JP2000194969A - Image sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly reliable image sensor capable of judging it as an abnormal and detecting maneuvering action when the maneuvering action such as to cover an image picking up means with a cover or the like exists by performing differentiation of a photographed image to judge an abnormality of the image. SOLUTION: The current image photographed by an image picking up means 203 is stored in a storing means 220. A controlling means 201 divides the current image into plural judging blocks. A differential filter such as a sobel filter performs differentiation for every judging block. The pixels of obtained differential image are compared with the threshold of edge intensity to be binarized. The ratio that the number of pixels (differential value) extracted by binarization occupies in the number of the entire pixels of the judging block decides whether or not the number of judging blocks being equal to or less than threshold for judging whether or not to have enough high frequency components exceeds a prescribed value. When it exceeds the prescribed value, it is judged abnormal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image sensor installed in a monitoring area, and more particularly to an image sensor for detecting a plotting action such as covering an imaging means of the image sensor.

[0002]

2. Description of the Related Art As a conventional image sensor, an image of a doorway of a building or another monitoring area is continuously photographed, a reference image is compared with a current image, and the presence or absence of an intruder is detected. Things have been put to practical use. Further, in these conventional image sensors, in order to distinguish between a sudden change in the image in the case of an intruder and a gradual change in the image such as a slow curtain sway caused by an air conditioner or sunlight entering the monitoring area, for example. The reference image is sequentially updated and stored with the latest photographed image at regular intervals.

[0003]

However, in the conventional image sensor, when the imaging means of the image sensor is covered with a cover or the like, the image covered with the cover or the like is updated and stored as a reference image. However, there is a problem that an abnormal condition cannot be detected because the person cannot be photographed. In particular,
In the security system, when the image sensor detects an abnormality in the monitoring area in the security set mode, an abnormality is reported, but not in the security release mode. In the conventional image sensor, if the image capturing means of the image sensor is covered with the cover during the security release mode, and the intruder enters during the unattended security set mode, the intruder cannot be detected. Therefore, an object of the present invention is to provide a highly reliable image sensor that can determine an abnormality and detect a planning action or the like when there is a planning action such as the imaging unit of the image sensor being covered with a cover or the like. is there.

[0004]

The inventor of the present invention has made intensive studies to solve the above-mentioned problems of the conventional image sensor.
As a result, it was found that many of the covers used in the plotting action on the image pickup means of the image sensor were applied in one color such as white, gray, black, and the like, and the captured image had little high frequency components. That is, it was found that when the differential image obtained by differentiating the above-described image was binarized, the number of extracted pixels was small.

Therefore, when the imaging means is covered with the cover, the captured image is differentiated, and the obtained differential image is binarized. ) Is lower than the “threshold value”, it has been found that it is possible to detect that the imaging means of the image sensor is covered with the cover. Furthermore, when the obtained differential value is low, it is possible to detect these even in the case of poor projection of the infrared projection unit, contamination of the lens of the imaging unit, defocus, and the like.

Therefore, the obtained image is differentiated, and if there is a predetermined area or more with a small amount of high frequency components, it is determined that the area is abnormal, and thereby the image sensing means of the image sensor can detect a painting action such as covering the cover. It was found that an image sensor having a high image quality can be provided.

The present invention has been made based on the above findings, and a first aspect of the image sensor of the present invention comprises means for differentiating an image picked up in a monitoring area to determine abnormality of the image. It is characterized by having.

In a second aspect of the image sensor according to the present invention, the means comprises the following. (1) imaging means for capturing an image of a monitoring area; (2) classification means for dividing the current image captured by the imaging means into a predetermined number of determination blocks; and (3) classification by the classification means. Differentiating means for differentiating the image for each determination block, and (4) determining means for determining whether or not a differential value for each determination block obtained by the differentiating means is equal to or less than a predetermined threshold value. (5) a determination unit that determines that there is an abnormality when the number of determination blocks equal to or smaller than the threshold is equal to or greater than a predetermined number as a result of the determination by the determination unit;

A third aspect of the image sensor according to the present invention is characterized in that the means comprises the following. (1) an imaging unit that captures an image of a monitoring area; (2) a storage unit that stores a reference image; and (3) the current image and the reference image captured by the imaging unit are divided into predetermined determination blocks. Classifying means; (4) differentiating means for differentiating the current image and the reference image for each judgment block divided by the dividing means; and (5) a reference obtained for each judgment block based on the differentiating means. Calculating means for subtracting the differential value of the current image from the differential value of the image;
(6) judgment means for judging whether or not the differential value obtained based on the calculation means is equal to or less than a threshold value; Judgment means for judging abnormal when there is more than a predetermined

A fourth aspect of the image sensor according to the present invention is characterized in that the determination means is activated when the monitoring area is in a warning release mode.

