Image transmission system, image transmission method, and program

Abstract

To provide an image transmission system, an image transmission method, and a program capable of stably transmitting an image picked up in an environment where radio communication using a high-speed communication line is limited.SOLUTION: The image transmission apparatus generates second images by dividing a first image captured by the imaging apparatus by a predetermined capacity based on a transmission capacity in first wireless communication that enables long-distance communication with low power consumption, and transmits each of the second images to the image transfer apparatus via the first wireless communication, the image transfer apparatus receives and accumulates the second image transmitted by the image transmission apparatus, and transmits the second image as a third image to the image reception apparatus by second wireless communication capable of communication faster than the first wireless communication in response to a request from the image reception apparatus, and the image reception apparatus requests transmission of the third image, receives the third image transmitted by the image transfer apparatus, and generates a fourth image reproducing the first image on the basis of the third image.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image transmission system, an image transmission method, and a program. [Background technology]

[0002] Conventionally, captured images have been transmitted wirelessly using high-speed communication lines such as cellular networks, the Internet, Wi-Fi (registered trademark), and Bluetooth (registered trademark). However, there are environments where wireless communication using high-speed communication lines is limited, such as mountainous regions and inside concrete buildings. For this reason, in environments where wireless communication using high-speed communication lines is limited, there is a growing demand for practical image transmission using a wireless communication method that enables long-distance communication with low power consumption, such as LPWA (Low Power Wide Area), instead of high-speed communication lines.

[0003] In this regard, techniques for wirelessly transmitting images in places that are difficult to access have been proposed (see, for example, Patent Document 1). The technique described in Patent Document 1 discloses determining the communication quality before transmitting an image, and dividing and transmitting the image according to the communication quality. By applying this conventional technique, it is believed that it will be possible to realize image transmission using a wireless communication method such as LPWA, which has a limited data transmission capacity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-087397 Summary of the Invention [Problem to be solved by the invention]

[0005] However, while the prior art discloses dividing and transmitting an image according to the determined communication quality, it does not disclose how to address limitations on data transmission capacity, which must be considered when dividing an image to be transmitted. Therefore, even if the prior art is applied to transmit captured images in an environment where wireless communication using high-speed communication lines is limited, it may be difficult to transmit the images stably. In the first place, wireless communication methods such as LPWA, which enable long-distance communication with low power consumption, are different from wireless communication methods using high-speed communication lines in that they do not check whether the transmitted data has been received correctly, making it difficult to confirm whether the image has been transmitted correctly.

[0006] The present invention has been made in light of the above-mentioned problems, and aims to provide an image transmission system, an image transmission method, and a program that can stably transmit captured images in an environment where wireless communication using high-speed communication lines is limited. [Means for solving the problem]

[0007] In order to solve the above problem, an image transmission system according to one embodiment of the present invention is an image transmission system that includes at least an image transmitting device, an image transfer device, and an image receiving device, and transmits a first image captured by an imaging device, wherein the image transmitting device generates second images by dividing the first image into predetermined capacity segments based on the transmission capacity of a first wireless communication that is capable of long-distance communication with low power consumption, and transmits each of the generated second images to the image transfer device via the first wireless communication, the image transfer device receives and stores the second images transmitted by the image transmitting device, and, in response to a request from the image receiving device, transmits the stored second images as third images to the image receiving device via a second wireless communication that is capable of communication at a higher speed than the first wireless communication, and the image receiving device requests the transmission of the third image, receives the third image transmitted by the image transfer device in response to the request, and generates a fourth image that reproduces the first image based on the received third images.

[0008] In addition, the image transmission device in the image transmission system according to one aspect of the present invention includes an acquisition unit that acquires the first image, a division unit that divides the first image to generate the second image, a first storage unit that stores the first image and the second image, and a first communication unit that transmits the second image to the image transmission device by the first wireless communication, and the image transmission device performs the first wireless communication with the first communication unit and includes a second communication unit that receives the second image transmitted by the image transmission device, a second storage unit that stores the second image, and and a third communication unit that transmits the image as the third image to the image receiving device via the second wireless communication, and the image receiving device comprises a fourth communication unit that performs the second wireless communication with the third communication unit and receives the third image transmitted by the image transfer device, a determination unit that determines whether the third images required to generate the fourth image are complete, a generation unit that generates the fourth image by combining the respective third images based on the result of the determination, and a third memory unit that stores the third image and the fourth image.

