Recording a sequence of images

• US 20050122397A1
• Filed: 12/02/2004
• Published: 06/09/2005
• Est. Priority Date: 12/03/2003
• Status: Active Grant

• Current Assignee: Envysion Incorporated (Motorola Solutions, Inc.)
• Original Assignee: Safehouse International Ltd.
• Inventors: Sherrah, Jamie Roy, Quartermain, Peter Richard, Henson, Michael Anthony
• Granted Patent: US 8,953,674 B2
• Time in Patent Office: Days
• US Class Current: 348/143
• 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 13/19613 Recognition of a predetermined image pattern or behaviour pattern indicating theft or intrusion
• CPC Class Codes: G08B 13/19656 Network used to communicate with a camera, e.g. WAN, LAN, Internet
• CPC Class Codes: G08B 13/19669 Event triggers storage or change of storage policy
• CPC Class Codes: H04N 7/181 for receiving images from a plurality of remote sources
• 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 sequence of images received from a camera is recorded according to a first procedure. The images are analysed to identify events of interest, and upon identifying an event of interest, an area of interest of a plurality of said images is identified. The identified area is recorded according to a second procedure.

Claims

1. A method of recording a sequence of images received from a camera, comprising the steps of

recording said sequence of images according to a first procedure;

analysing said images to identify events of interest;

upon identifying an event of interest, identifying an area of interest of a plurality of said images; and

recording said area according to a second procedure.

2. A method according to claim 1, wherein the detection of an event of interest is brought to the attention of an observer to allow action to be taken in response to an observation made by said observer.

3. A method according to claim 1, wherein said first procedure records images at a first definition and said second procedure records images at a second definition, and said second definition is higher than said first definition.

4. A method according to claim 1, wherein said first procedure compresses image data.

5. A method according to claim 4, wherein said second procedure compresses image data but said first procedure applies a greater degree of compression to images than said second procedure.

6. A method according to claim 5, wherein said first procedure causes data loss.

7. A method according to claim 1, wherein output image data is produced by compositing said areas of interest against respective frames recorded according to said first procedure.

8. A method according to claim 1, wherein said events of interest are identified by detecting new objects that have entered a captured scene, and said areas of interest include image data representing said objects.

9. A method according to claim 8, wherein new objects are detected by analysing incoming data frames with reference to a background model.

10. A computer-readable medium having computer-readable instructions executable by a computer or by a network of computers such that when executing said instructions said computer(s) will perform a method as defined by claim 1.

11. Image processing apparatus, comprising a data store, a processor, and an input, wherein said processing means is configured to:

receive, via said input, a sequence of images from a camera;

process said sequence of images according to a first procedure and store said images in said data store;

analyse said images to identify events of interest;

upon identifying an event of interest, identify an area of interest of a plurality of said images; and

process the image data representing said area according to a second procedure and store said data in said data store.

12. A method of detecting activity in image frames defined by a plurality of pixel values, comprising the steps of

analysing a plurality of image frames to produce a background model;

processing a new image frame in combination with said background model to determine an activity value for said new image frame; and

comparing said activity value against a threshold value to determine whether said activity value indicates an event, wherein

said threshold value is modified in response to calculating the number of isolated event pixels present in a processed image frame.

13. A method according to claim 12, wherein said processed image frame is said new image frame.

14. A method according to claim 12, wherein said threshold value is adjusted according to the proportion of isolated event pixels to total pixels present in said processed image frame.

15. A method according to claim 14, wherein said proportion is compared against a predetermined comparison value to determine said adjustment.

16. A method according to claim 15, wherein said predetermined comparison value is 0.2%.

17. A method according to claim 12, wherein said threshold value is derived as an output from a low-pass adaptive filter.

18. A method according to claim 12, wherein said activity value is produced by counting the number of foreground pixels present in an image.

19. Apparatus configured to carry out a method according to claim 12.

20. A computer-readable medium having computer-readable instructions executable by a computer or by a network of computers such that when executing said instructions said computer(s) will perform a method as defined by claim 12.