JP2007013697A - Image receiver and image receiving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a possibility of failing in image transmission by distributing processing on a time base and reducing a processing load when receiving image data from a plurality of network cameras without greatly increasing cost on a system design. <P>SOLUTION: When a PC 601 functioning as an image receiver respectively receives an image from three network cameras 602 at frame rates of 2(fps), 3(fps) and 5(fps), the PC 601 uses a value N=7 which is larger than a value 3 of the number of network cameras and is mutually a prime number to values 2, 3 and 5 of the frame rates to equally divide a unit time into seven parts. Then, transmission timing A1, B1 and C1 of image request commands to the first to third network cameras are set to time T1 (=1/7 seconds), time T2 (=2/7 seconds) and time T3 (=3/7 seconds), respectively and an image receiving operation from the three network cameras is started with the transmitting timing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image receiving apparatus and an image receiving method for acquiring and displaying or storing an image of a camera (network camera) via a network.

  2. Description of the Related Art Conventionally, there is known a network image transmission system that transmits an image captured by a network camera via a network for the purpose of, for example, video surveillance or sightseeing spot guidance (for example, see Patent Document 1 below).

  FIG. 6 shows an example of the configuration of a conventional general network image transmission system. Here, a PC (Personal Computer) 601 that functions as an image receiving device that receives a video (image) captured by the network camera 602 and a plurality of network cameras 602 having an imaging function are connected via the network 603. A network configuration connected to each other is shown. Here, videos (images) captured by a plurality of network cameras 602 are transmitted to the PC 601 via the network 603 through processes such as digitization and data compression. The PC 601 stores the video received from each of the plurality of network cameras 602 via the network 603 as it is in a data storage device (not shown in FIG. 6) such as a hard disk, or displays the display device (FIG. 6) after data decoding. 6) (not shown in FIG. 6).

  FIG. 7 is a sequence chart showing an example of an image acquisition procedure in the network image transmission system according to the prior art. First, the PC 601 transmits an image request command for requesting image data to a certain network camera 602 via the network 603 (step S701). At this time, the network camera 602 that has received the request for image data compresses the captured image using a method such as JPEG (Joint Picture Experts Group) as a response to the request for image data, and the compressed image data. It returns to PC601 (step S702). If the frame rate (which is also the image acquisition rate, the image acquisition request frequency, and the number of image data acquisitions) is, for example, 10 [fps] (frames / second: number of frames per second), this exchange is performed for 1 second. As a result, the PC 601 acquires 10 images per second.

Also, as shown in FIG. 6, when there are a plurality of network cameras 602, the PC 601 transmits a request for image data to each network camera 602 at a specified interval. As a result, the received image data is received and processed. Note that the frame rate (image acquisition request frequency) of image data requested for each of the plurality of network cameras 602 can be set to an arbitrary value without depending on the other network cameras 602.
JP-A-8-317374 (FIG. 1, paragraphs 0026 to 0035)

  However, in the conventional network image transmission system, the processing in the PC that receives image data from a plurality of network cameras is inefficiently performed only by considering the frequency of image acquisition requests to the network cameras as described above. In the worst case, a predetermined allowable processing load range determined by the performance of the PC is exceeded, and image data processing on the PC may become difficult.

  For example, if a PC acquires one image per 10 seconds for 1000 network cameras via a network, the image acquisition request timing from the PC to the network camera is not considered at all, and simply 1000 It is assumed that the control is performed considering only that an image acquisition request is made once every 10 seconds to the network camera. In this case, the difference between the state in which a large amount of image data is transmitted to the PC and the processing is performed and the state in which the image data is not transmitted increases, and in an extreme example, a predetermined 1 of 10 seconds. There may be a case in which 1000 sheets of image processing are performed per second and nothing is performed for the remaining 9 seconds.

