JP4698260B2 - Image recording apparatus and monitoring system - Google Patents

Description

  The present invention relates to an image recording apparatus mainly used for recording a monitoring image and a monitoring system including such an image recording apparatus.

  In a building such as a building or a store such as a shopping center, in general, moving images (hereinafter referred to as “images”) taken by a plurality of surveillance cameras are displayed in a monitoring room, so that a suspicious person can Theft is monitored. Images taken with a surveillance camera by improving the density density of recording media represented by hard disks, by developing image compression coding technology represented by the MPEG (Moving Picture Experts Group) system, and by developing network communication technology Is compressed and encoded by an image recording device and recorded on a recording medium, and the compressed and encoded image is transmitted to a management device including a reproducing unit and a display unit via a network such as a LAN (Local Area Network). A monitoring system for transferring is becoming widespread (see Patent Document 1).

  The larger the number of buildings and stores, the greater the number of surveillance cameras and image recording devices installed. Therefore, even if the images of all the monitoring cameras are displayed on the management device, it is difficult for the surveillance staff to see those images at the same time. Further, due to the installation space, the number of display screens of the management device is Less than the number of monitored cameras. In addition, when there are a large number of surveillance cameras, if the image data of all the image recording devices is constantly transferred to the management device, the network bandwidth is insufficient and the transfer of the image data is hindered.

  From the above circumstances, in a certain type of monitoring system, a sensor for detecting a person is provided together with a monitoring camera, and when that sensor reacts, an alarm signal is sent from the image recording device to the management device to that effect, The management apparatus acquires an image from the image recording apparatus and displays it. In addition, when an image recording apparatus is provided with a motion detect function that detects an image change such as movement of a person by analyzing the image, and an image change or movement is detected, an alarm signal is sent from the image recording apparatus to the management apparatus. Sending is also done. With such a configuration, it becomes possible for the monitoring staff to quickly know the occurrence of an abnormality, and if there is any change in the monitoring area of the monitoring camera when the image of the monitoring camera is not displayed on the management device Instead of another surveillance camera image, the surveillance camera image is displayed on the management device. Further, it is not necessary to always transfer images of all the monitoring cameras to the management apparatus. Note that an image (or an image in a certain time period) that cannot be confirmed in real time by the management apparatus can be separately confirmed by reproducing the image data recorded in the image recording apparatus.

JP 2000-106667 A

  However, the monitoring system provided with the sensor together with the monitoring camera has the following problems. For example, even if a passive infrared sensor is provided, only a person (or animal) that is a heat source can be detected, and even if a shielded infrared sensor is provided, only a person (or object) crosses a certain place. It cannot be detected. Therefore, when the sensor output is used as a trigger for transmitting an alarm signal or as a trigger for switching the monitoring image in the management apparatus, it is necessary to install several sensors around the monitoring camera. This increases the cost of the monitoring system and the trouble of installing and setting the monitoring system. In addition, there are various environments in which surveillance cameras are arranged, and a situation in which certain sensors cannot be arranged frequently occurs.

  On the other hand, in order to provide a motion detection function to the image recording apparatus, it is necessary to add hardware corresponding to the function, and thus the cost of the monitoring system increases. Furthermore, in the motion detect function, since a change in the image within a predetermined range is detected, if the image changes outside the range, the alarm signal is transmitted and the monitoring image is switched. Things that don't happen in can happen.

  The present invention solves the above-mentioned problem, enables detection of an abnormality and transmission of an alarm signal without using a sensor or a motion detection function, and manages an image of a monitoring camera having an abnormality in a monitoring area. An image recording apparatus and a monitoring system that enable switching display on the apparatus are provided.

  An image recording apparatus of the present invention is an image recording apparatus that records an image signal output from an imaging apparatus by predictive compression encoding using frame correlation, and transmits the encoded image signal to a network as appropriate. Each time one frame is encoded, the total data size of a predetermined number of frames encoded in the past including the frame is obtained, and it is determined whether or not the total data size is a predetermined threshold value or more. When the total data size is equal to or larger than the threshold, an alarm signal is transmitted to the network.

