JP3222237B2 - Security monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a security monitoring device using a security camera.

[0002]

2. Description of the Related Art FIG. 1 shows a conventional security monitoring device. The security camera 1 installed toward the security target area supplies image signals obtained by photographing the security target area to the image memory 2 and the reference image memory 3, respectively. The image memory 2 temporarily stores the binary image signal supplied from the security camera 1 in units of one frame, and supplies the stored image signal of one frame to the comparing unit 4. In the reference image memory 3, image information (a binary image signal for one frame) of a crime prevention target area in a normal state, which is captured by the security camera 1, is stored in advance. The comparing unit 4 is configured to output 1 from the image memory 2.
The image signal for the frame is compared with the image signal for one frame stored in the reference image memory 3. If the number of mismatches between the two exceeds a predetermined number, an alarm signal is supplied to the alarm device 5. The alarm 5 responds to the supplied alarm signal,
For example, an alarm sound is generated, and an alarm lamp is turned on.

As described above, in the conventional security monitoring apparatus, first, a security target area is photographed by a security camera in a normal state, and image information at this time is stored in a reference image memory in advance. Next, in the surveillance operation, the image information currently being photographed by the security camera is compared with the image information stored in the reference image memory. The system was configured to notify the monitoring personnel of the abnormality that occurred in the target area.

However, in the conventional security monitoring device having the above configuration, if the position of the security camera during monitoring is shifted from the position of the security camera when the reference image is generated, an abnormality occurs in the security target area. Even without this, there is a difference between the image information currently being photographed and the reference image information, and there is a problem that a normal monitoring operation cannot be performed.

For example, as shown in FIG. 2, a security camera 1 suspended from a ceiling and installed is initially set at a position where an image of a security target area is taken with a solid arrow as a center point. However, the security camera 1 is gradually inclined downward due to the weight of the security camera 1 itself, and moves to a position where the security target area is photographed with the broken arrow as a center point. As a result, the reference image information captured using the solid arrow as the center point and the current image information during monitoring captured using the dashed arrow as the center point are different from each other, and the alarm can be activated even if no abnormality has occurred in the crime prevention target area. It will operate, and the normal security monitoring operation will not be performed.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and provides a security monitoring device capable of continuing normal monitoring operation even if the security camera is displaced. The purpose is to do.

[0007]

A security monitoring apparatus according to the present invention comprises a binarizing means for converting an image signal supplied from a security camera into a binary image signal, and accumulating the binary image signal for each frame. Cumulative average calculating means for calculating the cumulative image signal by adding the image signal, calculating the average of the image signal in one frame from the cumulative image signal every predetermined number of times, and outputting the average as a reference image signal; Counting means for comparing the reference image signal to count the number of mismatches with respect to each pixel position in one frame and outputting a count value; and determining means for performing an abnormality determination based on the count value and a predetermined abnormality determination threshold value. A security monitoring device comprising: a total number of logic “1” of the binary image signal and the reference image signal; an average value and a standard deviation value of the number of logic “1” on the vertical axis of the screen;
Image analysis means for obtaining an image analysis parameter comprising an average value and a standard deviation value of the number of logic "1" on the horizontal axis of the screen, and accumulating the binary image signal for each frame in response to an accumulation start command An accumulating means for supplying the added signal as the accumulative image signal to the accumulative averaging means; and an abnormality judging unit for judging an abnormality, and using each value of the image analysis parameter generated from the reference image signal as a reference. And a position shift judging unit that sends the accumulation start command to the accumulation operation unit when each value of the image analysis parameter generated from the binary image signal exists within the predetermined range.

[0008]

An image signal obtained by photographing a crime prevention target area is compared with a reference image signal, and when it is determined that the two are different image signals, an image analysis of the two (a logical " 1), the average value and the standard deviation value of the number of logic “1” in the vertical and horizontal directions of the screen of one frame of the image are calculated), and each value of the image analysis result generated from the reference image signal is used as a reference. If each value of the image analysis result generated from the image signal falls within the predetermined range,
At this point, the average image of the image signals captured by the security camera is set as a new reference image signal.

