JP2001251607A - Image monitor system and image monitor method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image monitor system an image storage type that can reduce a retrieval time and storage capacity of image data, record image data at the moment of a fault occurrence point of time with high reliability and recognize the process until the occurrence of a fault to some degree. SOLUTION: A change quantity calculation section 110a calculates image change quantity per unit time denoting rapidness of a time change in an image, a fault level setting section 103a sets a fault level on the basis of the image change quantity per unit time, a recording rate setting section 104a sets a recording rate for a detailed recording when the fault level is high. A monitor log write section 105a writes the image data according to the recording rate together with attached information consisting of the fault level, a monitored place and a monitor time to a monitor log storage section 106.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image storage type image monitoring system in which images of a surveillance camera are stored and reproduced after the fact to ascertain an abnormal situation and its cause.

[0002]

2. Description of the Related Art Conventionally, surveillance cameras have been installed in buildings, factories, and the like, and image data obtained from the surveillance cameras has been used.
2. Description of the Related Art Image monitoring systems for monitoring the occurrence of abnormalities such as fire and illegal intrusion have been put to practical use. Some of these image monitoring systems have a function of storing image data generated by a monitoring camera.

In an image monitoring system having such a storage function, after the occurrence of an abnormal situation, the state of the abnormal situation and its cause can be grasped by reproducing and viewing the stored image data. it can.

[0004]

However, in the above-described image monitoring system, usually, all the image frames (for example, 30 frames per second) generated by digitizing the image of the surveillance camera are recorded. So
The recording amount has to be large. In addition, there is a problem that an image at an abnormal point must be found while reproducing a large amount of image data in the storage device, and it takes a long time to search.

On the other hand, instead of recording all the image frames obtained from the surveillance camera, a method of recording every fixed time (for example, every 10 seconds) can be considered. This method can certainly reduce the recording amount and shorten the search time, but may fail to record an important image frame at the moment of occurrence of an abnormality. As another method, a method of detecting an abnormality by image processing or another sensor and recording only the image frames before and after the occurrence of the abnormality can be considered. With this method, the recording amount and search time can be reduced, but only the image frames before and after the occurrence of the abnormality are stored. Therefore, in the case of a fire, etc., subtle changes until the fire (abnormal) occurs If we want to know the process, we cannot respond to such a request. Also,
The determination as to whether or not there is an abnormality is usually made based on whether or not the temporal change amount of an image frame or other sensor values exceed a certain reference value. Depending on how to take the value, too many image frames are recorded at the time when no abnormality occurs, or conversely,
Even the image frame at the moment of occurrence of the abnormality cannot be recorded, or the same problem as in the above-described method occurs.

Accordingly, the present invention has been made in view of such a problem, and it is possible to efficiently record an image frame without waste, to shorten a search time, and to obtain a highly reliable image frame at the moment of an abnormal point. It is an object of the present invention to provide a harmonious image storage type image monitoring system and an image monitoring method that can record information with a certain characteristic and can also know the process up to an abnormality to some extent.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method of sampling an image frame obtained by capturing an image of a monitoring target with a camera in a time series and storing the sampled image frame in a storage unit. An image monitoring system that searches for and presents image frames stored when grasping, and that refers to image frames obtained in chronological order, and a change detection unit that detects a state change of a monitoring target, An interval setting unit that sets a sampling interval of an image frame stored in the storage unit according to the detected state change, and a storage unit that stores the image frame in the storage unit for each set sampling interval.

Further, the present invention provides a terminal device for sampling an image frame obtained by a camera and obtained in time series and transmitting the sampled image frame to a center device, storing the received image frame in a storage unit, and detecting an abnormal situation after the fact. An image monitoring system including a center device that searches and presents image frames stored when grasping, wherein the terminal device includes:
Means for receiving data indicating the sampling interval of the image frame from the center device, and, for each of the sampling intervals, means for transmitting an image frame to the center device, the center device refers to the received image frame, Change detection means for detecting a change in state of the monitoring target, interval setting means for setting a sampling interval of an image frame according to the detected state change, and means for transmitting data indicating the sampling interval to the terminal device, Storage means for storing the received image frame in the storage unit.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> In this embodiment, an abnormal level is set in accordance with the time change amount of an image frame from a surveillance camera, and an image frame is recorded at a recording rate corresponding to the abnormal level.
The present invention relates to an image monitoring system that accumulates information together with the abnormal level (used as a search key). (Configuration of Image Monitoring System) FIG. 1 is a block diagram showing a configuration of an image system according to the present embodiment. The image monitoring system 100 monitors abnormalities such as illegal intrusion or fire in a building. The image monitoring system 100 includes image capturing units 101a to c, image processing units 102a to 102c, change amount calculating units 110a to 110c,
Abnormal level setting units 103a to 103c and recording rate setting unit 1
04a-c, monitoring log writing units 105a-c, monitoring log storage unit 106, input unit 107, and search unit 108
, Playback unit 109, display unit 130, timer unit 150
It is composed of

The photographing units 101a to 101c are constituted by CCD cameras, are installed at various points in a building, and photograph image of a monitoring place which is a different monitoring target to generate an image signal. The photographing unit 101a is at the monitoring place A (in front of the entrance).
The photographing unit 101b photographs the monitoring place B (before receiving the first floor), and the photographing unit 101c photographs the monitoring place C (before the first floor elevator).

The image processing unit 102a performs processing on photographed image data in order to calculate a temporal change amount of an image, which will be described later. The image processing unit 102a includes a digital conversion unit 124a, a first memory 120a, and a second memory 121a. And the third memory 122
a and a conversion processing unit 123a. The digital conversion unit 124a converts the analog image signal sent from the photographing unit 101a into digital image data (128 pixels × 1).
(28 pixels, gradation value 0-16, 30 frames / sec), and sends it to the first memory 120a.

The first memory 120a is provided with the digital conversion unit 1
The image data for one frame sent from 24a is stored. Here, since image data of 30 frames / sec is sent from the digital conversion unit 124a, it is updated at a rate of 30 times per second. The conversion processing unit 123a copies the image data in the first memory 120a to the second memory every time the image data is updated, that is, at a rate of 30 times per second, and performs the conversion processing of the image data. Specifically, after performing noise removal processing of image data, threshold processing is performed to binarize the image data. The conversion processing unit 123a includes the second memory 1
The converted image data in the memory 21a is sent to the third memory 122a immediately before 1/30 second elapses, and after the elapse of 1/30 second, the converted image data of the next frame is stored in the second memory 1a.
21a. As described above, the second memory 12
Image data obtained by binarizing an image frame having a 1/30 second imaging time difference is stored in 1a and the third memory 122a.

