JPH0271397A - Picture monitoring device - Google Patents

Abstract

PURPOSE:To detect the presence or absence of an invader, etc., with no malfunction caused even with a fast change of luminous intensity within a monitor range by using an image pickup device like a TV camera, etc., to compare the present picture with a reference picture. CONSTITUTION:The picture signal obtained by an image pickup means 1 is converted into the digital signal by an A/D conversion means 2 and stored in a present picture storing means 3. An area division means 4 divides a monitor area into minor areas having the similar correlations in terms of the time change of luminance of each picture element. At the same time, the means 4 obtains the threshold value of luminance which is proportional to the size of each area. These information are stored in an area division information storing means 5. An area-based change detecting means 7 calculates the difference of the luminance absolute value between the present picture and a reference picture stored previously in a reference picture storing means 6. Then the difference values of each area are totalized. When the total difference value exceeds a threshold level, the presence of a change, i.e., an invader is decided.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an image capturing device such as a television camera to detect the presence or absence of an intruder by comparing the current image with a reference image. This invention relates to a monitoring device.

[Conventional technology] A conventional device of this type is shown in block diagram form in FIG.

The image signal from the imaging means l such as a television camera is A/D
It is sampled and digitized by the conversion means 2. The digitized image signal is stored in the current image storage means 3 as a current image. The reference image storage means 6 stores reference images such as background images. A difference image between the current image and the reference image is obtained and stored by the difference image storage means 9, and the binarization means 10 converts the brightness value of each pixel of this difference image into invalid data and valid data using a predetermined threshold. The determination means 11 detects an intruder into the monitoring area from a change in the number of valid data (Japanese Patent Laid-Open No. 5'1160282).

However, in such a device, when a change in brightness occurs in a certain place in the monitoring area due to a change in sunlight, the difference in brightness from the reference image will reach a predetermined threshold even if there is no abnormality such as the presence of an intruder. Since the number of pixels exceeding the specified value will be greater than the specified value and a false alarm will be issued, it is not practical in places where the illuminance changes, such as near windows, and can only be used indoors with stable lighting. There was a problem.

In order to improve the above-mentioned problems, a method has been devised in which the reference image is updated at regular intervals to cope with changes in illuminance.

[Problems to be Solved by the Invention] However, this method cannot cope with cases where illuminance changes are fast compared to the update time of the reference image, and it is still difficult to identify intruders into the monitoring area and illuminance changes. The problem was that it couldn't be done enough.

The present invention has been made in view of the above points, and its purpose is to provide image monitoring that can detect the presence or absence of an intruder without malfunctioning even in the face of rapid changes in illuminance within a monitoring area. The goal is to provide equipment.

(Means for Solving the Problems) The image monitoring device of the present invention includes an imaging means 1 that photographs a monitoring area, and an A/D converter that samples and A/D converts an image signal output from the imaging means 1. Means 2 and
A current image storage means 3 that sequentially stores the current image output from the A/D conversion means 2; a reference image storage means 6 that stores a reference image representing the normal state of the monitoring area; A region dividing means 4 divides a region based on the correlation of temporal changes in brightness and sets a brightness threshold corresponding to the area of each divided region, and a region dividing information storage means 5 stores the region dividing information and the threshold. , a region-by-region change detection means 7 that detects a change in each region, and a combination of each region when there is a change in illuminance in the monitoring region is stored in advance, and from this combination information and the result of the change detection. It is characterized by comprising a changed area combination determining means 8 for determining the presence or absence of an intruder.

[Effect]

The area dividing means divides the monitoring area into areas with similar correlations in temporal changes in brightness, and for each divided area, the difference image between the current image and the reference image is binarized using a predetermined threshold. By calculating the effective pixels, and comparing the number with a brightness threshold proportional to the area of each area, change detection is performed, and the combination of changed areas is detected by detecting changes due to illuminance changes that have been stored in advance. This is intended to detect changes in the entire monitoring area by comparing with area combination information, and to prevent malfunctions due to rapid changes in illuminance.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

Reference numeral 1 denotes an imaging means such as a television camera, which takes an image of the monitoring area and outputs an image signal. 2 is an A/D conversion means,
The image signal is sampled and digitized. Reference numeral 3 denotes a current image storage means for sequentially storing the digitized current image output from the A/D conversion means 2.

Reference numeral 4 denotes a region dividing means which divides the monitoring region into small regions having similar correlations in time change in brightness of each pixel. In other words, for example, the monitoring area is monitored for about one day in advance, the daily change in luminance value of each pixel is examined, and adjacent pixels that change in the same way are collected into one area. , to divide the area. Furthermore, it also has a function of determining a brightness threshold proportional to the area of each divided area.

Reference numeral 5 denotes a region division information storage means, which stores information on the divided regions obtained by the region division means 4 and threshold values for each region. Reference numeral 6 denotes a reference image storage means for storing reference images such as background images representing the normal state of the monitoring area.