[0009]

Embodiments of the present invention will be described below. FIG. 3 shows the configuration of a security monitoring device according to the present invention. The security camera 1 installed toward the crime prevention target area supplies an image signal obtained by photographing the crime prevention target area to the contour extraction means 6 and the average luminance calculation means 7, respectively. The contour extraction means 6
The outline component of the image is extracted for each frame of the supplied image signal and supplied to the binarization circuit 8. The contour extraction means 6
For example, it is configured by a Sobel operation circuit or the like, and the supplied image signal is differentiated by the Sobel operation circuit to extract an outline component of the image. The average luminance calculating means 7 calculates the average value of the luminance of the image for each frame of the supplied image signal and supplies the average value to the binarization circuit 8. The binarizing circuit 8 uses the value based on the average value of the luminance calculated by the average luminance calculating means 7 as a threshold, and converts the contour components of the image extracted by the contour extracting means 6 into logic "1" and "0". The signal is converted into a binary image signal and supplied to the image memory 2a.

The image memory 2a temporarily stores the image signal supplied from the binarizing circuit 8 in a unit of one frame, and compares the stored image signal of one frame with the comparing means 4, the image analyzing means 9, the cumulative average calculating circuit. 10 and the accumulating operation circuit 17 respectively. The image analysis means 9 calculates the signal density, the average and the standard deviation of the image signal for one frame supplied from the image memory 2a and sends it to the signal bus 11. The cumulative average operation circuit 10 cumulatively adds the image signals of one frame unit sequentially supplied from the image memory 2a for each pixel position, and binarizes the cumulative addition result using the cumulative number of times as a threshold. The cumulative average operation circuit 10 calculates the average image signal from the cumulative result for each supplied image signal of one frame by the operation described above to generate an average image signal in one frame, and uses this as a reference image memory. 3a. The reference image memory 3a includes a cumulative average operation circuit 10
The average image signal for each frame supplied from
The stored contents are sent to the comparing means 4 and the image analyzing means 12. The image analysis means 12 calculates the signal density, the average and the standard deviation of the image signal for one frame supplied from the image memory 2a and sends it to the signal bus 11.

Here, the image analyzing means 9 and 12 have the same configuration, and the internal configuration is shown in FIG. In the figure,
The density measuring means 91 counts the total number of logic "1" in the supplied one-frame image signal, and outputs this as the density information of the one-frame image signal. Vertical axis average calculation means 9
Reference numeral 2 denotes a vertical coordinate axis of a supplied one-frame image signal on a two-dimensional screen (one frame includes 43
2, and 512 in the horizontal direction (composed of a total of 221184 image signals), and calculate and output the average value of the number of logic “1”. The vertical axis standard deviation calculating means 93 calculates and outputs the standard deviation value of the number of logic "1" on the vertical coordinate axis of the supplied one-frame image signal on the two-dimensional screen. The horizontal axis average calculating means 94 calculates and outputs the average value of the number of logic "1" on the horizontal coordinate axis of the supplied one-frame image signal on the two-dimensional screen.
The horizontal axis standard deviation calculating means 95 calculates and outputs the standard deviation value of the number of logic "1" on the horizontal coordinate axis of the supplied one frame image signal on the two-dimensional screen.

The comparing means 4 compares the one-frame image signal supplied from the image memory 2a with the one-frame image signal stored in the reference image memory 3a for each pixel position. Is generated for each pixel position, and is supplied to the data correction means 13 for each pixel position. The data correction unit 13 divides the supplied comparison result signal for each pixel position into predetermined pixel position areas. At this time, if there is a comparison result signal indicating an isolated comparison result in each section, The logic of the comparison result signal is inverted, and the comparison result signal for each pixel position in one frame is corrected and supplied to the counter 14. The counter 14 counts the number of “1” in one frame of the corrected comparison result signal, that is, the number of mismatches in one frame, and supplies the counting result to the signal bus 11 and the mismatch number memory 15, respectively. The mismatch number memory 15 is
The supplied number of inconsistencies is divided into addresses for each frame and stored, and the stored contents are supplied to the threshold value calculation circuit 16. The threshold value calculation circuit 16 calculates an average value and a standard deviation value of the contents stored in the number-of-mismatches memory 15, and further calculates a threshold value A by Expression 1. The threshold value calculation circuit 16 sends the obtained average value, standard deviation value and threshold value A to the signal bus 11.