The change amount calculation unit 110a compares the image data in the second memory 121a with the third memory 1 every 1/30 second.
By comparing with the image data in 22a, a time change amount indicating the degree of time change of the image is calculated, and the time change amount is sent to the abnormal level setting unit 103a. Specifically, the ratio (%) of the total number of pixels in which 0 and 1 have changed between two image data with respect to the total number of pixels (128 × 128) of the image data is defined as the time change amount.

The abnormal level setting unit 103a sets an abnormal level based on the time change amount sent from the change amount calculating unit 110a, and sets the abnormal level value to a recording rate setting unit 104a.
And the monitoring log writing unit 106. Here, the abnormal level indicates the level of the possibility of an abnormal state at the monitoring location based on the time change amount of the image data. Based on this value, the recording rate setting and the search file described later are performed. Is created. FIG. 2 shows the correspondence between the time variation and the abnormal level. As shown in the figure,
When the amount of time change is large, the occurrence of an abnormal situation such as intrusion or fire is expected, so the abnormal level is set high.

The recording rate setting section 104a sets a recording rate based on the abnormal level set by the abnormal level setting section 103a. The recording rate refers to the monitoring log writing unit 105
The time interval (sampling interval) for writing image data into the monitoring log storage unit 106 according to a. FIG. 3 shows the correspondence between the abnormal level and the recording rate. In the figure, the recording rate at the abnormal level 1 is 0.1 frames / sec.
It means that only one frame is recorded out of 300 frames photographed for 10 seconds. As shown in the figure, when the abnormal level is high, the recording rate is set high and many frames are recorded.

The monitoring log writing unit 105a writes image data in the monitoring log storage unit 106 according to the recording rate set by the recording rate setting unit 104a, together with additional information including an abnormal level, a monitoring location, and a monitoring time.
Here, the image data read from the first memory 120a is written. As the monitoring location, an identifier (A, B, or C) for specifying the location where the image is being captured is written. Further, the current time notified from the timer unit 150 is written as the monitoring time.

The monitoring log storage unit 106 stores the image data and the attached information written by the monitoring log writing units 105a to 105c in an image file and a search file. Here, it is assumed that separate image files and search files are created every day. Image data is sequentially added to the image file. FIG.
The example of the format of the file for a search is shown. As shown in the drawing, the search file records a record including a record number, a pointer in the image file of the image data, and attached information (monitoring location, monitoring time, abnormal level). Record numbers are given in the order of records to be recorded within a certain range set for each monitoring location. The certain range is set to be large enough to record one day's worth of records. Here, monitoring location A
Is in the range of "0" to "9999", the monitoring location B is in the range of "10000" to "19990", and the monitoring location C is "20000" to "299".
In the range of "99", the record number is sequentially incremented by 1 each time the record is recorded.

The input unit 107 receives a browsing request for a stored image in which an abnormal level, a monitoring place, and a monitoring time are specified from an operator. FIG. 5 shows items input from the input unit 107. The search unit 108 specifies a record in the monitoring log file corresponding to the abnormal level, monitoring time, and monitoring location specified by the input unit 107, and sends the record number to the reproducing unit 109.

The reproducing unit 109 reads out the attached information (abnormal level, monitoring location, monitoring time) and the pointer of the image data from the monitoring log file based on the record number sent from the searching unit 108. Further, the playback unit 109
The image data is read from the image file based on the pointer to the image data. The reproduction unit 109 obtains the recording rate corresponding to the abnormal level from the correspondence table shown in FIG. Further, the reproducing unit 109 generates character data indicating the attached information (abnormal level, monitoring location, monitoring time). Then, the reproducing unit 109 displays the image data and the character data at the same rate as the recording rate.
Send to 30.

The display unit 130 displays image data and character data sent from the reproduction unit 109. The timer unit 150 notifies the monitoring log writing units 105a to 105c of the current time. (Operation of Accumulating Image Data) The operation of accumulating image data in the image monitoring system according to the present embodiment will be described. FIG. 6 is a flowchart showing an operation procedure for storing image data. Here, an operation in the case where the monitoring location monitors and records image data near the entrance (A) will be described as an example.

The photographing unit 101a photographs the monitoring place A at a rate of 30 frames per second, generates image data, and processes the image data (128 pixels × 128 pixels, gradation values 0 to 16) by image processing. First memory 120 in unit 102a
a (step S2001). Image processing unit 102a
The conversion processing unit 123a copies the image data in the first memory 120a to the second memory 121a, removes noise from the image data, and binarizes the image data by threshold processing (step S2002).

The change amount calculating section 110a is provided in the second memory 12
Between the image data in 1a and the binarized image data before one time stored in the third memory 122a, the pixels whose pixel values are changed are specified, and the total number thereof is obtained. And
The change amount calculation unit 110a calculates a value obtained by dividing the total number by the total number of pixels as a time change amount, and sends the time change amount to the abnormal level setting unit 103a. As a specific example, here
It is assumed that the time change amount is calculated as “32%”.
Then, the change amount calculation unit 110a stores the second memory 121a
The image data in the area is moved to the third memory 122a for the next processing (step S2003).

The abnormal level setting section 103a sets an abnormal level corresponding to the calculated time change amount based on the correspondence table shown in FIG. 2, and sets the abnormal level to the recording rate setting section 104a and the monitoring log writing section 105a. Notify.
As a specific example, here, it is assumed that the abnormal level is set to “3” corresponding to the time change amount of 32% (step S2004).

The recording rate setting section 104a sets a recording rate corresponding to the abnormal level based on the correspondence table shown in FIG.
Send to 5a. As a specific example, here, the recording rate is “0.5 frames /
Seconds ”, that is, image data is recorded once every two seconds (step S2005).

The monitoring log writing unit 105a writes the image data and the attached information to the image file and the search file in the monitoring log storage unit 106 according to the notified recording rate. That is, the monitoring log writing unit 105a
The image data in the memory 120a is added to the image file. Further, the monitoring log writing unit 105a includes a pointer in the image file of the written image data, attached information (notified abnormal level “3”, monitoring time (current time notified by the timer unit), The monitoring location “A” is written as one record of the search file (step S2006). (Image Data Retrieval Operation) Next, an operation of retrieving and browsing image data in the image monitoring system according to the present embodiment will be described. FIG. 7 is a flowchart showing an operation procedure for searching for and browsing image data.

