Video monitoring system and method

• US 4,257,063 A
• Filed: 03/23/1979
• Issued: 03/17/1981
• Est. Priority Date: 03/23/1979
• Status: Expired due to Term

• Current Assignee: Ham Industries Incorporated
• Original Assignee: Ham Industries Incorporated
• Inventors: Zeewy, Abraham, Loughry, H. Hampton
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US06/023,032
• Time in Patent Office: 725 Days
• Field of Search: 358/108, 358/105, 340/529, 340/715
• US Class Current: 348/155
• CPC Class Codes: G08B 13/19602 Image analysis to detect motion of the intruder, e.g. by frame subtraction
• CPC Class Codes: G08B 13/19634 Electrical details of the system, e.g. component blocks for carrying out specific functions
• CPC Class Codes: G08B 13/19691 Signalling events for better perception by user, e.g. indicating alarms by making display brighter, adding text, creating a sound

Abstract

A television system and method are disclosed for monitoring and indicating changes in a scene from which electromagnetic radiation, such as visible light, emanates. A television system including a television camera scans the scene in known raster fashion in a series of image frames, producing an amplitude modulated video signal describing the energy intensity distribution of the scene. Clocking and gating circuitry triggered in synchronism with television camera synchronization signals defines a set of predetermined discrete spaced locations of the raster during each image frame and samples video signal amplitude at each of the defined locations. The same discrete locations are sampled during each frame. Video selection circuitry, during a succession of sampling periods, inputs in real time a representation of each video amplitude sample to one of several storage channels of a multi-channel memory system including a multi-channel counter. The video amplitude samples are allocated among the channels as a function of their amplitude values. The collection of stored amplitude samples in the multi-channel memory system thus constitutes a profile of the amplitude distribution of the video samples made during the frame. This first amplitude profile is then stored. The scanning, allocating and counting operation is repeated. Subsequently, comparison circuitry, in response to the development of a subsequent amplitude distribution profile, corresponding to a selected later frame, actuates an alarm in response to the occurrence of a predetermined threshhold difference between (1) the earlier and (2) a succession of later developed amplitude distribution profiles. Circuitry is also provided for modifying characteristics of the threshhold difference required to trigger the alarm.

It has been found that even a single channel counter, responsive to video count samples in only a single amplitude range, can often provide enough information for a workable and inexpensive surveillance system.

Claims

1. A system for sensing changes in distribution of energy emanating from a scene, said system comprising:

(a) pickup means for converting the energy to electrical signals representing intensity distribution of said emanation from the scene;

(b) circuitry cooperative with the pickup means for sampling energy intensity of each of a predetermined set of locations of the scene;

(c) circuitry for accumulating during a sampling period a count of the number of said sampled locations which emanate energy within a predetermined intensity range, said count being produced independently of the relative spatial positions within the scene of the sampled locations, and

(d) comparison circuitry for detecting at least a predetermined difference between the value of said count and a predetermined value.

2. The system of claim 1, further comprising:

(a) said counting circuitry comprising a multi-channel counter and associated circuitry for counting the numbers of said sampled locations whose emanated energy intensities lie respectively within each of a plurality of different ranges;

(b) circuitry for resetting said multiple counting channels after a prior sampling period;

(c) a memory for storing count information derived during said prior sampling period for comparison with count information derived during a subsequent sampling period, and

(d) circuitry for actuating said sampling and counting circuitry during said subsequent sampling period to resample the energy intensities at said same set of locations in the scene.

3. The system of claim 2, wherein said comparison circuitry comprises means for indicating at least a predetermined degree of change in the count accumulations in any of a plurality of channels of the multi-channel counter between said prior and subsequent sampling periods.

4. The system of claim 1, further comprising:

apparatus coupled to the comparison circuitry for producing an alarm signal in response to the detection of said predetermined difference.

5. The system of claim 1, wherein:

(a) said pickup means comprises a television camera pickup tube and circuitry for operating the pickup tube of the camera to scan the scene in a series of frames, and

(b) said comparison circuitry comprises circuitry for producing an indication in response to changes in said counted number of locations between a prior frame and a subsequent frame.

6. The system of claim 1, wherein:

(a) said pickup means and sampling circuitry comprise a television camera pickup tube and video processing circuitry, said video processing circuitry producing horizontal and vertical synchronization pulses and associated control signals for causing the television camera pickup tube to scan the scene in a rectilinear fashion, and

(b) said sampling circuitry further includes clocking and gating circuitry for defining said sampled locations of the scene as a function of timing of said synchronization signals.

7. The system of claim 6, wherein:

said video processing circuitry includes means for triggering said clocking circuitry to subdivide said television image to define said locations as a function of the time of coincidence of a vertical and a horizontal television synchronization signal.

8. An area surveillance system comprising:

(a) video pickup apparatus for producing a frame of information describing energy emanating from the area;

(b) processing circuitry for defining a set of predetermined locations in the frame;

(c) circuitry for sensing the emanated energy level of each of the locations;

(d) circuitry for summing the numbers of frame portions having an energy level lying within each of a plurality of predetermined range, independent of the relative spatial locations of the members of the location set;

(e) means for producing a reference signal describing a reference number, and

(f) comparison circuitry for producing an alarm signal in response to a predetermined relationship between the reference signal and the number of portions summed in the counter.

9. A system for monitoring changes in a scene from which radiant energy emanates, said system comprising:

(a) a television camera including control circuitry for producing horizontal and vertical synchronization signals for causing the television camera to scan at least a portion of the scene in repeated rectilinear frames, to produce a video signal indicating energy level distribution of each frame;

(b) clocking circuitry for defining sampling times during which the television camera scans each of a same predetermined set of sampling locations of each frame;

(c) multi-channel accumulating count circuitry, and

(d) circuitry responsive to the clocking circuitry and the video signal for steering a representation of the value of the video signal at each sampling location into a channel of the multi-channel counting circuitry, the selection of the channel to which each video representation is steered being a function of value of the video signal at its respective sampling time.