[0009] In addition, in an image transmission system according to one embodiment of the present invention, the division unit deletes at least fixed information contained in prefix data added to the first image, and then generates the second image by dividing the first image into the specified capacity, and the generation unit complements the information contained in the deleted prefix data to generate the fourth image.

[0010] Furthermore, in an image transmission system according to one aspect of the present invention, the division unit generates the second image by dividing the first image for each of the predetermined capacities within the constraints of the transmission capacity.

[0011] In addition, in an image transmission system according to one embodiment of the present invention, the division unit adds information indicating the order in which the first image was divided to each of the second images, and generates the second images by dividing the first image so that the capacity of the second images becomes the predetermined capacity with the information indicating the division order added; the determination unit determines whether there are any missing parts in the third images required to generate the fourth image based on the information indicating the division order; and the generation unit generates the fourth image by combining the respective third images based on the information indicating the division order and the result of the determination.

[0012] In addition, in an image transmission system according to one embodiment of the present invention, when the result of the judgment indicates that there is a gap in the third image required to generate the fourth image, the generation unit generates the fourth image by complementing the missing third image with a predetermined substitute image.

[0013] Furthermore, in an image transmission system according to an aspect of the present invention, when the determination unit determines that the third image required to generate the fourth image is missing, the determination unit outputs a first retransmission request to the fourth communication unit, requesting retransmission of the missing third image as a specific third image, the fourth communication unit transmits the first retransmission request to the third communication unit, the third communication unit receives the first retransmission request and outputs the received first retransmission request to the second communication unit, and the second communication unit transmits a second retransmission request to the first communication unit, requesting retransmission of a specific second image, which is the second image corresponding to the specific third image requested by the first retransmission request. The first communication unit receives the second retransmission request and transmits the specific second image requested by the received second retransmission request to the second communication unit, the second communication unit receives the specific second image and stores the received specific second image in the second memory unit, the third communication unit, in response to a request from the image receiving device, transmits the specific second image stored in the second memory unit as the specific third image to the fourth communication unit, the fourth communication unit receives the specific third image, and the generation unit regenerates the fourth image by replacing the substitute image in the generated fourth image with the specific third image.

[0014] Furthermore, an image transmission method according to one embodiment of the present invention is an image transmission method in an image transmission system that includes at least an image transmitting device, an image transfer device, and an image receiving device, and that transmits a first image captured by an imaging device, wherein a computer of the image transmitting device generates second images by dividing the first image into predetermined capacity segments based on the transmission capacity of a first wireless communication that is capable of long-distance communication with low power consumption, and transmits each of the generated second images to the image transfer device via the first wireless communication, and the computer of the image transfer device receives and stores the second images transmitted by the image transmitting device, and, in response to a request from the image receiving device, transmits the stored second images as third images to the image receiving device via a second wireless communication that is capable of communication at a higher speed than the first wireless communication, and the computer of the image receiving device requests the transmission of the third image, receives the third image transmitted by the image transfer device in response to the request, and generates a fourth image that reproduces the first image based on the received third images.

[0015] In addition, a program according to one embodiment of the present invention is a program that includes at least an image transmitting device, an image transfer device, and an image receiving device in an image transmission system that transmits a first image captured by an imaging device, and causes a computer of the image transmitting device to generate second images by dividing the first image into predetermined capacity segments based on the transmission capacity of a first wireless communication that enables long-distance communication with low power consumption, and transmits each of the generated second images to the image transfer device via the first wireless communication.

[0016] In addition, a program according to one aspect of the present invention is a program for an image transmission system including at least an image transmitting device, an image transfer device, and an image receiving device, which transmits a first image captured by the image transmitting device, and causes a computer of the image transfer device to receive and store second images, which are generated in the image transmitting device and transmitted by a first wireless communication capable of long-distance communication with low power consumption, and which are obtained by dividing the first image into predetermined capacity portions based on the transmission capacity of the first wireless communication, and which transmits the stored second images as third images to the image receiving device by the second wireless communication capable of faster communication than the first wireless communication, in response to a request from the image receiving device.

