Method and apparatus for detecting changes in a video display

• US 5,880,775 A
• Filed: 01/24/1997
• Issued: 03/09/1999
• Est. Priority Date: 08/16/1993
• Status: Expired due to Fees

• Current Assignee: Videofaxx Incorporated
• Original Assignee: Videofaxx Incorporated
• Inventors: Ross, Jay B.
• Primary Examiner(s): Chin, Tommy P.
• Assistant Examiner(s): Le, Vu
• Application Number:
  US08/787,255
• Time in Patent Office: 774 Days
• Field of Search: 358/105, 358/108, 358/125, 358/126, 358/103, 358/109, 379/53, 348/155, 348/82, 348/143, 348/150, 348/152, 348/153, 348/154, 348/161
• US Class Current: 348/143
• CPC Class Codes: G08B 13/19602 Image analysis to detect motion of the intruder, e.g. by frame subtraction
• CPC Class Codes: G08B 13/19652 Systems using zones in a single scene defined for different treatment, e.g. outer zone gives pre-alarm, inner zone gives alarm
• CPC Class Codes: H04N 19/142 Detection of scene cut or scene change
• CPC Class Codes: H04N 19/179 the unit being a scene or a shot
• CPC Class Codes: H04N 19/87 involving scene cut or scene change detection in combination with video compression
• CPC Class Codes: H04N 7/188 Capturing isolated or intermittent images triggered by the occurrence of a predetermined event, e.g. an object reaching a predetermined position signal generation from motion picture films H04N5/253

Abstract

A scene change monitor includes a camera (12) for monitoring a given scene. The camera (12) is operable to sequentially generate frames (18) of visual information, which frames are then divided up into pixels and the value of the pixels for each frame accumulated in an accumulator (25). The accumulator (25) provides on the output thereof a frame value for each frame (18) and stores this value in a register (22). A difference generator (24) is operable to generate the difference between select ones of the registers (22) for select ones of the frames (18) and generate a difference value for input to a comparator (26). The comparator (26) compares the difference value to a scene change threshold and, if it exceeds this value, a VCR activation signal is generated for turning a VCR (16) on to record the scene.

Claims

1. A scene change monitor for monitoring a given scene, comprising:

a display device for converting said scene into a plurality of sequentially generated pixels to represent a frame at a given time, said display device operable to generate a plurality of frames, each of said pixels having a video value representing the relative intensity of said pixel in said associated frame;

an accumulator for generating a single value for each of said frames, said single value for a given one of said frames representing the average intensity of substantially all of said pixels associated with said given frame, said accumulator operating on said pixels in said given frame as they are sequentially generated such that said video values for all of said pixels in said given frame are not stored;

a memory for storing said single value for select ones of said frames;

an averaging circuit for averaging each of said stored single values with single values for a predetermined number of adjacent frames and generating a single accumulated frame value for the frame associated with said each stored single value for storage in said memory; and

a comparison circuit for comparing select ones of said stored single accumulated frame values that are associated with different frames that are not adjacent to each other and outputting a scene change alarm if the comparison of said select accumulated frame single values meets user defined comparison criteria.

2. The scene change monitor of claim 1, wherein said display device comprises a camera for converting said given scene into analog video signals, and circuitry for converting said analog video signals to pixels representing individual segments of said given scene.

3. The scene change monitor of claim 1, wherein said comparison circuit comprises:

a difference generator for calculating the difference between select ones of the stored accumulated frame single values;

a comparator for comparing the output of said difference generator with a predetermined threshold; and

an alarm device for generating said scene change alarm when the output of said difference generator is determined by said comparator to exceed said threshold.

4. The scene change monitor of claim 1, wherein said accumulator is operable to sum all of the video values of all of the pixels in said given frame to provide said associated single value.

5. The scene change monitor of claim 4, wherein said accumulator is operable to divide said sum by a predetermined value to generate said associated single value.