First, a request for browsing the "abnormal level", the "monitoring time", the "monitoring location", or a storage image in which the range is specified by a combination thereof is input from the operator via the input unit 107. As a specific example, here, as shown in FIG. 5, it is assumed that an abnormal level “3 to 5”, a monitoring time “1 to 4:00 on March 4, 2000”, and a monitoring location “A” are specified ( Step S3001).

Next, the search unit 108 checks the monitoring log storage unit 1
A record included in the specified range is specified from the search file for the specified day in 06, and the record number of the record is notified to the reproducing unit 109. As a specific example, record numbers “876 to 1246” of records included in the specified range are notified from the search file shown in FIG. 4 (step S3002).

Next, the reproducing unit 109 reads the records corresponding to the record numbers (the abnormal level, the pointer to the image data, the monitoring time, and the like) from the search file in the order of the record numbers until all the notified records are read. (Monitoring location). The image data is read from the image file based on the pointer to the read image data (steps S3003, S3004).

The reproducing unit 109 specifies the recording rate corresponding to the read abnormal level from the correspondence table shown in FIG. 3 (step S3005). The reproduction unit 109 sends the image data and the character data indicating the abnormal level, the monitoring place, and the monitoring time to the display unit 130 at the same rate as the recording rate (step S3006).

The display unit 130 displays the image data and character data sent from the reproduction unit 109 (step S3007). (Summary) As described above, in the image monitoring system according to the present embodiment, when the temporal change of the image frame is large, the possibility of occurrence of an abnormality is high, so that the recording rate is set to collect detailed information. Raise and accumulate image frames. On the other hand, when the time change of the image frame is small,
Since the possibility of occurrence of abnormality is low, the recording rate is reduced to accumulate image data in order to eliminate useless recording as much as possible. Therefore, efficient and efficient storage of image frames is possible, and image frames at the time of occurrence of abnormality can be recorded with high certainty.

Further, since an abnormal level serving as an index of the magnitude of the temporal change of the image frame is stored together with the image frame as a search key, the image frame can be quickly searched and displayed simply by specifying the abnormal level. Can be. In addition, since the recording rate level is adjusted according to the time change of the image frame, the image at the time when it is not determined to be abnormal can be recorded to some extent, so the process up to the occurrence of the abnormality can be specified and the cause of the abnormality can be investigated. And so on. (Modifications) The present invention is not limited to the above embodiment, and the following modifications are naturally assumed. (1) Recording of Image Data In this embodiment, the image data is recorded in the monitoring log storage unit 106 as it is. However, the present invention is not limited to this. For example, data compressed by JPEG or the like is recorded. It may be a thing. At this time, if the recording rate is low, data compressed at a high compression rate may be recorded, or binarized data in the second memory 121a may be recorded. (2) Format of Search File The search file described in the present embodiment is not limited to this, and other information may be added.
For example, a search file as shown in FIG. 8 may be used. The number of consecutive levels in the figure indicates the number of times the same abnormal level continues. By using the number of consecutive levels, it is not necessary to check all the abnormal levels of the records, so that the time for specifying the records belonging to the specified range can be reduced. (3) Regarding an image of a monitoring place In the present embodiment, one camera (the image capturing units 101a to 101a)
Although one monitoring place is monitored using the image data obtained in c), the present invention is not limited to this. For example, it is assumed that one camera monitors four locations, one image data obtained from the camera is divided into regions for each location, and a temporal change is detected and a recording rate is set for each divided image data. For example, the above-described processing may be performed. (4) Playback Function In the present embodiment, the playback unit 109 includes the monitoring log storage unit 1
Although the image data is reproduced at the same rate as the recording rate corresponding to the abnormal level written in 06, the present invention is not limited to this. For example, the monitoring log storage unit 1
The monitoring time written in 06 may be a finer unit of 1 second or less, and the image data may be reproduced according to the time interval of the monitoring time.

In the present embodiment, the reproduction unit 109
Is for reproducing image data at the same rate as the recording rate at the time of storing the image data. However, the present invention is not limited to this, and may have more various reproduction functions. FIG. 9 shows an example of a display screen in an image monitoring system having various types of reproduction functions. Playback (displayed at the same rate as the recording rate) in operation panel 601 shown in FIG.
In addition, the operator inputs frame-by-frame (one by one), high-speed playback (display at a higher rate), low-speed playback (display at a lower rate), and reverse playback (playback in reverse order of time).
07, the reproduction unit 109 may adjust the speed of the image data sent to the display unit 130 according to the selection. (5) Movement and rotation function of camera In the present embodiment, the camera is fixed.
It is not limited to this. For example, a plurality of locations may be monitored by rotating the camera at a fixed cycle or moving the camera at a fixed cycle while being mounted on a traveling robot. For example, after one camera stays in the direction of the monitoring place A for 10 seconds, it rotates in the direction of the monitoring place B and
Stay for 0 seconds, then rotate in the direction of surveillance location C for 10 seconds
After staying for a second, it can be rotated in the direction of the original monitoring place A. In this case, it is necessary to adjust the recording rate and accumulate image data within a range of 10 seconds for each monitoring location.

