JPH07105381A - Monitor and picture processing system for monitor - Google Patents

Abstract

PURPOSE:To provide the monitor monitoring a different object even when an image pickup device is being moved. CONSTITUTION:Lots of background pictures obtained by picking up an image of a monitored area in various moving positions of an image pickup device 4 are stored in advance in a background picture storage section 14. The image pickup device 4 picks up an image of the monitored area while being moved. The picture picked up by the image pickup device 4 is fed to a different object detection section 15 through a picture input section 12. Simultaneously a CPU 11 reads plural background pictures highly possible to be a background of the received picture from the storage section 14 and the background pictures are fed to the different object detection section 15. The different object detection section 15 obtains a difference between each of the selected background pictures and the input picture from the image pickup device 4 to discriminate the presence of a different object depending whether a background picture having a very small difference is in existence in the differences.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surveillance device used for surveillance of people, articles and the like, and more particularly to improvement of an image processing system for a surveillance device using an image processing technique.

[0002]

2. Description of the Related Art In recent years, as a safety measure, computers and image processing technology have been used to monitor illegal intruders in places where humans are prohibited and to monitor illegal parking in prohibited areas. There is increasing interest in surveillance devices that provide automatic surveillance.

In general, these conventional apparatuses perform image processing such as image conversion processing and feature extraction processing on an input image obtained from a fixed image pickup apparatus such as a television camera,
A person or an object (hereinafter referred to as a "foreign body") invading the surveillance area is detected.

FIG. 3 shows a conventional monitoring device of this type (hereinafter, referred to as
(Also referred to as “apparatus”).

This monitoring device comprises a computer 101, a display unit (CRT) 102, a memory 103, and an image pickup device 1.
The computer 101 is provided with an arithmetic processing unit (CPU) 111, an image input unit 112, a background image storage unit 116, and a foreign body detection unit 114, and these units are connected by a data bus 115. There is.

In this device, the grayscale image of the monitoring area input from the image pickup device 104 is converted into a digital frame image by the image input unit 112. This digital frame image is input to the foreign body detection unit 114. The foreign body detection 114 performs a process of detecting a foreign body from the input image. As a method of detecting a foreign body, for example, as described in "Moveable Object Extraction Technology" by Kawabata, Tanito, and Morooka (Information Processing Society of Japan, April 1987),
Background difference processing technology is generally used that performs a difference process of a brightness value between a background image in which a foreign body (moving object) stored in the background image storage unit 116 does not exist and an input image.

If the difference value between the background image and the input image is larger than a predetermined threshold value, it is determined that a foreign object exists in the monitoring area, and the display unit 102 displays the current time and the input image. The current time and the input image are also recorded in the memory 103.

[0008]

This conventional apparatus cannot detect the presence / absence of a foreign body because the difference from the background image over the entire area of the image occurs when the image pickup apparatus 4 itself moves. . Therefore, the imaging device 4 must always be fixed.

Therefore, when one surveillance camera is to be moved (pivoted or moved up and down) to perform a wide-range surveillance, the above-mentioned nature of the conventional device becomes a major obstacle, and the surveillance is always performed while the camera is moved. Can't do.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a monitoring device capable of constantly monitoring the presence or absence of a foreign object even while the image pickup device is moving.

[0011]

A monitoring device of the present invention accumulates a movable image pickup device and a background image sequence imaged in advance at various different moving positions of the image pickup device in a situation where a foreign object is not present. The background image sequence accumulating device and the background device that selects from the accumulating device a plurality of background images located within a region near the position of the input image at the current time from the imaging device when the imaging device is moved and photographed. The present invention is characterized by having a candidate selecting unit and a foreign body detecting unit that determines the presence or absence of a foreign body by performing a difference process between the selected background image and the input image.

[0012]

In the monitoring device according to the present invention, the background image sequence obtained by photographing the monitoring region at various different moving positions of the image pickup device is stored in advance in a situation where there is no foreign body. . Then, when actually moving the imaging device to perform monitoring, a plurality of background images (background candidate image strings) located in a region near the position of the input image at the current time are selected from the accumulated background image strings. . And
Difference processing is performed between the background candidate image sequence and the input image input from the imaging device, and the presence or absence of a foreign body is determined from this difference value.

As a result, even if the image pickup device is moved, the background image of the image pickup device is automatically selected, so that the foreign object can be monitored.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings.

