Surveillance apparatus and recording medium recorded surveillance program

• US 6,798,908 B2
• Filed: 12/22/2000
• Issued: 09/28/2004
• Est. Priority Date: 12/27/1999
• Status: Expired due to Fees

• Current Assignee: Hitachi Industry & Control Solutions, Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Nagaya, Shigeki, Miyatake, Takafumi, Nagasaka, Akio, Fujita, Takehiro
• Primary Examiner(s): Mehta, Bhavesh M.
• Assistant Examiner(s): DESIRE, GREGORY M
• Application Number:
  US09/741,808
• Publication Number:
  US 20010010731A1
• Time in Patent Office: 1,376 Days
• Field of Search: 345/419-425, 345/430, 345/435, 345/437, 345/442, 345/582, 382/103, 382/107, 382/168-176, 382/180, 382/190, 382/192, 382/203, 382/268, 382/270-272, 382/275, 382/283, 382/285, 382/302, 382/304, 348/135, 348/152, 348/169
• US Class Current: 382/190
• CPC Class Codes: G06T 7/254 involving subtraction of images
• CPC Class Codes: G06V 10/255 Detecting or recognising potential candidate objects based on visual cues, e.g. shapes
• 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 13/19606 Discriminating between target movement or movement in an area of interest and other non-signicative movements, e.g. target movements induced by camera shake or movements of pets, falling leaves, rotating fan
• CPC Class Codes: G08B 13/19671 Addition of non-video data, i.e. metadata, to video stream
• CPC Class Codes: G08B 13/19676 Temporary storage, e.g. cyclic memory, buffer storage on pre-alarm
• CPC Class Codes: G08B 13/1968 Interfaces for setting up or customising the system
• CPC Class Codes: G08B 13/19682 Graphic User Interface [GUI] presenting system data to the user, e.g. information on a screen helping a user interacting with an alarm system
• 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

An economical surveillance apparatus robust to an environmental change includes an input unit for inputting images in a time series, a background image memory unit for storing a plurality of input images, a difference image memory unit for calculating and storing difference degree between a plurality of background images of the background image memory unit and an image inputted afresh, and a judging unit for judging an existence/absence of an invading object by utilizing the value of the difference degree of the difference image memory unit. This surveillance apparatus can automatically register a plurality of background images from a camera image. Since the background images that are no longer used are automatically erased, the drop of detection speed and detection sensitivity can be prevented.

Claims

1. A surveillance apparatus comprising:

input means for inputting images in a time series;

background image memory means for registering a plurality of different background images from said images;

difference image memory means for calculating and storing a minimum value of a difference between each of said plurality of different background images and an image inputted afresh for each pixel; and

judgment means for judging an existence/absence of an invading object on the basis of said difference.

2. A surveillance apparatus according to claim 1, wherein each of said plurality of different background images comprises a single or a plurality of pixel values registered for each pixel.

3. A surveillance apparatus according to claim 2, wherein:

each background image is registered or erased for each pixel;

erasing is determined on the basis of a period from a registration time of said pixel to a time at which said pixel is last looked up, and a period from a time at which said pixel is last looked up to a present time;

when registration is made, a new pixel value is written to an empty region if said empty region exists in said background image memory means, and if said empty region does not exist, importance of each pixel value of a corresponding pixel is calculated and is overwritten to an image value having the lowest degree of importance.

4. A surveillance apparatus according to claim 1, further comprising:

memory means for recording said image inputted afresh for each pixel, when said judgment means judges that an invading object exists.

5. A surveillance apparatus according to claim 1, wherein:

said difference image memory means includes minimum value image memory means for storing a minimum value image comprising an absolute value of a difference for each pixel, and block-wise mean image memory means for dividing said minimum value image into blocks, and calculating and storing a mean value of an absolute value of a difference for each block; and

said judgment means judges an existence/absence of an invading object on the basis of a time series change of said mean value.

