Method of updating reference background image, method of detecting entering objects and system for detecting entering objects using the methods

• US 6,546,115 B1
• Filed: 09/09/1999
• Issued: 04/08/2003
• Est. Priority Date: 09/10/1998
• Status: Expired due to Term

• Current Assignee: Hitachi Denshi Kabushiki Kaisha
• Original Assignee: Hitachi Denshi Kabushiki Kaisha
• Inventors: Yamada, Hiromasa, Ito, Wataru, Ueda, Hirotada
• Primary Examiner(s): Patel, Jayanti K.
• Assistant Examiner(s): AZARIAN, SEYED H
• Application Number:
  US09/392,622
• Time in Patent Office: 1,307 Days
• Field of Search: 382/100, 382/103, 382/155, 382/181, 382/190, 382/209, 382/134, 382/169, 382/700, 382/454, 356/364
• US Class Current: 382/100
• CPC Class Codes: G08B 13/19602 Image analysis to detect motion of the intruder, e.g. by frame subtraction
• CPC Class Codes: G08B 13/19604 involving reference image or background adaptation with time to compensate for changing conditions, e.g. reference image update on detection of light level change
• 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 method of updating a reference background image used for detecting objects entering an image pickup view field based on the binary image generated from the difference between an input image and the reference background image of the input image. The image pickup view field is divided into a plurality of view field areas, and a reference background image corresponding to each of the fixed divided view field areas is updated. An entering object detection apparatus using this method has an input image processing unit including an image memory storing an input image from an image input unit, a program memory storing the program for activating the entering object detecting unit, a work memory and a central processing unit activating the entering object detecting unit in accordance with the program. The processing unit has an entering object detecting unit determining intensity difference for each pixel between the input image and the reference background image not including an entering object to be detected and detecting an area with the difference larger than a predetermined threshold as an entering object, a dividing unit dividing the image pickup view field of the image input unit into a plurality of view field areas, an image change detecting unit detecting the change of the image in each of the divided view field areas, and a reference background image updating unit updating each portion of the reference background image corresponding to each of the divided view field areas associated with the portion of the input image free of the image change, wherein the entering object detecting unit detects entering objects based on the updated reference background image.

Claims

1. A method of updating a reference background image for use in detecting an object entering an image pickup view field of an image pickup device based on a difference between an input image from said image pickup device and a reference background image of said input image, comprising the steps of:

displaying said image pickup view field on a display;

dividing said image pickup view field into a plurality of view field areas based on at least one of predetermined position information and time information of said image pickup view field displayed on said display;

detecting whether said object from said input image exists with each of said divided view field areas; and

updating divided view field areas of the reference background image in which said object is not detected.

2. A method according to claim 1, wherein said detecting step includes the step of detecting a movement of said object.

3. A method according to claim 1, wherein said predetermined position information is one or more boundary lines substantially parallel to the direction of movement of said object.

4. A method according to claim 1, wherein said predetermined position information is information relating to the average movement range of said object.

5. A method according to claim 1, wherein said predetermined position information is one or more boundary lines substantially parallel to the direction of movement of said object,

said method further comprising the step of:

sub-dividing each of said divided new field areas based on information relating to the average movement range of said object.

6. A method according to claim 1, further comprising the step of:

displaying the boundary of said divided view field areas on said display in different colors.

7. A method according to claim 3, wherein said object is a vehicle moving on a road and said boundary lines is that of a roadway.

8. A system for updating a reference background image for use in detecting an object entering an image pickup view field based on a difference between an input image and a reference background image of said input image, said system comprising:

an image pickup device for generating said input image;

a processing unit coupled with said image pickup device for processing said input image to detect said object; and

a display unit coupled with said processing unit on which said image pickup view field is displayed,

wherein said processing unit comprises;

a dividing unit for dividing said image pickup view field into a plurality of view field areas based on at least one of predetermined position information and time information of said image pickup view field displayed on said display,

a detecting unit for detecting whether said object from said input image exists within each of said divided view field areas, and

an updating unit for updating divided view field areas of the reference background image in which said object is not detected.

9. A system according to claim 8, wherein at least one of said predetermined position information and time information is either one of average value of movement of said object and distance covered by said object for a predetermined unit of time.

10. A system according to claim 8, wherein said updating unit comprises:

an image change detection unit for detecting a change of said input image within each of said divided view field areas; and

a background image updating unit for updating part of said reference background image corresponding to each of said divided view field areas in which said object is not detected.

11. A computer readable medium having program code means executable by a computer embodied therein for detecting an object in an image pickup view field based on a difference between an input image and a reference background image of said input image, comprising:

first code means for displaying said image pickup view field on a display;

second code means for dividing said image pickup view field into a plurality of view field areas based on at least one of predetermined position information and time information of said image pickup view field displayed on said display;

third code means for detecting whether said object from said input image exists within each of said divided view field areas; and

fourth code means for updating divided view field areas of the reference background image in which said object is not detected.

12. A computer readable medium according to claim 11, wherein said fourth code means comprises:

fifth code means for detecting a change of said input image within each of said divided view field areas; and

sixth code means for updating part of said reference background image corresponding to each of said divided view field areas in which said object is not detected.

13. A method of updating a reference background image for use in detecting an object entering an image pickup view field of an image pickup device based on a difference between an input image from said image pickup device and a reference background image of said input image, comprising the steps of:

displaying said image pickup view field on a display;

dividing said image pickup view field into a plurality of view field areas based on at least one of predetermined position information and time information of said image pickup view field displayed on said display;

detecting whether said object from said input image exists within each of said divided view field areas; and

updating each of said divided view field areas of the reference background image in which said object is not detected in order to detect a next entering object.

14. A method according to claim 13, wherein said updating step comprises the steps of:

detecting a change of the image signal of an input image portion corresponding to each of said divided view field areas; and

updating a portion of said reference background image corresponding to each of said divided view areas corresponding to said input image portion in which said object is not detected.

15. A method according to claim 13, wherein said change of said image signal is movement of said object.

16. A method according to claim 13, wherein said dividing step comprises the step of:

dividing said image pickup view field by one or more boundary lines substantially parallel to the direction of movement of said object.

17. A method according to claim 13, wherein said dividing step comprises the step of:

dividing said image pickup view field by an average movement range of said object during a predetermined unit time.

18. A method according to claim 13, wherein said dividing step comprises the step of:

dividing said view field by one or more boundary lines substantially parallel to the direction of movement of said object, and

sub-dividing said divided view field by an average movement range of said object during each predetermined unit time.

19. A method according to claim 13, wherein said input image includes at least a lane, and

said dividing step comprises the step of:

dividing said image pickup view field by one or more lane boundaries.

20. A method according to claim 13, wherein said input image includes a lane, and

said dividing step comprises the step of:

dividing said image pickup view field by an average movement range of a vehicle during a predetermined unit time.

21. A method according to claim 13, wherein said input image includes a lane, and

said dividing step comprises the step of:

dividing said image pickup view field by one or more lane boundaries, and

sub-dividing said divided image pickup view field by an average movement range of the vehicle during a predetermined unit of time.

22. A method according to claim 13, wherein said dividing step divides said image pickup view field into a plurality of view field areas based on at least one of the average direction of movement of said object and the distance covered by said entering object during a predetermined unit of time.