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a monitoring device according to an embodiment of the present invention. This monitoring device includes a computer 1, a display unit (CTR) 2 that displays information such as characters and images, a memory 3 that stores information such as characters and images, an imaging device 4 such as a television camera, and an imaging device 4.
Moving device 5 for moving (pivoting, moving up and down, etc.)
Is equipped with.

The computer 1 includes an arithmetic processing unit 11, an image input unit 12, a position input unit 13, and a background image sequence storage unit 1.
4 and a foreign body detection unit 15 are provided, and these units are connected by a data bus 16.

The display unit 2 is composed of, for example, a CRT display device, and the memory 3 is composed of a main storage device of the computer 1 and an auxiliary storage device such as a magnetic disk device or an optical disk device. In addition, the imaging device 4
The mobile device can scan the surveillance area so that the surveillance area wider than its field of view can be imaged.

The image input unit 12 in the computer 1 converts the grayscale image input from the image pickup device 4 into a digital frame image. The position input unit 13 receives coordinate information indicating the moving displacement of the image pickup device 4 from the moving device 5 and sends it to the CPU 11.

The background image sequence accumulating unit 14 takes images at predetermined intervals while moving the image pickup device 4 along a predetermined scanning path at a predetermined speed in a situation where a foreign body does not exist in the monitoring area in advance. A large number of background images covering the entire monitoring area obtained as a whole are accumulated.

The foreign body detection unit 15 detects a foreign body such as an illegal intruder in the monitoring area based on the image obtained from the image pickup device 4 through the image input unit 12. Note that the foreign body detection method used here is based on, for example, the background subtraction processing technique as described in the above-mentioned document, but as described below, an improvement according to the present invention is added. Has been.

Next, the operation of the present embodiment configured as described above will be described in detail with reference to the flowchart of FIG.

First, as a preparatory work before starting the actual monitoring, the imaging device 4 is moved along the predetermined route at a constant speed over the entire monitoring target area in a situation where there is no foreign object in the monitoring area. The image input unit 12 samples and holds the photographed background image while scanning, under the control of the CPU 11, at predetermined time intervals or at predetermined movement displacement intervals, and converts it into a digital frame image. The background image sequence thus sampled is stored in the background image sequence storage unit 13 (step 201). In parallel with this, the coordinate information from the moving device 5 is transferred to the position input unit 1
3 is input to the CPU 11. The CPU 11 uses coordinate information (hereinafter,
The “position” of the background image) is stored in the background image sequence storage unit 13 in association with each background image. Alternatively, each sampled background image is stored in the address location in the storage unit 13 associated with the position of each background image.

When all the background images sampled from the entire monitoring area are accumulated in this way, this preparatory work is completed, and thereafter actual monitoring can be started.

When the actual monitoring is started, the image pickup device 4 constantly moves to take an image of the inside of the monitoring area. In this case, the imaging device 4
There is no special limitation on the moving method of. For example, a method of performing regular scanning along a predetermined path at a predetermined speed, or a method of moving randomly and freely by a manual operation of an observer may be used.

Now, during monitoring, the image within the field of view at the current time output from the moving image pickup device 4 is input to the image input section 12 and converted into a digital frame image (step 202).

Next, in step 203, the image input unit 1
The digital frame image from 2 is the foreign body detection unit 15
Entered in. At the same time, the CPU 11 causes the storage unit 1 to
The position of the background image selected in this step 203 at the previous time (recorded in the memory 3 in step 205 at the previous time) and the movement of the imaging device 4 from among the many background images stored in Based on the direction (which can be inferred from the displacement between the background images selected at the previous time and the time before the previous time), the plurality of backgrounds positionally shifted in the moving direction from the position of the background image selected at the previous time. The image is selected and read out and input to the foreign body detection unit 15 (step 20).
3). It should be noted that in this selection process, even if the moving speed of the image pickup device 4 is slightly faster or slower, the background image positioned in the area near the position of the input image can be selected without fail (that is, the selected plural images are selected). The background image of the input image always includes an image substantially equivalent to the background image of the input image), and the amount of shift and the number of background images to be selected from the previous time position are appropriately selected in advance. Has been. Hereinafter, the selected plurality of background images will be referred to as "background candidate image sequence".

Next, the foreign object detection unit 15 performs difference processing between each of the selected background candidate image sequences and the input image, and calculates a difference value for each background candidate image (step 204). ).

As a result, when there is no foreign body in the input image, the difference value for one candidate image (substantially equivalent to the background image of the input image) in the background candidate image sequence is The value is obviously smaller than that of other candidate images. Therefore, when such a result is obtained, a candidate image whose difference value is obviously small is selected as the background image corresponding to the current input image, its position is recorded in the memory 3, and the process returns to the processing step 202. (Step 205).