[0017] Furthermore, a program according to one aspect of the present invention is a program that includes at least an image transmitting device, an image transfer device, and an image receiving device, and that transmits a first image captured by an imaging device, and that requests a computer of the image receiving device to transmit, as a third image, a second image that the image transmitting device has generated by dividing the first image into predetermined capacity segments based on the transmission capacity of a first wireless communication that is capable of long-distance communication with low power consumption, and that receives, in response to the request, the third image transmitted by the image transfer device via a second wireless communication that is capable of faster communication than the first wireless communication, and that generates a fourth image that reproduces the first image based on the received third image. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide an image transmission system, an image transmission method, and a program that can stably transmit captured images in an environment where wireless communication using high-speed communication lines is limited. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram showing an example of the configuration of each component constituting an image transmission system according to an embodiment of the present invention, and an example of a usage environment. [Figure 2] FIG. 2 is a sequence diagram showing an example of the overall processing flow in the image transmission system according to the embodiment of the present invention. [Figure 3] FIG. 10 is a sequence diagram showing an example of another overall processing flow in the image transmission system according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an image transmission system, an image transmission method, and a program according to an embodiment will be described with reference to the drawings. In the following description, it is assumed that the image transmission system of the embodiment transmits images captured by a camera installed in a mountainous region to a monitoring station located in an urban area in order to monitor forest damage caused by wild birds and animals. In other words, in the image transmission system of the embodiment, it is assumed that the location where the image is captured and the location where the image is viewed are separated by, for example, several kilometers to several tens of kilometers.

[0021] [Image transmission system usage environment] 1 is a diagram showing an example of the configuration of each component constituting an image transmission system according to an embodiment of the present invention, and an example of a usage environment. The image transmission system 1 includes, for example, an image transmitting device 100, an image transfer device 200, and an image receiving device 300. In the image transmission system 1 shown in FIG. 1, a camera C is connected to the image transmitting device 100.

[0022] Camera C captures, for example, images (still images) for monitoring a predetermined imaging range. Camera C may be configured to capture images at predetermined time intervals, such as every two minutes, or may be equipped with a motion detection function and capture images when a moving (moving) subject is present within the imaging range, i.e., within the angle of view. Camera C captures images in a still image compression format, such as JPEG (Joint Photographic Experts Group) or PNG (Portable Network Graphics). The format of the images captured by camera C is not limited, and may be, for example, image formats such as GIF (Graphics Interchange Format), TIFF (Tagged Image File Format), or bitmap (BMP), or may be raw image format (RAW) data (so-called raw data). Camera C outputs the captured images to image transmitting device 100.

[0023] Camera C is an example of an "imaging device." The image captured and output by camera C is an example of a "first image."

[0024] The image transmitting device 100 is an edge device in the image transmission system 1. The image transmitting device 100 transmits an image output by a camera C to the image transfer device 200 using, for example, a wireless communication method that enables long-distance communication with low power consumption, such as LPWA (Low Power Wide Area) (hereinafter referred to as "LPWA communication"). LPWA communication is a communication standard that transmits and receives data less frequently, consumes less power, has a slower communication speed, and has a longer communication distance than high-speed communication using high-speed communication lines such as a cellular network, the Internet, Wi-Fi (registered trademark), or Bluetooth (registered trademark). For this reason, LPWA communication has limitations on the amount of data that can be transmitted at one time (transmission capacity). For this reason, the image transmitting device 100 divides the image data output by the camera C into predetermined amounts based on the transmission capacity of the LPWA communication. More specifically, the image transmitting device 100 divides the image data output by the camera C into predetermined amounts within the constraints of the transmission capacity. Then, the image transmitting device 100 sequentially transmits each of the divided data of a predetermined capacity (hereinafter referred to as "divided images") to the image transferring device 200 via LPWA communication. For example, when the communication distance between the image transmitting device 100 and the image transferring device 200 is long, the image transmitting device 100 may transmit the divided images to the image transferring device 200 via an LPWA repeater or LPWA access point (not shown). The LPWA repeater and LPWA access point (not shown) are equivalent to a repeater or access point that is generally used to widen the communication range or suppress attenuation of the communication signal (amplify the communication signal), and therefore detailed description thereof will be omitted.

