary bits and the memory array has m rows and ₂ n columns.

3. A method according to claim 1, further comprising over all the rows, updating the value of memory pointed to by the content of each pointer, summing the updated values for each row, selecting the maximum memory value in each row, and summing the maximum memory value for all rows, subjecting the ratio of the two sums to a time weighted averaging with respect to the ratios obtained from previous frames, comparing the ratio with the time weighted average and using the result to determine the occurrence or non-occurrence of a significant event within the image.

4. A method according to claim 2, wherein the binary bits of the pointers are set in accordance with characteristic values generated for consecutive frames of the monitored image according to the detailed content of the image.

5. A method according to claim 4, wherein the characteristic values are accumulated for consecutive image frames so that in a single operational mode, a time history of the image, stored in a memory, is updated and an indication is produced indicative of the occurrence or non-occurrence of an event not associated with image background.

6. A device for analyzing an electronic image signal associated with an image that is being monitored, the device comprising electronic means for:

(a) processing the image signal as one or more cells each comprising a plurality of pixels;

(b) for each consecutive frame of the monitored image, generating a set of pointers by randomly or pseudo-randomly selecting pairs of pixels within a frame and for each pair comparing a light intensity of one pixel against a light intensity of the other pixel, each pointer corresponding to a predefined subset of said plurality of pixels for a cell and each containing a value related to the detailed content of the portion of the frame of the monitored image corresponding to said predefined subset of said plurality of pixels;

(c) using the pointers to address a memory array, each pointer corresponding to a row of the memory array, and the content of each pointer pointing to a memory element in the corresponding row, each cell having its own memory array; and

(d) for successive frames, updating the value of each memory element addressed by a pointer during monitoring of the image.

7. A device according to claim 6, wherein said electronic means is adapted to generate said set of pointers as pointers al, ... , am, each of n binary bits and the memory array has m rows and ₂ n columns.

8. A device according to claim 6, wherein said electronic means is adapted for, over all the rows, updating the value of memory pointed to by the content of each pointer, summing the updated values for each row, selecting the maximum memory value in each row, and summing the maximum memory value for all rows, subjecting the ratio of the two sums to a time weighted averaging with respect to the ratios obtained from previous frames, comparing the ratio with the time weighted average and using the result to determine the occurrence or non-occurrence of a significant event within the image.

9. A device according to claim 8, wherein said electronic means is adapted to set the binary bits of the pointers in accordance with characteristic values generated for consecutive frames of the monitored image according to the detailed content of the image.

10. A device according to claim 9, wherein said electronic means is adapted to accumulate the characteristic values so that in a single operation mode, a time history or the image, stored in a memory, is updated and an indication is produced indicative of the occurrence or non-occurrence of an event not associated with image background.

11. A device according to claim 7, wherein said electronic means comprises an image frame grabber, a memory and one or more computer processors.

12. A method of analyzing an electronic image signal associated with an image that is being monitored, the method comprising:

(a) processing the image signal as one or more cells each comprising a plurality of pixels;

(b) for each consecutive frame of the monitored image, generating characteristic values by randomly or pseudo-randomly selecting pairs of pixels within a frame and for each pair, generating a binary signal in dependence upon whether or not the intensity of light incident on one predetermined pixel of the pair of pixels is greater than the intensity of light incident on the other; and

(c) for consecutive image frames, accumulating the characteristic values so that in a single operational mode, a time history of the image, stored in a memory, each cell having its own memory array is updated during monitoring of the image and an indication is produced indicative of the occurrence or nonoccurrence of an event not associated with image background.

13. A method according to claim 12, wherein the image is represented as a plurality of cells.

14. A method according to claim 13, wherein said plurality of cells is adjusted for perspective.

15. A device for analyzing an electronic image signal associated with an image that is being monitored, the device comprising electronic means for:

(a) processing the image signal as one or more cells each comprising a plurality of pixels;

(b) for each consecutive frame of the monitored image, generating characteristic values by randomly or pseudo-randomly selecting pairs of pixels within a frame and for each pair, generating a binary signal in dependence upon whether or not the intensity of light incident on one predetermined pixel of the pair of pixels is greater than the intensity of light incident on the other; and

(c) for consecutive image frames, accumulating the characteristic values so that in a single operational mode, a time history of the image, stored in a memory, each cell having its own memory array is updated during monitoring of the image and an indication is produced indicative of the occurrence or nonoccurrence of an event not associated with image background.

16. A device according to claim 15, wherein the image is represented as a plurality of cells.

17. A device according to claim 16, wherein said electronic means is adapted to adjust said plurality of cells for perspective.

18. A device according to claim 15, wherein said electronic means comprises an image frame grabber, a memory and one or more computer processors.

19. A method of analyzing an electronic image signal associated with an image that is being monitored, the method comprising:

(a) processing the image signal as one or more cells each comprising a plurality of pixels; and

(b) for each consecutive frame of the monitored image, randomly or pseudo-randomly selecting pairs of pixels in the cell or cells within a frame, and for each pair, generating a binary signal in dependence upon whether or not the intensity of light incident on one predetermined pixel of the pair of pixels is greater than the intensity of light incident on the other.