In addition to adjusting the recording rate within the range of 10 seconds, the recording time may be adjusted. For example, in the above case, if the abnormal level is equal to or higher than the predetermined value at the monitoring location B, the camera is stopped in the direction of the monitoring location B until the abnormal level becomes lower than the predetermined value. The image data of the monitoring place B may be continuously stored. (6) Time Change Amount In the present embodiment, the number of time-varying pixel values of the binarized image (that is, the changed area) is used by the image processing units 102a to 102c and the change amount calculation units 110a to 110c. The time change of the image data was detected by using
Alternatively, the following method may be used to detect a temporal change in image data. (A) Change in Color Component A change in color component may be detected from a color image using a camera that generates a color image. This is particularly effective for detecting an intruder indoors or detecting a fire. (B) Change in power spectrum The power spectrum related to the frequency of the image data may be calculated, and the change may be detected. The power spectrum related to the frequency of the image data indicates the correlation of the image data.
/ F fluctuation. By utilizing this property, detection of an abnormality such as intrusion in which the correlation of the image data greatly changes can be detected.
For more information on 1 / f fluctuations, see "Bluebacks World of Fluctuations" (Toshimitsu Musha, Kodansha, 1980)
Therefore, a more detailed description is omitted here. (C) Infrared Camera An infrared camera may be used to detect a change in temperature at the monitoring location. This is particularly effective for monitoring at night and for monitoring when a manufacturing defect (abnormal situation) occurs at a factory or the like due to an abnormal temperature. (D) Satellite Image A wide area may be monitored using image data from a satellite. This is particularly effective for monitoring the movement of people in a specific area and for monitoring disasters such as floods in rivers. (E) Other Feature Processing More complicated image processing may be performed on image data to extract higher-order feature amounts, and to calculate changes in the feature amounts. (7) Target Image of Time Change In the present embodiment, the change amount calculation units 110a to 110c calculate 1 /
Although the images having a 30-second imaging time difference are compared to calculate the time change amount, the present invention is not limited to this, and the following images may be used as compared images. (A) Reference image For each monitoring location, when normal (when no abnormalities occur)
The reference image that has been captured and generated in is stored, and the time change amount can be calculated by comparing the reference image with the captured image. (B) Predicted image In a monitoring place where image data usually changes, such as monitoring of manufacturing equipment where products are assembled by a belt conveyor, when the change occurs under a certain law In this method, a predicted image at the time of image capturing is generated based on the rule, and the temporal change amount can be calculated by comparing the predicted image with the captured image. (C) An image having a shooting time difference according to the current recording rate An image having a shooting time difference according to the recording rate at that time is not always targeted for an image having a shooting time difference every 1/30 seconds. May be used. For example, when the recording rate is set to 0.1 frame / second, the conversion processing unit 123a and the change amount calculation unit 110a
By performing the processing every 10 seconds, it is possible to calculate a time change between images having a shooting time difference of 10 seconds. (8) Record Number In this embodiment, the record number of the search file is
A new record is to be recorded by sequentially increasing the number of records within a certain range, and the certain range is set to a size that does not exceed the number of record records for one day. It is not limited. Monitoring log storage unit 1
When the recording capacity of the record No. 06 is smaller than the capacity of the record for one day, the fixed range is set narrow, and when the newly recorded record exceeds the fixed range, the record number returns to the minimum record number. Alternatively, the record recorded most recently may be overwritten and disappear. (9) Detection of Abnormal Level Based on Other Sensor Data In the present embodiment, the abnormal level (probability of abnormality) is detected based on the time change of the image data. However, the present invention is not limited to this. An abnormal level may be detected based on a time change of data. (10) Recording Rate In this embodiment, an example of a recording rate is shown as an example of a comparatively low rate as shown in FIG. 3. However, if there is sufficient recording capacity, recording is performed at a higher rate. Things. In particular, when the level of abnormality is the highest, the probability of occurrence of abnormality is high, so it is desirable to be able to see the image as close as possible to the video after the fact. Recording may be performed at a recording rate. <Second Embodiment> In this embodiment, in addition to the function of the first embodiment, when the abnormal level is equal to or more than a certain value, a function of detecting with another sensor and recording the sensing data together is provided. Image monitoring system.

FIG. 10 is a block diagram showing the configuration of the image monitoring system according to the present embodiment. In the figure,
The components denoted by the same reference numerals as those in the first embodiment have the same functions as those in the first embodiment, and a description thereof will not be repeated. Hereinafter, different components will be described. When the set abnormal level is equal to or higher than a predetermined value (for example, level “5” or higher), the abnormal level setting units 3103 a to 3103 c
It instructs the sensing units 3120a to 3120c to execute sensing.

The sensing units 3120a to 3120c are installed at the monitoring locations, receive the instructions from the abnormal level setting units 3103a to 3103c, collect the audio data of the monitoring locations, and write the audio data to the monitoring log writing units 3105a to 3105c. Send to The monitoring log writing units 3105 a to 3105 c
In addition to the image data and the attached information described in the first embodiment, when the abnormal level is a predetermined value or more, the sensing unit 31
The voice data sent from the storage units 20a to 20c is written in the monitoring log storage unit 3106. For example, when the recording rate is one frame / second, audio data from one second before to the present time is written.

The monitoring log storage unit 3106 stores an image file, an audio file, and a monitoring log file.
Among them, the image file is the same as in the first embodiment. The audio file additionally records audio data. FIG.
1 shows the configuration of the monitoring log file. As shown in the figure, a pointer to an audio file to audio data is also recorded.

When the read abnormal level is equal to or higher than a predetermined value, the reproducing unit 3109 also reads out the audio data and sends it to the audio generating unit 3110. Voice generator 3110
Outputs the audio sent from the reproduction unit 3109. (Summary) As described above, in the image monitoring system according to the present embodiment, when the image frame changes greatly with time and the abnormal level is set to a high level, in addition to the image frame, the audio data collected at the monitoring location Is stored and, when viewed later, not only the image frames but also the audio data are reproduced, so that the abnormal situation can be reproduced more realistically. (Modifications) The present invention is not limited to the above embodiment, and the following modifications are naturally assumed. (1) Other Sensor Data In the present embodiment, audio data has been described. However, the present invention is not limited to this, and data from other sensing means may be recorded. For example, the following may be used. (A) Gas Sensor A sensor that detects a gas such as CO, H ₂ , CH ₄ , C ₂ H ₅ OH, SO ₂ , CO ₂ , and NO _x may be used. This is effective for monitoring disasters due to gas leaks, lack of oxygen, and the like, and monitoring the combustion state of manufacturing equipment. For example, when a fire or the like occurs in a factory or home, it is possible to investigate a process leading to the occurrence of a fire accompanying the progress of filling with city gas or propane gas. (B) Temperature, humidity, and barometric pressure sensors In the event of a defective product manufactured in a factory or the like, this can be useful for investigating whether the manufacturing apparatus was operated at an appropriate temperature, humidity, or pressure. it can. (C) Other Sensors for Detecting Magnetism, Vibration, Radio Waves, etc. According to other uses, magnetism, vibrations, radio waves, etc. may be detected and the detected data may be recorded.
As a result, for example, the cause of the device failure can be detected by magnetic detection, the presence or absence of use of a mobile phone by an intruder by detection of a radio wave of a specific frequency, and the magnitude of shaking during an earthquake can be detected by vibration. <Third Embodiment> This embodiment is an image monitoring system having a function of increasing the abnormal level at another monitoring place in the vicinity when the abnormal level at one monitoring place becomes a certain value or more. About. (Configuration) FIG. 12 is a functional block diagram showing the configuration of the image monitoring system according to the present embodiment. In the figure,
The components denoted by the same reference numerals as those in the first embodiment have the same functions as those in the first embodiment, and a description thereof will not be repeated. Hereinafter, different components will be described. Although FIG. 1 shows a configuration in which three cameras (photographing units) are connected, it is assumed that several other cameras are connected.

