Patent Publication Number: US-8115812-B2

Title: Monitoring system, camera, and video encoding method

Description:
TECHNICAL FIELD 
     The present invention relates to a monitoring system including plural cameras, and relates in particular to a monitoring system and a camera, which automatically adjust the code amount for data transmitted from the cameras via a network, based on the monitoring conditions of each of the cameras (the presence or absence and movement of an object or an abnormal point). 
     BACKGROUND ART 
     Recently, functions and services to distribute videos from plural monitoring cameras have been provided via networks such as the Internet and LANs. 
     Conventionally, for an apparatus which adjusts the code amount (coding rate) of videos distributed from plural cameras, there is an apparatus which determines, in a centralized manner, the assignment of code amounts to all the cameras (See Patent Reference 1). 
     Patent Reference 1 discloses a technique for promoting efficient use of a network by: automatically assigning the band (code amount) for each camera, based on an instruction from a console processing apparatus which collectively sets the transmission bands for plural cameras, so that the summation of the data, which is distributed from the plural cameras distributing videos at a constant bit rate, does not exceed a predetermined transmission capacity; and reassigning the bands, in the case where the traffic in the network increases, so that the transmission band of each camera automatically becomes narrower. 
     In addition, there is another conventional technique which allows the code amounts of videos distributed from cameras to be autonomously judged and adjusted by the respective cameras themselves. In these conventional techniques, a predetermined object or abnormality is detected with sensors, image processing, and so on, and the code amount value of the video to be distributed is changed based on the detected details (See Patent References 2 and 3). 
     Patent Reference 2 discloses the following technique: when a network camera which distributes a video on a network such as a LAN and the Internet detects the presence of an object with a sensor, the network camera switches the video capturing mode, from the first capturing mode in which ordinary capturing is performed, to the second capturing mode in which capturing is performed with higher resolution and at a lower frame rate than in the first capturing mode, thereby avoiding the distribution of an unnecessarily large amount of video pictures to the network in the case where no object is present. 
     In addition, Patent Reference 3 discloses the following technique: when a monitoring camera which remotely monitors a traffic state detects the traffic as abnormal, the monitoring camera decreases the compression rate for the monitoring video and automatically distributes, as a high-quality monitoring video, the picture of the spot on which the abnormality is occurring.
     Patent Reference 1: Japanese Unexamined Patent Application Publication No. 2004-32680   Patent Reference 2: Japanese Unexamined Patent Application Publication No. 2004-236235   Patent Reference 3: Japanese Unexamined Patent Application Publication No. 9-305891   

     DISCLOSURE OF INVENTION 
     Problems that Invention is to Solve 
     However, for the technique disclosed in Patent Reference 1, in which the code amounts (bands and transmission rates) of the plural cameras are adjusted, with respect to all of the cameras, in a centralized manner, there is a problem in terms of expandability that the number of cameras capable of the real-time adjustment of code amounts (bands and transmission rates) is limited, since the processing time required for the reassignment of code amounts (bands and transmission rates) to respective cameras increases as the number of such cameras becomes larger. 
     In addition, in the centralized adjustment of code amounts as described in Patent Reference 1, there is another problem in terms of fault-tolerance that in the case of malfunction of a monitoring apparatus which collectively adjusts code amounts (bands and transmission rates), the adjustment of code amounts becomes impossible for all the cameras. 
     In addition, in the techniques disclosed in Patent References 2 and 3, the code amount (the number of pixels, frame rate, compression rate) is changed based on the detection of an object or the detection result of an abnormal traffic state. However, it is difficult to rapidly change the code amount for transmitted data since, generally, the changing of amount of data transmitted via a network such as a LAN and the Internet is performed in consideration of the level of traffic congestion caused by the variation of the transmitted data. 
     Therefore, in the techniques described in Patent References 2 and 3, there is a problem that, in the case where the code amounts (the number of pixels, frame rates, compression rates, an so on) of videos distributed to the network are changed after detecting an object or abnormality, it takes time for the code amount (the number of pixels, frame rate, compression rate, and quantization step) of the distributed video to attain an appropriate value, and this results in a lowering of the ability to trace the behavior of an object or abnormality. 
     In addition, in the techniques described in Patent References 2 and 3, there is also a problem that, in the case where respective cameras change their code amounts autonomously based on the result of abnormality detection, the traffic, flowing through the network, increases at a time when respective cameras detect an object or abnormality simultaneously, and this results in a lowering of utilization efficiency of the transmission line. 
     Hereinafter, the problems in the techniques as described in Patent References 2 and 3 shall be described with reference to the drawings.  FIG. 1  is a diagram describing the problem of a camera according to the conventional techniques, as disclosed in the above Patent References 2 and 3, which adjusts the value of its code amount autonomously. In  FIG. 1 , a camera  101 A and a camera  101 B have a function to detect the object  104  by image processing when an object  104  appears in a video capturing region, and increase their code amount values autonomously by increasing the quantization step size (QSTEP) and frame rate for the video to be distributed. 
     In  FIG. 1 , at time T 0 , only the camera  101 A is capturing video of the object  104 , and the assignment of code amounts is adjusted so that the code amount for the camera  101 A becomes larger and that the code amount for the camera B becomes smaller. However, at time T 1 , when the cameras  101 A and  101 B switch to the state of capturing the object at the same time, both cameras distribute videos of an identical object  104  redundantly with large code amounts. Therefore, in the case where respective cameras operate autonomously, there is a case where utilization efficiency of the transmission band of a communication network  102  becomes deteriorated. 
     In this manner, there is a problem that, in the case where plural cameras change their code amounts autonomously, a situation arises which results in the lowering of utilization efficiency of the communication network  102 . 
     In addition, generally, in video distribution using a communication network such as the Internet and a LAN, a method is taken by which the condition of the transmission line is measured, and the values of transmission amounts are adjusted little by little while checking that no data delay or collision is occurring. Therefore, video distribution in which the transmission rate is rapidly changed cannot be performed. In other words, since the transmission amounts are adjusted little by little on the network side, the available band in the network is unable to follow in time with the change in the code amounts of the cameras, and it takes time until the code amounts are changed to appropriate values by detecting the object, and this results in the lowering of the ability to trace the movement of the object. 
     In addition, in the case where the transmission amounts from the cameras are rapidly increased without measuring the traffic condition of the transmission line, the network cannot trace the fluctuation of load, and congestion occurs, causing picture quality deterioration on the receiving side. 
     The present invention is conceived in view of these points and has as an object to provide a monitoring system, a camera, and so on, which have, in the automatic adjustment of code amounts for respective cameras in a monitoring system which distributes video from plural cameras via a common network, expandability and fault tolerance that are independent of the number and structure of the cameras making up the monitoring system, and further, which enable the capturing with a high level of ability to trace the movement of the object, and which can perform automatic assignment of code amounts that improves the utilization efficiency of the entire transmission line. In other words, the object of the present invention is to provide a monitoring system, a camera, and so on, which can efficiently determine, according to the movement of the object and so on, the code amount for each camera which is a monitoring camera. 
     In addition, another object of the present invention is to provide a monitoring system, a camera, and so on which can continue capturing video with a large code amount, in an area to be monitored for which the level of monitoring importance differs from place to place, even when the object suddenly changes its moving direction toward a region of higher importance. 
     Furthermore, another object of the present invention is m to provide a monitoring system, a camera, and so on which can reduce the trouble for a user of finding out which camera is monitoring an object or an abnormal point from among a number of cameras, and improve the utilization efficiency of the recording medium such as a hard disk in the case where video pictures are recorded. 
     Means to Solve the Problems 
     In order to solve the above problems, the monitoring system according to the present invention includes plural cameras connected through a transmission path, and each of the cameras includes: an object detecting unit which detects an object that is a moving object to be monitored; a video capturing unit which captures the object detected by the object detecting unit so as to obtain video; a video encoding unit which encodes the video obtained by the capturing unit; a collaboration parameter storage unit for storing a collaboration parameter indicating a relative amount of a target code amount assigned to a camera and a target code amount assigned to a neighboring camera, the target code amount being a target value for video encoding, and the neighboring camera being a predetermined camera, among the plural cameras, that is located near the camera; a communication interface unit which exchanges, by communicating with the neighboring camera, the collaboration parameter stored in the collaboration parameter storage unit of the camera and the target code amount assigned to the camera; a neighboring camera information storage unit for storing position identification information for identifying a position of the neighboring camera, as well as the collaboration parameter and the target code amount for the neighboring camera that are obtained by the communication interface unit; a collaboration parameter updating unit which updates the collaboration parameter stored in the collaboration parameter storage unit, based on a position of the object detected by the object detecting unit as well as the position identification information and the collaboration parameter of the neighboring camera that are stored in the neighboring camera information storage unit, so that (i) a distribution pattern, which indicates a distribution of a value of the collaboration parameter in a space in which the plural cameras are present, forms concentric circles having the object detected by the object detecting unit as an origin, and that (ii) the target code amount for a camera capturing the object becomes larger than the target code amount for a camera not capturing the object; and a target code amount determining unit which determines the target code amount to be assigned to the camera, based on the collaboration parameter updated by the collaboration parameter updating unit as well as the collaboration parameter and the target code amount for the neighboring camera that are stored in the neighboring camera information storage unit, and wherein the video encoding unit which encodes the video so that an amount of code generated in the encoding attains the target code amount determined by the target code amount determining unit. 
     Note that the object in the Claims is a concept which includes the “object” and the “abnormal point” in the embodiments. 
     Here, the present invention can be implemented not only as a monitoring system, but also as a camera making up the monitoring system, a video encoding method in the camera, a program which causes a computer to execute the video encoding method, and a computer-readable recording medium, such as a CD-ROM, on which the program is recorded. 
     EFFECTS OF THE INVENTION 
     According to the monitoring system and the camera in the monitoring system in the present invention, it is possible to make gradual adjustments taking the movement speed of the object into consideration and based on the positions of plural cameras and the movement of the object, so that the code amount for a camera placed in the moving direction of the object becomes larger in advance. Accordingly, this produces an effect of being able to trace the movement of the object and continuously distribute, with low-loss and low-delay, high-quality videos with a code amount increased as compared to those of surrounding regions, without causing any congestion on the network side due to rapid increases in transmission amounts from the cameras. 
     In addition, even among cameras that are capturing regions closer to the object, it is possible to adjust code amounts automatically in advance, in order to make the code amount smaller for a camera having a low possibility of capturing the object as estimated from the movement of the object. Accordingly, this produces an effect of improving the utilization efficiency of the entire transmission line. 
     Furthermore, an effect is produced which enables a continuous distribution of a high-quality video with a code amount larger than the code amounts of the videos of surrounding spaces, even when, in the case where information on an area of particularly high monitoring importance within the area to be monitored is assigned to each camera, the object suddenly starts to approach a region of higher importance. 
     In addition, since a large code amount is automatically assigned to a camera which is capturing the object and its surroundings from among a number of cameras, it becomes possible to find out the camera which is capturing the object and its surroundings to be displayed on the monitor, by simply identifying the camera with a large code amount, and thus reduce the trouble of finding out the camera. 
     In addition, videos are automatically encoded so that a video in which the object is present is coded as a high-quality video having a large code amount and that the other videos are coded as low-quality videos having small code amounts. Therefore, in the case where the captured videos are recorded onto a recording medium such as a hard disk, video data of lower-level importance in which no object is present is automatically compressed into a smaller size and stored, and thus this produces an effect of efficient utilization of the recording medium. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram describing an example of assignment of code amounts in the conventional technique. 
         FIG. 2  is a diagram describing a concept of the structure of the monitoring system in the present invention. 
         FIG. 3  is a diagram showing an example of efficient assignment of code amounts. 
         FIG. 4(   a ) and ( b ) are a diagram describing the pattern forming by a reaction-diffusion phenomenon. 
         FIG. 5  is a block diagram showing the structure of the camera in the first embodiment. 
         FIG. 6  is a flowchart showing the operation of the camera in the first embodiment. 
         FIG. 7  is a diagram showing the content of the data transmitted or received between the cameras. 
         FIG. 8(   a ), ( b ), and ( c ) are a diagram describing the operation of the cameras (an example of the distribution of a collaboration parameter). 
         FIG. 9(   a ) and ( b ) are a diagram describing the operation of the cameras (examples of the distribution of the collaboration parameter and the target code amount). 
         FIG. 10  is a diagram describing the operation of the cameras (an example of the distribution of the collaboration parameter) in the first embodiment. 
         FIG. 11(   a ) and ( b ) are a diagram describing the operation of the cameras in the first embodiment. 
         FIG. 12(   a ) and ( b ) are a diagram showing the content of the data transmitted and received between the cameras. 
         FIG. 13  is a diagram of the communication sequence in the first embodiment. 
         FIG. 14  is a diagram showing the operation of each camera in the first embodiment. 
         FIG. 15  is a diagram showing the operation of each camera in the first embodiment. 
         FIG. 16(   a ) and (b) are a diagram showing the content of the data transmitted from a surveillance monitor to each camera. 
         FIG. 17(   a ), ( b ), ( c ), and ( d ) are a diagram describing an example of a monitoring video displayed on the surveillance monitor. 
         FIG. 18  is a diagram describing Embodiment 1-1 (an example of the monitoring of a parking lot with plural in-vehicle cameras) in the first embodiment. 
         FIG. 19  is a diagram describing Embodiment 1-2 (live video distribution service) in the first embodiment. 
         FIG. 20  is a block diagram showing the structure of cameras in the second embodiment. 
         FIG. 21  is a diagram showing an example of the details of the priority monitoring area information. 
         FIG. 22  is a flowchart showing the operation of the camera in the second embodiment. 
         FIG. 23  is a diagram describing Embodiment 2-1 (an example of adjusting the details of collaboration with neighboring cameras) in the second embodiment. 
         FIG. 24(   a ) and ( b ) are a diagram describing Embodiment 2-2 (an example of adjusting the details of collaboration with neighboring cameras) in the second embodiment. 
     