[0013]

## EQU1 ## Threshold A = mean + standard deviation × K1 (K1 is a coefficient determined empirically.
The accumulation operation circuit 17 accumulates the image signal for each frame supplied from the image memory 2a for each pixel position in response to the operation start command supplied from the determination circuit 20, and accumulates the accumulation. Cumulative average operation circuit 10 of the addition result
To supply. At this time, the cumulative addition result of the cumulative average arithmetic circuit 10 is rewritten to the cumulative addition result supplied from the cumulative arithmetic circuit 17. Since the cumulative average capacity of the cumulative average arithmetic circuit 10 and the cumulative arithmetic circuit 17 is finite, for example, when the number of times of accumulation reaches 200, the accumulated addition result is reduced to 1/2 and the overflow of data is reduced. To prevent.
At this time, in the cumulative average operation circuit 10, the number of times of the cumulative addition is also halved. The alarm device 5 generates an alarm sound, turns on an alarm lamp, and the like according to an alarm device operation command supplied from the determination circuit 20. The judgment circuit 20 is connected to the signal bus 11
Of the information from the image analysis means 9 and 12 and the threshold value calculation circuit 16 which are supplied via the CPU, and supplies various control commands to the alarm device 5 and the accumulation calculation circuit 17.

Next, the operation of the security monitoring device according to the present invention having the above-described configuration will be described. First, the initial operation will be described. An image signal obtained by photographing the security target area with the security camera 1 is sequentially stored in the image memory 2a for each frame via the contour extracting means 6, the average luminance calculating means 7, and the binarizing circuit 8, The stored contents are supplied to the cumulative average operation circuit 10 and the comparison means 4. The cumulative average operation circuit 10 cumulatively adds the image signals sequentially supplied from the image memory 2a for each frame, and uses the average image signal in one frame obtained by averaging the predetermined number of cumulative additions (for example, 20) as a reference. It is supplied to the image memory 3a. The comparison means 4 uses the image signal stored in the reference image memory 3a as reference image information, and uses the image signal 1 supplied from the image memory 2a.
The image signal of the frame is compared with the reference image information. The counter 14 counts the number of mismatches in one frame from the comparison result, and supplies the counting result to the mismatch number memory 15 and the signal bus 11. Threshold calculation circuit 16
Calculates the average value and the standard deviation value of the number of mismatches in one frame based on the contents stored in the mismatch number memory 15 and sends them to the signal bus 11.

By the above operation, the image signal for 20 frames is supplied from the security camera 1 to the cumulative average operation circuit 10, and when the accumulation operation for 20 frames is completed, the judgment circuit 20 is switched to the threshold value operation circuit. It is determined whether the average value and the standard deviation value supplied from 16 satisfy Expression 2. At this time, when Expression 2 is satisfied, it is determined that the image signal obtained by the security camera 1 has little disturbance, and the initial operation is ended to shift to the normal monitoring operation.
If not, the number of trials in Equation 2 is increased by 1 and the initial operation as described above is repeatedly executed until Equation 2 is satisfied.

[0016]

## EQU2 ## Standard deviation ≦ (number of trials × K2 + K3) × average value (K2 and K3 are empirically determined coefficients, here, for example, K2 = 0.1 and K3 = 0.5). The operation will be described.

First, the threshold value calculation circuit 16 calculates an average value and a standard deviation value from the contents stored in the number-of-mismatches memory 15 set in the initial operation, and calculates a threshold value A according to Equation 3.