  Further, for example, in the network configuration illustrated in FIG. 6, the image is captured by, for example, three network cameras 602 (here, the three network cameras 602 are described as the first to third network cameras 602). Consider a case where an image is viewed on a single PC 601. In this case, for example, if the frame rate of the first network camera 602 is 2 [fps], the frame rate of the second network camera 602 is 3 [fps], and the frame rate of the third network camera 602 is 5 [fps], the PC 601 In FIG. 8, when browsing of each image of the first to third network cameras 602 is started at the same time as the transmission of images to the three first to third network cameras 602 is requested, a timing chart shown in FIG. become that way.

  FIG. 8 is a timing chart showing an example of image transmission in a network image transmission system according to the prior art. In FIG. 8, the passage of time is shown from the left to the right of the drawing. When the PC 601 starts browsing the images of the first to third network cameras 602 at the same time, first, the PC 601 sends a browsing start instruction to all three of the first to third network cameras 602. Request images at the same time. This image request timing is the timing indicated by the arrow α in FIG. Thereafter, the PC 601 makes image requests to the first to third network cameras 602 at intervals of 1/2 second, 1/3 second, and 1/5 second, respectively. As a result, as indicated by arrows β and γ in FIG. 8, image requests are simultaneously made from the PC 601 to all three of the first to third network cameras 602 every second.

  As described above, in the network image browsing system according to the related art, the processing load or network load of the PC that receives image data from the network camera is determined at a predetermined time only by considering the frequency of image acquisition requests to the network camera. Concentration, the peak value becomes high, processing cannot catch up, image transmission fails, and in order to build a system that can withstand the processing load when processing is concentrated, the system design cost There is a problem of becoming higher.

  In view of the above problems, the present invention provides an image receiving apparatus and an image receiving method capable of distributing processing to reduce processing load when receiving image data from a plurality of network cameras. The purpose is to do.

In order to achieve the above object, according to the present invention, there is provided an image receiving device that receives images captured by each of S imaging devices (S is a natural number of 2 or more) via a network,
When the number of images per unit time received from each of the S imaging devices is Fq (q is a natural number from 1 to S), it is a natural number greater than or equal to S and each of the S Fqs. Is a calculating means for calculating the number N of periodic divisions satisfying a condition that is relatively prime;
The unit time is divided into N equal parts using the periodic division number N calculated by the calculating means, and each time when the unit time is divided into the N equal parts is time Tp (p is a natural number from 1 to N). When,
Communication request timing Zk (k is a natural number from 1 to S) for starting the request for the image to each of the S imaging devices when requesting the image at regular intervals based on the Fq, Start time setting means for setting any value of S times Tp so that they are not set at the same time,
Image request means for starting a request for the image to each of the S imaging devices based on the time of the communication start timing Zk set by the start time setting means;
Image receiving means for receiving an image transmitted as a response to the image request from each of the S imaging devices;
An image receiving apparatus is provided.

In order to achieve the above object, according to the present invention, an image performed by an image receiving device that receives an image captured by each of S imaging devices (S is a natural number of 2 or more) via a network. A receiving method,
When the number of images per unit time received from each of the S imaging devices is Fq (q is a natural number from 1 to S), each is a natural number greater than or equal to S and each of S Fqs. Is a calculation step for calculating a periodic division number N that satisfies a condition that is relatively prime;
The unit time is divided into N equal parts using the periodic division number N calculated in the calculation step, and each time when the unit time is divided into N equal parts is time Tp (p is a natural number from 1 to N). Steps,
Communication request timing Zk (k is a natural number from 1 to S) for starting the request for the image to each of the S imaging devices when requesting the image at regular intervals based on the Fq, A start time setting step of setting any value of S times Tp so that they are not set at the same time;
An image requesting step for starting a request for the image to each of the S imaging devices based on the time of the communication start timing Zk set in the start time setting step;
An image receiving step of receiving an image transmitted as a response to the image request from each of the S imaging devices,
An image receiving method is provided.

  The image receiving apparatus and the image receiving method of the present invention have the above-described configuration, and when receiving image data from a plurality of network cameras without significantly increasing the cost of system design, the time axis This has the effect of reducing the processing load by distributing the processing above and reducing the possibility of image transmission failure.

  Hereinafter, an image receiving apparatus and an image receiving method according to an embodiment of the present invention will be described with reference to the drawings. First, the configuration of the network image transmission system and the configuration of the image receiving apparatus in the embodiment of the present invention will be described.