6. A surveillance system comprising:

one or more cameras arranged at different designated locations to capture images in a time series;

a display unit arranged to provide a visual display of the images from one or more cameras; and

a surveillance apparatus arranged to detect and analyze the images from one or more cameras, said surveillance apparatus comprising;

a memory device to store a surveillance program, and to register in advance a plurality of different background images; and

a controller configured to execute the surveillance program to detect a presence/absence of an invading object from the images of one or more cameras, by determining an absolute value of a difference between an input image and each of said plurality of different background images for each pixel, determining a minimum value image among all the background images at which the difference between the input image and each of said plurality of different background images is minimal, determining a mean value of a difference for each discrete block within the minimum value image, and determining the presence/absence of an invading object on the basis of a time series change of said mean value.

7. A surveillance system according to claim 6, wherein each of said plurality of different background images comprises a single or a plurality of pixel values registered for each pixel.

8. A surveillance system according to claim 6, wherein:

each background image is registered or erased for each pixel;

erasing is determined on the basis of a period from a registration time of said pixel to a time at which said pixel is last looked up, and a period from a time at which said pixel is last looked up to a current time; and

when registration is made, a new pixel value is written to an empty region if said empty region exists in a background image memory section of said memory device, and if said empty region does not exist, importance of each pixel value of a corresponding pixel is calculated and is overwritten to an image value having the lowest degree of importance.

9. A surveillance system according to claim 6, wherein said memory device comprises an input image section for recording an input image afresh for each pixel, when said controller determines that an invading object is present.

10. A surveillance system according to claim 6, wherein said memory device comprises:

an input image storage section for storing an input image afresh for each pixel;

a background image storage section for registering a plurality of different background images; and

a difference image storage section for storing the minimum value image in discrete blocks, and for storing the mean value of the difference for each block.

11. A surveillance apparatus comprising:

an input device to input images in a time series;

a memory device to store a surveillance program, and to register in advance a plurality of different background images; and

a controller configured to execute the surveillance program to detect a presence/absence of an invading object from the images of one or more cameras, by;

determining an absolute value of a difference between an input image and each of said plurality of different background images for each pixel,

determining a minimum value image among all the background images at which the difference between the input image and each of said plurality of different background images is minimal,

determining a mean value of a difference for each discrete block within the minimum value image, and

determining the presence/absence of an invading object on the basis of a time series change of said mean value.

12. A surveillance apparatus according to claim 11, wherein each of said plurality of different background images comprises a single or a plurality of pixel values registered for each pixel.

13. A surveillance apparatus according to claim 11, wherein:

each background image is registered or erased for each pixel;

erasing is determined on the basis of a period from a registration time of said pixel to a time at which said pixel is last looked up, and a period from a time at which said pixel is last looked up to a current time; and

when registration is made, a new pixel value is written to an empty region if said empty region exists in a background image memory section of said memory device, and if said empty region does not exist, importance of each pixel value of a corresponding pixel is calculated and is overwritten to an image value having the lowest degree of importance.

14. A surveillance apparatus according to claim 11, wherein said memory device comprises an input image section for recording an input image afresh for each pixel, when said controller determines that an invading object is present.

15. A surveillance apparatus according to claim 11, wherein said memory device comprises:

an input image storage section for storing an input image afresh for each pixel;

a background image storage section for registering a plurality of different background images; and

a difference image storage section for storing the minimum value image in discrete blocks, and for storing the mean value of the difference for each block.

16. A surveillance apparatus comprising:

an input device to input images;

a memory device to store in advance a plurality of different background images; and

a controller configured to compare an image input afresh from the input device with each of said plurality of different background images stored in the memory device to obtain a minimum value of a difference between an input image and each of said plurality of different background images, and to determine whether an invading object is present in the input image base on the minimum value of the difference between the input image and each of said plurality of different background images,

wherein said memory device comprises an input image storage section to store the image input afresh from the input device, a background image storage section to register the plurality of different background images, and a difference image storage section to store the minimum value of the difference between the input image and each of said plurality of different background images.

17. A surveillance apparatus according to claim 16, wherein each of said plurality of different background images comprises a single or a plurality of pixel values registered for each pixel.