  The monitoring system of the present invention includes a plurality of image recording devices and a management device that is connected to the plurality of image recording devices, and each image recording device outputs an image output from an imaging device connected thereto. A signal is encoded and recorded, and the encoded image signal is appropriately transmitted to the management apparatus, and the management apparatus transmits an image signal transmitted from at least one of the plurality of image recording apparatuses. In the monitoring system for reproducing the image, each image recording device performs predictive compression encoding using the frame correlation on the image signal, and each time one frame is encoded, the image is encoded in the past including the frame. The total data size of a predetermined number of frames is obtained to determine whether or not the total data size is equal to or greater than a predetermined threshold. If the total data size is equal to or greater than the threshold, Transmits a beam signal to the management apparatus, the management apparatus, after receiving the alarm signal of an image recording apparatus, characterized in that the picture signals sent from the image recording apparatus.

  In the present invention, when one frame constituting an image signal is encoded by the image recording apparatus, the total data size of a predetermined number of frames encoded in the past including the frame is obtained. Since the image signal is subjected to predictive compression coding using frame correlation, the total data size is almost constant when there is no change or movement in the image, but when a change or movement occurs in the captured image, Increase significantly. Therefore, by determining whether or not the total data size is greater than or equal to a certain threshold, it is determined whether or not an abnormality has occurred in the imaging area of the imaging device, and when an abnormality has occurred, an alarm signal is transmitted, This can be notified to the monitoring room. Moreover, the monitoring person in the monitoring room can know the occurrence of abnormality without looking at the image of the imaging device.

  Further, in the monitoring system of the present invention, after receiving the alarm signal, the image signal sent from the image recording device that transmitted the alarm signal is reproduced by the management device, so that the occurrence of an abnormality The monitoring image is switched by the management apparatus. Furthermore, since occurrence of an abnormality is determined based on the total data size of a predetermined number of frames, the image recording apparatus and the monitoring system of the present invention can be used without adding special hardware to the conventional image recording apparatus. It can be implemented by making changes or additions. Note that the predictive compression encoding is performed in a VBR (variable bit rate) mode. Predictive compression encoding is performed based on the MPEG system, and the number of frames for obtaining the total data size is preferably equal to the number of frames included in one GOP.

  Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an overview of a monitoring system according to an embodiment of the present invention. The monitoring system includes a plurality of imaging devices, specifically, a monitoring camera (1), an image recording device (3) provided for each of the monitoring cameras (1), an image recording device (3) and a network ( And a management device (7) communicating via 5). An image signal related to an image taken by the monitoring camera (1) is compressed and encoded by the image recording device (3) and recorded. Since the surveillance camera (1) always shoots, the image recording device (3) deletes the old image signal so that the data amount of the recorded image signal does not exceed the predetermined value. A signal is recorded on a recording medium. The network (5) is a LAN or WAN (Wide Area Network) or the like. For example, a management device (7) is provided at a location that is geographically far from the monitoring camera (1) or the like, and the management device (7) And the image recording device (3) may communicate with each other via a public communication network and the Internet. The management device (7) selectively acquires an image signal from the image recording device (3) connected to the network (5), and reproduces and displays it. As will be described later, when an alarm signal is sent from a certain image recording device (3) to the management device (7), the management device (7) acquires the image signal from the image recording device (3) and reproduces it. To do.

  In the image recording device (3), the (digital) image signal sent from the surveillance camera (1) is subjected to predictive compression coding using frame correlation. In this embodiment, the image signal of the surveillance camera (1) is compression-encoded based on the MPEG system. FIG. 2 is an explanatory diagram showing the frame structure of an image signal in the MPEG system in time series. As is well known, in the MPEG system, frames constituting an image signal are classified into three types and encoded. A frame (I picture) with the letter “I” in FIG. 2 is an intra picture (intra-frame encoded image), and is encoded using only its own information without using other picture information. . A frame (P picture) with the letter “P” is called a predictive encoded picture (inter-frame predictive encoded picture), and refers to a past intra picture or predictive encoded picture on the time axis. Forward-predictive coding. A frame (B picture) with the letter “B” is a bidirectional predictive coded picture (bidirectional predictive coded picture), and is forward-facing on the time axis with reference to past and future I pictures or P pictures. And backward predictive coding. Since the B picture data is created using the correlation between the previous and next pictures, the B picture data increases if there is a change or motion in the image without being affected by the complexity of the background of the image.