When the abnormal level is equal to or higher than a predetermined value (for example, level “4” or higher), the abnormal level setting unit 3503
The abnormal level is notified to the abnormal level compulsory setting unit 3501. The abnormal level compulsory setting unit 3501 specifies the group to which the monitoring place of the abnormal level setting unit 3503 that sent the notification of the abnormal level belongs. Then, the abnormal level compulsory setting unit 3501 causes all the other abnormal level setting units 3503 belonging to the group to stop setting the abnormal level based on the change in the image data, and to set the same abnormal level as the notified abnormal level. Force setting to abnormal level.

FIG. 13 shows a group classification of monitoring places. As shown in the figure, monitoring places that are geographically close to each other belong to the same group. FIG.
The example of the abnormal level before and after the forced setting of the abnormal level is shown. As shown in the figure, since the monitoring places A, B and C belong to the same group, for example, the abnormal level compulsory setting unit 350
When receiving the notification of the abnormal level “4” from the abnormal level setting unit 3503a, the abnormal level setting unit 3503b
The setting of the abnormal level based on the change in the image data in the steps 3503c and 3503c is stopped, and the notified abnormal level "4"
Forcibly set to the same abnormal level as. (Summary) As described above, in the image monitoring system according to the present embodiment, the time change of the image frame at one monitoring location is drastic, and when the abnormal level is set high, the abnormal level at the other monitoring locations is the same. As long as the time change of the image frame can be captured at one monitoring location, even if the time change of the image frame is not well captured at the other monitoring location due to clever intrusion etc. It is possible to avoid a situation in which an image frame at the moment of an important abnormality is missed. (Modifications) The present invention is not limited to the above embodiment, and the following modifications are naturally assumed.

That is, in the present embodiment, when the abnormality level of a specific monitoring location becomes equal to or higher than a predetermined value, the abnormality level of all monitoring locations belonging to the same group as the monitoring location is forcibly set to the same level. Although set, it is not limited to this. For example, in the monitoring of illegal intrusion, etc., the moving direction of the intruder is recognized by further processing the image data of the specific monitoring place where the abnormal level is equal to or higher than a predetermined value, and the monitoring place located in the direction is recognized. Only the abnormal level may be forcibly set. <Fourth Embodiment> The present embodiment relates to an image monitoring system having a system configuration including a terminal device installed at each monitoring location and a remote center device connected to a communication line. (Configuration) FIG. 15 is a block diagram showing the configuration of the image monitoring system according to the present embodiment. As shown in the figure,
The image monitoring system includes terminal devices 3602a to 3602a and a center device 3601 connected by a communication line 3610.

The terminal device 3602a sends image data of a monitoring place in charge of the terminal device to the center device at a density corresponding to the current abnormal level. The photographing unit 3604a, the transmission rate adjusting unit 3609a, and the transmitting / receiving unit 3605a It is composed of The image capturing unit 3604a captures an image of a monitoring place and generates digitized image data of 30 frames / second.

The transmission rate adjusting unit 3609a is provided by the photographing unit 3
Of the 30 frame / second image data generated by the transmission / reception unit 604a, the transmission / reception unit 3605 transmits the image data at a transmission rate corresponding to the recording rate transmitted from the transmission / reception unit 3605a.
Send to a. For example, when the recording rate is 0.5 frames / second, of the 60 frames generated in 2 seconds, 1
Only the image data of the frame is transmitted.

The transmitting / receiving section 3605a is connected to the center device 360.
1 and receives a recording rate from the transmission rate adjusting unit 3609
a, and the image data sent from the transmission rate adjusting unit 3609a to the center device 3601. The center device 3601 has a function of setting an abnormal level and a recording rate from the received image data, and has a function of storing and retrieving the image data. Each component of the center device 3601 is substantially the same as that of the first embodiment, and therefore, different portions will be described below.

Image processing units 3606a-c, change amount calculation units 3607a-c, and abnormal level setting units 3608a-c
In the first embodiment, the recording rate setting units 3611 a to 3611 c are set to 1/3 according to the interval at which the image data is generated.
In contrast to the operation at a time interval of 0 seconds, the present embodiment operates according to a set recording rate. For example, if the recording rate is 0.5 frames / 1 second, 2
Process every second. Monitoring log writing units 105a to 105c
Retrieves image data from the image processing units 3606a to 3606c in accordance with the recording rate. The same applies to the first embodiment. Note that, since the image data sent to the image processing units 3606a to 3606c has already been digitized, this embodiment does not include the digital conversion units 124a to 124c as in the first embodiment.

The recording rate setting section 3611a notifies the monitoring log writing section 1050 of the set recording level, and also transmits and receives the information to the terminal device 3602a through the transmission / reception section 3603.
Send to The transmission / reception unit 3603 includes a recording rate setting unit 3
The recording rates transmitted from the terminals 611a to 611c are transmitted to the corresponding terminal devices 3602a to 3602c, and the image data received from the terminal devices 3602a to 3602c is transmitted to the corresponding image processing unit 3603a.
To c. (Summary) As described above, in the image monitoring system according to the present embodiment, an image frame photographed and generated at a remote monitoring location is transmitted to the center device at a transmission rate corresponding to the abnormal level of the monitoring location. Therefore, it is possible to prevent useless use of the communication line for transmission of an image frame of low importance (there is little possibility of being used afterwards). (Modification) The present invention is not limited to the above-described embodiment, and the following system forms are naturally assumed.

That is, in the present embodiment, the terminal device shoots and transmits image data, and detects a change in the image data on the center device side to set the abnormal level. For example, the terminal device itself detects a change in the image data, sets an abnormal level based on the detection, and communicates the image data and the auxiliary information at a recording rate according to the abnormal level with a communication line. The center device may have only the function of storing the image data and the attached information sent from the terminal device and the function of searching.

[0047]

As is apparent from the above description, according to the present invention, an image frame obtained by capturing an object to be monitored by a camera and obtained in a time series is sampled and stored in a storage unit, and an abnormal situation is grasped afterwards. An image monitoring system for retrieving and presenting an image frame stored at a time, wherein a change detection unit that detects a change in the state of the monitoring target with reference to the image frame obtained in chronological order, An interval setting unit that sets a sampling interval of an image frame stored in the storage unit according to a state change, and a storage unit that stores the image frame in the storage unit for each set sampling interval. I do.