  The network configuration in the embodiment of the present invention is the same as that of the prior art, that is, the network image transmission system shown in FIG. That is, a PC (image receiving device) 601 and a plurality of network cameras 602 are connected via a network 603, and the PC 601 receives images captured by the plurality of network cameras 602 via the network 603. The image data constituting the video can be stored in a predetermined data storage device or displayed on a display device after data decoding. In the following, a case where the image receiving apparatus of the present invention is realized by the PC 601 will be described as an example. However, the present invention is not limited to this, and can be realized by a video recorder connected to a network, for example.

  Next, the configuration of the image receiving apparatus in the embodiment of the present invention will be described. FIG. 4 is a block diagram showing an example of the configuration of the image receiving apparatus according to the embodiment of the present invention. Note that the image receiving apparatus shown in FIG. 4 is a PC 601 shown in FIG.

  The PC 601 illustrated in FIG. 4 includes a user interface 401, a setting holding unit 402, a communication management unit 403, a communication unit 404, a data processing unit 405, a communication interface 406, a time measuring unit 407, and a data storage unit 408. .

  A user interface 401 shown in FIG. 4 is an interface for the user to input information and to output information to the user. In other words, the user interface 401 has an input interface (for example, a mouse) for specifying the network camera 602 that the user desires to receive an image, instructing to start browsing the image, and inputting other setting information and instructions. And a display device for displaying image data received from the network camera 602.

  The setting holding unit 402 has a function for holding various setting information when image data is received from the network camera 602. The setting information held in the setting holding unit 402 includes, for example, the IP address of the network camera 602, the frame rate when image data is received from the network camera 602, and the network camera 602 that performs browsing simultaneously. The number of units (simultaneous communication number S) may be mentioned. In FIG. 4, the setting holding unit 402 is configured to hold information input from the user interface 401 as setting information, but other information (for example, information received via the communication interface 406). Can be stored as setting information.

  In addition, the communication management unit 403 refers to information input by the user from the above-described user interface 401 and information stored in the setting storage unit 402, and performs communication with the network camera 602 performed in the communication unit 404. Has the function to manage. For example, the communication management unit 403 starts a request for image data for each of the plurality of network cameras 602 so that processing of image data received from each of the plurality of network cameras 602 does not concentrate at a specific time. (Communication start timing) is calculated, and based on the calculation result, the communication unit 404 is instructed to start communication with each network camera 602.

  The communication unit 404 has a function of communicating with communication devices (including the network camera 602) connected to the network 603 via the communication interface 406. It has a function of transmitting an image request command for requesting data. Communication by the communication unit 404 is started by a communication start instruction received from the communication management unit 403 together with the communication start timing. At this time, information relating to communication (information such as the IP address and frame rate of the network camera 602) may be notified from the communication management unit 403 to the communication unit 404, and the communication unit 404 may also notify the setting holding unit 402. May be obtained from Here, for convenience, it is assumed that the communication unit 404 includes communication units 404_1 to 404_S equal to the number of network cameras 602 that perform simultaneous communication (simultaneous communication number S).

  The data processing unit 405 has a function of performing processing related to image data received from the network camera 602. In the data processing unit 405, for example, image data decoding processing or processing processing is performed in order to display an image through a user interface (display device) or to store image data in the data storage unit 408.

  The communication interface 406 is a communication interface connected to the network 603 in order to communicate with communication devices (including the network camera 602) connected to the network 603.

  Further, the timer unit 407 has a function of outputting the current time. Note that the time output from the time measuring unit 407 is preferably in milliseconds, for example. Further, the time output from the time measuring unit 407 is used as a reference that is referred to for determining the transmission timing of the image request command to the network camera 602. Therefore, the time measuring unit 407 has a predetermined time period ( For example, a timer that repeatedly measures time in 1 second may be used.

  The data storage unit 408 has a function of storing image data received from the network camera 602. For example, a CD (Compact Disc) drive or a DVD (Digital Versatile Disc) drive that can use a write-compatible disc, And a hard disk drive.