Reference numeral 7 denotes a change detection means for each region, which calculates the difference in luminance value between the current image from the current image storage means 3 and the reference surface image from the reference image storage means 6, and calculates the difference in luminance value between the current image from the current image storage means 3 and the reference surface image from the reference image storage means 6, and calculates the difference in the luminance value between the current image from the current image storage means 3 and the reference surface image from the reference image storage means 6, and calculates the difference in the luminance value between the current image from the current image storage means 3 and the reference plane image from the reference image storage means 6, By using the information and the threshold for each region, calculate the sum of the absolute values of the differences for each region, and compare it with the threshold for each region.
Change detection is performed in which it is determined that there is a change when the threshold value is exceeded.

As a result, a combination of regions with changes is obtained.

Reference numeral 8 denotes a change area combination determination means, which determines whether there is a change in the divided areas in response to a change in illuminance in the monitoring area (for example, a change in illuminance due to a ceiling light or a window that lets in outside light). The combination of areas to be determined is memorized in advance,
When the combination of areas determined to have changed by the area-based change detection means 7 matches any of the previously stored combinations of areas, it is determined that the change is due to a change in illuminance and not the presence of an intruder; - It is determined that there is an intruder only when there is no defeat.

Next, the operation of this embodiment will be explained.

The image signal obtained by the imaging means 1 is converted into a digital signal by the A/I conversion means 2 and stored in the current image storage means 3. The area dividing means 4 divides the monitoring area into small areas having similar correlations in time changes in brightness of each pixel, and determines a brightness threshold proportional to the area of each area. These pieces of information are stored in the area division information storage means 5. The regional change detection means 7 calculates the difference in the absolute value of the luminance value between the reference image stored in the reference image storage means 6 in advance and the current image, calculates the sum of the difference values for each region, and calculates the threshold value. When it is exceeded, there is a change.

Here, 211(a) is a diagram showing a reference image of the monitoring area, L is a lighting, and W is a window. FIG. 2(b) is a diagram showing regions divided by the region dividing means 4. FIG. In other words, it is divided into areas from ■ to @.

In the change area combination determination means 8, for example, when outside light enters from the window W, the window part ■ and the areas ■, ■, o, and ■ change as shown in FIG. 2(c). Therefore, remember the combinations of these areas. There may be combinations other than this depending on the position of the sun, so remember these as well. Furthermore, if the lighting changes (for example, lights turn on),
As in d), area excluding ceiling and windows■,■,■,■,■
, ■, ■, ■, ■, [phase], ■, ■ change, so the combination of these areas is memorized. ”2 combinations are memorized in advance, and in the actual monitoring state,
The combination of regions determined to have changed by the region-specific change detection means 7 is compared with the previously stored combination of regions, and only when there is no match, it is determined that an intruder exists. be.

In other words, as shown in FIG. 2(e), if the intruder M exists in area ■, only area ■ is judged to have changed.
Since this is not in the combination of areas stored in advance, it is determined that there is an intruder.

〔Effect of the invention〕

The image monitoring device of the present invention includes: an imaging means for photographing a monitoring area; an A/D conversion means for sampling and A/D converting an image signal output from the imaging means;
current image storage means for sequentially storing the current image output from the D conversion means; reference image storage means for storing a reference image representing the normal state of the monitoring area; area dividing means for dividing an area based on correlation and setting a brightness threshold according to the area of each divided area; area dividing information storage means for storing the area dividing information and the threshold; and a change in each area. A region-specific change detection means for performing detection, and a changing region that stores in advance a combination of each region when there is a change in illuminance in the monitoring region, and determines the presence or absence of an intruder from this combination information and the result of the change detection. Since the image monitoring apparatus includes the combination determination means, it is possible to provide an image monitoring apparatus that can detect the presence or absence of an intruder, etc., without malfunctioning even when the illuminance within the monitoring area changes quickly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram showing an image for explaining the operation of the same, and FIG. 3 is a block diagram showing a conventional example. Imaging means A/D conversion means Current image storage means Area division means Area division information storage means Reference image storage means Area change detection means Change area combination determination means

Claims (1)

[Claims] (1) Imaging means for photographing the monitoring area, sampling the image signal output from the imaging means, and A/D
A/D conversion means for converting, current image storage means for sequentially storing current images output from the A/D conversion means, and reference image storage means for storing a reference image representing a normal state of the monitoring area; area dividing means for dividing the monitoring area into areas based on the correlation of temporal changes in brightness of each pixel, and setting a brightness threshold for each divided area according to its area;
Area division information storage means for storing the area division information and threshold values; area-by-area change detection means for detecting changes for each area; and a combination of areas to be stored in advance when there is a change in illuminance in the monitored area. and a change area combination determination means for determining the presence or absence of an intruder from this combination information and the result of the change detection.