    
    
     NUMERICAL REFERENCES 
     
         
         
           
               101  Camera 
               101 N,  101 A,  1016 ,  101 L,  101 R Neighboring camera 
               102  Communication network 
               103  Surveillance monitor 
               104  Object 
               105  Operator 
               106 ,  401  Sensor 
               402  Capturing unit 
               403  Communication interface 
               404  Collaboration parameter storage unit 
               405  Neighboring camera information storage unit 
               406  Collaboration partner selecting unit 
               407  Collaborating operation executing unit 
               408  Autonomous operation executing unit 
               409  Transmission band estimating unit 
               410  Target code amount determining unit 
               411  Video encoding unit 
               412  Image processing unit 
               413  Collaboration parameter updating unit 
               414  Priority monitoring area storage unit 
               701  Details of transmitted and received data 
               1401  Live video monitor 
               1402  Synthesized video monitor 
               1403  Monitoring pattern selecting panel 
               1404  Setting panel 
               1405  Synthesis range setting panel 
               1501  In-vehicle camera 
               1502  Transmitting and receiving antenna 
               1503  Monitoring camera 
               1601  Mobile camera 
               1602  Receiving base station 
               1603  Content provider 
               1604  Video receiving terminal 
               1801  Priority monitoring area 
               2001  Priority monitoring area 
               2002  Safe 
               2003  Entrance door 
               2201 ,  2202  Information transmitted from the surveillance monitor to each camera 
             T 0 , T 1  Time 
           
         
       
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, embodiments of the present invention shall be described with reference to the drawings. 
     First Embodiment 
     First, an outline of the monitoring system in a first embodiment of the present invention shall be described. 
       FIG. 2  is a diagram describing a mode of use for the monitoring system in the first embodiment of the present invention. 
       FIG. 2  illustrates a structure of the monitoring system in which videos captured by plural cameras  101  are distributed to a surveillance monitor  103  via a communication network  102  in town monitoring, indoor monitoring, an intelligent transport system (ITS), and so on. This monitoring system is a system for monitoring an object while making automatic adjustments to the code amounts for the plural cameras  101  having an identical function. The monitoring system includes: the plural cameras  101 , plural sensors  106 , a surveillance monitor  103 , and a communication network  102  connecting them. 
     Note that a camera  101  may not only be a fixed camera but also be a moving camera, such as a camera equipped on a cell-phone or an in-vehicle camera. A sensor  106  is an infrared sensor or the like which detects an object  104  and an abnormal point. The communication network  102  is an example of transmission lines and may be wired (such as an Ethernet™ and a cell-phone) or may be wireless (such as a wireless LAN and a cellular phone). In addition, the surveillance monitor  103  is a terminal apparatus including a display which receives and decodes encoded videos transmitted from the plural cameras  101 , spatially synthesizes the decoded videos according to the positions of the plural cameras  101 , and displays the obtained synthesized video. There are no restrictions on the number, the connection method, and the performance of terminal apparatuses, and specifically any terminal equipped with a function to display videos may be used, such as a PC, a TV, a cell-phone, and a car navigation system. The camera  101  has a function to detect the object  104  or an abnormal point by image processing of the captured video or by an exterior sensor  106 . Moreover, upon detecting the object or the abnormal point, the camera  101  has a function to adjust the video to be distributed with a given code amount (coding rate) and distribute the adjusted videos by changing its own frame rate, quantization step size, or the like of the camera  101 . 
     Note that an “object” that is assumable in town monitoring, indoor monitoring such as building security, an ITS, and so on, can be a moving object such as a passenger and a car, and that an “abnormal point” can be a point of abnormality generated in a monitoring target, such as a site in which a prowler appears, an object who is sick, a site where a fire has broken out, a point at which a window is broken, and a site where a traffic accident occurs. 
     The first embodiment of the present invention is to provide a monitoring system in which the assignment of code amounts to the plural cameras  101  is automatically adjusted and a camera used in the monitoring system while considering the utilization efficiency of the transmission band of the communication network  102  so that the video of a place where an object or abnormal point has occurred is distributed with a large code amount and that the videos of other places are distributed with small code amounts. 
     With respect to the above-described problems in the conventional techniques, that is, the problems of deterioration in the utilization efficiency of the transmission line and the ability to trace the movement of the object, the monitoring system in the first embodiment solves such problems by assigning code amounts to respective cameras in consideration of the positions of the plural cameras.  FIG. 3  shows an exemplary method for assigning code amounts, which is to realize the solution of the problems. 
       FIG. 3  is a diagram showing, in three types of patterns according to respective sizes (large, medium, and small), the values of code amounts assigned to the plural cameras  101  surrounding the object based on the positions of the plural cameras laid out in a plane-like state (the layout of a video capturing region) and the position of the object  104 . 
     As shown in  FIG. 3 , in the monitoring system of the first embodiment, a code amount of the largest value is assigned to a region in which the object  104  is present, and further, larger code amounts are assigned, in advance, to the moving direction of the object  104  as well as to neighboring spaces. With this, even when the object  104  appears in the capturing space of a neighboring camera, a video can be distributed immediately with a large code amount. 
     In addition, with respect to a region located in a direction opposite to the moving direction of the object  104 , since the probability of appearance of the object  104  is low even when the distance from the object  104  is short, the utilization efficiency of the transmission band can be improved by assigning a lower code amount to the region. 
     The monitoring system in the present embodiment solves the problem of assigning code amounts to videos distributed by plural cameras, by automatically forming, as shown in  FIG. 3 , a distribution pattern (spatial pattern) of the code amounts with respect to the plural cameras  101  laid out in a real space. Hereinafter, the method for automatically adjusting the assignment of code amounts to plural cameras shall be described. 
     In addition, in order to achieve high expandability and high fault-tolerance, the monitoring system in the present embodiment automatically adjusts the assignment of code amounts as shown in  FIG. 3 , by causing respective cameras to adjust their own code amounts collaborating with each other without using an apparatus which intensively controls the plural cameras. As shown in  FIG. 3 , the monitoring system in the present embodiment allows: (i) assignment of a larger code amount, with respect to a capturing region in which the object  104  is captured, as compared to a capturing space in which the object  104  is not captured; (ii) assignment of a larger code amount, with respect to a capturing space closer to the object  104 , as compared to a distant capturing space; and (iii) assignment of a larger code amount, with respect to a capturing space located in the moving direction of the object  104 , as compared to a capturing space located in a direction opposite to the moving direction. 
     First, as a mechanism used in the monitoring system in the present embodiment, the following is a description of a mechanism which, in a general distributed system not including any intensive control apparatus, spontaneously forms spatial rules (a spatial pattern) with respect to the entire system by causing respective subsystems making up the system to locally interact with each other. Here, as a specific example of the system which forms spatial rules (a spatial pattern), the mechanism of the skin cells (subsystems) of tropical fish or the like to form a striped pattern (spatial pattern) as a whole by exchanging chemical substances with neighboring cells and thereby determining the colors of their own. 
     Turing mathematically shows: as is the case with the striped pattern of tropical fish, a phenomenon in which a spatial pattern is formed as a result of plural cells locally interacting with each other is achieved due to a chemical interaction and a diffusion phenomenon of chemical substances (See Non-patent Reference 1). Non-patent Reference 1: A. M. TURING, The chemical basis of morphogenesis, Phil. Trans. R. Soc. Lond. B327, pp. 37-72 (1952). 
     The mathematical model shown by Turing is expressed in two reaction-diffusion equations (simultaneous differential equations) shown in the following Expression 1. Equation 1 is an expression which represents the amount of increase or decrease of the concentration u of an activator involved in the positive feedback of a chemical reaction taking place within respective cells and of concentration v of an inhibitor involved in the negative feedback of a chemical reaction taking place within respective cells. In the right-hand side of Expression 1, the first term is referred to as a reaction term, which is a term determining the amount of generation and decomposition of the activator and the inhibitor in accordance with the ratio of concentrations of the activator and the inhibitor (u, v) within each cell. In addition, the second term is referred to as a diffusion term, which is a term determining the amounts of the activator and the inhibitor moving between adjacent cells due to diffusion phenomena. 
     