10. The system of claim 9, further comprising:

means associated with the steering circuitry for preventing each sampled video value representation from affecting any channel of the multi-channel circuitry but that channel to which that representation is steered.

11. A method for sensing changes in distribution of energy emanating from a scene, comprising the steps of:

(a) converting energy from the scene to electrical signals representing spatial intensity distribution of the energy;

(b) sampling energy intensity of each of a predetermined set of locations of the scene;

(c) accumulating during a sampling period a count of the number of said sampled locations from which energy emanates within a predetermined intensity range, said accumulation step being performed independently of relative spatial positions within the scene of the sampled locations, and

(d) detecting the existence of at least a predetermined difference between the value of the count accumulated in the previous step and a predetermined value.

12. The method of claim 11, wherein:

(a) said accumulation step comprises counting the numbers of said sampled locations whose emanated energy intensities lie respectively within each of a plurality of different ranges, said method further comprising;

(b) storing count information derived during said sampling step;

(c) repeating said sampling step, and

(d) comparing the counts obtained in the sampling step with those obtained in the repeated sampling step, and

(e) detecting predetermined differences in corresponding counts obtained in the two sampling steps.

13. The method of claim 11, further comprising the step of:

producing an alarm signal in response to the detection of said predetermined difference.

14. The method of claim 11, wherein:

(a) said converting step includes operating a pickup tube of a television camera to scan the scene in a series of frames, and

(b) said detection step comprises producing an indication in response to changes in said counted number of locations between a prior frame and a subsequent frame.

15. The method of claim 11, wherein said conversion and sampling steps comprise:

(a) producing horizontal and vertical synchronization pulses for controlling a television camera pickup tube to scan the scene in a rectilinear fashion, and

(b) said sampling step further includes clocking and gating operations for defining the sampled location of the scene as related to the synchronization signals.

16. The method of claim 15, wherein:

said defining step comprises defining the locations in response to the coincidence of vertical and horizontal television synchronization signals.

17. An area surveillance method comprising:

(a) producing a frame of information describing energy emanating from the area;

(b) defining a set of predetermined locations in the frame;

(c) sensing the emanating energy level of each of the locations;

(d) summing the numbers of frame locations having an energy level lying within each of a plurality of predetermined ranges, said summing step taking place independently of the relative spatial positions of the members of the location set;

(e) producing a reference signal describing a reference number, and

(f) producing an alarm signal in response to a predetermined relationship between the number represented by the reference signal and a number of locations summed in the summing step.

18. A method for monitoring changes in a scene from which radiant energy emanates the method comprising the steps of:

(a) producing horizontal and vertical synchronization signals for causing a television camera to scan at least a portion of the scene in repeated rectilinear frames to produce an amplitude modulated video signal indicating spatial energy intensity distribution within each frame;

(b) triggering clocking circuitry to define a set of sampling times during which the television camera scans each of a same predetermined set of sampling locations of each frame;

(c) responding to the clocking and to the video signal for steering a representation of the value of the video signal at each sampled location into one of a plurality of storage channels, the selection of the storage channel being a function of the value of the video signal at its respective sampling time.

19. An area monitoring system comprising:

(a) a television system for viewing a scene of the area and representing the spatial distribution of electromagnetic radiation emanating from the scene by producing electrical signals including video and synchronization signals and defining a sequence of raster formated frames;

(b) circuitry for effecting real time sampling of video signal value at each of a set of locations of the frame raster during a first;

(c) sorting circuitry for developing in real time an amplitude distribution profile of the video signal samples;

(d) a memory system for storing a representation of the amplitude profile;

(e) circuitry for actuating the sampling and sorting circuitry to repeat their operation over a second frame for the same set of raster locations, and

(f) comparison circuitry for producing an indication in response to the occurrence of a predetermined difference between the amplitude distribution profiles of the first and second frames.

20. The system of claim 19, further comprising:

circuitry for modifying the predetermined amplitude profile difference which causes the production of the indication by the comparison circuitry.

21. A system for monitoring changes in a characteristic of energy emanating from a scene, said system comprising:

(a) pickup means for converting the energy to electrical signals representing the measured characteristic;

(b) circuitry cooperative with the pickup means for sampling the measured characteristic at each of a predetermined set of locations of the scene;

(c) circuitry for accumulating during a defined sampling period a count of the number of said sampled locations the measured characteristic of whose energy lies within the scene of the sampled locations, and

(d) comparison circuitry for detecting at least a predetermined difference between the value of said count and a predetermined value.

22. A video monitoring system comprising:

(a) a television system for viewing an area;

(b) circuitry cooperating with the television system for electrically defining a predetermined set of locations of the viewed scene;

(c) accumulation circuitry coupled to the television system for producing an exclusively scalar count of the number of sampled locations at which the energy has a characteristic lying within a predetermined range, and

(d) comparison circuitry for producing an indication when the said count for a particular sampling period differs from a reference count by a predetermined threshhold value.

23. An area surveillance system comprising:

(a) pickup means for producing electrical information representing spatial energy distribution emanating from a scene, said representations being produced in a series of timed cycles;

(b) means for producing a series of information ensembles describing energy emanating from sampled points within the scene, the ensemble corresponding to a first cycle constituting a reference signal;

(c) means for comparing the reference signal with an analogous signal produced in a subsequent cycle, and

(d) means for periodically refreshing the reference signal.