  FIG. 3 is a block diagram showing the configuration of the image recording apparatus (3). The image signal output from the surveillance camera (1) is encoded by the MPEG encoding means (31). The MPEG encoding means (31) includes a motion estimation unit, a DCT (Discrete Cosine Transform) unit, a quantization unit, a local decoding unit, and the like (all not shown). The MPEG encoding means (31) performs encoding in the VBR mode. FIG. 4 shows an example of the order of pictures in the image signal encoded by the MPEG encoding means (31). As shown in FIG. 4, normally, in an image signal encoded by the MPEG method, a plurality of pictures of different types are arranged based on a predetermined rule, and a group of pictures constituting this arrangement is GOP ( Group of pictures). In the example shown in FIG. 4, usually, the picture from the I picture to the B picture before the next I picture is 1 GOP. Note that the numbers shown in FIG. 4 indicate the playback order of pictures.

  A general surveillance camera does not have functions such as zoom, pan, and tilt, and always captures a certain surveillance area. Moreover, even if the surveillance camera used in the surveillance system has these functions, it is long to photograph a certain surveillance area. The same applies to the monitoring camera (1) of the monitoring system of the present embodiment, and the image recording device (3) basically does not detect a scene change, so it is encoded by the MPEG encoding means (31). In the image signal, the GOP shown in FIG. 4 is repeated without changing the arrangement of pictures.

  Since the surveillance camera (1) captures a certain surveillance area, no change or movement occurs in the photographed image unless an intruder enters the surveillance area or the like. In such a case, the data size of the I picture is constant in the image signal encoded by the MPEG encoding means (31). Since the P picture and the B picture are predictively encoded using the frame correlation as described above, their data size is smaller than that of the I picture. On the other hand, when an abnormality occurs in the monitoring area of the monitoring camera (1) and a change or movement occurs in the image captured by the monitoring camera (1), the data size of the P picture and B picture increases. As a result, the data size of the entire GOP also increases.

  The picture size acquisition means (33) of the image recording device (3) obtains the data size of the picture every time the MPEG encoding means (31) completes the encoding of each picture constituting the image signal. Based on the data size information of the picture sent from the picture size acquisition means (33), the abnormality determination means (35) determines whether a change or movement caused by an abnormal situation has occurred in the image of the monitoring camera (1). If such a change or movement occurs, the control means (37) is informed that an abnormality has occurred. The control means (37) performs various controls and processes in the image recording device (3), and when notified that an abnormality has occurred, generates an alarm signal and sends it to the communication means (39), The transmission is instructed. The communication means (39) manages communication performed between the image recording device (3) and the management device (7) via the network (5) based on a predetermined communication protocol (for example, TCP / IP). When there is an instruction from the control means (37), an alarm signal is transmitted to the management device (7). When an image transmission request is sent from the management device (7) and the request is received by the communication means (39), the MPEG encoding means (31) Information necessary for the decoding process in the management device (7) is added, and the encoded image signal is output to the communication means (39). Then, the communication means (39) converts the image signal into a predetermined format based on the communication protocol, and transmits it to the management device (7).

  In parallel with the above processing, the image recording device (3) records the image signal encoded by the MPEG encoding means (31) on the recording medium (43) via the recording medium driver (41). Will continue. Further, when a transmission request for the image signal recorded on the recording medium (43) is sent from the management device (7) to the image recording device (3), the recorded image is transmitted according to an instruction from the control means (37). All or part of the signal is transmitted to the management device (7).

  For example, the control means (37) is realized by a CPU, a ROM, a RAM, and the like, and a program stored in the ROM and executed by the CPU. The MPEG encoding means (31) is realized by an ASIC (Application Specific Integrated Circuit). The picture size acquisition means (33) and the abnormality determination means (35) are realized by executing a program describing processing related to them on the CPU. Further, a hard disk is used as the recording medium (43), and a network interface card is used as the communication means (39).

