JPH0483489A - Image monitoring device - Google Patents

Abstract

PURPOSE:To shorten a calculation time required for detecting an image change and to execute detailed analysis by storing image data obtained by continuously fetching picked-up images and digitizing the images at a 1st period, and at the time of detecting an image change, processing the image data stored in a 1st storage means. CONSTITUTION:In a processor 3, an image signal from an ITV camera 1 is converted into a digital signal by an A/D converter 11 by using a sampling pulse with a prescribed period formed by a sampling pulse forming circuit 10 and stored in a 1st image memory 121 as image data. The image data are stored also in a 2nd image memory 122 as image data by a 2nd writing pulse having a different period. At the time of detecting a change in the image by referring the 2nd image memory 122, a CPU 13 executes the detailed analysis of an image in an area in which the change is detected at the time of referring the 2nd image memory 122 out of the 1st image memory 121 based upon prescribed invaded target discriminating algorithm. Consequently, calculation time required for detecting an image change can be shortened and detailed analysis can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an image monitoring device that detects an intruder within a monitoring area.

(Prior Art) As an example of this type of image monitoring device, the one shown in FIGS. 9 and 10, for example, is known. That is, for example, the ITV camera (imaging means) 1 captures an image within the monitoring area 7 and converts it into an electrical signal. This ITV camera 1
The captured image is sent to a processing device 3 and a display device 5 through a transmission path 2, and is also sent to a video tape recorder (hereinafter simply referred to as VTR) 9 through a transmission path 8. The display device 5 displays the images captured by the ITV camera 1, and the VTR 9 records the images captured by the ITV camera 1 continuously or as needed, as will be described later.

On the other hand, the image signal sent to the processing device 3 is converted into a digital signal by the A/D converter 11 using a device pulling pulse constituted by the sampling pulse generation circuit 10, and is converted into a digital signal by the A/D converter 11, for example, at time 1-1. Image memory 12 as image data of
stored within.

The CPU 13 detects and analyzes changes in the image.
Time 1-=1. The image data at time 1-t is compared pixel by pixel with the image data at time t-tlt that was captured before this, and if all the pixel data are the same, the image data at time 1-t is compared.
1. It is determined that no change has occurred within the monitoring area 7 during the time from t to time t.

Then, images are subsequently captured at predetermined intervals and the image data are compared. When comparing images, if there is a change in data at any pixel, there is a possibility that it is an intruder, so the CPU 13 analyzes the changed image using a predetermined intruder determination algorithm and determines whether it is an intruder. If it is determined that there is, the alarm device 6 will be sounded,
The supervisor confirms what the intruder is on the display screen of the display device 5, and if the VTR 9 is not operating, it is activated to record a surveillance image.

Although it is assumed here that all image data within the monitoring area 7 is compared, since comparing all pixels takes time, it is common to set the area in which intruder detection is to be performed in advance.

Furthermore, since digitized images generally contain noise components, it is common to perform filtering or processing such that if there is no difference greater than a predetermined detection level during comparison, it is assumed that there has been no change in the image. .

Next, the procedure for monitoring will be explained using FIG. 11. First, of the monitoring area 7 imaged by the ITV camera 1, an area where the processing device 3 detects an intruder is set. In this setting, as shown in FIG. 12, for example, an image within the monitoring area 7 sent from the ITV camera 1 is displayed on the screen of the display device 5, and the light ben 4 is used to detect the intruder on the screen of the display device 5. This is done by specifying the detection area (shaded area) 14. This operation causes the processing device 3 to process only the pixels in the intruder detection area 8.

Next, set the sensitivity level for detecting intruders.

This value is a threshold value for determining that a change has occurred when comparing the image data at time t''-tH and time 1-1 later.

The above is the preparation for starting monitoring. After completing the preparation in this manner, the processing device 3 A/D converts the image signal from the ITV camera 1 using the A/D converter 11 and continuously captures the image signal. Then, the image captured at time txt (see Figure 13a) is compared pixel by pixel with the image captured at the previous time 1 = 1 (see Figure 13), In other words, the difference is calculated pixel by pixel, as shown in Figure 13 (c
) will yield a difference image as shown in (). Originally, this difference image shows the image change including the movement of the intruder from time t m t t-t to time t-t, l, but since noise components are also mixed, this difference image is used first. The true change is extracted by binarizing it at a set appropriate detection level. This is a differential binarized image (see FIG. 13d).