[0025] LPWA communication is an example of a “first wireless communication.” The divided image is an example of a “second image.”

[0026] 1 shows a configuration in which the camera C and the image transmitting device 100 are separate entities, but the camera C and the image transmitting device 100 may be configured as an integrated unit. For example, the camera C may be configured to have the functions of the image transmitting device 100, or the image transmitting device 100 may be configured to have the functions of the camera C.

[0027] The image transfer device 200 is, for example, a server device compatible with LPWA communication. The image transfer device 200, for example, functions as a master device for LPWA communication and transfers segmented images (described later). The image transfer device 200 may be implemented, for example, in a provider device or a wireless base station. The image transfer device 200 may be implemented, for example, in a server device or a storage device incorporated in a cloud computing system. In this case, the functions of the image transfer device 200 may be implemented by multiple server devices and storage devices in the cloud computing system. For example, the functions of the image transfer device 200 may be implemented by a server device that functions as a master device for LPWA communication and a server device that communicates with the master device for LPWA communication. The image transfer device 200 receives and accumulates (stores) each segmented image transmitted from the image transmission device 100 via LPWA communication. In response to a request from the image receiving device 300, the image transfer device 200 transmits each accumulated (stored) segmented image to the image receiving device 300 via the network NW. In the following description, the divided images transmitted by the image transmitting device 200 to the image receiving device 300 via the network NW will be referred to as "image data" to distinguish them from the divided images transmitted from the image transmitting device 100 (divided images received by the image transferring device 200).

[0028] The image data is an example of a "third image."

[0029] The network NW is, for example, a communication network using a high-speed communication line. The network NW includes, for example, a cellular network such as a third-generation mobile communication system (so-called 3G), LTE (Long Term Evolution), a fourth-generation mobile communication system (so-called 4G), or a fifth-generation mobile communication system (so-called 5G), the Internet, a wide area network (WAN), a local area network (LAN), a Wi-Fi (registered trademark) network, a dedicated line, a provider device, a wireless base station, etc. The network NW may also include, for example, short-range wireless communication such as Bluetooth (registered trademark). In this case, for example, when some or all of the functions of the image receiving device 300 are realized by a portable terminal device, the image transfer device 200 can transmit image data to the image receiving device 300 realized by the terminal device when the portable terminal device enters a communication range of the short-range wireless communication.

[0030] The communication via the network NW is an example of a "second wireless communication."

[0031] The image receiving device 300 is, for example, a server device or a storage device incorporated in a cloud computing system. The image receiving device 300 may be realized by, for example, multiple server devices or storage devices in the cloud computing system. The image receiving device 300 may be realized by, for example, a portable terminal device such as a smartphone or a tablet terminal. The image receiving device 300 may be a dedicated terminal device compatible with the image transmission system 1. The image receiving device 300 requests the image transfer device 200 to transmit image data at predetermined timing (for example, at predetermined time intervals such as every 20 minutes). The image receiving device 300 generates images captured by the camera C from each piece of image data transmitted by the image transfer device 200 via the network NW in response to the transmitted image data request. More specifically, the image receiving device 300 performs a predetermined reconstruction process on each piece of image data to generate images (hereinafter referred to as "reconstructed images") that reproduce the original images captured by the camera C. The image receiving device 300 stores the generated reconstructed images. The image receiving device 300 provides the stored reconstructed image to a monitor who performs monitoring by checking the image captured by the camera C, for example.

[0032] The reconstructed image is an example of a "fourth image."

[0033] [Configuration of image transmitting device, image transfer device, and image receiving device] Next, the configurations of the image transmitting device 100, the image transferring device 200, and the image receiving device 300 that make up the image transfer system 1 will be described in more detail.