  FIG. 5 is a block diagram showing an outline of the management device (7). The management device (7) appropriately transmits an image transmission request to the image recording device (3), decodes the received image signal, and reproduces it on the display means (71). The communication means (73) manages communication performed between the management device (7) and the image recording device (3) via the network (5). The control means (75) performs various controls and processes in the management device (7). For example, when an alarm signal is sent from the image recording device (3), the control means (75) sends an image transmission request to the image recording device (3) through the communication means (73). The image signal received from the image recording device (3) is decoded by the MPEG decoding means (77) and reproduced by the display means (71). Based on the command of the control means (75), the communication means (73) sequentially sends an image transmission request or a transmission stop request to the image recording device (3) connected to the network (5). By transmitting in a cycle, the display means (71) switches the monitoring images in order and periodically. It should be noted that a plurality of control images (75), MPEG decoding means (77), etc. are provided so that the display screen of the display means (71) can be divided, thereby displaying a plurality of monitoring images in the management device (7). be able to. In this case, for example, a plurality of monitoring images are sequentially switched. Alarm means (79) is connected to the control means (75), and when an alarm signal is sent to the management device (7), the control means (75) issues an alarm to the alarm means (79). Issue a command.

  Similarly to the above, for example, the control means (75) is realized by a CPU, a ROM, a RAM and the like and a program stored in the ROM and executed by the CPU. An ASIC is used for the MPEG decoding means (77), and a network interface card is used for the communication means (73). An LCD display device is used as the display means (71). The alarm means (79) is composed of a speaker, a lamp, and the like, and notifies the occurrence of an abnormality in the monitoring area by sound and visual.

  Next, the image signal transmission operation of the image recording device (3) using the abnormality determination means (35) will be described. FIG. 6 is a flowchart showing this operation. The MPEG encoding means (31) encodes the image signal output from the surveillance camera (1) based on the MPEG system and records it on the recording medium (43) (S1). The process of step S1 is always performed, and when the MPEG encoding means (31) completes the encoding of the I picture, P picture or B picture for one frame of the output image signal, the picture size acquisition means ( 33) acquires the picture size of the picture that has been encoded, and sends it to the abnormality determination means (35) (S3). Then, the abnormality determination means (35) uses the picture size information sent this time and in the past to calculate the total data size for 1 GOP pictures that have been encoded so far (S5).

  When the image signal output from the MPEG encoding means (31) has a picture arrangement as shown in FIG. 4, for example, when the encoding of the B picture numbered 14 is completed, The total data size (the sum of these data sizes) is calculated in step S5 for a total of 15 pictures indicated by G1 from the I picture with the number 3 to the B picture with the number 14. . Step S5 is repeatedly executed, but after the picture group G1, all data sizes are obtained for the picture groups G2, G3, and further G4.

  After step S5, the abnormality determining means (35) determines whether or not the calculated total data size is equal to or larger than a predetermined threshold (S7). This threshold value is determined in consideration of the characteristics of the MPEG encoding means (31). If the total data size is less than the predetermined threshold value in step S7, step S3 is performed again. When the total data size is equal to or larger than the predetermined threshold, that is, when it is determined that an abnormality has occurred, the control means (37) transmits an alarm signal to the management device (7) through the communication means (39) (S9). ). After step S9, the image recording device (3) checks whether or not the image signal is currently being transmitted (S11). When the image signal is not transmitted, it is determined whether or not the image transmission request is received by the communication means (39) (S13), and when the transmission request transmitted from the management device (7) is received, An image signal is output from the MPEG encoding means (31) to the communication means (39) and transmitted to the management device (7) (S15). In step 13, when the image recording device (3) is transmitting an image signal, the transmission of the image signal is continued without performing step S13. Further, after step S15, the processing after step S3 is performed again.