Then, CPolB analyzes the differential binarized image, calculates, for example, the sum of the number of pixels of "1" in the intruder detection area 14 in the differential binarized image, and if this calculated value is greater than a predetermined value. or by comparing the shape of the "1" area in the differential binarized image with a predetermined pattern, it is determined that there is an intruder.If it is determined that there is an intruder,
A command is issued to the alarm device 6, and the alarm device 6 issues an alarm to detect an abnormality, and operates the VTR 9 as necessary.
Record an image of the monitored area containing the intruder.

(Problem to be Solved by the Invention) However, the detection of an intruder in the conventional image monitoring device described above is performed by calculating the difference for each pixel of two images with a time difference. In such cases, it is common practice to sound an alarm, confirm what the intruder is on the display screen of the display device, or record surveillance images on a VTR to confirm the intruder later. be. Here, the larger the number of pixels in the image, the more detailed the detection can be, so for example, the vertical and horizontal pixels are 256 pixels x 256
In many cases, A/D conversion is performed to the level of a pixel. However, when the number of pixels is large, it takes time to calculate the difference between images, and there is a problem that intruder detection cannot be performed quickly.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image monitoring device that requires less calculation time to detect a change in an image using image data, and that enables detailed analysis when a change is detected. shall be.

[Structure of the Invention] (Means for Solving the Problems) The image monitoring device of the present invention includes an imaging means for capturing images within a monitoring area, and a digital camera that continuously captures the images captured by the imaging means. A/D conversion means to convert
a first storage means for storing the image data digitized by the conversion means in a first period; and a second storage means for storing the image data digitized by the A/D conversion means in a second period longer than the first period. a second storage means for storing data, and usually said second storage means for storing
A change in the image is detected by processing the image data in the storage means, and when a change in the image is detected, the first
and a detection means for detecting an intruder within the monitoring area by processing image data stored in the storage means.

[Effect]

By storing A/D converted image data in a storage means at two types of cycles, first image data with a large number of pixels and second image data with a small number of pixels are created. Then, normally, image change detection is performed using the second image data with a small number of pixels, and when a change in the image is detected, the first image data with a large number of pixels is used to detect an intruder. It is something.

As a result, calculation time is usually shortened because changes in the image are detected using image data with a small number of pixels, and when a change in the image is detected, it is necessary to use image data with a large number of pixels in the range corresponding to the change. Detailed analysis is possible to detect intruders using image data.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

Figure 1 shows the configuration of an image monitoring device according to the present invention.
The same parts as in FIGS. 9 and 10 are given the same reference numerals. That is, an image within the monitoring area 7 captured by the ITV camera 1 is sent to the processing device 3 via the transmission path 2, and is also sent to the display device 5 and the VTR 9.

The processing device 3 converts the image signal from the ITV camera 1 into a digital signal using the A/D converter 11 using sampling pulses of a predetermined period outputted from the sampling pulse generation circuit 10 (see FIG. 2C). This digitized image data is outputted from the sampling pulse generation circuit 10, for example, by a first write pulse having the same period as the sampling pulse (see FIG. 2).
Then, the image data is stored in the first image memory 121 as image data at time ts-t. At the same time, the A/D converter 1
The image data digitized in step 1 is outputted from the sampling pulse generation circuit 10 by a second write pulse (see FIG. 2C) having, for example, a quarter of the period of the sampling pulse. Also stored in the image memory 122 at time 1-1. The images are stored as image data.

The CPU 13 is the first. Second image memory 121°12□
It detects and analyzes changes in the image by sampling the images, and normally refers to the second image memory 122 and samples the images at time 1-1. A change in the image is detected by performing a pixel-by-pixel comparison between the image data at time t=tl-1 and the image data captured earlier at time t=tl-1. Here, if all the pixel data are the same, it is determined that nothing has occurred within the intruder detection area 14 from time 1-1° to time 1-1 +-+, and the predetermined period of time continues. Images are captured at intervals and the image data is compared.

When a change in the image is detected by referring to the second image memory 122, the CPU 13
Now, first image memory 12. Among these, for the area in which a change was detected when referring to the second image memory 122,
Detailed analysis of the image is performed using a predetermined intruder discrimination a11, f rhythm. As a result, if it is determined that there is an intruder, the alarm device 6 is sounded or the VTR 7 is activated if it was not operating, and a surveillance image is recorded, as in the past. .