Thus, based on the image frames obtained in time series, the possibility of an abnormal state of the monitoring target is determined,
Efficient image frame storage because image frames at the time of high probability of abnormal state are recorded with a short sampling interval and image frames of low probability of abnormal state are recorded with a long sampling interval. And the image frame at the time of occurrence of the abnormality can be recorded with high certainty. In addition, since unnecessary recording at the time when the possibility of occurrence of abnormality is low is suppressed, the amount of stored image frames is reduced, and as a result, the time required for searching for a desired image frame can naturally be shortened. .

Further, since the sampling interval is adjusted in accordance with the change of the monitoring target, an image frame at a time when the possibility of an abnormal state is low can be recorded to some extent. Investigation of the cause becomes easy. Here, the change detecting means detects a level indicating the magnitude of the state change, and the storage means stores the detected state change level in the storage unit in association with the image frame, and The system further presents a level input unit for designating a search for an image frame by a level of a state change, a search unit for searching an image frame corresponding to the designated level from the storage unit, and presenting the searched image frame. And a presentation unit.

Thus, the level of the state change of the monitoring target based on the image frame is recorded in association with the image frame. Therefore, by using the level of the change as a search key, the operator can simply specify the level of the state change. Thus, an image frame corresponding to the level of the change can be quickly searched and displayed. Here, the image monitoring system further includes a sensing unit that detects a sound, a temperature, a humidity, an atmospheric pressure, a gas, a magnetism, a vibration, or a radio wave generated in a monitoring target to generate sensor information, and is stored in a storage unit. Presentation means for presenting an image frame, wherein the storage means associates the sensor information generated by the sensing means with the image frame when a detected state change level is equal to or higher than a predetermined value. And the presenting means presents the sensor information stored in the storage unit corresponding to the image frame to be presented.

Thus, other sensor information besides the image frame is also recorded, and at the time of reproduction, the sensor information is presented in addition to the image frame, so that the abnormal situation can be reproduced more realistically. Here, the storage unit includes a clock timer, stores the storage time of the image frame to be stored in the storage unit in association with the image frame, and the image monitoring system further stores the storage time in the storage unit. The image processing apparatus may further include a presentation unit that presents the image frame at the same time interval as the storage time interval of the image frame.

As a result, the recorded image frame is reproduced with a time interval corresponding to the recorded time, so that the image frame can be reproduced on the same time scale as the actual one, and the abnormal situation can be more realistically reproduced. You can figure out. Here, the interval setting means sets a sampling interval according to a state change level, and the presenting means sets the searched image frame at the same time as a sampling interval corresponding to the state change level of the image frame. It can be characterized by being presented at intervals.

As a result, the recorded image frames are sequentially reproduced while maintaining the sampling interval at the time of recording, so that the image frames can be reproduced on the same time scale as the actual one, and the abnormal situation can be grasped more realistically. can do. Here, the image monitoring system acquires an image frame for each of a plurality of monitoring targets, the change detection unit detects a change for each image frame in which the monitoring target is different, and the interval setting unit determines a change for each monitoring target. Setting a sampling interval, the storage unit stores the image frame in the storage unit in association with the monitoring target of the image frame, and stores the image frame in the storage unit for each sampling interval of the monitoring target; Input means for specifying a search in units of monitoring targets, searching means for searching the storage unit for an image frame corresponding to the specified monitoring target, and presentation means for presenting the searched image frames. It can be.

Thus, since the data indicating the monitoring target is also recorded, the search can be narrowed down to a specific monitoring target after the fact, and the necessary image frame can be quickly searched and displayed. Here, the image monitoring system further includes, when the sampling interval of one monitoring target is set to be equal to or less than a predetermined value by the interval setting unit, the interval setting unit associates the monitoring target with the one monitoring target. There may be provided a control means for stopping the setting of the sampling interval of another monitoring target and setting the sampling interval of the other monitoring target to the same value as the sampling interval of one monitoring target.

As a result, when the state of a specific monitoring target changes and the sampling interval is shortened, the sampling interval of the monitoring target, which is likely to cause a change in the status of the monitoring target in the near future such as in the vicinity thereof, is also set short. Therefore, an image frame at an important moment can be reliably recorded without detecting a state change in the monitoring target. In addition, especially in the case of subtle intrusion, etc., even when the status change of the monitoring target cannot be captured well, if the status change of one monitoring target can be captured, the change cannot be captured by other monitoring targets. However, it is possible to avoid a situation where an image frame at the moment of an important abnormality cannot be recorded.

Here, the change detecting means may detect a change in the state of the monitoring target based on an image frame obtained in time series and a reference image frame stored in advance. . This makes it easy to change the state of the monitoring target by comparing the reference image frame with the image frame at the time when the change is detected, using the monitoring target image frame at the time when no abnormality occurs (normal time) as the reference image frame. And it can detect correctly. Also, for example, even when an intruder is stationary for a certain period of time, the image frame obtained at that time is different from the reference image frame in a normal state where there is no intrusion, so that changes in the monitoring state can be detected well. can do.

Here, the change detecting means may detect a change in the state of the monitoring target based on the preceding and succeeding image frames obtained in time series. This makes it possible to easily and accurately detect a change in the state of the monitoring target by comparing the image frame at the time when the change is detected with the image frame one frame before. Also, even when the image frame to be monitored under normal conditions changes due to conditions such as the weather, and an appropriate reference image frame cannot be prepared properly, a change in the state of the monitoring target can be detected properly by comparing the preceding and following image frames. can do.

Here, the change detecting means may detect a change in the state of the monitored object between the two image frames based on the number of pixels whose pixel values have changed. . Thus, by a simple process of calculating the area in which the value of the pixel has changed, it is possible to successfully detect a change in the state of the monitoring target such as an illegal intrusion.

Here, the change detecting means may detect a change in the state of the monitoring target by comparing color components between the two image frames. Thereby, by a simple process of detecting a color change of a color image, an illegal intruder wearing a costume of a color different from the background color (as is the case with a normal illegal intrusion) and a red hue increase. It is possible to detect a change in the state of a monitoring target, such as a fire, in a good manner.

Here, the change detecting means may detect a change in the state of the monitoring target by comparing a power spectrum related to a spatial frequency of a pixel value between the two image frames. . This makes it possible to successfully detect a change in the state of the monitoring target such as an illegal intrusion by a simple process of calculating the power spectrum of the image frame.