[0018]

Threshold A = Average value + Standard deviation value × 5 Next, an image signal obtained by photographing the crime prevention target area with the security camera 1 is obtained by extracting the contour extraction means 6, the average luminance calculation means 7 and the binary signal The image data is sequentially stored in the image memory 2a frame by frame through the conversion circuit 8, and the stored contents are stored in the cumulative average operation circuit 10a.
And the comparison means 4. Cumulative average operation circuit 10
Accumulatively adds image signals sequentially supplied from the image memory 2a for each frame, and performs a predetermined number of additions (for example, 20
Each time), an average image signal in one frame obtained by averaging with the cumulative number of additions is supplied to the reference image memory 3a. At this time, the contents of the reference image memory 3a are updated by the average image signal supplied from the cumulative average operation circuit 10 at every predetermined number of additions. The comparing means 4 uses the image signal stored in the reference image memory 3a as reference image information,
One frame of the image signal supplied from the image memory 2a is compared with the reference image information. The counter 14 counts the number of mismatches in one frame from the comparison result. The determination circuit 20 compares the threshold value A generated as described above with the count value of the counter 14, and if the count value of the counter 14 is equal to or less than the threshold value A, determines that there is no intrusion of foreign matter into the crime prevention target area. , The normal monitoring operation as described above is continued. At this time, the threshold value calculating circuit 16 stores the mismatch number memory 15 every predetermined number of times (for example, 10 times) of the cumulative average calculating circuit 10.
The threshold value A is calculated from the stored contents of the above, and the value is updated.

When the value of the counter 14 exceeds the value of the threshold A, the judgment circuit 20 determines that some abnormality has occurred and performs the following processing. First, in the image signal of one frame supplied from the image analysis means 9, the total number 9 of logic "1"
A, average value 9B of the number of logic "1" in the vertical direction of the two-dimensional screen coordinate axis 9B, standard deviation value 9C of the number of logic "1" in the vertical direction of the two-dimensional screen coordinate axis, and logic in the horizontal direction of the two-dimensional screen coordinate axis Average value 9D of the number of “1” 9D standard deviation value 9E of the number of logic “1” in the horizontal direction of the two-dimensional screen coordinate axis
In addition, the total number 12A of logic “1” in the image signal of one frame supplied from the image analysis unit 12 and the average value 12B of the number of logic “1” in the vertical direction of the two-dimensional screen coordinate axis, 2
The standard deviation value 12C of the number of logic "1" in the vertical direction of the two-dimensional screen coordinate axis 12C, the average value 12D of the number of logic "1" in the horizontal direction of the two-dimensional screen coordinate axis, and the logical "1" of the two-dimensional screen coordinate axis in the horizontal direction The standard deviation values 12E of the number are taken, and it is determined whether or not all of the following five relationships are satisfied.

0.8 × Total 9A ≦ Total 12A ≦ 1.2 × Total 9A 0.8 × Average 9B ≦ Average 12B ≦ 1.2 × Average 9B 0.6 × Standard deviation 9C ≦ Standard deviation 12C ≦ 1.4 × Standard deviation 9C 0.8 × Average value 9D ≦ Average value 12D ≦ 1.2 × Average value 9D 0.6 × Standard deviation value 9E ≦ Standard deviation value 12E ≦ 1.4 × Standard deviation value 9E If all of the above five relationships are satisfied, the position of the security camera 1 is shifted. The determination circuit 20 sends an operation start instruction to the accumulation operation circuit 17 assuming that there is a possibility that an error has occurred. The accumulating operation circuit 17 accumulatively adds the image signal for each frame supplied from the image memory 2a for each pixel position according to the operation start command.

The above operation is performed by the security cameras 1 to 30
The operation is performed until the image signal for the frame is output. During this time, the state in which all of the above five relationships are satisfied is 2
When the number of consecutive times is equal to or greater than 0 (in the number of additions of the cumulative average operation circuit 10), the cumulative addition result of the cumulative operation circuit 17 is supplied to the cumulative average operation circuit 10. As a result, the cumulative addition result of the cumulative average operation circuit 10 is replaced with the cumulative addition result supplied from the cumulative operation circuit 17. After that, the normal monitoring operation as described above is continuously performed.

If there is no state that satisfies all of the above-mentioned five relations more than 20 times, it is determined that an abnormality has occurred in the crime prevention target area itself, not due to the positional shift of the security camera 1, and The determination circuit 20 sends an alarm device operation command to the alarm device 5. Further, the judgment circuit 20 sends an alarm device operation command to the alarm device 5 even when the state where the value of the counter 14 exceeds the threshold value A and does not satisfy all of the above-mentioned five relations is repeated five or more times. .