       
         
           
             
               
                 
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     Note that Du(s) and Dv(s) are diffusion coefficients that determine the diffusion speed of a chemical substance between cells. In addition, f(u, v) and g(u, v) are functions of variables u and v. 
       FIG. 4  is a diagram showing the outline of the pattern of distribution of a chemical substance, which occurs within the cell based on Equation 1. 
     Normally, as shown in  FIG. 4(   a ) (Time T 0 →T 1 ), the chemical substance that is present within the cell moves from a cell having a high concentration of the chemical substance toward a cell having a low concentration of the chemical substance, and the level of concentration becomes the same in all the cells. 
     However, the activator which activates the chemical reaction and the inhibitor which inhibits the chemical reaction are different in diffusion speed, and in the case where the inhibitor diffuses to neighboring cells faster than the activator, an activator, which is trying to activate the chemical reaction, diffuses earlier into a wider range and inhibits the diffusion of the activator which diffuses later. Accordingly, as shown in  FIG. 4(   b ) (Time T 0 →T 1 ), a state is formed in which the concentrations of the activator and the inhibitor (u, v) within each cell are uneven. 
     It is known that by adjusting the balance between such chemical reaction and diffusion taking place between the activator and the inhibitor, the uneven diffusion pattern of concentrations of the activator and the inhibitor can be adjusted in various forms, such as a striped pattern as seen in tropical fish and spots as seen in leopards or the like. 
     In the above example, the concentrations of the activator and the inhibitor (u, v) are described as an example. However, in the monitoring system including plural cameras, the cameras correspond to the activator and the inhibitor, respectively, and reciprocally exchange the parameter for adjusting the assignment of their own code amount based on the behavior shown by the reaction-diffusion equation of Expression 1. With this, a diffusion pattern of the parameter which determines the code amount according to the position of each camera can be formed. 
     Furthermore, other than the parameter exchange between neighboring cameras, the pattern of assigning code amounts for the entire monitoring system can also be changed by increasing and decreasing the amount of parameters for part of the cameras based on the information from the external sensor  106  or the like which has detected the object. 
     In the first embodiment, a formation model of the distribution pattern of parameters, which is based on the above-described reaction-diffusion equations of Equation 1, is applied for adjustments in assignment of the code amount to each camera  101 . 
     In the present embodiment, collaboration, a parameter (u, v) is used as the parameter exchanged between cameras  101  for making adjustments of code amounts for the plural cameras  101 . Note that the collaboration parameter (u, v) is a parameter corresponding to each of the concentrations of the activator and the inhibitor within each cell. 
     Next, the camera  101  making up the monitoring system in the first embodiment shall be described in details. 
       FIG. 5  is a block diagram showing the structure of the monitoring system in the first embodiment. Here, the structure of one camera  101  is shown in details. Although in the figure, for sake of convenience in explanation, different numerals are given to the current camera  101  and plural neighboring cameras  101 N, both of these cameras, that is, the camera  101  and the cameras  101 N have the same structure. Note that regarding the same structure as in  FIG. 2 , the same numerals are given and the description is omitted. 
     As shown in  FIG. 5 , each camera  101  in the first embodiment has a sensor  401  which detects the behavior of the object  104  and the occurrence of an abnormal point, and a video capturing unit  402  which captures the object and the abnormal point. The sensor  401  and the video capturing unit  402  correspond to an object detection unit which detects the object  104  or an abnormal point that is present within the area to be monitored. 
     The detection of the position, the moving direction, and the moving speed of the object  104  using the sensor  401  is possible by the following methods: a technique in which magnetic sensors are paved in the area to be monitored, and thereby the identity, the position, and the direction of the object  104  are detected from the footprints of a permanent magnet attached to the object  104  (See Non-patent Reference 2); a technique to estimate the movement of the object according to the amount of change in acceleration that is obtained from an acceleration sensor equipped on a mobile terminal (See Non-patent Reference 3); and positioning systems using infrared radiation, radio field intensity, or ultrasonic waves, and so on, such as a GPS in which positions are measured using electric waves from a satellite (See Non-patent Reference 4). 
     Non-patent Reference 2: “ Jikiteki shuho wo mochiita ichihoko kenshutsu kinotogogata menjo tsushin shisutemu no sekkei to jisso  (MAGIC-Surfaces: Magnetically Interfaced Surfaces for Ubiquitous Computing Applications)” by Youhei Nishizawa, Ryuichi Kurakake, Masateru Minami, Hiroyuki Morikawa, Tomonori Aoyama, Information Processing Society of Japan Research Report, UBI-9(9) November 2005.
 
Non-patent Reference 3: “ Sensa sochakubasho wo koryo shia  3  jiku kasokudo sensa wo mochiita shiseisuitei shuho  (User Posture and Movement Estimation Based on 3-Axis Acceleration Sensor Position on the User&#39;s Body)” by Hisashi Kurasawa, Yoshihiro Kawahara, Hiroyuki Morikawa, Tomonori Aoyama, Information Processing Society of Japan Research Report, UBI-11-3 May 2006.
 
Non-patent Reference 4: “ Jiritsubunsangata okunai sokui sisutemu no jisso to hyoka  (Implementation and Evaluation of a Distributed Ultrasonic Positioning System)” by Kazuki Hirasawa, Masateru Minami, Shigeaki Yokoyama, Moriyuki Mizumachi, Hiroyuki Morikawa, Tomonori Aoyama, Information Processing Society of Japan Research Report, MoMuC2004-3, May 2004.
 
     In addition, as a method for detecting an abnormal point by the sensor  401 , the following techniques are possible: on an expressway, for example, it is possible to detect a point at which a traffic jam or accident has occurred; when the target is human, a change in physical conditions can be detected by a biologic sensor (pulse, breathing, and so on); and, in buildings and cars, an intruder can be detected by installing infrared sensors or pressure sensors on doors and windows. 
     For a method of detecting an abnormal point, the detection of a place in which a traffic jam or accident has occurred shall be given as a specific example. First, the traffic volume of vehicles is observed as needed by measuring the number of passing vehicles per hour using a vehicle detection system or the like. Then, with the abnormal traffic volume of vehicles being predefined, the measuring site in the vehicle detection system at which the defined abnormal traffic volume of vehicles has been observed is detected as an abnormal point. 
     Note that, although  FIG. 5  illustrates the case where the sensor  401  is built in the camera  101 , it is also possible, as shown in  FIG. 2 , to have a structure in which information on the object  104  or the abnormal point detected by the exterior sensor installed in the area to be monitored is obtained via the communication network  102  and used. 
     In addition, each camera has a communication interface  403  for transmitting, via the communication network  102  such as an Ethernet, video data to the surveillance monitor  103  and reciprocally exchanging control signals with a neighboring camera  101 N. 
     Furthermore, the camera  101  includes: a collaboration parameter storage unit  404 , a neighboring camera information storage unit  405 , a collaboration partner selecting unit  406 , a collaborating operation executing unit  407 , an autonomous operation executing unit  408 , a transmission band estimating unit  409 , a target code amount determining unit  410 , and a video encoding unit  411 . 
     The collaboration parameter storage unit  404  is a storage unit such as memory, which stores a collaboration parameter indicating the relative level of the target code amount that is a target value for video encoding assigned to the neighboring camera  101 N, which is a camera predetermined as a camera located closer to the camera from among plural cameras, and the target code amount assigned to the camera. That is, the unit  404  is a storage unit which stores the collaboration parameter (u, v) for adjusting the relationship between the code amount for the camera and the code amount for its neighboring camera. 
     The neighboring camera information storage unit  405  is a storage unit, such as memory, in which the camera identification information, the position information, the collaboration parameter (u n , v n ), and the target code amount for a camera selected by the collaboration partner selecting unit  406  are stored out of identification information (for example, camera IDs), position information, collaboration parameter (u n , v n ), and target code amounts Qn on other cameras, which are obtained via the communication network  102 . 
     As a method for identifying the installation position of each camera, it is possible to obtain the position coordinate of each camera by using an apparatus such as a GPS. 
     In addition, as described in the above Non-patent Reference 4, each camera may prepare information on their relative position and use the relative position information by measuring the distant relationship with its neighboring camera using an ultrasonic sensor or the like. 
     The collaboration partner selecting unit  406  is a processing unit which selects, from among plural cameras, a camera  101 N capturing the neighborhood. 
     Note that the neighboring camera  101 N selected by the collaboration partner selecting unit  406  is predetermined based on the position of the camera. 
     In addition, based on the position information on each camera  101 , the collaboration partner may also be determined on the side of the camera  101  according to the environment in which the camera is installed and the position of the camera, by, for example, selecting its neighboring camera  101 N, as a collaboration partner, that is present within a certain distance range from the camera  101 . 
     Thus, even when the installation position of the camera is changed or when a new camera is added, the communication partner can be automatically determined. 
     The collaborating operation executing unit  407  is a processing unit which determines the amount of increase and decrease of the collaboration parameter (u, v) involved in the collaborating operation of the camera  101  and the neighboring camera  101 N. The collaborating operation executing unit  407  adjusts the values of the collaboration parameter (u, v) of the camera  101  so that the values become the same as the values of the collaboration parameter (u n , v n ) of the neighboring camera  101 N. 
     In addition, the autonomous operation executing unit  408  is a processing apparatus which determines the amount of increase and decrease of the collaboration parameter (u, v) based on the autonomous operation of the camera  101 , and adjusts the values of the collaboration parameter (u, v) based on its own collaboration parameter (u, v). 
     The collaboration parameter updating unit  413  includes the autonomous operation executing unit  408  and the collaborating operation executing unit  407  and updates the values of the collaboration parameter of the camera  101 . At this time, the collaboration parameter updating unit  413  updates the collaboration parameter stored in the collaboration parameter storage unit  404 , based on the position of the object detected by the sensor  401  or the like, as well as the position identification information and the collaboration parameter of the neighboring cameras stored in the neighboring camera information storage unit  405 , so that: (i) the distribution pattern, which indicates the distribution of the values of the collaboration parameter in the space in which the plural cameras are present, forms a concentric circle having the object or the abnormal point detected by the sensor  401  as the origin, and that (ii) the target code amount for the camera capturing the object or the abnormal point becomes larger than the target code amount for the cameras not capturing the object or the abnormal point. 
     In addition, the amount of increase and decrease of the collaboration parameter (u, v) adjusted by the collaboration parameter updating unit  413  is determined based on the reaction-diffusion equations shown in Equation 2 below. 
     Note that collaborating operation in the collaborating operation executing unit  407  is determined by the diffusion term shown in the second term on the right-hand side of Equation 2. In addition, autonomous operation in the autonomous operation executing unit  408  is determined by the reaction term shown in the first term on the right-hand side of Equation 2. 
     