FIG. 3(a) shows time 1-1. This is the content of the first image memory 121 representing a part of the monitoring area 7 in FIG.
b) is the content of the second image memory 122 representing the same area at the same time. The second image memory 12□
Since the image memory 12 is written at a period of 1/4 of the image memory 12, the pixels (i, j) in FIG.
4j-3) pixel. Therefore, it can be said that the number of data in the second image memory 122 is approximately 1/4 of that in the first image memory 121, and the number of data in the second image memory 122 is about 1/4 of that in the first image memory 121. Image memory 121
This takes about 1/4 of the time compared to when referring to . Furthermore, when a change is detected in the (i, j) pixel of the second image memory 122, it corresponds to (t, 4j-3) in the first image memory 12□, so the first image It is easy to determine in which area of the memory 121 detailed analysis should be performed.

Next, the process flow of the CPUI 3 when a change occurs in an image will be explained using FIGS. 4 to 6. Figure 4(a) shows the area selected as the intruder detection area 14 including four roads, and Figures 4(b) and (c)
1 and 2 show captured images when no person has entered the intruder detection area 14 and when a person has entered the intruder detection area 14, respectively. Further, FIG. 5 shows image data of a part of the area 20 in FIG. 4, and FIGS. The image data corresponding to c), FIGS. 6(a) and 6(b), are stored in the second image memory 1, respectively.
This is image data corresponding to FIGS. 4(b) and 4(c) in 22.

Normally, the CPU 13 detects changes in the image by referring to the second image memory 122, that is, the data shown in FIG. If no person has entered the intruder detection area 14, the image data shown in FIG. 6(a) will be captured every unit time, and the difference image after the unit time will be as shown in FIG. 6(C). contains only noise, and for example, when binarized with "4", no image change is detected. In this case, CPU1B
does not perform any processing that refers to the first image memory 121. Time 1-1. If a person intrudes in Figure 6 (b)
) image data is obtained and time txt.

The difference image at time 1-1 +-1 is as shown in FIG. 6(d).

The CPU 3 binarizes this difference image using a predetermined threshold value, for example, "4" to obtain the difference binarized image shown in FIG. Detect what happened. Then this picture! In order to confirm whether or not the change is an intruder, the image data stored in the first image memory 121 is referred to, and the second image memory 122 is referred to to confirm whether or not the change is an intruder. Compute the difference image. That is, among FIGS. 5(a) and (b),
Calculate the difference image (Fig. 5C) around the area where the change was detected,
Binaryization is performed using a predetermined threshold value to create a difference binarized image (Fig. 5d)
).

Then, the CPU 13 analyzes the differential binarized image, and, for example, calculates the sum of the number of pixels of 1° in the differential binarized image, and if the calculated value is greater than a predetermined value, or By comparing the shape of the "1" area in the image with a predetermined pattern, it is determined that there is an intruder.

Note that when obtaining a difference binarized image in the first image memory 121, the difference is performed only in the periphery where a change in the image is detected in the second image memory 122. (i, j) of the second image memory 122
Since the pixel is the (i, 4j-3) pixel of the first image memory 12+, it can be easily calculated.

Next, the monitoring procedure of the present invention will be explained.

First, of the monitoring area 7 imaged by the ITV camera 1, an area where the processing device 3 detects an intruder is set. In making this setting, for example, as shown in FIG. This is done by specifying this as the intruder detection area 14. This operation causes the processing device 3 to process only the pixels within the intruder detection area 14. Next, set the detection sensitivity for detecting intruding objects. This detection sensitivity is a threshold value for determining that a change has occurred when comparing the image data at time t-t I-1 and time t, -tl later.

With the above preparations completed, the processing device 3 uses the ITV camera 1
An A/D converter 11 performs A/D conversion on the image signal from the A/D converter 11, and continuously captures the image signal. Then, the A/D converted image data is stored in the first image memory 121 as image data at time 1-1° using, for example, a first write pulse having the same period as the sampling pulse of A/D conversion, At the same time, the image data is also stored in the second image memory 122 as image data at time t-tl, for example, with a second write pulse having a period of 1/4 of the sampling pulse of A/D conversion.

The CPU 13 normally refers to the second image memory 122 to determine time 1-1. A pixel-by-pixel comparison is made between the image data of and the image data of time 1-t, -1 that was captured before this, and a differential binarized image is obtained.
Detect changes in images.

If no change is detected in the differential binarized image, time t-t
It is determined that no change has occurred in the monitoring area 7 during the period from time 1 to time 1-1 to time 1, and images are subsequently captured at predetermined intervals and the image data are compared.