As described above, the security monitoring apparatus according to the present invention compares an image signal obtained by photographing a security target area with a reference image signal generated by accumulating and averaging this image signal. If the number of mismatches in one frame of the image signal exceeds a predetermined number (threshold A), it is determined that some abnormality has occurred in the crime prevention target area. If this abnormality determination is made and the image analysis results of the image signal and the reference image signal obtained by photographing the crime prevention target area at that time are relatively similar, the abnormality of the crime prevention target area is It is determined that the error is not caused by the abnormality of the target area itself but caused by a positional shift of the security camera. With this determination, the cumulative averaging of the image signal is newly performed from 0, and the monitoring operation is continued with the obtained average image signal as a new reference image signal.

In the above embodiment, the image signal is binarized. However, unless the configuration of the comparing means is complicated, n
Processing can be performed by converting the value. If the processing speed is allowed to decrease, the reference image is multiplied so that the cumulative average arithmetic circuit 10 and the cumulative arithmetic circuit 17
The overflow prevention operation can be made unnecessary.

In the contour extracting means 6 of the above embodiment, the amount of change of the component having a high spatial frequency (corresponding to the contour component of the image) in the image is focused on using the Sobel arithmetic circuit. It is also possible to use a monitoring device that focuses on the amount of change of each frequency component using an operator that extracts the other frequency components. Furthermore, in the five conditions of the above embodiment, the condition is that the image analysis result of the reference image signal is included in the range of ± 20% or ± 40% of the image analysis result of the image signal. The range is not limited, and can be set arbitrarily according to the nature of the monitoring target area.

[0026]

As described above, the security monitoring apparatus according to the present invention can be used in spite of the fact that it is determined that both are different image signals in the comparison between the image obtained by photographing the security target area and the reference image. , Both image analysis results (total number of logic “1” in one image frame, logic “1” in the vertical and horizontal directions with respect to the two-dimensional screen coordinate axis of one image frame)
If the difference between the average value and the standard deviation value falls within a predetermined range, it is determined that the abnormality in the crime prevention target area is not caused by the abnormality in the crime prevention target area itself but is caused by a positional shift of the security camera. At this point, the monitoring operation is continued with the average image signal of the image signals captured by the security camera as a new reference image signal.

Therefore, according to the security monitoring apparatus of the present invention, it is possible to distinguish and detect the abnormality in the security target area itself and the abnormality caused by the positional deviation of the security camera, and detect the positional deviation of the security camera. In this case, the image signal having the position shift becomes a new reference image signal, so that it is possible to continue the normal monitoring operation even if the security camera has a position shift, and the monitoring operation with high accuracy is performed. You.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a conventional security monitoring device.

FIG. 2 is an installation diagram of a security camera.

FIG. 3 is a configuration diagram of a security monitoring device according to the present invention.

FIG. 4 is a configuration diagram of an image analysis unit.

[Description of Signs of Main Parts]

 2a Image memory 3a Reference image memory 4 Comparison means 9, 12 Image analysis means 14 Counter 16 Threshold operation circuit 17 Accumulation operation circuit 20 Judgment circuit

Claims (1)

(57) [Claims] 1. An image signal supplied from a security camera is
A binarizing means for converting the image signal into a value image signal; calculating a cumulative image signal by cumulatively adding the binary image signal for each frame; Cumulative average calculating means for calculating an average and outputting the average image signal as a reference image signal; and a counter for comparing the binary image signal and the reference image signal to count the number of mismatches with respect to each pixel position in one frame and outputting a count value. And a determining means for performing an abnormality determination based on the count value and a predetermined abnormality determination threshold value, wherein the total number of logic “1” of the binary image signal and the reference image signal, a screen Image analysis means for obtaining an image analysis parameter comprising an average value and a standard deviation value of the number of logic "1" on the vertical axis and an average value and a standard deviation value of the number of logic "1" on the screen horizontal axis; Accumulating means for supplying a signal obtained by accumulatively adding the binary image signal for each frame in response to a calculation start instruction to the accumulating means as the accumulated image signal; And when each value of the image analysis parameter generated from the binary image signal exists within a predetermined range based on each value of the image analysis parameter generated from the reference image signal, the accumulation is performed. A security monitoring device comprising: a calculating means; and a position shift determining means for sending the accumulation start command.