  Next, the operation in the embodiment of the present invention will be described. First, a process in the communication management unit 403 when the PC 601 starts an operation of receiving image data from a plurality of network cameras 602 will be described with reference to FIG. FIG. 2 is a flowchart showing an example of processing of the communication management unit in the embodiment of the present invention.

  It is assumed here that the PC 601 communicates with S network cameras 602 (hereinafter, the S network cameras 602 may be referred to as first to S network cameras 602). In addition, the number of times (frame rate) of image data acquisition from each of the S network cameras 602 is Fq (q = 1 to S natural number) times per unit time. Note that the number of times Fq of image data is acquired for the network camera 602 is equal to the frame rate when image data is received from the network camera 602, and further, the number of times image data is requested to the network camera 602.

  When the PC 601 receives image data from each of the S network cameras 602, the communication management unit 403 first receives a browsing start instruction from the user interface 401, and simultaneously performs network camera 602 that performs communication from the setting holding unit 402. (Number of simultaneous communication) S is acquired (step S201), and the frame rate Fq (q = 1 to S natural number) of each network camera 602 is acquired (step S202). As described above, the setting storage unit 402 stores setting information such as the IP address of each network camera 602, the frame rate related to image acquisition from each network camera 602, and the number S of simultaneous communications. ing.

Then, the communication management unit 403 performs the periodic division number N based on the simultaneous communication number S for simultaneous communication and the frame rates Fq (q = 1 to S natural number) of the first to S-th network cameras 602. Is obtained (step S203). This period division number N is a reference value used for setting the communication start timing so that the image request timing for each of the S network cameras 602 does not overlap on the time axis. For example, as the periodic division number N,
1. 1. The periodic division number N is a natural number equal to or greater than the simultaneous communication number S The periodic division number N and the frame rate Fq (q = 1 to S) are calculated as values that satisfy two prime conditions. Note that a specific method of calculating the periodic division number N in step S203 will be described later.

Next, the communication management unit 403 uses the periodic division number N calculated in step S203 to set an N division time Tp (a natural number between p = 1 to N) for dividing the unit time into N equal parts (step S204). . If the unit time is Q,
N division time Tp = (Q / N) × (p−1)
It becomes.

  Subsequently, the communication management unit 403 performs different N division times Tp (p = 1 to N natural numbers) for the communication start timing Zk (k = 1 to S natural number) with each of the S network cameras 602. Is assigned (step S205). That is, an arbitrary N division time Tp (p = 1 to N natural number) is set so that the values of S communication start timings Zk (k = 1 to S natural number) do not become the same value.

  The communication management unit 403 notifies the communication unit 404 of the communication start timing Zk (k = 1 to S natural number) with each of the S network cameras 602 set as described above. An instruction to start communication with the network camera 602 is given (step S206). Through the above operation, the communication management unit 403 performs communication start timing Zk (k for distributing processing on the time axis when an image request is made to each of the S network cameras 602 at a predetermined frame rate. = 1 to S (natural number) can be calculated.

  Next, a specific calculation method of the periodic division number N in the above-described step S203 will be described with reference to FIG. FIG. 5 is a flowchart showing an example of the calculation operation of the number N of periodic divisions by the communication management unit in the embodiment of the present invention.

  First, the communication management unit 403 initializes the number of simultaneous communications S by substituting the number S of simultaneous communications (that is, N = S) (step S501), and initializes the index number i to i = 1 (step S501). S502). Then, it is checked whether or not the period division number N and the frame rate Fi (where i is the index number at this time) are relatively prime (step S503).

  In the method of checking whether or not these two numerical values are relatively prime, for example, a generally known Euclidean mutual division method can be used. That is, first, the greatest common divisor of the periodic division number N and the frame rate Fi is obtained. If the greatest common divisor is 1, it is determined to be relatively prime, and if it is greater than 1, it is determined to be not relatively prime.

  If it is determined in step S503 that they are not disjoint, the number of periodic divisions N is increased by 1 (step S504), the process returns to step S502, the index number i is initialized to i = 1, and step S503 is performed again. It is checked whether the period division number N and the frame rate Fi are relatively prime.