[0011]

FIG. 1 is a diagram showing the overall configuration of a monitoring system to which an image sensor according to the present invention is applied. As shown in FIG. 1, a controller 1 is installed in a building to be monitored, and a plurality of image sensors 2, fire sensors 3, emergency buttons 4, and mode setting devices 5 are connected to the controller 1.
The controller 1 is connected to a security center device 7 provided at a remote monitoring center via a telephone line 6 as a communication line.

The connection between the image sensor 2 and the controller 1 is made by an analog signal line 8 and a digital signal line 9. The analog signal line 8 is constituted by a coaxial cable and transmits a video signal (NTSC system), and the digital signal line 9 is constituted by a twisted pair line and transmits a control signal by a digital signal line.

Here, the overall operation of the monitoring system of FIG. 1 will be briefly described. The mode setting unit 5 sets the monitoring system to the alert release mode or the alert set mode. When the image sensor 2 detects an abnormality in the alert set mode, the controller 1 transmits an abnormality signal indicating that an abnormality has occurred to the security center device 7 via the telephone line 6.

When an abnormal signal is output from the fire sensor 3 and the emergency button 4, the controller 1 transmits data indicating the type of abnormality and the location of the abnormality to the security center device 7 via the telephone line 6 regardless of the security mode. I do. As a method for detecting and transmitting such an abnormal signal, a method well known in the art can be used.

A plurality of image sensors 2 are installed in a building, for example, and photograph a monitoring area including a monitoring target (monitoring point) such as a window or a door, and determine whether there is an abnormality such as intrusion from the obtained image. .

FIG. 2 shows the configuration of the image sensor 2 of the present invention. The image sensor 2 includes a control unit 201 including a CPU and a power supply 202. Each part inside the apparatus is controlled by a control means 201 and a power supply 202
Power supply from.

The control means 201 is provided with a not-shown timing means for controlling the timing of taking in the current image. This timing means is activated, for example, every 0.5 seconds. Further, the control means includes a dividing means for dividing the reference image and the current image into judgment blocks, for example, 48 judgment blocks. Further, a differentiating means for differentiating an image for each of the divided determination blocks is provided. A threshold value is provided for determining the number of pixels (hereinafter, referred to as “differential value”) extracted when the differential image is binarized by the differentiating means. Then, when the number of determination blocks equal to or smaller than the threshold value exceeds a predetermined number, for example, a majority, there is a determination means for determining an abnormality.

The power supply 202 comprises a converter for converting an externally supplied AC power into a DC voltage. Note that instead of providing the power supply 202 in the image sensor 2, power may be supplied from the controller 1. Control means 2
01 is connected to storage means 220. FIG. 3 is a diagram illustrating an example of a storage unit of the image sensor. The storage means 220 will be described in detail with reference to FIG.

The storage means 220 has a program area 221 for storing a program for causing the image sensor 2 to execute a predetermined operation, and parameters for storing parameters such as the installation height and depression angle of the image sensor, monitoring points, sensitivity settings, and the like. The state storage area 224 stores the state of the area 222, the work area 223, and the monitoring area, that is, whether the current state is normal or abnormal, and sets the monitoring area to either the alert set mode or the alert release mode. A mode storage area 225 for storing is provided.

The storage means 220 further stores a reference image storage area 226, a current image storage area 227, and an abnormal image storage area 22 as areas for storing images captured by the imaging means 203.
8. A reference differential value storage area 229 is provided for storing a differential value for each determination block of the reference image. Current image storage area 2
27 stores the latest image taken by the image pickup means 203 and the image up to two frames before the latest image.

The imaging means 203 for photographing the monitoring area is provided with a CC
It is composed of a D camera and has sensitivity from the visible region to the infrared region. An infrared light projecting unit 204 is provided, and emits infrared light to the monitoring area when it becomes dark such as at night.
The image processing unit 205 compares and compares the current image stored in the storage unit 220 with the reference image to obtain a difference and binarize the image.

