Slow change detection system

Patent metadata

Field	Value
Publication number	US-9864908-B2
Application number	US-201414542797-A
Country	US
Kind code	B2
Filing date	Nov 17, 2014
Priority date	Nov 19, 2013
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A slow change detection system includes: an image acquisition unit adapted to acquire a photographed image including consecutive images of a monitored object; a reference image acquisition unit adapted to acquire a reference image corresponding to the photographed image of the monitored object; a reference image area extraction unit adapted to extract, from the reference image, a reference image area that is an area corresponding to a photographed area of the photographed image; a change detection unit adapted to acquire a change area that is an area of the photographed image which is different from the reference image area and acquire a slow change area by excluding, from the acquired change area, a sudden change area derived from a history of the change area; and a display control unit adapted to superimpose and display information indicating the slow change area on the photographed image.

First claim

What is claimed is:

1. A slow change detection system comprising at least one central processing unit operating in conjunction with a memory to:
acquire a photographed image including a plurality of consecutive images of a monitored object;
acquire a reference image corresponding to the photographed image of the monitored object, the reference image having been photographed prior to acquiring the photographed image including the plurality of consecutive images;
extract, from the reference image, a reference image area that is an area corresponding to a photographed area of the photographed image;
identify a sudden change area in the acquired photographed image based on differences in the plurality of consecutive images of the photographed image;
acquire a change area that is an area of the photographed image which is different from the reference image area and acquire a slow change area by excluding, from the acquired change area, the sudden change area; and
superimpose and display information indicating the slow change area on the photographed image.

2. The slow change detection system according to claim 1 , wherein
the photographed image is associated with information of a photographed position, and
the reference image corresponding to the photographed image is acquired based on the information of the photographed position.

3. The slow change detection system according to claim 1 , wherein the change area is acquired by:
dividing the photographed image and the reference image area into subareas, and
determining whether or not the photographed image is different from the reference image area on a subarea basis and acquiring, as the change area, an area of the photographed image including a difference subarea that is a subarea in which a degree of difference is greater than or equal to a reference value.

4. The slow change detection system according to claim 2 , wherein the change area is acquired by:
dividing the photographed image and the reference image area into subareas, and
determining whether or not the photographed image is different from the reference image area on a subarea basis and acquiring, as the change area, an area of the photographed image including a difference subarea that is a subarea in which a degree of difference is greater than or equal to a reference value.

5. The slow change detection system according to claim 3 , wherein the change area is acquired by:
calculating a pixel value difference between pixels positionally corresponding to the photographed image and the reference image area in the subarea and further calculating a similarity evaluation value that becomes a higher value for a smaller accumulated total of absolute values of the pixel value difference, and
determining whether or not the subarea is the difference subarea by using the similarity evaluation value.

6. The slow change detection system according to claim 4 , wherein the change area is acquired by:
calculating a pixel value difference between pixels positionally corresponding to the photographed image and the reference image area in the subarea and further calculating a similarity evaluation value that becomes a higher value for a smaller accumulated total of absolute values of the pixel value difference, and
determining whether or not the subarea is the difference subarea by using the similarity evaluation value.

7. The slow change detection system according to claim 5 , wherein the change area is acquired by:
shifting the subarea of the photographed image vertically and laterally by a predetermined amount, calculating the similarity evaluation value for a plurality of shifted subareas, and determining whether or not the subarea is the difference subarea by using the highest similarity evaluation value.

8. The slow change detection system according to claim 6 , wherein the change area is acquired by:
shifting the subarea of the photographed image vertically and laterally by a predetermined amount, calculating the similarity evaluation value for a plurality of shifted subareas, and determining whether or not the subarea is the difference subarea by using the highest similarity evaluation value.

9. The slow change detection system according to claim 1 , wherein a shape of the extracted reference image area is changed so that the extracted reference image area has a same shape and a same size as the photographed image.

10. The slow change detection system according to 2 , wherein a shape of the extracted reference image area is changed so that the extracted reference image area has a same shape and a same size as the photographed image.

11. The slow change detection system according to claim 3 , wherein a shape of the extracted reference image area is changed so that the extracted reference image area has a same shape and a same size as the photographed image.

12. The slow change detection system according to claim 4 , wherein a shape of the extracted reference image area is changed so that the extracted reference image area has a same shape and a same size as the photographed image.

13. The slow change detection system according to claim 5 , wherein a shape of the extracted reference image area is changed so that the extracted reference image area has a same shape and a same size as the photographed image.

14. The slow change detection system according to claim 6 , wherein a shape of the extracted reference image area is changed so that the extracted reference image area has a same shape and a same size as the photographed image.

15. The slow change detection system according to claim 7 , wherein a shape of the extracted reference image area is changed so that the extracted reference image area has a same shape and a same size as the photographed image.

16. The slow change detection system according to claim 8 , wherein a shape of the extracted reference image area is changed so that the extracted reference image area has a same shape and a same size as the photographed image.

17. The slow change detection system according to claim 3 , wherein the change area is acquired by:
defining a difference subarea group surrounded by subareas that are not the difference subareas, as one object; and
calculating a change amount of a center of gravity and an area in the object and, when the change amount is greater than or equal to a predetermined reference value, acquiring an area including difference subareas forming the object as the sudden change area.

18. The slow change detection system according to claim 1 , wherein the sudden change area is determined by comparing the change area with an image of the area acquired before the acquisition of the change area.

19. The slow change detection system according to claim 17 , wherein the change amount of the center of gravity and the area in the object is calculated by comparing a photographed image of the object at time T(t) with a photographed image of the object at time T(t−1) that is before the time T(t).

20. A slow change detection system comprising at least one central processing unit (CPU) configured to:
acquire, from a camera, a plurality of consecutive images of a monitored object;
acquire a reference image of the monitored object, the reference image having been obtained by photographing the monitored object in a reference state prior to acquiring the consecutive images;
identify a sudden change area of the monitored object based on differences in the plurality of consecutive images;
determine a change area between the reference image and the consecut

Assignees

• Yokogawa Electric Corp

Inventors

• Ishikawa Tetsuya
• Okabe Nobuo
• Ishii Yosuke
• Kamada Ken'Ichi

Classifications

• G06V20/40 Primary

  in video content (extracting overlay text G06V20/62; video retrieval G06F16/70; processing of video elementary streams in video servers H04N21/234; processing of video elementary streams in video clients H04N21/44) · CPC title

• G06T7/248

  involving reference images or patches · CPC title

• G06K9/00624 Primary

  Physics · mapped topic

• G06T2207/10016

  Video; Image sequence · CPC title

• G06T7/254

  involving subtraction of images · CPC title