  On the other hand, if it is determined in step S503 that they are relatively prime, it is checked whether or not the current index number i and the simultaneous communication number S are the same value (step S505). If the values are not the same, the index number i is incremented by 1 (step S506), and it is checked again in step S503 whether the periodic division number N and the frame rate Fi are relatively prime. The increase in the index number corresponds to checking whether or not the frame rate Fi related to another network camera 602 and the periodic division number N are relatively prime.

In step S505, if the current index number i and the simultaneous communication number S are the same value, the value of the periodic division number N at this point is set to the desired periodic division number N value. Is done. Note that the value finally set as the periodic division number N is
1. 1. The periodic division number N is a natural number equal to or greater than the simultaneous communication number S The number N of periodic divisions and the frame rate Fq (q = 1 to S natural number) satisfy two prime conditions.

  Next, the operation of the communication unit 404 after receiving a communication start instruction from the communication management unit 403 will be described with reference to FIG. FIG. 3 is a flowchart showing an example of the operation of the communication unit after receiving a communication start instruction from the communication management unit in the embodiment of the present invention.

  The communication unit 404 receives a communication start timing (k = 1 to S natural number) for each of the S network cameras 602 together with a communication start instruction (corresponding to the communication start instruction in step S206 shown in FIG. 2). First, the current time is acquired from the time measuring unit 407 (step S301). Then, the communication unit 404 normalizes the current time acquired from the time measuring unit 407 to unit time, and sets the normalized time t (step S302). Note that normalization here means conversion to time within a unit time. That is, for example, when the unit time is 1 second, paying attention to the time in a unit of less than 1 second, if the current time is 7: 10: 22: 123 milliseconds, only 123 milliseconds of less than 1 second are extracted. , 123 milliseconds is a normalized time t. Therefore, the normalized time t is a time with the unit time as a time period.

  Next, the communication unit 404 compares the normalized time t with the communication start timing Zk (k = 1 to S natural number) notified from the communication management unit 403 (step S303). Then, the processes of steps S301 and S302 are repeated until the normalized time t becomes equal to the communication start timing Zk (k = 1 to S natural number), and the normalized time t becomes the communication start timing Zk ( k = 1 to S) (t = Zk), the communication unit 404 transmits an image request command from the communication interface 406 to the network camera 602 corresponding to the communication start timing Zk. (Step S304).

  In addition, after transmitting the first image request command to the network camera 602, the communication unit 404, for each image acquisition cycle obtained from the frame rate Fq (q = 1 to S natural number) related to the network camera 602, Send an image request command. That is, the communication unit 404 transmits the image request command until the transmission of the next image request command (the frame rate Fq (q = 1 to S natural number) related to the network camera 602 during the image acquisition interval. ) Enters a sleep state (a state in which nothing is performed) (step S305). When the sleep state for the image acquisition cycle is completed, the operation of transmitting the next image request command to the network camera 602 is repeated. Note that the above sleep state indicates that no processing related to the transmission of the image request command is performed, and the communication unit 404 receives, for example, an image transmitted from the network camera 602 as a response to the image request command. Data reception processing (specifically, processing for passing image data received through the communication interface 406 to the data processing unit 405) is performed.

  The communication unit 404 performs the operation illustrated in FIG. 3 described above on the S network cameras 602. Therefore, in the configuration illustrated in FIG. 4, the communication units 404_1 to 404_S that communicate with each of the S network cameras 602 have communication start timings Zk (k = 1) related to the S network cameras 602, respectively. ~ S natural number) and frame rate Fq (q = 1 to S natural number) are acquired, and communication with the network camera 602 is started at time t = Zk.

  Next, the configuration and operation in the above-described embodiment of the present invention will be described by setting specific numerical values. In the following, the PC 601 receives image data from three network cameras 602 (simultaneous communication number S = 3), and sets frame rates F1 to F3 related to the first to third network cameras 602 as F1 = 2 [fps], F1 = 3 [fps], and F3 = 5 [fps].