       
         
           
             
               
                 
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     In Equation 2, s is sensor information transmitted from the sensor  401  and a value that is determined based on the presence or absence, the moving speed, and the moving direction of the object. 
     Du(s) and Dv(s) are functions for determining the value of the diffusion coefficient and adjusting the amount of increase and decrease of the collaboration parameter (u, v), which is exchanged between neighboring cameras based on the value of the sensor information s. 
     f(u, v, s) and g(u, v, s) are reaction terms and functions for adjusting the amount of increase and decrease of the collaboration parameter (u, v) according to the collaboration parameter (u, v) and the sensor information s. In the first embodiment, the following Equation 3 is used for reaction terms f(u, v, s) and g(u, v, s). 
     
       
         
           
             
               
                 
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     In Equation 3, Su(s) and Sv(s) are functions for determining the amount of increase and decrease of the values of the collaboration parameter (u, v) according to the values in the sensor information s. a to g are coefficients. 
     The transmission band estimating unit is a processing apparatus which measures the amount of traffic for the communication network  102  and estimates a free space r of the transmission band available for transmitting encoded vides to the surveillance monitor  103 . 
     As a method of obtaining the transmission band, the transmission band can be estimated by: the pathchar method (see Non-patent Reference 5) for measuring round-trip propagation delay time (RTT: Round Trip Time) with each router by causing n th  router on the path to send a TTL Expired message of the Internet Control Message Protocol (ICMP) packet by transmitting the packet with its Time To Live (TTL) field set as n, and estimating the band from the RTT data through statistical processing; and the pair packet method (see Non-patent Reference 6) for successively transmitting packets for band estimation to the receiving terminal and calculating the bottleneck-link band from the inter-packet transmission interval, which occurs when the packets for band estimation pass through the bottleneck link, and the packet size. 
     Non-patent Reference 5: A. B. Downey et al., “Using pathchar to estimate Internet link characteristics”, ACM SIGC OMM&#39;99 
     Non-patent Reference 6: R. L. Carter et al., “Measuring Bottleneck Link Speed in Packet-Switched Networks,” Technical Report BU-CS-96-006, Computer Science Department, Boston University, March 1996. 
     Based on the values of the collaboration parameter (u, v) stored in the collaboration parameter storage unit  404 , the values of the collaboration parameter of the neighboring camera (u n , v n ) stored in the neighboring camera information storage unit  405 , and the transmission band r obtained by the transmission band estimating unit  409 , the target code amount determining unit  410  sets the target code amount to be assigned to the camera, and further, calculates the quantization step size (QSTEP) and the frame rate within the coding frame in order to achieve the target code amount Q. 
     Note that in an encoding method such as MPEG, the methods for controlling the code amount with respect to each coding macroblock are standardized, and the quantization step size can be derived by setting the target code amount with respect to each coding frame, so that the target code amount is achieved (For example, see Non-patent Reference 7). 
     Non-patent Reference 7: J. R. Corbera, S. Lei “Rate Control in DCT Video Coding for Low-Delay Communications”, “IEEE Transactions on Circuits and Systems for Video Technology, Vol. 9, No. 1, pp. 172-185, February 1999.” 
     In addition, in order to attain the target code amount Q, it is also possible to change which of the quantization step size (QSTEP) and the frame rate according to the situation should be preferentially adjusted. 
     For example, in the case where priority is given to image quality, the code amount is adjusted preferentially according to the frame rate, and thereby code amounts can be adjusted while maintaining image quality with respect to each frame. In addition, in order to increase the ability to trace the movement of the object, the code amount is adjusted preferentially according to the quantization step size (QSTEP), and thereby the code amount can be adjusted without lowering the frame rate. 
     In addition, as a method for making the code amount for an encoder closer to the target code amount Q, the code amount may be adjusted by, other than quantization step (QSTEP) and frame rate, changing the image size of a distributed video, deleting color information, changing the encoding method, and so on. 
     The video encoding unit  411  is an encoder which encodes videos so that the code amount generated by encoding becomes the target code amount determined in the target code amount determining unit  410 . In the present embodiment, the video encoding unit  411  is an encoder which encodes the video captured in the video capturing unit  402  in the encoding methods such as Motion JPEG and MPEG with quantization step size (QSTEP) and the frame rate determined in the target code amount determining unit  410 , and distributes the video with the target code amount Q. 
     Note that in the first embodiment, since it is assumed that videos are distributed via the communication network  102 , the encoder is assumed to encode the video at a constant bit rate (CBR). Note that when recording captured video onto a medium such as a hard disk drive, the video may be encoded at a variable bit rate (VBR) in order to improve utilization efficiency of the medium. 
     An image processing unit  412  is an image processing apparatus which detects the presence and the movement of the object  104  from the video captured by the video capturing unit  402 . 
     As a method for detecting the presence of the object  104  from the captured video, the detection can be achieved by using a background subtraction method, a frame difference method (see Non-patent Reference 8), and so on with respect to the video captured by the camera  101 . In addition, the movement of the object  104  can also be detected by obtaining optical flow (see Non-patent References 6 and 9) and so on with respect to the captured video. 
     Non-patent Reference 8: “ Head Finder: furehmukan sabun wo behsu ni shia jinbutsu tsuiseki  (A Person Tracking System Based on Frame Difference)” by Naruatsu Baba, Tsuyoshi Ohashi, Tsukasa Noma, Hideaki Matsuo, Toshiaki Ejima, Symposium on sensing via Image Information 2000, pp 329-334, 2000.
 
Non-patent Reference 9: “Performance of optical flow techniques” by 3. L. Barron, D. 3. Fleet, S. S. Beauchemin, and T. A. Burkitt, CVPR, pp. 236-242, 1992.
 
     Next, the operation of the camera  101  shall be described. 
       FIG. 6  is a flowchart describing the adjustment operation for adjusting the target coding rate of the camera  101  in  FIG. 5 . Note that the flowchart shall be described by giving an exemplary case where the cameras  101  making up the monitoring system are arranged like a lattice as shown in  FIG. 3 . 
     (Step S 601 : Communication with a Neighboring Camera) 
     The camera  101  communicates its collaboration parameter (u, v) with the neighboring camera  101 N via the communication network  102 . 
       FIG. 7  is a diagram showing an example of the content of the data that the cameras  101  and the neighboring camera  101 N communicate with each other. As shown in  FIG. 7 , the data communicated between cameras includes: camera ID for identifying each camera; position information (“position identification information”) on the position at which the camera is installed (or at which the capturing is performed); and the value of the target code amount Q for the current camera, which is determined by the collaboration parameter (u, v) and the processing described later. 
     Subsequently, in the collaboration partner selecting unit  406 , the camera that is to be the partner of collaboration is selected based on the camera ID and the position information in the transmitted data, and stored in the neighboring camera information storage unit  405 . 
     (Step S 602 : Detecting an Object) 
     The sensor  401  or the image processing unit  412  detects the presence of the object  104 . 
     Note that in the case where plural objects  104  are present in distant places, the distribution pattern of the collaboration parameter (u, v), having the position of each of the objects  104  as the origin, may be formed in the manner described below, and then the target code amount Q may be assigned to each camera according to the position of each of the objects  104 . 
     In addition, in the case where the objects  104  are present in a cluster with a distance between each of the objects  104  being within a given distance, the distribution pattern of the collaboration parameter (u, v), having barycentric coordinates or the like of the position of the clustered objects  104  as the origin, may be formed in the manner described later. With this, the respective objects  104  that are present in a cluster can be treated as a group. 
     (Step S 603 ) 
     In the case where the presence of the object is detected (Yes in Step S 602 ), the sensor information s is transmitted to the autonomous operation executing unit  408 , and the values of Su(s) and Sv(s) in Equation 3 are changed. 
     Here, it is assumed that the value of the collaboration parameter u of the camera detecting the object is increased by only a given amount according to Su(s) and Sv(s). 
     (Step S 604 : Detecting the Movement of the Object) 
     The sensor  401  and the image processing unit  412  detect the moving direction and moving speed of the object  104 . 
     When the moving direction and the moving speed of the object  104  are detected (Yes in Step S 604 ), the sensor  401  or the image processing unit  412  notifies the information to the collaborating operation executing unit  407 . 
     Next, the operation flow of the case where the movement of the object is not detected (No in Step S 602 ) shall be described first. 
     (Step S 605 : Forming the Distribution Pattern) 
     The collaboration parameter updating unit  413 , which includes the collaborating operation executing unit  407  and the autonomous operation executing unit  408 , determines the collaboration parameter (u, v) according to the position of each camera by adjusting the values of the collaboration parameter (u, v) of the camera  101  based on Equations 2 and 3, and, as a result, forms distribution patterns of the collaboration parameter (u, v) with respect to the plural cameras  101 . 
       FIG. 8  is a diagram showing an example of a spatial distribution pattern of the value of the collaboration parameter u, which is generated according to Equations 2 and 3. 
     In  FIG. 3(   b ), an exemplary case where cells are arranged one-dimensionally is given so as to describe the formation of a distribution pattern in which the concentrations of the activator and the inhibitor (u, v) are uneven. However, in  FIGS. 8(   a ) to  8 ( c ), in the case where an infinite number of cameras are arranged on a two-dimensional plane surface, the region in which the collaboration parameter u held by each of the cameras becomes relatively large and the region in which the collaboration parameter u held by each of the cameras becomes relatively small are shown in two colors, that is, black and white, respectively. 
     For example, as shown in  FIG. 8(   a ), by setting the values of coefficients in Equations 2 and 3 as: a=0.1, b=−0.06, c=0.0, d=0.05, e=0.05, f=0.1, g=−0.1, Du(s)=0.01, and Dv(s)=0.01, a distribution pattern referred to as “bistable” is formed in which the value of the collaboration parameter u of a camera located closer to the presence of the object  104  becomes larger, and the value u becomes smaller for cameras in other places. 
     In addition, as shown in  FIG. 8(   b ), by setting the values of coefficients in Equations 2 and 3 as: a=0.08, b=−0.08, c=0.04, d=0.03, e=0.01, f=0.06, g=−0.15, Du(s)=0.02, and Dv(s)=0.5, a distribution pattern referred to as “spot” is formed in which regions having large values of the collaboration parameter u and regions having small values of collaboration parameter u are alternately formed, with the position of the object  104  being the origin. 
     Furthermore, as shown in  FIG. 8(   c ), by setting the values of coefficients in Equations 2 and 3 as: a=0.08, b=−0.08, c=0.04, d=0.03, e=0.06, f=0.03, g=−0.15, Du(s)=0.01, and Dv(s)=0.25, a distribution pattern referred to as a “pulse train” is formed in which a pattern of regions having large values of the collaboration parameter u and regions having small values of the collaboration parameter u, which are alternately formed in a concentric state with the position of the object  104  being the origin, moves dynamically from the origin. 
     (Step S 606 ) 
     The transmission band estimating unit  409  obtains the free space r of the transmission band that is available in the communication network  102 . 
     (Step S 607 ) 
     The target code amount determining unit  410  calculates the target code mount Q according to Equation 4 below, using the collaboration parameter stored in the collaboration parameter storage unit  404 , the neighboring camera collaboration parameter (u n , v n ) stored in the neighboring camera information storage unit  405 , the target code mount Q n  of the neighboring camera  101 N stored in the target code mount determining unit  410  in the neighboring camera, and the value of the available space of transmission band r that is obtained by the transmission band estimating unit  409 . However, u n  and v n  are assemblies u n =(u1, u2, u3, . . . , uN) and v n =(v1, v2, v3, vN). In addition, Qn is an assembly Q n =(Q1, Q2, Q3, . . . , QN) of the target code amount for the neighboring camera  101 N.
 