The display means 206 is constituted by an LED,
Lights up when an abnormality is detected, and goes out when no abnormality is detected, and the presence or absence of abnormality detection is displayed outside the image sensor 2. Communication means 20
Reference numeral 7 denotes an interface for transmitting and receiving signals to and from the controller 1, and is connected to the controller 1 via a digital signal line 9. An image output unit 208 is an interface for outputting an image when an abnormality has occurred.
Is connected to the analog signal line 8 via the.

The analog signal line 8 connects the controller 1 and each image sensor 2 in series as shown in FIG. The switching unit 209 of the image sensor 2 connects the input side and the output side of the analog signal line 8 in a normal state, disconnects the input side analog signal line in an abnormal state, and connects the image output unit to the output side analog signal line 8. To be connected. In FIG. 2, the input side is “from another image sensor” and the output side is “to the controller”.
Is displayed.

The address setting section 210 is constituted by a dip switch, and an address for the controller 1 to specify the image sensor 2 is set. Operation means 211
Is a means for turning on / off the power. Further, when the operation unit 211 is turned off, the switching unit 209 connects the input side and the output side of the analog signal line 8 to bypass the image sensor 2 from the analog signal line 8. As the current image, an image captured by the imaging unit 203 is stored in the current image storage area every 0.5 seconds, for example, when the timing unit starts.

FIG. 4 is a diagram showing the configuration of the controller 1. As shown in FIG. The controller 1 includes a control unit 101 including an MPU and the like, and a power supply circuit 102. Each part in the controller 1 is controlled by the control unit 101 and receives power from a power supply circuit 102. Power supply circuit 102
Has a conversion circuit for converting an external AC voltage to a DC voltage, and a battery. Also, a mode setting device 5 is connected.

The controller 1 is further provided with the following parts. The sensor monitoring circuit 103 is an interface with the fire sensor 3 and the emergency button 4. A modem 104 is provided between the telephone line 6. The image sensor communication control unit 105 is connected to the image sensor 2 via the digital signal line 9. The video input / output control unit 106 is connected to the image sensor 2 via the analog signal line 8. This video input / output control unit 10
Reference numeral 6 distributes the image signal sent from the image sensor 2 to the modem 104 and the monitor device 10 connected to the outside.

The display unit 107 displays the monitoring state of the normal monitoring area on the screen, and when an abnormality is detected, sounds a buzzer and displays the type of abnormality, the location where the abnormality has occurred, and the like on the screen. FIG. 5 is a flowchart illustrating the abnormality detection logic of the image sensor. The operation of the image sensor of the present invention will be described with reference to the flowchart of FIG.

The current image taken by the image pickup means 203 is fetched every time the timing means is started (0.5 seconds) and stored in the current image storage area 208 (step S1). Step S
The current image captured in step 1 is divided by a not-shown dividing means.
For example, it is divided into 48 decision blocks (step S
2). For each of the 48 decision blocks, the differentiation is performed by a differentiating means (not shown) such as a differential filter such as a Sobel filter. (Step S3).

The pixel of the differentiated image obtained by the differentiating means is compared with a threshold value of the edge intensity by a judging means (not shown).
If it does not exceed the threshold value, it is binarized to "0" (step S4). The ratio of the number of pixels (differential value) extracted by binarization to the total number of pixels in the determination block is not more than a threshold value for determining whether or not the determination block has sufficient high frequency components by a determination unit (not shown). It is determined whether or not the number of determination blocks having the value exceeds a predetermined value (step S5). If the number exceeds the predetermined value, it is determined that there is an abnormality (step S6). If determined to be abnormal, the current image is stored in the abnormal image storage area 229 (step S7). Then, the status storage area 224 is stored as abnormal (step S8).

When the image sensor 2 receives the status call signal from the controller 1 via the communication unit 207, the image sensor 2 transmits the abnormal signal stored in the status storage area 224 to the communication unit 207.
To the controller 1 via Thereafter, when an abnormal image transmission request signal is received from the controller 1 via the communication unit 207, the abnormal image stored in the abnormal image storage area 229 is transmitted to the controller 1 via the image output unit 208.

FIG. 6 is another flowchart showing the abnormality detection logic of the image sensor. A second embodiment of the present invention will be described with reference to FIG. First, the reference image is stored in the reference image storage area 226 of the storage unit 220 (step S11), and is divided into, for example, 48 determination blocks by a division unit (not shown) (step S1).
2). Then, for each of the 48 determination blocks, the control means 20
1 is differentiated by one differentiating means (step S13). The differential value obtained as a result of the differentiation is stored in the reference differential value storage area 229 of the storage means 220 for each determination block (step S14).