On the other hand, when a foreign body is present in the input image, a large difference value occurs to some extent in any of the candidate images due to the presence of the foreign body, so that an image whose difference value is extremely smaller than the other candidate images is generated. It does not exist, or a difference value larger than a predetermined threshold occurs in all candidate images. Therefore, when such a result is obtained, it is determined that the foreign body has entered the monitoring area (step 205).

Steps 202 to 205 described above
By repeating the above process, the monitoring area is constantly and continuously monitored. If an invasion of a foreign body in the monitoring area is detected during the monitoring, in response to this, the CPU 11 performs an operation for displaying an input image on the display unit 2, generating an alarm, notifying a surveillance staff, or the like. Do.

According to the above-described embodiment, a large number of background image sequences imaged at various different positions over the entire monitoring area are stored in advance, and when monitoring is performed, an input from a moving imaging device is input. A plurality of background images (background candidate image strings) included in the area near the position of the image are selected from the accumulated images, the difference processing between this background candidate image string and the input image is performed, and these background image strings are included. Whether or not there is a foreign body in the monitoring area is determined by whether or not there is one sheet whose difference value is significantly low. According to this method, the presence or absence of a foreign object can be relatively easily and reliably determined during the movement of the imaging device even if the imaging device is freely moved.

As a processing method different from the above embodiment, the displacement amount of the image pickup device is constantly monitored, the position of the input image is accurately calculated, and one background image that matches the position is selected from the storage unit to obtain the difference. A method of performing processing is also conceivable. However, in this method, it is actually difficult to accurately calculate the position of the input image in real time due to a delay caused by calculation processing time and the like. Therefore, the above embodiment is more practical than this method.

The above-mentioned embodiment shows an example of the present invention, and the present invention should not be limited to this.
For example, in the above-described embodiment, a wide monitoring area that does not fit in one visual field is scanned and covered by the imaging device.
In order to monitor a narrow surveillance area within one field of view from different directions, the imaging device revolves around the surveillance area,
The present invention can also be applied to the case where an image is taken while moving linearly. The present invention, in addition to detecting illegal intruders, detecting illegally parked vehicles, counting gate visitors, etc.
It can be used for a wide range of purposes.

[0035]

As described above in detail, according to the present invention, it is possible to monitor a foreign body while moving the image pickup device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a monitoring device according to an embodiment of the present invention.

FIG. 2 is a flow chart showing the operation of the embodiment.

FIG. 3 is a block diagram showing a configuration example of a conventional monitoring device.

[Explanation of symbols]

 1 Computer 11 CPU 12 Image Input Section 13 Position Input Section 13 Background Image Sequence Storage Section 15 Foreign Object Detection Section 16 Data Bus 2 CRT 3 Memory 4 Imaging Device

Claims (5)

[Claims] 1. A monitoring device for monitoring using an image processing technique, wherein a movable imaging device for photographing a monitoring area, and various different movements of the imaging device in the absence of a foreign object. A background image sequence storage device that stores a background image sequence captured in advance at a position, and when the image capture device is moved and imaged, it is located in a region near the position of the input image at the current time from the image capture device. A plurality of background images, a background candidate selecting unit that selects from the storage device, and a foreign object detecting unit that determines the presence or absence of a foreign object by performing a difference process between the selected background image and the input image, A monitoring device comprising: 2. The monitoring device according to claim 1, wherein the background candidate selecting means selects a plurality of the background images based on a position of the background image selected with respect to the input image at the previous time and a moving direction of the imaging device. A monitoring device characterized by determining one background image. 3. The monitoring device according to claim 2, wherein the foreign object detecting unit has a difference value with the input image in the selected plurality of background images that is clearer than that of other background images. A monitoring device, characterized in that when there is one small sheet, it is judged that there is no foreign body. 4. The monitoring device according to claim 1, wherein the foreign object detection unit has no apparent difference between the selected background images and the input image, or The monitoring device is characterized by determining that there is a foreign body when both are larger than a predetermined threshold value. 5. An image processing method for determining the presence / absence of a foreign object within an imaging field of view based on an input image from a moving image pickup device, wherein various different moving positions of the image pickup device stored in advance. Background candidate selection for selecting, from the accumulated background image sequence, a background image sequence obtained by shooting and a plurality of background images located in a region near the position of the input image from the moving imaging device. An image processing method comprising: a means; and a foreign body detection unit that determines the presence or absence of a foreign body by performing a difference process between the selected background image and the input image.