(Expression 4)
 
 Q=h ( u,v,u   n   ,v   n   ,Q   n )* I ( r )  (Equation 4)
 
     Note that, in Equation 4, h(u, v, u n , v n , Q n ) is a function for determining the target code amount Q for the camera  101  with respect to the neighboring camera  101 N, based on the collaboration parameter (u, v) of the camera  101 , and the collaboration parameter (u n , v n ) of the neighboring camera  101 N, and the value of the target code amount Q n  for the neighboring camera  101 N. 
     In addition, I(r) is a function for adjusting the absolute amount of the target code amount Q by decreasing the target code amount Q when the communication network is busy, and increasing the target code amount Q when the communication network  102  is available. For an example of I(r), the following Equation 5 is used.
 
(Expression 5)
 
 I ( r )= I   0 +α∫( r   t   −r ( t )) dt   (Equation 5)
 
Note that
 
     in Equation 5, I 0  is the initial value for I(r). In addition, r t  is the target value for the free space in the transmission band, and r(t) is the free space in the transmission band at time t. a is a coefficient. Equation 5 shows a function I(r) for adjusting the value of I so that the difference between the free space r in the transmission band measured at time t and the target value for the free space r t  becomes smaller. In other words, the function I(r) works so that the value of I becomes larger when the actual free space r is larger than the target value for the free space in the transmission band r t , and so that, on the contrary, the value of I becomes smaller when the actual free space is larger than the target value for the free space in the transmission band r t . 
     For example, when the target value for the free space in the transmission band r t  is set to be 20% of the total amount of the transmission band, the value of I(r) is adjusted, according to Equation 5, so that the amount of free space in the transmission band r approaches 20% of the total amount of the transmission band. 
     Next, an example of the function h(u, v, U n , V n , Q n ) is shown in Equation 6 below. 
     
       
         
           
             
               
                 
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     In Equation 6, N is the number of neighboring cameras  101 N with which each camera exchanges its collaboration parameter (u, v) 
     Each camera  101  adjusts the target code amount Q according to Equation 6 so that the value of the target code amount Q for the camera  101  with respect to the target code amount Q n  for each of the neighboring cameras  101 N becomes equal to the average of the value of the collaboration parameter u of the camera  101  and the ratio of the collaboration parameter u n  of the neighboring cameras  101 N. 
       FIG. 9(   a ) and  FIG. 9(   b ) are a diagram describing, in the case where the distribution pattern of the collaboration parameter u of each camera  101  is in a “bistable” state, how the distribution pattern of the target code amount Q for each camera  101  is made to approximate the distribution pattern of the “bistable” type according to Equation 6. 
       FIG. 9(   a ) shows the pattern of distribution of regions having large values of collaboration parameter u in three kinds of patterns according to the largeness of values (large, medium, and small) of the collaboration parameter u when the distribution pattern of the collaboration parameter u of each camera  101  is bistable (See  FIG. 8(   a )). In addition,  FIG. 9(   b ) shows the change of the value of the target code amount Q for each camera  101 , which is located in the same place as in  FIG. 9(   a ), in three kinds of patterns according to the largeness of the target code amount Q (large, medium, and small). 
     When, due to the reciprocal action of the neighboring camera, the distribution pattern of the collaboration parameter (u, v) is a distribution pattern as shown in  FIG. 9(   a ), and when the distribution pattern of the target code amount Q is in the state as shown in  FIG. 9(   b− 1), each camera  101  automatically adjusts the target code amount Q according to Equation 6 so that the ratio between the target code amount Q for the camera and the target code amount Q n  for the neighboring camera attains the ratio (u:u n ) between their respective values of the collaboration parameter. 
     In this manner, since in each camera  101 , the ratio between the target code amount Q and the target code amount Qn is made closer to the ratio of (u:u n ), it is possible, as sown in  FIG. 9(   b− 2), to make the distribution pattern of the target code amount Q closer to the distribution pattern in  FIG. 9(   a ). 
     In addition, in the case where the collaboration parameter u shows, as shown in  FIG. 8(   b ), a “spot”-type distribution pattern having the position of the object as the origin, the distribution of the collaboration parameter u of the neighboring camera comes to have a pattern of circular stripes having the position of the object as the origin as shown in  FIG. 10 . With this, each camera having a large code amount and each camera having a small code amount can be assigned at a given distance. In addition, it is possible to change the interval and the width of the stripes in  FIG. 8(   b ) by adjusting the values of the respective coefficients in Equations 2 and 3. Therefore, by changing the interval and width of the stripes, it is possible to automatically adjust the number and the density of cameras which should be assigned with a large code amount. 
     In addition, when using a distribution pattern in which the distribution changes dynamically, such as the “pulse-train” type shown in  FIG. 8(   c ), the region having a high collaboration parameter u propagates like spreading from the position of the object as the origin into the whole area to be monitored, thereby assigning a large target code amount Q, dynamically and periodically, to all the areas to be monitored. 
     This allows an automatic assignment of code amounts to respective cameras so that all the areas to be monitored are captured with a large target code amount Q within a given time. 
     In addition, as another method for determining the code amount Q, the target code amount Q for the camera may be determined not only by the values of the collaboration parameter (u, v), but also by the geometric features of the distribution pattern. 
     For example, as shown in  FIG. 10 , a pattern of stripes always makes a curve (arc) towards the object, and the curve becomes larger as the distance from the position of the object becomes larger. Therefore, the distance and the direction towards the object can be estimated based on the largeness of the curve (arc) of the stripes. In other words, the target code amount determining unit  410  may specify, in the distribution pattern of the collaboration parameter updated in the collaboration parameter updating unit  413 , the curvature of the arc in the region in which the camera is present, and may determine the target code amount for the camera so that the target code amount becomes larger as the determined curvature is larger. 
     Here, for example, template matching can be given as a specific method for estimating the distance and the direction with respect to the subject based on the largeness of the curve (arc) of the stripes. In template matching, the distribution pattern of the collaboration parameter (u, v), which is formed in advance with the object as the origin, is stored as template information together with the direction k and distance I from the subject for each given direction k and given distance I from the object as the origin. Then, the template information, which is the closest in shape to the distribution pattern that is actually formed surrounding the camera, is selected by template matching. Subsequently, the direction k and the distance I of the object can be specified according to the details described in the selected template information. 
     When the direction k and the distance I towards the object can be specified, the target code amount Q can be determined by using the function, for example, as shown in Equation 7 below.
 
(Expression 7)
 
 Q=J ( {right arrow over (k)},l )* I ( r )  (Equation 7)
 
     In Equation 7, I(r) is a function described in Equation 5. In addition, 3(k, l) is a function in which the direction k and the distance l toward the object are assumed as variables. For example, by using a function as shown in Equation 8 below, the value of the target code amount Q can be made smaller as the distance from the object becomes larger, with the position of the object being as the origin. 
     
       
         
           
             
               
                 
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                               δ 
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                       ) 
                     
                   
                 
               
               
                 
                   ( 
                   
                     Equation 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     8 
                   
                   ) 
                 
               
             
           
         
       
     