Here, the change detecting means detects the level of the state change, and the interval setting means sets the sampling interval to be shorter as the detected level of the state change is larger. Accordingly, when the level of the state change of the monitoring target is large, the image frame is recorded with the sampling interval shortened, so that it is possible to collect the information in detail at the time when the possibility of occurrence of the abnormality is high. On the other hand, when the change level of the image frame is small, the image frame is recorded with the sampling interval lengthened, so that useless recording at the time when the possibility of the abnormal state is low can be eliminated as much as possible.

Here, the change detecting means detects the level of the state change, and the interval setting means sets the sampling interval in a time series when the detected level of the state change is equal to or more than a predetermined value. The time interval is set to be the same as the above time interval. Thus, when the level of the state change of the monitoring target is equal to or higher than the predetermined value and the probability of abnormality is high, the acquired image frames are recorded as they are without being scattered, so that the image frames at that time are reliably recorded. be able to.

Further, according to the present invention, a terminal device for sampling an image frame obtained by a camera and obtained in a time series and transmitting the sampled image frame to a center device, and storing the received image frame in a storage unit so that an abnormal situation can be detected after the fact. An image monitoring system including a center device that searches and presents image frames stored when grasping, wherein the terminal device includes:
Means for receiving data indicating the sampling interval of the image frame from the center device, and, for each of the sampling intervals, means for transmitting an image frame to the center device, the center device refers to the received image frame, Change detection means for detecting a change in state of the monitoring target, interval setting means for setting a sampling interval of an image frame according to the detected state change, and means for transmitting data indicating the sampling interval to the terminal device, Storage means for storing the received image frame in the storage unit.

As a result, the image frame to be monitored is sent from the terminal device to the center device, and sampling of the image frame sent from the terminal device to the center device is performed in the image monitoring system in which the center device collectively manages the image frames. The interval is adjusted so as to increase when the state change of the monitoring target is large and to decrease when the state change is small, so that the communication line is used efficiently,
Image frames can be sent.

Further, according to the present invention, an image frame captured by a camera and obtained in a time series is sampled and stored in a storage unit, and the image frame stored when an abnormal situation is grasped afterwards is searched. Detecting a state change of a monitoring target with reference to an image frame obtained in time series, and displaying an image frame stored in a storage unit according to the detected state change. The method includes the steps of: setting a sampling interval; and storing an image frame in a storage unit for each set sampling interval.

As a result, the sampling intervals of the image frames are set based on the image frames obtained in time series, so that the image frames can be efficiently accumulated and the image frames at the time of occurrence of the abnormality can be highly reliably determined. Can be recorded with gender. Further, since unnecessary recording at the time when the possibility of occurrence of abnormality is low is suppressed, the time required for searching for a desired image frame can be shortened. In addition, since an image frame at a time when it is unlikely to be in an abnormal state can be recorded to some extent, it is easy to identify a process up to the occurrence of the abnormality and to investigate a cause of the abnormality.

Further, according to the present invention, an image frame captured by a camera and obtained in time series is sampled and stored in a storage unit, and the image frame stored when grasping an abnormal situation afterwards is searched. A computer-readable recording medium recording a program to be presented and presented,
Detecting a state change of the monitoring target with reference to the image frames obtained in time series; and setting a sampling interval of the image frames stored in the storage unit according to the detected state change. And storing the image frame in the storage unit at each sampling interval.

As a result, the sampling interval of the image frames is set based on the image frames obtained in time series, so that the image frames can be efficiently stored and the image frame at the time of occurrence of the abnormality can be highly reliably determined. Can be recorded with gender. Further, since unnecessary recording at the time when the possibility of occurrence of abnormality is low is suppressed, the time required for searching for a desired image frame can be shortened. In addition, since an image frame at a time when it is unlikely to be in an abnormal state can be recorded to some extent, it is easy to identify a process up to the occurrence of the abnormality and to investigate a cause of the abnormality.

As described above, the image surveillance system according to the present invention is used to identify situations such as illegal intrusion into buildings and houses, fires, manufacturing defects in factories, disasters in wide areas, etc. and their causes. Under the constraints of limited system resources (recording capacity and communication capacity) and limited human resources (time and effort to search for images at abnormal times), the degree of detail of an image frame to be monitored according to its utility value In addition, since the data is accumulated in a format suitable for a subsequent search, the practical effect is extremely large.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image system according to an embodiment of the present invention.

FIG. 2 shows a correspondence relationship between a time change amount and an abnormal level.

FIG. 3 shows a correspondence between an abnormal level and a recording rate.

FIG. 4 shows a format of a search file.

FIG. 5 shows items input from the input unit 107.

FIG. 6 is a flowchart showing an operation procedure for accumulating image data.

FIG. 7 is a flowchart showing an operation procedure for searching for and browsing image data.

FIG. 8 shows a format of a search file.

FIG. 9 shows an example of a display screen.

FIG. 10 is a block diagram showing a configuration of an image monitoring system according to an embodiment of the present invention.

FIG. 11 shows a configuration of a monitoring log file.

FIG. 12 is a functional block diagram illustrating a configuration of an image monitoring system according to an embodiment of the present invention.

FIG. 13 shows a group classification of monitoring places.

FIG. 14 shows examples of abnormal levels before and after forced setting of abnormal levels.

FIG. 15 is a block diagram illustrating a configuration of an image monitoring system according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 image monitoring system 101 a-c imaging unit 102 a-c image processing unit 103 a-c abnormal level setting unit 104 a-c recording rate setting unit 105 a-c monitoring log writing unit 106 monitoring log storage unit 107 input unit 108 search unit 109 playback unit 110a-c Change amount calculation unit 120a-c First memory 121a-c Second memory 122a-c Third memory 123a-c Conversion processing unit 124a-c Digital conversion unit 130 Display unit 150 Timer unit 601 Operation panel 3100 Image monitoring system 3103a-c abnormal level setting unit 3105a-c monitoring log writing unit 3106 monitoring log storage unit 3109 reproducing unit 3110 sound generating unit 3120a-c sensing unit 3500 image monitoring system 3501 abnormal level compulsory setting unit 3503a-c abnormal level setting unit 3601 center device 3602a-c terminal device 3603 transmission / reception unit 3604a-c imaging unit 3605a-c transmission / reception unit 3606a-c image processing unit 3607a-c change amount calculation unit 3608a-c abnormal level setting unit 3609a-c transmission rate adjustment unit 3610 communication Line 3611a-c Recording rate setting unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/225 H04N 5/225 CF term (Reference) 5C022 AA01 AA03 AA05 AA15 AB61 AB65 AC18 AC42 AC69 AC75 CA00 5C054 AA02 AA05 CA04 CA05 CA07 CA09 CA10 CC05 CE12 CE14 CG06 CG07 CH01 CH04 DA06 EA01 FA09 FC13 FE28 FF02 GB11 HA02 HA18 HA19 HA20 5C084 AA02 AA07 AA08 AA13 BB31 CC19 DD11 EE04 GG07 GG09 HGG GG20 GG20 GG20 GG20 GG20 GG20 H AA02 AA03 AA04 AA09 AA10 AA19 AA37 AA41 BB11 BB74 CC51 DD02 DD04 DD05 DD07 DD23 EE16 FF01 FF04 FF19 GG02 GG03 GG07 GG10 GG18 GG19 GG21 GG22 GG23 GG29 GG30 GG37 GA02 GA03 BA02 GA02