6. The scene change monitor of claim 1, wherein said display device is divided into predetermined zones and said accumulator is operable to generate a single value for each of said zones for each of said frames, with said associated single value for each of said frames for each of said zones representing the average intensity of substantially all of said pixels associated with each of said zones in each of said frames, and wherein said memory is operable to store said single values for select ones of said frames and their associated zones.

7. The scene change monitor of claim 1 wherein said display device is operable to scan said given scene in different positions and divide said given scene into segments, wherein different segments of said given scene are displayed at different intervals of time, said scanning operation being repetitive such that each of said segments of said given scene is scanned at a predetermined time, and wherein said comparison circuit is operable to only compare said select ones of said stored single values associated with said frames that correspond to the same one of the scanned segments of said given scene scanned by said display device.

8. A system for recording a scene when a change has occurred in the scene, comprising:

a display device for converting said scene into a plurality of sequentially generated pixels to represent a frame of pixels at a given time, and said display device operable to generate a plurality of sequential frames, each of said pixels having a video value representing the relative intensity of said pixel in said associated frame;

an accumulator for generating a single value for each of said frames, said single value for a given one of said frames representing the average intensity of substantially all of said pixels associated with said given frame, said accumulator operating on said pixels in said given frame as they are sequentially generated such that said video values for all of said pixels in said given frame are not stored,

a memory for storing said single value for select ones of said frames;

an averaging circuit for averaging each of said stored single values with said single values for a predetermined number of adjacent frames and generating a single accumulated frame value for the frame associated with said each stored single value for storage in said memory;

a comparison circuit for comparing select ones of said stored single accumulated frame values that are associated with different frames that are not adjacent to each other and outputting a scene change alarm if the comparison of said select single accumulated frame values meets user defined comparison criteria; and

a recording device for being activated by said scene change alarm and recording the scene output by said display device.

9. The system of claim 8, wherein said display device comprises a camera for converting said given scene into analog video signals, and circuitry for converting said analog video signals to pixels representing individual segments of the given scene, said analog video signals input to said recording device.

10. The system of claim 8, wherein said compare circuit comprises:

a difference generator for calculating the difference between select ones of the stored single accumulated frame values;

a comparator for comparing the output of said difference generator with a predetermined threshold; and

an alarm device for generating said scene change alarm when the output of said difference generator is determined by said comparator to exceed said threshold.

11. The system of claim 8, wherein said accumulator is operable to sum all of the video values of all of the pixels in said given frame to provide said associated single value.

12. The system of claim 11, wherein said accumulator is operable to divide said sum by a predetermined value to generate said associated single value.

13. The system of claim 8, wherein said display device is divided into predetermined zones and said accumulator is operable to generate a single value for each of said zones for each of said frames, with said associated single value for each of said frames for each of said zones representing the average intensity of substantially all of said pixels associated with each of said zones in each of said frames, and wherein said memory is operable to store said single values for select ones of said frames and their associated zones.

14. The system of claim 8 wherein said display device is operable to scan said given scene in different positions and divide said given scene into segments, wherein different segments of said given scene are displayed at different intervals of time, said scanning operation being repetitive such that each of said segments of said given scene is scanned at a predetermined time, and wherein said comparison circuit is operable to only compare said select ones of said stored single values associated with said frames that correspond to the same one of the scanned segments of said given scene scanned by said display device.

15. A method for monitoring a given scene, comprising the steps of:

converting the scene into a plurality of sequentially generated pixels to represent a frame of pixels at a given time as a given frame, and the step of converting operable to generate a plurality of sequential frames, each of the pixels in each of the frames having a video value representing the relative intensity of the pixel in the associated frame;

generating a single value for each of the frames, the single value for the given frame representing the average intensity of substantially all of the associated pixels, the step of generating operating on the pixels in the given frame as they are sequentially generated such that the video values for all of the pixels in the given frame are not stored;

storing in a memory the single value for select ones of the frames;

averaging each of the stored single values with the single values for a predetermined number of adjacent frames and generating a single accumulated frame value for the frame associated with said each stored single value for storage in the memory; and

comparing select ones of the stored single accumulated frame values that are associated with different frames that are not adjacent to each other and outputting a scene change alarm if the comparison of the select single accumulated frame values meets user defined comparison criteria.