[0034] [Configuration of image transmission device] First, a description will be given of the configuration of the image transmitting device 100. The image transmitting device 100 includes an image acquiring unit 120, a processing circuit 140, an image storage unit 160, and an LPWA communication unit 180, for example.

[0035] The image storage unit 160 stores data of images output by the camera C (original images), images being processed by the processing circuit 140, or images for which processing has been completed. The image storage unit 160 is a storage device with a storage capacity for storing data of at least a predetermined number of images. The image storage unit 160 is realized by, for example, semiconductor memory elements such as ROM (Read Only Memory), RAM (Random Access Memory), and flash memory.

[0036] Image storage unit 160 is an example of a "first storage unit."

[0037] The image acquisition unit 120 acquires images output by the camera C. The image acquisition unit 120 acquires each image each time it is output from the camera C. The image acquisition unit 120 outputs each acquired image to the processing circuit 140. The image acquisition unit 120 may be configured to sequentially store acquired image data in the image storage unit 160, notify the processing circuit 140 of this, and the processing circuit 140 reads the image data stored in the image storage unit 160, thereby outputting the images acquired by the image acquisition unit 120 to the processing circuit 140. In this case, the image acquisition unit 120 may be configured to always store a predetermined number of image data, starting from the most recent image, in the image storage unit 160 within the storage capacity of the image storage unit 160, for example, after storing a predetermined number of image data, or after storing image data up to the storage capacity of the image storage unit 160, overwrite the oldest image data with newly acquired image data.

[0038] Image acquisition unit 120 is an example of an "acquisition unit."

[0039] The processing circuitry 140 performs processing for transmitting the image output by the image acquisition unit 120 to the image transfer device 200. The processing circuitry 140 executes processing such as an image division function 142 and a divided image transmission function 144. The processing circuitry 140 realizes each function such as the image division function 142 and the divided image transmission function 144 by, for example, a hardware processor executing a program (software) stored in a memory (not shown) (which may be the image storage unit 160). The memory (not shown) is realized by, for example, a semiconductor memory element such as a ROM, a RAM, or a flash memory.

[0040] The term "hardware processor" refers to a circuit such as a central processing unit (CPU), a graphics processing unit (GPU), a large-scale integration (LSI), a system on chip (SOC), an application-specific integrated circuit (ASIC), or a programmable logic device (e.g., a simple programmable logic device (SPLD) or a complex programmable logic device (CPLD), or a field programmable gate array (FPGA)). Instead of storing a program in a memory (not shown), the program may be directly embedded in the hardware processor. In this case, the hardware processor realizes each function by reading and executing the program embedded in the circuit. The hardware processor is not limited to a single circuit, but may be configured as a single hardware processor by combining multiple independent circuits to realize each function. Multiple components may be integrated into a single hardware processor to realize each function. Multiple components may be integrated into a single dedicated LSI to realize each function. Here, the program (software) may be stored in advance in a storage device (a non-transitory storage device (which may be the image storage unit 160)) such as a semiconductor memory element such as a ROM, RAM, or flash memory. The program (software) may be downloaded in advance from another computer device by a predetermined method and installed in a storage device (which may be the image storage unit 160) included in the image transmitting device 100. The program (software) installed in the storage device included in the image transmitting device 100 may be transferred to the processing circuit 140 included in the image transmitting device 100 and executed.

[0041] Each time an image is output from the image acquisition unit 120, that is, each time the camera C captures a new image, the image division function 142 divides the data of each image into predetermined sizes within the transmission capacity constraints of LPWA communication, thereby generating divided images. At this time, the image division function 142 adds a consecutive serial number to each divided image as information indicating the order in which the image data was divided. For example, the image division function 142 adds the serial number to the beginning of each divided image. Therefore, the image division function 142 generates each divided image by dividing the image data so that the size of the divided image with the serial number added falls within the transmission capacity constraints. For example, when dividing 1 kilobyte of image data to generate 50-byte divided images, if the serial number is 2 bytes, the image division function 142 divides the image data into 48 bytes each (50 bytes - 2 bytes). In this case, the image division function 142 divides the image data into 21 pieces (1000 bytes / 48 bytes = ≈ 21 pieces), adds a serial number to the beginning, and generates divided images of 50 bytes each (however, the number of bytes in the last divided image is different).

