Smoke detection

• US 6,844,818 B2
• Filed: 04/20/2001
• Issued: 01/18/2005
• Est. Priority Date: 10/20/1998
• Status: Expired due to Fees

• Current Assignee: VSD Limited
• Original Assignee: VSD Limited
• Inventors: Grech-Cini, Henry Joseph
• Primary Examiner(s): Wu, Daniel J.
• Assistant Examiner(s): Nguyen, Phung
• Application Number:
  US09/838,795
• Publication Number:
  US 20020024446A1
• Time in Patent Office: 1,369 Days
• Field of Search: 340/628, 340/511, 340/630, 340/577, 382/103, 382/100, 382/228, 382/157
• US Class Current: 340/628
• 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 17/125 by using a video camera to detect fire or smoke

Abstract

A smoke detection system comprising video camera monitoring means, video frame comparison means, signal processing means, and alarm generating means dependant on an output from the signal processing means; the signal processing means being arranged to analyse successive frames acquired by the video camera monitoring means and to compare the intensity and/or colour of individual pixels or group of pixels so as to consider the overall characteristics and inter-relationships of these pixels so as to detect the presence of smoke characterised in that the signal processing means analyses a plurality of different types of change in the said characteristics and inter-relationships.

Claims

1. A smoke detection system comprising a video camera monitoring arrangement to capture successive frames of an image to be monitored, a video frame comparator coupled to the video camera monitoring arrangement, a signal processor coupled to the frame comparator, and an alarm generator coupled to the signal processor, the alarm generator operating in dependence on an output of the signal processor;

the signal processor being operable to analyze the successive frames and to compare at least one an intensity and a color of one of individual pixels and groups of pixels of at least two of the successive frames to consider overall characteristics and inter-relationships of the one of pixels and groups of pixels to detect a presence of smoke wherein the signal processor analyses a plurality of different types of change in the characteristics and inter-relationships by a combination of a weighted rule based analysis and a statistically based analysis.

2. A smoke detection system according to claim 1 in which the statistically based analysis is a Bayesian analysis.

3. A smoke detection system according to claim 1 in which one of the different types of change in the characteristics and inter-relationships includes whether the at least one of intensity and color are converging towards a mean value.

4. A smoke detection system according to claim 3 in which a plurality of the successive frames are arranged to be analyzed and the at least one of intensity and color is examined to determine whether the at least one of intensity and color is converging to a mean value.

5. A smoke detection system according to claim 1 in which the pixels include edge defining pixels that define edge information, one of the different types of change in the characteristics and inter-relationships including whether the edge defining pixels change from showing a structured level of information to showing a less structured level of information.

6. A smoke detection system according to claim 1 in which one of the different types of change in the characteristics and inter-relationships includes whether dynamic portions of the successive frames are becoming static.

7. A smoke detection system according to claim 1 in which one of the different types of change in the characteristics and inter-relationships includes whether measured differences of the at least one of intensity and color are distributed in small isolated groups.

8. A smoke detection system according to claim 1 in which the successive frames include a reference frame and a current frame, one of the different types of change in the characteristics and inter-relationships including whether measured changes in a value of the at least one of intensity and color between the reference frame and the current frame indicate a reduction in visibility.

9. A smoke detection system according to claim 1 in which one of the different types of change in the characteristics and inter-relationships includes whether new regions of the successive frames have characteristics of shape that resemble those of known shape characteristics of one of an emerging smoke and an emerging fire condition.

10. A smoke detection system according to claim 1 in which the pixels include edge defining pixels that define edge information an the different types of change in the characteristics and inter-relationships include a first type of change and a second type of change, the first type of change including whether the at least one of intensity and color are converging towards a mean value, the second type of change including whether the edge defining pixels change from showing a structured level of information to showing a less structured level of information.

11. A smoke detection system according to claim 1 in which the different types of change in the characteristics and inter-relationship include a first type of change and a second type of change, the first type of change including whether the at least one of intensity and color are converging towards a mean value, the second type of change including whether dynamic portions of the successive frames are becoming static.

12. A smoke detection system according claim 1 in which the different types of change in the characteristics and inter-relationship include a first type of change and a second type of change, the first type of change including whether the at least one of the intensity and color are converging towards a mean value, the second type of change including whether measured differences of the at least one of intensity and color are distributed in small isolated groups.

13. A smoke detection system according claim 1 in which the successive frames include a reference frame and a current frame, the different types of change in the characteristics and inter-relationships including a first type of change and a second type of change, the first type of change including whether the at least one of intensity and color are converging towards a mean value, the second type of change including whether the at least one of intensity and color of the reference current frames indicate a reduction in visibility.