16. The method of claim 15, wherein the step of converting comprises converting said given scene into analog video signals with a camera, and converting the analog video signals to pixels representing individual segments of the given scene.

17. The method of claim 15, wherein the step of comparing comprises:

calculating the difference between the select ones of the stored single accumulated frame values;

comparing the difference with a predetermined threshold; and

generating the scene change alarm when the difference is determined by the step of comparing to exceed the threshold.

18. The method of claim 15, wherein the step of generating is operable to sum all of the video values of all of the pixels in the given frame to provide the associated single value.

19. The method of claim 18, wherein the step of generating is operable to divide the sum by a predetermined value to generate the associated single value.

20. The method of claim 15, wherein the step of converting comprises dividing the scene into predetermined zones and generating a single value for each of the zones for each of the frames, with the associated single value for each of the frames for each of the zones representing the average intensity of substantially all of the pixels associated with each of the zones in each of the frames, and wherein the step of storing is operable to store the single values for select ones of the frames and their associated zones.

21. The method of claim 15 wherein the step of converting comprises scanning the given scene in different positions and dividing the given scene into segments, wherein different segments of the given scene are displayed at different intervals of time, said scanning operation being repetitive such that each of the segments of the given scene is scanned at a predetermined time, and wherein the step of comparing is operable to only compare select ones of the stored single values associated with frames that correspond to the same one of the scanned segments of the given scene scanned by the step of scanning.

22. A method for recording a scene where a change has occurred in the scene, comprising the steps of:

converting the scene into a plurality of sequentially generated pixels to represent a frame of pixels at a given time as a given frame, and the display device operable to generate a plurality of sequential frames, each of the pixels having a video value representing the relative intensity of the pixel in the frame;

generating a single value for each of the frames, the single value for each of the frames representing the average intensity of substantially all of the associated pixels, the step of generating operating on the pixels in the given frame as they are sequentially generated such that the video values for all of the pixels in the given frame are not stored;

storing in a memory said single values for select ones of said frames;

averaging each of the stored single values with the single values for a predetermined number of adjacent frames and generating a single accumulated frame value for the frame associated with said each stored single value for storage in the memory;

comparing select ones of the stored single accumulated frame values that are associated with different frames that are not adjacent to each other and outputting a scene change alarm if the comparison of the select single accumulated frame values meets predetermined comparison criteria; and

activating a recording device in response to the generation of the scene change alarm to record the scene.

23. The method of claim 22, wherein the step of converting comprises converting a predetermined scene into analog video signals with a camera, and converting the analog video signals to pixels representing individual segments of the scene.

24. The method of claim 22, wherein the step of comparing comprises:

calculating the difference between select ones of the stored single accumulated frame values;

comparing the output of the step of calculating with a predetermined threshold; and

generating the scene change alarm when the output of the step of calculating is determined by the step of comparing to exceed the threshold.

25. The method of claim 22, wherein step of generating is operable to sum all of the video values of all of the pixels in a given one of the frames to provide said associated single value.

26. The method of claim 25, wherein the step of generating is operable to divide the sum by a predetermined value to generate the associated single value.

27. The method of claim 22, wherein the scene is divided into predetermined zones and the step of generating is operable to generate a single value for each of the zones for each of the frames, with the associated single value for each of the zones representing the average intensity of substantially all of the pixels associated with each of the zones in each of the frames, and wherein the step of storing is operable to store the single values for select ones of the frames and their associated zones.

28. The method of claim 22 wherein the step of converting is operable to scan the given scene in different positions and divide the scene into segments, wherein different segments of the given scene are displayed at different intervals of time, the scanning operation being repetitive such that each segment of the given scene is scanned at a predetermined time, and wherein the step of comparing is operable to only compare select ones of the stored single values associated with frames that correspond to the same one of the scanned segments of the given scene that is scanned.