[0042] In addition to the serial number, the image division function 142 may add a consecutive image number as information for identifying the order of the images output by the image acquisition unit 120, in other words, the order of the images captured by the camera C. In this case, the image division function 142 generates each divided image by dividing the image data so that the capacity of the divided image with the serial number and image number added is within the constraints of the transmission capacity.

[0043] Incidentally, the image captured and output by camera C is provided with prefix data, so-called header data, that represents information about the image. For example, an image in an image format such as JPEG has header data that includes information such as the image size and resolution, the image file size, the image capture conditions (exposure, shutter speed, etc.), the capture time, and the manufacturer of camera C. This header data includes information that varies for each captured image, such as the image file size, and fixed information that remains constant for each image, such as the manufacturer of camera C. This fixed information can be supplemented, for example, by the image receiving device 300. For this reason, the image segmentation function 142 deletes at least the fixed information that is added as header data to the image output by the image acquisition unit 120, and then generates each divided image by dividing the image data. For example, if the header data of an image is all fixed information, the image segmentation function 142 deletes the header data added to the image, leaving only data representing the subject captured by camera C, and then segments the image into each divided image. This makes it possible to reduce the number of LPWA communications performed when all divided images corresponding to one image are transmitted from the image transmitting device 100 to the image transferring device 200.

[0044] The header data information deleted by the image division function 142 is not limited to fixed information, and information specific to the captured image may be deleted if it is information that can be supplemented by the image receiving device 300 or information that is not necessary when an observer checks the image. In this case, it is considered that a reconstructed image can be generated in the image receiving device 300 if there is at least information on the size of the captured image.

[0045] The image division function 142 stores the divided images thus obtained (including serial numbers and may also include image numbers) in the image storage unit 160.

[0046] The image division function 142 is an example of a "division unit."

[0047] Each time the image segmentation function 142 generates a segmented image corresponding to an image output by the image acquisition unit 120, the segmented image transmission function 144 controls transmission of each segmented image stored in the image storage unit 160 to the image transfer device 200. More specifically, the segmented image transmission function 144 sequentially specifies, to the LPWA communication unit 180, the serial numbers (which may include image numbers) of the segmented images to be transmitted to the image transfer device 200, or the storage areas of the image storage unit 160 in which the segmented images are stored, and causes the segmented images to be transmitted via LPWA communication. Instead of sequentially specifying, to the LPWA communication unit 180, the segmented image transmission function 144 may sequentially read out each segmented image stored in the image storage unit 160, output the segmented images to the LPWA communication unit 180, and cause the output segmented images to be transmitted to the image transfer device 200. The divided image transmission function 144 may cause the LPWA communication unit 180 to start transmitting the divided images when the image division function 142 has completed generating the first divided image corresponding to a new image, or may cause the LPWA communication unit 180 to start transmitting the divided images when the image division function 142 has completed generating all divided images corresponding to one image.

[0048] The divided image transmission function 144 causes the LPWA communication unit 180 to transmit start data prior to transmitting the divided images corresponding to one image, then causes the LPWA communication unit 180 to transmit each divided image sequentially, and after transmitting all divided images corresponding to one image, causes the LPWA communication unit 180 to transmit end data. The start data includes, for example, information indicating that transmission of divided images is about to begin, information indicating the number of divided images to be transmitted (i.e., the number of divisions into which the image division function 142 divided the image), and information indicating the size of the image captured by the camera C (i.e., the size of the original image). The start data may also include information that needs to be communicated to a supervisor or the like in order for the camera C or the image transmission device 100 to operate, such as a battery (not shown) provided in the camera C or the image transmission device 100. The end data includes, for example, information indicating that transmission of the divided images has ended (completion). The end data may be the same data as the operating data that the image transmitting device 100 periodically transmits to the image transferring device 200 to indicate that the camera C and the image transmitting device 100 are operating. The divided image transmitting function 144 may store the start data and the end data in the image storage unit 160 and transmit them to the LPWA communication unit 180 by designating them as divided images to be transmitted to the image transferring device 200, or may read out the start data and the end data stored in the image storage unit 160 at suitable timing as divided images to be transmitted to the image transferring device 200 and output them to the LPWA communication unit 180, thereby transmitting them to the LPWA communication unit 180.