     Note that Equation 8 is a function drawing the Gaussian distribution with the position of the object being the origin. 
     Thus, it is possible to assign the target code amount Q based on the direction k and the distance l of the object that are estimated based on the geometric features of the distribution pattern of the collaboration parameter (u, v). 
     In addition, like the “pulse-train” distribution pattern shown in  FIG. 8(   c ), the target code amount Q may be adjusted by identifying the position of the object based on the geometric features of the distribution pattern that is dynamically changing. 
     For example, in the “pulse-train” distribution pattern, it is possible to obtain the moving direction of the stripes from changing difference information on the parameter (u, v), and to estimate from the camera  101 , the direction in which the object is present. 
     In addition, in the case where the entire region to be monitored cannot be captured due to a small number of cameras or in the case where the installation density of cameras differs from place to place according to the level of importance in monitoring, the spatial resolution of the distribution pattern of the collaboration parameter (u, v) of each camera becomes low and unsuitable for assignment of the target code amount Q. 
     Therefore, with respect to the camera having a small number and density of neighboring cameras  101 N, assuming that a virtual camera is installed around the camera, the increase and decrease of the collaboration parameter (u n , v n ) and the target code amount Q n  for the virtual camera are calculated in the same manner as the target code amount Q, and these values are used for the assignment of the target code amount Q. With this, the spatial resolution of the distribution pattern of the collaboration parameter (u, v) can be virtually improved. 
     In addition, the collaboration parameter (u n , v n ) and the target code amount Q n  for the virtual camera and a neighboring camera  101 N may be reciprocally communicated and used. With this, when the camera  101  determines the target code amount Q, the collaboration parameter (u n , v n ) and the target code amount Q n  for the virtual camera, which is calculated by another camera  101 , can be used, thereby offsetting the shortage in number and density of the neighboring cameras more efficiently. 
     In addition, in the case where, as a result of using a wide angle camera, the surface area of the video capturing region per camera becomes larger and the installation density of cameras becomes smaller, the video capturing region of the camera  101  may be divided into plural regions, and virtual cameras may be installed in each of the divided region; thereby assigning different values of the collaboration parameter (u, v) to the respective areas within the capturing region of the camera  101 . With this, even in the case where the video capturing region of the camera  101  is wide and the installation density of the camera  101  is lower, the spatial resolution of the distribution pattern of the collaboration parameter (u, v) can be improved. 
     In addition, as data for determining the condition of the virtual camera, the data having the same details as the data described in  FIG. 7  is used. Such data of the virtual camera is stored in the neighboring camera information storage unit  405 . 
     Note that although the description in the first embodiment has centered on the method of determining the target code amount Q by using only the distribution pattern of the collaboration parameter u, it is also possible to design the values of reaction terms f(u, v, s) and g(u, v, s) and values of the diffusion coefficients Du(s) and Dv(s) and determine the target code amount Q using v and the combination (u, v) so that the distribution pattern of the collaboration parameter v or the distribution pattern of a combination of both values of the collaboration parameter (u, v) has a shape of “bistable,” “spot,” or the like. 
     (Step S 608 : Determining Quantization Parameter) 
     The target code amount determining unit  410 , when the target code amount Q is determined as described earlier, determines the quantization step size (QSTEP) and the frame rate value of the encoder so that the code amount for the video approximates the target code amount Q. 
     The video encoding unit  411  encodes the video transmitted from the video capturing unit  402  according to the parameter determined in the target code amount determining unit  410  and transmits the encoded video to the surveillance monitor  103  via the communication interface  403  and the communication network  102 . 
     Next, the case where the movement of the object is detected (Yes in Step S 604 ) shall be described. 
     (Step S 609 ) 
     When the moving direction and moving speed of the object is detected by the sensor  401  and so on (Yes in Step S 604 ), information regarding the detected behavior of the object is transmitted to the collaborating operation executing unit  407 , and the values of the diffusion coefficients Du(s) and Dv(s) are changed. 
       FIG. 11  is a diagram illustrating changes in diffusion coefficients Du(s) and DV(S) with respect to the behavior of the object, as well as the changing situation of the distribution pattern of the collaboration parameter (u, v) that is formed as a result of the changes in diffusion coefficients Du(s) and Dv(s). 
     As  FIG. 11(   a ) shows, the size of the distribution pattern of the collaboration parameter (u, v) can be adjusted by adjusting the size of the diffusion coefficients Du(s) and DV(s). For example, the sensor  106  detects the moving speed of the object, and the collaboration parameter updating unit  413  updates the collaboration parameter so that the intervals at which the regions having a large collaboration parameter and the regions having a small collaboration parameter alternate become larger as the moving speed of the object becomes larger. 
     Therefore, since the size of the distribution pattern of the collaboration parameter (u, v) can be adjusted according to the moving speed of the object by decreasing the values of coefficients Du(s) and Dv(s) when the object is moving slowly and increasing the values of coefficients Du(s) and Dv(s) when the object is moving fast, and the range and number of the cameras can be automatically adjusted to the moving speed of the object  104  so that the value of the code amount is increased. 
     In addition, as shown in  FIG. 11(   b ), it is possible to cause the distribution pattern of the collaboration parameter (u, v) to have a bias toward the same direction as the proceeding direction of the object  104  by increasing the values of the diffusion coefficients Du(s) and Dv(s) with a neighboring camera  101 N that is present, as seen form the camera, in the same direction as the moving direction of the object  104 , and decreasing the values of the diffusion coefficients Du(s) and Dv(s) with respect to the other neighboring cameras  101 N that are present in the other directions. That is, the sensor  106  detects the moving speed of the object, and the collaboration parameter updating unit  413  updates the collaboration parameter so that a distribution pattern in which the intervals at which the regions having a large collaboration parameter and the regions having a small collaboration parameter alternate becomes larger towards the moving direction of the object. 
     By thus adjusting the values of the diffusion coefficients Du(s) and Dv(s) according to the movement of the object  104 , a distribution pattern is formed in which the values of the collaboration parameter (u, v) increase towards the moving direction of the object  104  to the extent according to the moving speed. 
       FIG. 12  is a diagram showing an example of data communicated reciprocally between each camera  101  in the case where the diffusion coefficients Du(s) and Dv(s) are adjusted according to the movement of the object  104 . 
     By communicating the data as shown in  FIG. 12(   a ), the camera, which has detected the object, adjusts the values of its own diffusion coefficients Du(s) and DV(s) based on the detected details, and can also change values of the diffusion coefficients Du(s) and Dv(s) of its neighboring camera  101 N by notifying the adjusted coefficients Du(s) and Dv(s) to the neighboring camera. 
     In addition, when changes to the diffusion coefficients Du(s) and Dv(s) are made with all the cameras based on the movements of the plural objects, there is a case where such changes to the diffusion coefficients Du(s) and Dv(s) according to the movements of the respective objects interfere with each other, and where, as a result, the coefficients Du(s) and Dv(s) are adjusted to the values not applicable for any of the objects. In addition, when the diffusion coefficients Du(s) and Dv(s) continue to hold the same value even after the object has disappeared, the time to assign code amounts becomes longer when a new object appears that is moving in an opposite direction of the object that was present before. Therefore, as shown in  FIG. 12(   b ), by notifying, at the same time, information which specifies the application range and the application time for adjusting the diffusion coefficients Du(s) and Dv(s), the range and the time for changing the diffusion coefficients may be limited. 
     In the example shown in  FIG. 12(   b ), the range of change (“application range”) for diffusion coefficients Du(s) and Dv(s) is specified to a camera that is present within a 5-meter radius around the object, and as for the time (“application time”) from when the diffusion coefficients Du(s) and Dv(s) are changed till when the diffusion coefficients Du(s) and Dv(s) are returned to the initial values, an example of transmitted or received data, in the case where the time is specified as 120 seconds after the diffusion coefficients are changed, is shown. With this, the diffusion coefficients Du(s) and Dv(s) that have been changed with respect to an unnecessary camera and adjustments of the diffusion coefficients Du(s) and Dv(s) which are no longer necessary can be automatically set back to initial values. 
       FIG. 13  is a diagram describing the timing for the camera  101  having detected the object  104  to notify the change in diffusion coefficients Du(s) and Dv(s) to the neighboring camera. 
     As shown in  FIG. 13 , for changing the diffusion coefficients Du(s) and Dv(s), when the camera  101  detects the object  104  (Step  1 ), the camera changes the value of its own diffusion coefficients Du(s) and Dv(s) (Step  2 ), and further notifies the changed values of the diffusion coefficients Du(s) and Dv(s) to a neighboring camera A (Step  3 ). Likewise, the neighboring camera A, upon receiving the changed values of diffusion coefficients Du(s) and Dv(s), changes its own diffusion coefficients Du(s) and Dv(s) to the received values (Step  4 ), and further notifies, to a neighboring camera B, the diffusion coefficients Du(s) and Dv(s) that have been changed (Step  5 ). Furthermore, the values of the diffusion coefficients Du(s) and Dv(s) are changed by repeating the same process to the extent that changes to the values of the diffusion coefficients Du(s) and Dv(s) of the neighboring cameras can be applied (Steps  6  and  7 ). 
       FIG. 14  is a diagram showing an exemplary distribution pattern of the collaboration parameter (u, v) and an exemplary assignment of the target code amount Q for each camera in the case where the diffusion coefficients Du(s) and Dv(s) are changed according to the movement of the object. 
       FIG. 14  shows a situation in which a distribution pattern of the collaboration parameter (u, v), which has a large bias toward the moving direction of the object, is formed by increasing the values of the diffusion coefficients Du(s) and Dv(s) with respect to a neighboring camera  101 R installed in the moving direction of the object  104  whereas decreasing the values of the diffusion coefficients Du(s) and Dv(s) with respect to a camera  101 L installed in a direction opposite to the moving direction of the object  104 . Subsequently, adjustments are made with the respective cameras based on the distribution pattern of the collaboration parameter (u, v) that reflects the movement of the object. For example, the values of the target code amount Q for the camera  101  and the camera  101 R whose neighboring space has a striped distribution pattern of the collaboration parameter (u, v) are adjusted higher whereas the values of the target code amount Q for the other cameras are adjusted lower. 
     Thus, with the monitoring system according to the first embodiment, the assignment of the target code amount Q, which allows a high level of ability to trace the movement of the object as well as high utilization efficiency of the transmission band, can be adjusted automatically by local collaborating operations of the plural cameras  101 . 
     In addition, although the spatial pattern formed by the plural cameras varies according to the type of mathematical expressions and the value of each coefficient as shown in Equations 2 and 3, an operator  105  of the monitoring system may instruct these expressions, the values of coefficients, or the like to the respective cameras according to the purpose and the structure of the cameras. 
       FIG. 15  is a diagram showing an example of a GUI on which the operator  105  gives instructions to the respective cameras  101 . A synthesized video monitor  1402  and a live video monitor  1401  are display units for displaying, respectively, a video synthesized from the videos from the plural cameras and the magnified video (live video). A monitoring pattern selecting panel  1403  is an operation panel on which switches for selecting a distribution pattern of the code amount for the plural cameras are displayed. When the operator  105  selects the target spatial pattern of the code amount assignment from the monitoring pattern selecting panel  1403 , the data regarding the collaboration method (mathematical expressions, coefficients, and so on) required for forming the predetermined distribution pattern of the code amount assignment is transmitted to the respective cameras  101 . 
     Note that plural collaboration methods (mathematical expressions and coefficients) are preset in the respective cameras, and that the operator  105  may instruct the respective cameras on what collaboration method (mathematical expression and coefficients) to use. 
       FIG. 16(   a ) and  FIG. 16(   b ) are a diagram showing an example of data in which the details of the collaboration method (mathematical expressions and coefficients) notified by the monitoring pattern selecting panel  1403  to respective cameras is described. 
       FIG. 16(   a ) shows the details of the data with which the surveillance monitor  103  notifies, to the respective cameras  101 , the details of the collaboration method as mathematical expressions and coefficient values. A monitor ID is a unique ID given to each monitor so as to identify the monitor transmitting information to the plural cameras  101 . 
     When an instruction to change the collaboration method is given from plural surveillance monitors  103 , it is also possible to predetermine a preferential order for respective monitors and follow the instruction of the camera  101  having the highest preferential order. With this, even when instructions are simultaneously transmitted from the plural monitors, all the cameras can operate in accordance with an identical collaboration method. In addition, it is also possible to predetermine the preferential order for operators  105  instead of the predetermined preferential order for the surveillance monitors  103 , and to use an operator ID unique to each of the operators  105  instead of the monitor ID transmitted form the monitoring pattern selecting panel  1403 . 