Claims (17)

[Claims] 1. An image frame obtained by capturing an image of a monitoring target by a camera and obtained in time series is sampled and stored in a storage unit, and the image frame stored when grasping an abnormal situation afterwards is searched. An image monitoring system for presenting, comprising: a change detection unit configured to detect a state change of a monitoring target with reference to an image frame obtained in a time series; and an image frame stored in a storage unit according to the detected state change. An image monitoring system comprising: an interval setting unit that sets a sampling interval of the image data; and a storage unit that stores an image frame in a storage unit for each set sampling interval. 2. The change detecting means detects a level indicating a magnitude of a state change, and the storage means stores the detected state change level in a storage unit in association with the image frame. The image monitoring system further includes: a level input unit that specifies a search for an image frame by a level of a state change; a search unit that searches an image frame corresponding to a specified level from the storage unit; The image monitoring system according to claim 1, further comprising: a presentation unit for presenting. 3. The image monitoring system further comprises: sensing means for detecting sound, temperature, humidity, atmospheric pressure, gas, magnetism, vibration, or radio waves generated in a monitoring target to generate sensor information, and stored in a storage unit. Presentation means for presenting the detected image frame, wherein the storage means associates the sensor information generated by the sensing means with the image frame when the level of the detected state change is equal to or greater than a predetermined value. The image monitoring system according to claim 1, wherein the storage unit stores the sensor information corresponding to an image frame to be presented, the sensor information being stored in the storage unit. 4. The storage means includes a clock timer, and stores a storage time of an image frame to be stored in a storage unit in association with the image frame, wherein the image monitoring system further stores in the storage unit The image monitoring system according to claim 1, further comprising a presentation unit configured to present the selected image frame at the same time interval as the interval of the storage time of the image frame. 5. The interval setting means sets a sampling interval according to a state change level, and the presentation means sets the searched image frame to the same as a sampling interval corresponding to the state change level of the image frame. 3. The image monitoring system according to claim 2, wherein the image is presented at a time interval of: 6. The image monitoring system acquires an image frame for each of a plurality of monitoring targets, the change detecting unit detects a change for each image frame having a different monitoring target, and the interval setting unit includes a monitoring target. The storage unit associates the image frame with the monitoring target of the image frame and stores the image frame in the storage unit at each sampling interval of the monitoring target. The image system further includes: Input means for designating a frame search in a monitoring target unit; search means for searching an image frame corresponding to the specified monitoring target from the storage unit; and presentation means for presenting the searched image frame. The image monitoring system according to claim 1, wherein: 7. The image monitoring system, further comprising: when the interval setting unit sets a sampling interval of one monitoring target to be equal to or smaller than a predetermined value, the image monitoring system determines that one monitoring target is set to the interval setting unit. A control means for stopping setting of a sampling interval in another related monitoring target and setting a sampling interval in the other monitoring target to the same value as a sampling interval of one monitoring target. 6. The image monitoring system according to item 6. 8. The apparatus according to claim 1, wherein the change detecting means detects a change in the state of the monitoring target based on an image frame obtained in time series and a reference image frame stored in advance. Image monitoring system. 9. The image monitoring system according to claim 1, wherein the change detection unit detects a change in the state of the monitoring target based on preceding and succeeding image frames obtained in time series. 10. The method according to claim 8, wherein the change detection unit detects a change in the state of the monitoring target between the two image frames based on the number of pixels whose pixel values have changed. 9. The image monitoring system according to item 9. 11. The image monitoring system according to claim 8, wherein the change detection unit detects a change in the state of the monitoring target by comparing color components between the two image frames. . 12. The method according to claim 8, wherein the change detection unit detects a change in the state of the monitoring target by comparing a power spectrum related to a spatial frequency of a pixel value between the two image frames. 9. The image monitoring system according to item 9. 13. The change detecting means detects a level of a state change, and the interval setting means sets a sampling interval to a shorter interval as the detected level of the state change is larger. Item 2. The image monitoring system according to Item 1. 14. The change detecting means detects a level of a state change, and the interval setting means, when the level of the detected state change is equal to or more than a predetermined value, sets a sampling interval of an image frame obtained in time series. 2. The image monitoring system according to claim 1, wherein the interval is set to be the same as the time interval. 15. A terminal device for sampling an image frame captured by a camera and obtained in a time series and transmitting the sampled image frame to a center device, and storing the received image frame in a storage unit to recognize an abnormal situation afterwards. An image monitoring system comprising a center device for searching and presenting stored image frames, the terminal device comprising: means for receiving data indicating a sampling interval of an image frame from a center device; Means for transmitting an image frame to a center device, wherein the center device refers to the received image frame to detect a change in the state of the monitoring target, and responds to the detected state change. An interval setting means for setting a sampling interval of an image frame; and transmitting data indicating the sampling interval to a terminal device. Image monitoring system characterized by comprising: means, and storage means for storing the image frame received in the storage unit to be. 16. An image that is sampled by a camera and obtained in a time series and stored in a storage unit, and an image frame that is stored when an abnormal situation is grasped afterwards is retrieved and presented. A monitoring method, comprising the steps of: detecting a state change of a monitoring target with reference to an image frame obtained in a time series; and setting a sampling interval of an image frame to be stored in a storage unit according to the detected state change. An image monitoring method, comprising the steps of: storing an image frame in a storage unit at each set sampling interval. 17. A program for sampling an image frame obtained by a camera and obtained in a time series, storing the sampled image frame in a storage unit, and searching for and presenting the stored image frame when grasping an abnormal situation afterwards. Detecting a state change of a monitoring target with reference to an image frame obtained in time series, and storing the change in a storage unit according to the detected state change. A computer-readable storage medium storing a program for causing a computer to execute a step of setting a sampling interval of an image frame and a step of storing an image frame in a storage unit at each set sampling interval.