[0049] When information requesting the retransmission of a specific divided image is output from the LPWA communication unit 180, the divided image transmission function 144 causes the LPWA communication unit 180 to retransmit the requested specific divided image from among the divided images stored in the image storage unit 160. The information requesting the retransmission of the specific divided image indicates, for example, a serial number (which may include an image number) attached to the specific divided image. In this case, too, the divided image transmission function 144 may specify the serial number (which may include an image number) of the requested specific divided image to be retransmitted to the image transfer device 200, or the storage area of ​​the image storage unit 160 in which the divided image is stored, or may read the requested specific divided image from the image storage unit 160 and output it to the LPWA communication unit 180.

[0050] The LPWA communication unit 180 performs LPWA communication with the image transfer device 200. When a divided image (including start data and end data) to be transmitted to the image transfer device 200 is specified by the processing circuit 140 (more specifically, the divided image transmission function 144), the LPWA communication unit 180 reads the specified divided image from the image storage unit 160 and transmits the read divided image to the image transfer device 200. When a divided image (including start data and end data) to be transmitted to the image transfer device 200 is output by the divided image transmission function 144, the LPWA communication unit 180 transmits the divided image to the image transfer device 200.

[0051] When the image transfer device 200 requests the retransmission of a specific divided image, the LPWA communication unit 180 outputs information representing the requested specific divided image to the processing circuit 140. Instead of outputting information representing the requested specific divided image to the processing circuit 140, the LPWA communication unit 180 may read the requested specific divided image from the image storage unit 160 and retransmit it to the image transfer device 200.

[0052] The configuration in which the divided image transmission function 144 and the LPWA communication unit 180 are combined is an example of a "first communication unit."

[0053] With this configuration, the image transmitting device 100 sequentially transmits divided images obtained by dividing an image captured by the camera C to the image transfer device 200 via LPWA communication.

[0054] [Image transfer device configuration] Next, a description will be given of the configuration of the image transfer device 200. The image transfer device 200 includes an LPWA communication unit 220, a processing circuit 240, a divided image storage unit 260, and a network communication unit 280, for example.

[0055] The divided image storage unit 260 stores divided images transmitted by the image transmission device 100 via LPWA communication. The divided image storage unit 260 is a storage device with a storage capacity for storing divided images corresponding to at least a predetermined number of images captured by the camera C. The divided image storage unit 260 is realized by, for example, a semiconductor memory element such as a ROM, RAM, or flash memory, a hard disk drive (HDD), an optical disk, or the like.

[0056] The divided image storage unit 260 is an example of a "second storage unit."

[0057] The LPWA communication unit 220 performs LPWA communication with the image transmitting device 100 (more specifically, the LPWA communication unit 180 included in the image transmitting device 100). The LPWA communication unit 220 receives the divided images (including start data and end data) transmitted by the LPWA communication unit 180, and outputs each of the received divided images to the processing circuit 240. The LPWA communication unit 220 may be configured to sequentially store each of the received divided images in the divided image storage unit 260, notify the processing circuit 240 of this fact, and the processing circuit 240 may read out the divided images stored in the divided image storage unit 260, thereby outputting the divided images received by the LPWA communication unit 220 to the processing circuit 240. In this case, the LPWA communication unit 220 may be configured to always store in the split image storage unit 260 split images corresponding to a predetermined number of images, starting from the most recent image, within the storage capacity of the split image storage unit 260, by overwriting the oldest split image with a newly received split image, after storing split images corresponding to a predetermined number of images, or until the split image storage unit 260 has reached its storage capacity.

[0058] When information indicating that the image receiving device 300 has requested the retransmission of specific image data (divided images including start data and end data) is output from the processing circuit 240 or the network communication unit 280, the LPWA communication unit 220 transmits information requesting the retransmission of specific divided images (including start data and end data) corresponding to the requested specific image data to the LPWA communication unit 180 via LPWA communication.