14. A smoke detection system according to claim 1 in which the different types of change in the characteristics and inter-relationship include a first type of change and a second type of change, the first type of change including whether the at least one of intensity and color are converging towards a mean value, the second type of change including whether new regions of the successive frames have characteristics of shape that resemble those of known shape characteristics of one of an emerging smoke and an emerging fire condition.

15. A smoke detection system according to claim 1 in which the pixels include edge defining pixels that define edge information, the different types of change in the characteristics and inter-relationships including a first type of change and a second type of change, the first type of change including whether the edge defining pixels change from showing a structured level of information to showing a less structured level of information, the second type of change including whether dynamic portions of the successive frames are becoming static.

16. A smoke detection system according to claim 1 in which the pixels include edge defining pixels that define edge information, the different types of change in the characteristics and inter-relationships including a first type of change and a second type of change, the first type of change including whether the edge defining pixels change from showing a structured level of information to showing a less structured level of information, the second type of change including whether measured differences in the at least one of intensity and color are distributed in small isolated groups.

17. A smoke detection system according to claim 1 in which the successive frames include a reference frame and a current frame, the pixels including edge defining pixels that define edge information, the different types of change in the characteristics and inter-relationships including a first type of change and a second type of change, the first type of change including whether the edge defining pixels change from showing a structured level of information to showing a less structured level of information, the second type of change including whether changes of the at least one of intensity and color between the reference and current frames indicate a reduction in visibility.

18. A smoke detection system according to claim 1 in which the pixels including edge defining pixels that define edge information, the different types of change in the characteristics and inter-relationships including a first type of change and a second type of change, the first type of change including whether the edge defining pixels change from showing a structured level of information to showing a less structured level of information, the second type of change including whether new regions of the successive frames have characteristics of shape that resemble those of known shape characteristics of one of an emerging smoke and an emerging fire condition.

19. A smoke detection system according to claim 1 in which the different types of change in the characteristics and inter-relationships include a first type of change and a second type of change, the first type of change including whether dynamic potions of the successive frames are becoming static, the second type of change including whether measured differences of the at least one of intensity and color are distributed in small isolated groups.

20. A smoke detection system according to claim 1 in which the successive frames include a reference frame and a current frame, the different types of change in the characteristics and inter-relationships including a first type of change and a second type of change, the first type of change including whether dynamic potions of the successive frames are becoming static, the second type of change including whether change in the at least one of intensity and color between the reference and current frames indicate a reduction in visibility.

21. A smoke detection system according to claim 1 in which the different types of change in the characteristics and inter-relationships include a first type of change and a second type of change, the first type of change including whether dynamic potions of the successive frames are becoming static, the second type of change including whether new regions of the successive frames have characteristics of shape that resemble those of known shape characteristics of one of an emerging smoke and an emerging fire condition.

22. A smoke detection system according to claim 1 in which the successive frames include a reference frame and a current frame, the different types of change in the characteristics and inter-relationships including a first type of change and a second type of change, the first type of change including whether measured differences of the at least one of intensity and color are distributed in small isolated groups, the second type of change including whether changes in the at least one of intensity and color between the reference and current frames indicate a reduction in visibility.

23. A smoke detection system according to claim 1 in which the different types of change in the characteristics and inter-relationships include a first type of change and a second type of change, the first type of change including whether measured differences of the at least one of intensity and color are distributed in small isolated groups, the second type of change including whether new regions of the successive frames have characteristics of shape that resemble those of known shape characteristics of one of an emerging smoke and an emerging fire condition.

24. A smoke detection system according to claim 1 in which the successive frames include a reference frame and a current frame, the different types of change in the characteristics and inter-relationships include a first type of change and a second type of change, the first type of change including whether changes in the at least one of intensity and color between the reference and current frames indicate a reduction in visibility, the second type of change including whether new regions of the successive frames have characteristics of shape that resemble those of known shape characteristics of one of an emerging smoke and an emerging fire condition.

25. A smoke detection system according to claim 1 in which the pixels include edge defining pixels that define edge information, the different types of change in the characteristics and inter-relationships including first, second, third and fourth types of change, the first type of change including whether values of the at least one of intensity and color are converging towards a mean value, the second type of change including whether the edge defining pixels change from showing a structured level of information to showing a less structured level of information, the third type of change including whether the image of the successive frames moves in an unpredictable manner and ceases to be static and the fourth type of change including whether new regions of the successive frames have shape characteristics that resemble those of known shape characteristics of one of an emerging smoke and an emerging fire condition.