  In this case, the communication management unit 403 performs the process of step S203 shown in FIG. 2 (that is, the process of FIG. 5), and the value 3 of the simultaneous communication number S and the values of the frame rates F1 to F3 are 2, On the basis of 5, it is possible to obtain a periodic division number N = 7 that is relatively prime with each of the values 2, 3, and 5 of the frame rates F1 to F3.

Next, the communication management unit 403 obtains N division times Tp (p = 1 to N natural numbers) within each unit time by the process of step S205 shown in FIG. Here, since the number N of periodic divisions is 7, N division times T1 to T7 are:
T1 = (1-1) /N=0/7→0.0 [milliseconds]
T2 = (2-1) /N=1/7→142.9 [milliseconds]
T3 = (3-1) /N=2/7→285.7 [milliseconds]
T4 = (4-1) /N=3/7→428.6 [milliseconds]
T5 = (5-1) /N=4/7→571.4 [milliseconds]
T6 = (6-1) /N=5/7→714.3 [milliseconds]
T7 = (7-1) /N=6/7→857.1 [milliseconds]
It becomes.

  The communication management unit 403 prevents the communication start timing Zk (k = 1, 2, 3) with each of the three network cameras 602 from having the same value by the process of step S205 shown in FIG. However, it is set to one of N division times T1 to T7. That is, the communication management unit 403, for example, the communication start timing Z1 = T1 with the first network camera 602, the communication start timing Z2 = T2 with the second network camera 602, and the communication start timing Z3 = with the third network camera 602 = Set T3. As long as the communication start timing Zk (k = 1, 2, 3) does not overlap with the same time, the N division times T1 to T7 are set as the communication start timing Zk (k = 1, 2, 3). Also good.

  Further, the communication units 404_1 to 404_3 determine the times when the communication start timings Z1 = T1, Z2 = T2, and Z3 = T3 with the first to third network cameras 602 in step S303 shown in FIG. Sends an image request command.

  As a result, an image request command for each of the three network cameras 602 is transmitted at the timing shown in FIG. FIG. 1 is a timing chart showing an example of the transmission timing of an image request command from a PC to three network cameras in the embodiment of the present invention.

  In FIG. 1, the PC 601 first transmits an image request command to the first network camera 602 at time T1 (transmission timing A1). Thereafter, transmission is performed from the PC 601 to the first network camera 602 every 1 / F1 = 1/2 = 0.5 [milliseconds] with reference to the time T1 of the transmission timing A1 (transmission timing). A2-A4).

  The PC 601 first transmits an image request command to the second network camera 602 at time T2 (transmission timing B1). Thereafter, transmission is performed from the PC 601 to the second network camera 602 every 1 / F2 = 1/3 = 0.333 [milliseconds] with reference to the time T2 of the transmission timing B1 (transmission timing). B2-B6).

  The PC 601 first transmits an image request command to the third network camera 602 at time T3 (transmission timing C1). Thereafter, transmission is performed from the PC 601 to the third network camera 602 every 1 / F3 = 1/5 = 0.2 [milliseconds] with reference to the time T3 of the transmission timing C1 (transmission timing). C2-C9).

  These transmission timings A1 to A4, B1 to B6, and C1 to C9 are set with reference to times when the frame rates F1 to F3 are relatively prime, so that these transmission timings do not overlap at the same time, It becomes possible to distribute the processing load of the PC 601 and the traffic amount of the network 603 on the time axis.

  In the above-described embodiment of the present invention, the transmission timings of image request commands are not overlapped at the same time. Accordingly, for example, the timing of processing of image data received as a response to the image request command (that is, processing in the data processing unit 405) does not overlap at the same time, but the network between each network camera 602 When the upper distance is different, or when the processing capability and image size of each network camera 602 are different, the reception timing of the image data becomes the same even if the transmission timing of the image request command is the same time. Cases are also envisaged. In such a case, for example, the response time from each network camera 602 is calculated in advance, and the transmission timing of the first image request command (transmission timings A1 and B1 shown in FIG. 1) is taken into account. , C1) can be shifted so that the reception timing of image data does not overlap at the same time.