     Furthermore, in  FIG. 16(   a ), as information for determining the collaboration method, diffusion-reaction equations describing the method for adjusting the collaboration parameter (u, v) and values of the coefficients are assigned for each camera  101 . In addition,  FIG. 16(   b ) shows the details of the data transmitted from the monitoring pattern selecting panel  1403  to each camera in the case where the collaboration method is preset in each camera. A preset number shown in  FIG. 16(   b ) is the preset number selected by the operator from among the collaboration methods that are preset in each camera. 
     A setting panel  1404  is an operation panel for selecting whether or not to make adjustments to the range of assignment of the code amount according to the moving speed and the moving direction of the object  104 . In addition, in the case where the assignment of the code amount is adjusted in consideration of the moving speed and the moving direction, it is also possible to specify the application range within which the adjustments are made in consideration of the moving speed and the moving direction from the place in which the object is detected, and the length of application time for which the adjustments are maintained from the time at which the object is found. 
     A synthesis range setting panel  1405  is an operation panel on which switches are displayed for selecting a camera whose video is to be synthesized, in the case where videos from the plural cameras  101  are synthesized and displayed. 
     In synthesizing monitoring videos, the videos may be synthesized by specifying the region surrounding the object based on the distribution pattern of the collaboration parameter (u, v) that is assigned according to the movement of the object. With this, only the videos from the cameras assigned with large code amounts according to the movement of the object can be synthesized and displayed. 
     The synthesis range setting panel  1405  is a set of switches for selecting a method for synthesizing the videos in the case where videos from the plural cameras  101  are synthesized and displayed. For synthesizing monitoring videos from plural cameras into a video, it is also possible to make adjustments to the camera range and the details of video processing used for the video synthesis, based on the distribution pattern of the collaboration parameter (u, v) of each camera. 
       FIG. 17  is a diagram showing an example of a video synthesized from videos from plural cameras and displayed on the GUI, based on the distribution pattern of the collaboration parameter (u, v). Note that, as shown in  FIG. 17(   a ), the case is assumed where the installation position and the code amount for each camera is assigned so that a larger code amount is assigned to a camera installed in the region in which the object is present and the surrounding regions. At this time, the surveillance monitor  103  displays the synthesized video so that, a video having the largest code amount, from among the videos transmitted from the plural cameras, has pictures of higher quality, larger size, or higher-level gradation. Alternately, the surveillance monitor  103  performs edge enhancement processing on videos having large code amounts, from among the videos transmitted from the plural cameras, and performs mosaic processing on videos having small code amounts, and displays a synthesized video after the respective processes. Hereinafter, examples of display of synthesized videos are shown in  FIG. 17(   b ) to  FIG. 17(   d ). 
       FIG. 17(   b ) shows a display screen image synthesized into a video by enlarging the region surrounding the object and reducing the other regions based on the distribution pattern of the collaboration parameter (u, v). 
     With this, since it is possible to display, in an enlarged image, the appearance of the object which requires particular attention in monitoring, the facial expressions, gestures, and so on of the object can be monitored in more detail. 
     Note that a video to be displayed in a reduced size should preferably be adjusted and distributed as a video of a small image size so as to have a smaller code amount. With this, the utilization efficiency of the transmission path can be improved. 
     In addition, other than the video magnification or reduction, the position of the object can be highlighted for the operator by displaying the surrounding regions of the object as sterically emerging as shown in  FIG. 17(   b ). 
       FIG. 17(   c ) shows a screen display on which, based on the distribution pattern of the collaboration parameter (u, v), the surrounding regions of the object are displayed as color video (that is, images of high-level gradation), whereas the other areas are displayed as synthesized video in black and white. 
     With this, since the periphery of the object is displayed so as to stand out from the other regions, an effect is produced that the position of the subject can be easily identified. 
     Note that the video to be displayed in black and while should preferably be distributed as a video removed of color information in advance so as to have a smaller code amount. With this, the utilization efficiency of the transmission path can be improved. 
     In addition, other than selecting between color video and the black-and-white video, videos may also be synthesized so that the position and the air of the object can be easily identified. For example, in the case where videos from plural cameras are synthesized, hue, chroma saturation, luminosity, and so on may be changed based on the distribution pattern of the collaboration parameter (u, v) so that the regions distant from the object are shown in cold colors whereas the regions closer are shown in warm colors, or the level of gradation for the video may be changed with respect to each region. 
       FIG. 17(   d ) shows a screen display on which, based on the distribution pattern of the collaboration parameter (u, v), the images of the object and its surrounding regions are edge-enhanced through a highpass filter or the like and displayed; whereas the other regions are displayed as a synthesized image treated with mosaic processing. 
     With this, only the object can be clearly highlighted, whereas, for the other places, the respective videos can be automatically filtered and synthesized so as to be mosaiced in consideration of privacy, and so on. 
     Note that, as a filter for image processing, other than “edge enhancement” or “mosaicing,” filters such as “feathering” and “texture” attachment may also be used according to an intended use. 
     Note that although the description in the first embodiment has been focused on a camera whose position is already fixed, a structure using a moving camera whose capturing position is changeable is also adoptable.  FIG. 18  is a diagram showing an example of parking-lot monitoring with plural in-vehicle cameras using the moving camera (Embodiment 1-1). 
       FIG. 18  represents the structure of the monitoring system in which the plural in-vehicle cameras  1501  collaboratively capture the appearance of the object in the parking lot and distribute videos to the surveillance monitor. 
     In the example in  FIG. 18 , an in-vehicle camera  1501  equipped on each vehicle has the same structure as the camera  101  shown in  FIG. 5 . 
     In addition, for each in-vehicle camera  1501 , a wireless LAN card is used as the communication interface  403  for distributing captured videos, and the videos are distributed by wireless communication. 
     In addition, since the position information on the in-vehicle camera differs according to the place where the vehicle is parked, each in-vehicle camera  1501  identifies its own position when the vehicle is parked in the parking lot. 
     As a method for allowing the in-vehicle camera  1501  to detect its own position in the parking lot, in the case of an outdoor parking lot, it is possible to identify the position by using a GPS included in a vehicle navigation system or the like. 
     In addition, in the case of indoors or an underground parking lot out of reach of GPS radio waves, it is possible to identify the position information by, for example, embedding a tag in which a position coordinate with respect to each parking space is stored, and reading, with a tag reader or the like, the position information embedded within the parking space. 
     An in-vehicle camera  1501 , which has obtained its own position information, obtains the position information on the neighboring in-vehicle camera by wireless communication and selects an in-vehicle camera that is to be a collaboration partner. As a method for allowing each in-vehicle camera to determine the collaboration partner, the collaboration partner is selected according to the distance between in-vehicle cameras by, for example, selecting the in-vehicle camera of a vehicle parked within a 5-meter radius from the in-vehicle camera. 
     Furthermore, each vehicle has a sensor and an image processing apparatus, and thus is equipped with a function to detect the position, the moving speed, and the moving direction of the object  104 . Note that the sensor for detecting the position and the movement of the object  104  can be implemented by using a vibration sensor, an infrared sensor, or the like. 
     The transmitting and receiving antenna  1502  is an antenna installed in the parking lot so as to receive the videos captured by the in-vehicle cameras  1501 , and plural units of such antennas may be installed according to the size and the shape of the parking lot. 
     Each of the in-vehicle cameras  1501  communicates, with a nearby vehicle, the collaboration parameter (u, v) and the target code amount Q of its own, based on the position, the moving speed, and the moving direction of the object  104  detected by the sensor, and forms a distribution pattern of the collaboration parameter having the object  104  as the origin, as shown in  FIG. 18 . Subsequently, the assignment of code amounts to the respective in-vehicle cameras  1501  is adjusted based on the formed distribution pattern. With this, the target code amount to be assigned to each of the in-vehicle cameras  1501  is adjusted so that the code amount for an in-vehicle camera  1501  that is capturing video of the object becomes larger than the code amounts of the other in-vehicle cameras  1501 . 
     The monitoring camera  1503  is a monitoring camera that is pre-installed in the parking lot. 
     The monitoring camera  1503  has the same structure as the camera  101  shown in  FIG. 5  and can communicate, wiredly or wirelessly, with another monitoring camera  1503  and an in-vehicle camera  1501 . 
     In the monitoring within the parking lot, by capturing videos collaboratively, not only with an in-vehicle camera  1501  but also with a monitoring camera  1053  that is pre-installed in the parking lot, it becomes possible to automatically adjust the assignment of code amounts that involves the assignment to both of the in-vehicle camera  1501  and the monitoring camera  1503 . 
     With this, in the case where only a small number of vehicles are parked in the parking lot, the capturing with the in-vehicle cameras  1501  can be supported with the monitoring camera  1503 . 
     In addition, in the case where a Pan-Tilt-Zoom camera that allows pan, tilt, and zoom controls is installed in the parking lot, and when no in-vehicle camera is present although a larger code amount should be assigned to the place in the distribution of the collaboration parameter (u, v) formed by reciprocal communication between in-vehicle cameras, it is also possible to shift the field of the Pan-Tilt-Zoom camera to a region where no in-vehicle camera is present and cause the camera to monitor. 
     Thus, the distribution pattern of the collaboration parameter (u, v) may be used not only for assigning code amounts to cameras but also for assigning the video capturing regions for the Pan-Tilt-Zoom camera. 
     In addition, the distribution pattern of the collaboration parameter (u, v) can also be used for controlling the power of the in-vehicle camera  1501  in the parking lot. For example, it is possible to reduce unnecessary drain on battery power by holding, in a standby mode, an in-vehicle camera  1501  whose values of collaboration parameter (u, v) have not reached a certain level or higher and carrying out video capturing when the values of the collaboration parameter exceed certain values as a result of collaborating operation with a neighboring in-vehicle camera  1501 . 
     Therefore, in the monitoring system according to the present invention, only a camera necessary for capturing video of the object can be automatically selected, and the selected information can be used for controlling the power of each camera. 
     Thus far, as described in Embodiment 1-1, even when the video adjustment apparatus and the monitoring system according to the present invention are applied in the situation in which the construction of cameras is constantly changed, since the position information for a camera whose position has been changed is newly updated when the structure and arrangement of the monitoring system is changed, the assignment of code amounts to the respective cameras can be automatically adjusted according to the movement of the object  104 , as with the case of a monitoring system including fixed cameras. 
       FIG. 19  is a diagram showing an example of a service (Embodiment 1-2) in which the plural users each having a mobile camera  1601 , such as a camera equipped on a cellular phone, distribute live videos captured with the mobile camera  1601 . 
     As a service for distributing live videos using the mobile camera  1601 , various purposes can be given, such as: a real-time relay of a traffic accident or an incident that is encountered by chance, observing behaviors of children and seniors, and reporting of landscapes and events experienced while traveling. 
     In addition, a live video captured by each of the users with the mobile camera  1601  is transmitted, via a receiving base station  1602 , to a service provider such as a content provider  1603  and further distributed by the content provider  1603 , in real time, to the PCs and TVs of viewers who wish to watch the live video. 
     The mobile camera  1601  in  FIG. 19  is a camera having the same structure as the camera shown in  FIG. 5 , and the cellular phone line is used for the communication network for distributing the video. 
     In addition, each mobile camera  1601  can obtain information on its position according to the position of the receiving base station  1602  that is accessed by a GPS embedded in the cellular phone or cellular phone. 
     In addition, upon detecting that the user has stayed in the same position for a given length of time, the mobile camera  1601  notifies and exchanges position information with another mobile camera  1601  whose user has also stayed in the same position, and determines a collaboration partner. As a method for determining the collaboration partner, there is a method of selecting, as the collaboration partner, a camera with the distance between mobile cameras  1601  being within a certain range as with the case of the in-vehicle camera  1501 . 
     In the video distribution service shown in  FIG. 19 , since available transmission bands at the same receiving base station  1602  are limited, it is necessary to efficiently assign the transmission bands to the respective mobile cameras  1601  using the same receiving base station  1602  according to the content that is video-captured by the respective users. 
     Therefore, in a circumstance where plural users are distributing live videos, for example, the sensor  401  gives an input signal s, which corresponds to the signal given when the object  104  is detected, to the mobile camera  1061  capturing video of an accident such as a traffic accident, and the distribution pattern of the collaboration parameter (u, v) is formed with the spot of accident being the origin, thereby enabling automatic control by which a larger code amount is assigned to the mobile camera of the user who is in the closest position to the spot of accident. 