The current image taken by the image pickup means 203 is fetched every time the timing means is started (0.5 seconds) and stored in the current image storage area 208 (step S15). The current image fetched in step S15 is divided into, for example, 48 by a dividing means (not shown) (step S16). Differentiation is performed by a differentiating means (not shown) for each of the 48 determination blocks. (Step S17).

The differential value for each determination block in the reference differential storage area 229 of the storage means 220 is read out by calculation means (not shown), and the differential value obtained in step 17 is subtracted from the read reference differential value for each determination block. (Step S18). The differential value, which is the difference value obtained by the calculating unit, is compared with a threshold value by a determining unit (not shown).
If it does not exceed the threshold value, it is binarized to "0" (step S19). A determination unit (not shown) determines whether or not the number of determination blocks equal to or less than the threshold value exceeds a predetermined value. If the determination value exceeds the predetermined value, it is determined that there is an abnormality. (Step S2)
0). The operation after the abnormality is determined is described in step S in FIG.
Same as 7 and after.

Incidentally, such an action of covering the imaging means 203 with a cover or the like is usually performed in the alert release mode. Therefore, the above determination may be made when the security mode stored in the mode storage area 225 is the alert release mode.

[0035]

According to the image sensor of the present invention, the obtained image is differentiated, and when an area having a small amount of high frequency components is equal to or more than a predetermined area, it is determined that the image is abnormal. It is possible to detect a plotting act that covers such a place, and the reliability of the monitoring system is improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a monitoring system to which an image sensor according to the present invention is applied.

FIG. 2 is a diagram illustrating a configuration of an image sensor of the present invention.

FIG. 3 is a diagram illustrating an example of a storage unit of the image sensor;

FIG. 4 is a diagram illustrating a configuration of a controller in FIG. 1;

FIG. 5 is a flowchart illustrating an abnormality detection logic of the image sensor.

FIG. 6 is another flowchart illustrating the abnormality detection logic of the image sensor.

[Explanation of symbols]

 1. Controller 2. Image sensor 7. Security center equipment 8. Analog signal line 9. Digital signal line 101. Control unit 105. Image sensor communication control unit 106. Video input / output control unit 107. Display unit 108. Setting means 201. Control means 203. Imaging means 205. Image processing means 208. Image output means 220. Storage means 221. Program area 222. Parameter area 223. Work area 224. State storage area 225. Mode storage area 226. Reference image storage area 227. Current image storage area 228. Abnormal image storage area 229. Reference differential value storage area

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshiki Kobayashi 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Kazuo Ota 1410 Inada, Hitachinaka-shi, Hitachi F-term (reference) in AV Division of Hitachi, Ltd. BB12 BB74 DD04 DD05 DD20 EE16 FF01 FF04 FF05 FF12 FF13 FF20 FF23 FF30 GG02 GG08 GG18 GG19 GG21 GG24 GG29 GG30 GG31 GG32 GG37 GG71 GG57 GG71

Claims (4)

[Claims] 1. An image sensor comprising means for differentiating an image captured in a monitoring area to determine an abnormality of the image. 2. The image sensor according to claim 1, wherein said means comprises: (1) imaging means for capturing an image of a monitoring area; (2) classification means for dividing the current image captured by the imaging means into a predetermined number of determination blocks; and (3) classification by the classification means. Differentiating means for differentiating the image for each determination block, and (4) determining means for determining whether or not a differential value for each determination block obtained by the differentiating means is equal to or less than a predetermined threshold value. (5) a determination unit that determines that there is an abnormality when the number of determination blocks equal to or smaller than the threshold is equal to or greater than a predetermined number as a result of the determination by the determination unit; 3. The image sensor according to claim 1, wherein said means comprises: (1) an imaging unit that captures an image of a monitoring area; (2) a storage unit that stores a reference image; and (3) the current image and the reference image captured by the imaging unit are divided into predetermined determination blocks. Classifying means; (4) differentiating means for differentiating the current image and the reference image for each judgment block divided by the dividing means; and (5) a reference obtained for each judgment block based on the differentiating means. Calculating means for subtracting the differential value of the current image from the differential value of the image;
(6) judgment means for judging whether or not the differential value obtained based on the calculation means is equal to or less than a threshold value; Judgment means for judging abnormal when there is more than a predetermined 4. The apparatus according to claim 2, wherein said determination means is activated when said monitoring area is in a warning release mode.
Or the image sensor according to 3.