  Next, the operation of the management device (7) based on the alarm signal transmitted from the image recording device (3) will be described. FIG. 7 is a flowchart showing this operation. The control means (75) of the management device (7) determines whether or not the alarm signal is received by the communication means (73) (S31), and when the alarm signal is received, issues an alarm to the alarm means (79). (S33). Thereafter, it is determined whether or not the management device (7) is receiving an image signal from the image recording device (3) that has transmitted the alarm signal (S35).

  If it is determined in step S35 that no image signal has been received from the image recording device (3) that has transmitted the alarm signal, the image recording device (3) that is currently transmitting the image signal is informed of the image. A transmission stop request is transmitted (S37), and an image transmission request is transmitted to the image recording apparatus (3) that transmitted the alarm signal (S39). After step S39, the image signal sent from the image recording device (3) is reproduced on the display means (71) (S41). Thereafter, step S31 is performed again. In step S35, when the image signal is currently received from the image recording apparatus (3) that transmitted the alarm signal, the reproduction of the image signal is continued.

  In the above embodiment, the image signal is transmitted from the image recording device (3) based on the transmission request of the management device (7), but all the devices connected to the network (5) in the management device (7). An image signal transmitted from the image recording device (3) may be received, and an image signal to be reproduced may be selected in response to reception of the alarm signal. Further, in the above embodiment, in order to quickly perform processing from occurrence of abnormality to transmission of an alarm signal, every time one picture of an image signal is encoded, pictures for the past 1 GOP including that picture are included. Although the total data size is calculated, every time encoding is completed for one GOP, the total data size may be calculated for the GOP and abnormality determination may be performed.

  The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. Each part configuration of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

It is explanatory drawing which shows the outline | summary of the monitoring system which is an Example of this invention. It is explanatory drawing which shows the frame structure of the image signal in MPEG system in time series. 1 is a block diagram illustrating a configuration of an image recording apparatus that is an embodiment of the present invention. 4 shows the arrangement order of pictures in an image signal encoded by an image recording apparatus according to an embodiment of the present invention. It is a block diagram which shows the outline | summary of the management apparatus contained in the monitoring system of this invention. 3 is a flowchart showing an image signal transmission operation of the image recording apparatus of the present invention. It is a flowchart which shows operation | movement of the management apparatus based on an alarm signal.

Explanation of symbols

(1) Surveillance camera
(3) Image recording device
(5) Network
(7) Management device
(31) MPEG encoding means
(33) Picture size acquisition means
(35) Abnormality judgment means
(37) Control means
(71) Display means
(75) Control means
(77) MPEG decoding means
(79) Alarm means

Claims (4)

An image signal output from the imaging device, and records and predictive compressive coding utilizing the frame correlation, in the image recording apparatus to be transmitted to the network the coded image signal in response to a request from the network,
Every time one frame is encoded, the total data size of a predetermined number of frames encoded in the past including the frame is obtained, and it is determined whether or not the total data size is equal to or greater than a predetermined threshold. ,
When the total data size is equal to or larger than the threshold, an alarm signal is transmitted to the network.   The image recording apparatus according to claim 1, wherein the predictive compression encoding is performed based on an MPEG system, and the predetermined number is equal to the number of frames included in one GOP. A plurality of image recording devices and a management device that is connected to the plurality of image recording devices are provided. Each image recording device encodes and records an image signal output from an imaging device connected thereto. In addition, an image signal encoded in response to a request from the management apparatus is transmitted to the management apparatus, and the management apparatus transmits an image transmitted from at least one of the plurality of image recording apparatuses. In a monitoring system that reproduces signals,
Each image recording device performs predictive compression coding using frame correlation on the image signal,
Every time one frame is encoded, the total data size of a predetermined number of frames encoded in the past including the frame is obtained, and it is determined whether or not the total data size is equal to or greater than a predetermined threshold. ,
If the total data size is greater than or equal to the threshold, send an alarm signal to the management device,
The management apparatus, after receiving an alarm signal of an image recording apparatus, reproduces an image signal sent from the image recording apparatus.   The monitoring system according to claim 3, wherein the predictive compression encoding is performed based on an MPEG system, and the predetermined number is equal to the number of frames included in one GOP.

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