     Note that the input signal s for determining what place and what mobile camera  1601  to be preferentially assigned with code amounts may also be spontaneously inputted by the user on his/her own, based on the content of the live video being captured by the user who is distributing the video. 
     In addition, the content provider  1603  may select the place or the mobile camera  1601  which is distributing a video that might attracts the interests of many viewers, and may give an input signal corresponding to the sensor information with respect to the position or the mobile camera  1601 . 
     Furthermore, what place or what mobile camera  1601  should be assigned with the input signal corresponding to the sensor information may also be determined based on the requests from many viewers. 
     Thus, by applying the monitoring system and the camera in the monitoring system in the first embodiment of the present invention to the live video distribution service using the mobile camera  1601  or the like, it is possible to select, from among a number of mobile cameras  1601 , a mobile camera  1601  whose live video requires preferential distribution based on the requests from the viewers, and further to automatically adjust the assignment of code amounts to respective mobile cameras  1601  in consideration of the transmission band that can be accommodated at the receiving base station  1602 . 
     Second Embodiment 
     Next, a second embodiment of the present invention shall be described. 
     In the first embodiment of the present invention, the assignment of code amounts, which takes the movement of the object into consideration, is automatically adjusted by providing difference between the amounts of increase and decrease of the collaboration parameter (u, v) that is reciprocally adjusted between the cameras according to the moving speed and the moving direction of the object. 
     On the other hand, in the second embodiment, a code amount is preferentially assign to a camera which is capturing video of a region requiring prioritized monitoring by providing difference, with respect to each place to be monitored, and based on the layout of the area to be monitored, between the values of the collaboration parameter (u, v) that are reciprocally adjusted between the cameras. 
       FIG. 20  is a block diagram showing the structure of the camera  101  in the second embodiment. In  FIG. 20 , the same numerical references are given to constituent elements that are the same as those in  FIG. 5 , and their descriptions shall be omitted. 
     A priority monitoring area storage unit  414  is a memory for storing priority monitoring area information describing, according to the layout of the area to be monitored, the collaboration method for determining the details of the collaboration with a neighboring camera with respect to each place requiring prioritized monitoring. 
       FIG. 21  is a diagram showing an example of the priority monitoring area information. In the priority monitoring area information, the range of each area and the operation rule for the cameras in the place are defined in the form of reaction-diffusion equations and the values of the coefficients. 
     In  FIG. 21 , the range of each area is defined using a latitude-longitude coordinate system; however, other than this, a method of expression which allows a unique specification of the place and the camera, such as specifying the camera number or the like, may also be used. 
     In addition,  FIG. 21  shows an example in which, for a method of collaboration between the cameras in each area, reaction-diffusion equations and the values for the coefficients are directly specified. However, some other collaboration methods are also prepared in advance, and by specifying the number for selecting one of the methods, for example, it is possible to use an expression which allows the specification of the collaboration method with respect to the cameras that are present in each given area. In addition, the collaboration method may also be assigned via a recording medium, such as a communication network, an optical disc, a semiconductor memory, or the like. 
     The camera  101  compares the installation position of the camera  101  itself and the priority monitoring information stored in the priority monitoring area storage unit  414 , and adjusts the method of collaboration with the neighboring camera. Specifically, by checking the position of the camera against the priority monitoring area indicated by the priority monitoring area information, a collaboration parameter updating unit  413  updates the collaboration parameter according to the collaboration method corresponding to the position of the camera. 
       FIG. 22  is a diagram showing the procedure in which the camera  101  changes the method of collaboration with the neighboring camera  101 N. 
     (Step S 1901 ) 
     The camera  101  obtains a priority monitoring area  1801  from the priority monitoring area storage unit  414 . 
     (Step S 1902 ) 
     The camera  101  compares its position information with the acquired priority monitoring area  1801  and determines the method of collaboration with the neighboring camera according to the priority monitoring area  1801 . 
     (Step S 1903 ) 
     The camera  101  changes the collaboration method (reaction-diffusion equation and coefficient values) that is to be used as the method for collaboration with the neighboring camera in a collaborating operation executing unit  407  and an autonomous operation executing unit  408 . 
       FIG. 23  is a diagram showing Embodiment 2-1 in which the details of the collaboration between each camera  101  and its neighboring camera are adjusted with respect to the position of a priority monitoring area  2001  within the area to be monitored. 
       FIG. 23  represents a case where: in the area to be monitored, the neighborhood of a place requiring high security, such as a place where a safe is present, is assumed as the priority monitoring area  2001 , and the collaboration method of each camera is adjusted so that the diffusion coefficients Du(s) and Dv(s) become larger in the direction of the priority monitoring area  2001 , than in any other direction, from respective positions within the area to be monitored. With this, the distribution pattern of the collaboration parameter (u, v) is not only adjusted in the moving direction of the object  104 , but the value of the collaboration parameter u is also adjusted larger, from the position where the object  104  is present, in a direction toward the priority monitoring area  2001 . 
     In this manner, with the values of the diffusion coefficients Du(s) and Dv(s) being increased in the direction toward the priority monitoring area  2001 , it is possible to automatically assign code amounts not only to increase the code amount for the camera  101  located in a path expected from the movement of the object  104 , but also to increase the code amount for the camera in preparation for the movement of the object attempting to approach the priority monitoring area  2001 . 
     In addition, the priority monitoring area  1801  may also be distributed, by an operator  105 , from a surveillance monitor  103  to each camera  101 , and each camera  101  may automatically update the details of the collaboration based on the distributed information. With this, in the case where the position of the priority monitoring area is changed due to a layout change or the like within the area to be monitored, the details of the collaboration between each camera are adjusted so as to be adapted to the shifted position of the priority monitoring area  2001 . 
     Next,  FIG. 24  is a diagram showing Embodiment 2-2 in which the details of the collaboration between each camera  101  and its neighboring camera are adjusted based on the shape of the layout of the area to be monitored. 
       FIG. 24  is a diagram showing the case where the moving direction (moving path) of the object is restricted due to the shape of the layout of the area to be monitored, such as a corridor corner. 
     As shown in  FIG. 24(   a ), when only the proceeding direction of the object  104  is taken into account for forming the distribution pattern of the collaboration parameter (u, v), a distribution of the collaboration parameter is formed in which a larger code amount is assigned even to a place at which the object  104  cannot actually move forward, such as, as described above, at the corridor corner. 
     Therefore, as shown in  FIG. 24(   b ), for example, by making adjustments so that, at the corridor corner, the values of the diffusion coefficients Du(s) and Dv(s) become larger among the cameras installed in the direction along the corridor, it is possible to assign code amounts automatically in consideration of the moving direction of the subject that is restricted by the layout of the area to be monitored. With this, when the object approaches just before the corner, automatic adjustment becomes possible so as to increase the code amount for the camera located ahead of the corner. 
     Note that although in the second embodiment the priority monitoring area information is described with an exemplary case where the collaboration method and coefficient values for the cameras are changed with respect to each priority monitoring area  2001 , the collaboration method and coefficient values may be changed not only according to the place but also according to the conditions such as the time of the day, the day of the week, the date, and so on. 
     With this, for example,  FIG. 23  assumes a company office or the like where: the surrounding space of a safe  2002  is set as the priority monitoring area  2001  during working hours when people pass by the neighborhood of the safe  2002 , and the neighborhood of the entrance door  2003  to the office is set as the priority monitoring area during late night and holiday hours when people leave the office; thereby, in the case where it is known in advance that, late at night or on holidays, there is no one in the office and no one will approach the safe  2002 , it is possible to automatically assign code amounts in a more practical manner according to the time of the day. 
     Thus far, the monitoring system and the camera according to the present invention has been described based on the first and second embodiments. However, the present invention is not limited to these embodiments. Other embodiments achieved by any arbitrary combination of the constituent elements in these embodiments and variations to these embodiments that would occur to those skilled in the art without departing from the spirit of the present invention shall be included in the present invention. 
     For example, although in the above embodiments, the adjustment of video code amounts in a camera has been described as an exemplary monitoring system in the present invention, the camera in the present invention may also be an apparatus other than a camera or may also have a structure including a video encoding apparatus such as a PC or a video radar which can adjust and distribute the code amount of video data, and, as with the case of the camera, the assignment of code amounts to plural video encoding apparatuses can be automatically adjusted. 
     In addition, although the descriptions in the first and the second embodiments have been given with an exemplary case where the code amount is adjusted in the encoding process for distributing, in real time, the video captured by the camera. However, this may also be used for adjusting the code amount when the accumulated video data is transcoded and distributed. 
     For example, as for the code amount for a transcoder, when, at home, video data accumulated on plural recording media, such as hard disk recorders, is transmitted to plural receiving terminals, such as TVs and mobile devices, the distribution pattern of the collaboration parameter (u, v) is formed, based on the topology (the transmission path and the available band) of the network connecting the respective recording media with the receiving terminals, and the performance and the number of the receiving terminals; thereby a monitoring system and a camera, which assigns of a larger code amount to a receiving terminal of higher capacity, without causing any delay or deterioration in video at the respective receiving terminals, can be achieved. 
     In addition, the descriptions in the first and the second embodiments have been given with an exemplary case where each camera  101  calculates the collaboration parameter (u, v) and the target code amount Q of its own. However, even when the camera  101  calculates the collaboration parameter (u, v) and the target code amount Q n  for another camera  101 N and notifies the obtained result to the camera  101 N, the same effect can be produced as with the monitoring system and the camera in the monitoring system described in the first and the second embodiments. 
     In addition, even when a structure is adopted which causes an external apparatus connected via the communication network  102  to calculate the collaboration parameter (u, v) and the value of the target code amount Q for the camera  101 , and to notify the result to the camera  101 , the same effect is produced as with the case of the monitoring system and the camera in the monitoring system as described in the first and the second embodiments. 
     In addition, although in the first and the second embodiments, two variables (u, v) are used as variables used for Equation 2, two or more types of variables may be used as long as the method allows the forming of a spatial distribution pattern. In addition, although descriptions have been given using Equations 2 and 3 as an example of forming the spatial pattern of the collaboration parameter, the forming of the spatial distribution pattern may also be performed using another mathematical expression and coefficients. For example, in Equation 3, it is possible to form a more detail spatial distribution pattern by expanding the linear shape which assumes (u, v) as variables into a nonlinear shape. 
     In addition, the description has been given assuming encoding at a constant bit rate. However, for purposes, such as recording onto a HDD, or the like, that is equipped with each camera, encoding may also be carried out at a variable bit rate. 
     In addition, in the video capturing with the variable bit rate, the code amount for the video changes significantly according to the movement of the object. Thus, it is also possible to adopt a structure which uses the detection of a code amount equal to or larger than a given value to detect the movement of the object. 
     INDUSTRIAL APPLICABILITY 
     The monitoring system and the camera in the monitoring system according to the present invention have a high ability to trace the movement of the object and can automatically assign, to plural cameras, code amounts that allow high utilization efficiency of transmission, irrespective of the number and the type of cameras to be used. Therefore, the monitoring system and the camera in the monitoring system according to the present invention are useful in the anticrime-security field, such as town monitoring in which intruders, passengers, and so on are monitored with plural cameras, a building monitoring system, and a monitoring system for community facilities. 
     Furthermore, the above monitoring system and the camera in the monitoring system are also applicable as a video distribution system in the area of video distribution services, such as distributing images of an accident or a landscape from an outside location using a mobile camera and the area of ITS and so on, such as parking-lot monitoring using an in-vehicle camera, and as an in-vehicle control system.