When a change in the image is detected by referring to the second image memory 122, the CPU 13
Now, first image memory 12. Among them, by referring to the surrounding data for which changes have been detected in the second image memory 122, a detailed analysis of the image is performed using a predetermined intruder discrimination algorithm, and the presence or absence of an intruder is determined. If it is determined that there is an intruder, a command is issued to the alarm device 6 and the alarm bag is activated! F6 issues an alarm for abnormality detection.

In this way, A/D converted image data is sent to the first . By storing it in the second image memory 121° 122, first image data with a large number of pixels and second image data with a small number of pixels are created, and normally the second image data is used to detect changes in the image. When a change in the image is detected, the intruder is detected using data of a portion of the first image data that corresponds to the area where the change in the image was detected in the second image data.

As a result, calculation time is usually shortened because changes in the image are detected using image data with a small number of pixels, and when a change in the image is detected, it is necessary to use image data with a large number of pixels in the range corresponding to the change. Detailed analysis is possible to detect intruders using image data.

Note that in the above embodiment, the first. Second image memory 121
, 122 has been described as the same period as the sampling pulse of A/D conversion, and 1/4 of that period, but this is the case in the first image memory 12.
It does not need to be the same period as the sampling pulse of A/D conversion, as long as it is a period that allows detailed analysis of intruders.
The second image memory 12□ may be slow as long as the cycle is not so slow that changes cannot be detected when a person enters the room.

In addition, it was assumed that the data stored in the second image memory 12□ is the same data as the first image memory 121, except that the period is different from that of the first image memory 121, but as shown in FIG. If an average value circuit 15 is inserted to calculate and record the average value of data of several pixels, the influence of changes in the surroundings can be reflected, and the performance can be further improved.

Furthermore, although it has been explained that the cycle of storing image data in the second image memory 122 is set to 1/4 only in the horizontal direction of the screen, the write signal stored in the memory is set to N times in the horizontal cycle of the ITV camera 1. If it is generated only once, it can be reduced to 1/N even in the vertical direction, and the calculation time for the negative layer can be shortened.

Further, the A/D converter 11 is connected to the first. Second image memory 12
+ + 122 may be provided respectively, and as shown in FIG. Second image memory 12
．． ．． 122, the CPUs 13, . Have 1B□,
If the configuration is such that the image change detection result of the CPU 132 is sent to the CPU 131, a more efficient system can be constructed.

It goes without saying that various other applications are possible without departing from the gist of the present invention.

[Effects of the Invention] As detailed above, according to the present invention, the calculation time for detecting a change in an image using image data can be shortened;
Furthermore, it is possible to provide an image monitoring device that enables detailed analysis when a change is detected.

[Brief explanation of the drawing]

1 to 6 are for explaining one embodiment of the present invention, FIG. 1 is a block diagram showing the overall configuration, FIG. 2 is a timing chart explaining the writing timing of the image memory, 3 is a diagram showing an example of image data in the image memory, FIG. 4 is a diagram showing an example of a captured image, FIGS. 5 and 6 are diagrams showing an example of image data for detecting an intruder, and FIG.
8 and 8 are block diagrams showing other embodiments of the present invention, FIG. 9 is a block diagram showing an example of an image monitoring device, FIG. 10 is a block diagram showing the structure of a conventional image monitoring device, and FIG.
The figure is a flowchart for explaining the operation of a conventional image monitoring device.
Chart 1 FIG. 12 is a diagram illustrating a method of setting an intruder detection area, and FIG. 13 is a diagram illustrating an example of image data used to explain the operation of a conventional image monitoring device. 1.= ITV camera (imaging means), 3.. Processing device, 5.. Display device, 6.. Alarm device, 7..
Monitoring area, 9...VTR, 10...Sampling pulse generation circuit, 11...A/D converter, 121...
First image memory, 122...Second image memory, 1
3...CPU. 14... Intruder detection area. Applicant's Representative Patent Attorney Takehiko Suzue" - J- Figure 3 (b) Figure (a) Figure (b) Figure (c) Figure (d) Figure (a) Figure 6 (b) J '' Figure 6 (e) Figure 6 (a) Figure (b) Figure 13 (c) Figure 13 (d)

Claims (1)

[Scope of Claims] Imaging means for taking images within a monitoring area; A/D conversion means for continuously capturing and digitizing images taken by the imaging means; a first storage means for storing the digitized image data in a first period; and a first storage means for storing the digitized image data in the A/D conversion means in a second period longer than the first period. A second storage means; Normally, a change in the image is detected by processing the image data in the second storage means, and when a change in the image is detected, the image data in the first storage means is processed. An image monitoring device comprising: a detection means for detecting an intruder within the monitoring area.