20. A method according to claim 19, wherein in step (b), at least one pair of pixels is selected for each of a plurality of cells.

21. A method according to claim 20, wherein in step (b), a plurality of pixels is selected for each cell of the image field.

22. A method according to claim 19, wherein the same pixels are used in each frame until the end of a subsequent operating session.

23. A method according to claim 19, wherein the binary signals are used to generate pointer for addressing the memory containing the time history of the image.

24. A method according to claim 23, wherein a set of pointers a₁, . . . , _m is generated, each of n binary bits and said bits are sequentially set according to the respective binary values of the signals resulting from comparisons of the pixel pairs.

25. A device for analyzing an electronic image signal associated with an image that is being monitored, the device comprising electronic means for:

(a) processing the image signal as one or more cells each comprising a plurality of pixels; and

(b) for each consecutive frame of the monitored image, randomly or pseudo-randomly selecting pairs of pixels in the cell or cells within a frame, and for each pair, generating a binary signal in dependence upon whether or not the intensity of light incident on one predetermined pixel of the pair of pixels is greater than the intensity of light incident on the other.

26. A device according to claim 25, wherein said electronic means is adapted to select at least one pair of pixels for each of a plurality of cells.

27. A device according to claim 25, wherein said electronic means is adapted to select a plurality of pixels for each cell of the image field.

28. A device according to claim 25, wherein said electronic means is adapted to use the same pixels in each frame until the end of a subsequent operating session.

29. A device according to claim 25, wherein said electronic means is adapted to use the binary signals to generate pointers for addressing the memory containing the time history of the image.

30. A device according to claim 29, wherein said electronic means is adapted to generate a set of pointers a₁, . . . , a_m, each of n binary bits and sequentially to set these bits according to the respective binary values of the signals resulting from comparisons of the pixel pairs.

31. A device according to claim 29, wherein said electronic means comprises an image frame grabber, a memory and one or more computer processors.

32. A method of analyzing an electronic image signal associated with an image that is being monitored, the method comprising:

(a) processing the image signal as one or more cells each comprising a plurality of pixels;

(b) for each consecutive frame of the monitored image, generating characteristic values according to the detailed content of the image ;

and

(c) generating a set of pointers a₁, . . . a_m by randomly or pseudo-randomly selecting pairs of pixels within a cell and for each pair comparing a light intensity of one pixel against a light intensity of the other pixel, each pointer of n bits and sequentially setting these bits according to the characteristic values during monitoring of the image.

33. A method according to claim 32, wherein the pointers are used to address a memory array having m rows and 2ⁿ columns, each pointer corresponding to a row of the memory array and the content of each pointer pointing to a memory element in the corresponding row, and the value of each memory addressed by a pointer is updated.

34. A device for analyzing an electronic image signal associated with an image that is being monitored, the device comprising electronic means for:

(a) processing the image signal as one or more cells each comprising a plurality of pixels;

(b) for each consecutive frame of the monitored image, generating characteristic values according to the detailed content of the image; and

(c) generating a set of pointers a₁, . . . a_m by randomly or pseudo-randomly selecting pairs of pixels within a cell and for each pair comparing a light intensity of one pixel against a light intensity of the other pixel, each pointer of n bits and sequentially setting these bits according to the characteristic values during monitoring of the image.

35. A device according to claim 34, wherein the electronic means is adapted to use the pointers to address a memory array having m rows and 2ⁿ columns, each pointer corresponding to a row of the memory array and the content of each pointer pointing to a memory element in the corresponding row, and to update the value of each memory addressed by a pointer.

36. A device according to claim 34, wherein said electronic means comprises an image frame grabber, a memory and one or more computer processors.

37. A method of analyzing an electronic image signal, the method comprising:

(a) processing the image signal as one or more cells each comprising a plurality of pixels;

(b) for each consecutive frame of the monitored image, updating a predetermined address in each row of a memory array in dependence on the detailed content of the image; and

(c) over all the rows, updating the value of memory pointed to by the content of each pointer, summing the updated values for each row, selecting the maximum memory value in each row, and summing the maximum memory value for all rows, subjecting the ratio of the two sums to a time weighted averaging with respect to the ratios obtained from previous frames, comparing the ratio with the time weighted average and using the result to determine the occurrence or non-occurrence of a significant event within the image.

38. A device for analyzing an electronic image signal, the device comprising electronic means for:

(a) processing the image signal as one or more cells each comprising a plurality of pixels;

(b) for each consecutive frame of the monitored image, updating one address in each row of a memory array in dependence on the detailed content of the image; and

(c) over all the rows, updating the value of memory pointed to by the content of each pointer, summing the updated values for each row, selecting the maximum memory value in each row, and summing the maximum memory value for all rows, subjecting the ratio of the two sums to a time weighted averaging with respect to the ratios obtained from previous frames, comparing the ratio with the time weighted average and using the result to determine the occurrence or non-occurrence of a significant event within the image.

39. A device according to claim 38, wherein said electronic means comprises an image frame grabber, a memory and one or more computer processors.