  In the above-described embodiment of the present invention, the example in which the number of periodic divisions N is calculated using the Euclidean mutual division method has been described. However, when the number of simultaneous communication S is large, the frame rate Fq (q is 1 When the natural number of .about.S is high, it is expected that the calculation by the Euclidean algorithm will take time. Therefore, for example, the PC 601 holds a list of values (candidates of the number N of periodic divisions) that are relatively prime with respect to all integers that can be frame rates, and refers to this list, thereby An appropriate periodic division number N may be acquired.

  The image receiving apparatus and the image receiving method of the present invention distribute the processing on the time axis when receiving image data from a plurality of network cameras without significantly increasing the system design cost. And the possibility of failure in image transmission is reduced, and can be applied to a network image transmission technique for transmitting an image of a network camera via a network.

It is a timing chart which shows an example of the transmission timing of the image request command with respect to three network cameras from PC in embodiment of this invention. It is a flowchart which shows an example of a process of the communication management part in embodiment of this invention. 7 is a flowchart illustrating an example of an operation of a communication unit after receiving an instruction to start communication from a communication management unit in the embodiment of the present invention. It is a block diagram which shows an example of a structure of the image receiver in embodiment of this invention. It is a flowchart which shows an example of the calculation operation | movement of the periodic division number N by the communication management part in embodiment of this invention. It is a figure which shows an example of a structure of the network image transmission system common to embodiment of this invention and a prior art. It is a sequence chart which shows an example of the image acquisition procedure in the network image transmission system which concerns on a prior art. It is a timing chart which shows an example of the image transmission in the network image transmission system which concerns on a prior art.

Explanation of symbols

401 User Interface 402 Setting Holding Unit 403 Communication Management Unit 404, 404_1, 404_2, 404_S Communication Unit 405 Data Processing Unit 406 Communication Interface 407 Timekeeping Unit 408 Data Storage Unit 601 PC (Personal Computer: Image Receiving Device)
602 Network camera 603 Network A1-A4, B1-B6, C1-C9 Transmission timing of image request command

Claims (2)

An image receiving device that receives images captured by each of S imaging devices (S is a natural number of 2 or more) via a network,
When the number of images per unit time received from each of the S imaging devices is Fq (q is a natural number from 1 to S), each is a natural number greater than or equal to S and each of S Fqs. Is a calculating means for calculating the number N of periodic divisions satisfying a condition that is relatively prime;
The unit time is divided into N equal parts using the periodic division number N calculated by the calculation means, and each time when the unit time is divided into N times is set as time Tp (p is a natural number from 1 to N). When,
Communication request timing Zk (k is a natural number from 1 to S) for starting the request for the image to each of the S imaging devices when requesting the image at regular intervals based on the Fq, Start time setting means for setting any value of S times Tp so that they are not set at the same time,
Image request means for starting a request for the image to each of the S imaging devices based on the time of the communication start timing Zk set by the start time setting means;
Image receiving means for receiving an image transmitted as a response to the image request from each of the S imaging devices;
An image receiving apparatus. An image receiving method performed by an image receiving device that receives an image captured by each of S imaging devices (S is a natural number of 2 or more) via a network,
When the number of images per unit time received from each of the S imaging devices is Fq (q is a natural number from 1 to S), each is a natural number greater than or equal to S and each of S Fqs. Is a calculation step for calculating a periodic division number N that satisfies a condition that is relatively prime;
The unit time is divided into N equal parts using the periodic division number N calculated in the calculation step, and each time when the unit time is divided into N equal parts is time Tp (p is a natural number from 1 to N). Steps,
Communication request timing Zk (k is a natural number from 1 to S) for starting the request for the image to each of the S imaging devices when requesting the image at regular intervals based on the Fq, A start time setting step of setting any value of S times Tp so that they are not set at the same time;
An image requesting step for starting a request for the image to each of the S imaging devices based on the time of the communication start timing Zk set in the start time setting step;
An image receiving step of receiving an image transmitted as a response to the image request from each of the S imaging devices,
An image receiving method.

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