[0059] Information that requests retransmission of a specific divided image (including start data and end data) corresponding to specific image data, which is transmitted from LPWA communication unit 220 to LPWA communication unit 180, is an example of a "second retransmission request." The specific divided image (including start data and end data) is an example of a "specific second image."

[0060] The processing circuitry 240 performs processing for transmitting the divided images output by the LPWA communication unit 220 to the image receiving device 300. The processing circuitry 240 executes processing such as the divided image transfer function 242. The processing circuitry 240 realizes each function such as the divided image transfer function 242 by, for example, having a hardware processor execute a program (software) stored in a memory (not shown) (which may be the divided image storage unit 260). The memory (not shown) is realized by, for example, a semiconductor memory element such as a ROM, RAM, or flash memory, a hard disk drive (HDD), an optical disk, or the like.

[0061] A hardware processor refers to a circuit such as a CPU, GPU, LSI, SOC, application-specific integrated circuit (ASIC), or programmable logic device (e.g., simple programmable logic device (SPLD) or complex programmable logic device (CPLD), or field programmable gate array (FPGA)). Instead of storing a program in a memory (not shown), the program may be directly embedded in the circuit of the hardware processor. In this case, the hardware processor realizes each function by reading and executing the program embedded in the circuit. The hardware processor is not limited to being configured as a single circuit, but may be configured as a single hardware processor by combining multiple independent circuits to realize each function. Multiple components may be integrated into a single hardware processor to realize each function. Multiple components may be incorporated into a single dedicated LSI to realize each function. Here, the program (software) may be stored in advance in a storage device (non-transitory storage device (which may be the divided image storage unit 260)) such as a semiconductor memory element such as a ROM, RAM, or flash memory, or a HDD, or may be stored in a removable storage medium (non-transitory storage medium) such as a DVD or CD-ROM, and may be installed in the storage device of the image transfer device 200 by inserting the storage medium into a drive device of the image transfer device 200. The program (software) may be downloaded in advance from another computer device including a server device or storage device incorporated in a cloud computing system via a network (which may be a network NW) (not shown), and installed in the storage device of the image transfer device 200 (which may be the divided image storage unit 260). The program (software) installed in the storage device of the image transfer device 200 may be transferred to the processing circuitry 240 of the image transfer device 200 and executed.

[0062] The divided image transfer function 242 controls the transmission of the divided images (including start data and end data) output by the LPWA communication unit 220 to the image receiving device 300. In other words, the divided image transfer function 242 controls the transfer of the divided images transmitted by the image transmitting device 100 to the image receiving device 300.

[0063] The divided image transfer function 242 sequentially specifies a storage area in the divided image storage unit 260 each time an image is output from the LPWA communication unit 220, and sequentially stores the divided images in the divided image storage unit 260. When notified by the LPWA communication unit 220 that the received divided images have been stored in the divided image storage unit 260, the divided image transfer function 242 may manage the storage area in which the LPWA communication unit 220 has stored the divided images, or may manage the storage area of ​​the divided images by moving the divided images stored by the LPWA communication unit 220 to another storage area in the divided image storage unit 260. When start data is output as a divided image by the LPWA communication unit 220, the divided image transfer function 242 may add the time at which this start data was stored in the divided image storage unit 260 (which may be the time at which the LPWA communication unit 220 received the start data) to the start data as the time at which the image was captured by camera C (i.e., the shooting time) and store the result in the divided image storage unit 260.

[0064] When the network communication unit 280 outputs information indicating that the image receiving device 300 has requested transmission of a divided image, the divided image transfer function 242 causes the network communication unit 280 to transmit the divided image stored in the divided image storage unit 260 to the image receiving device 300 as image data via the network NW in response to this request. More specifically, the divided image transfer function 242 causes the network communication unit 280 to specify a storage area in the divided image storage unit 260 in which start data to be transmitted to the image receiving device 300 is stored, and transmit the image data via the network NW. Next, the divided image transfer function 242 causes the network communication unit 280 to sequentially specify storage areas in the divided image storage unit 260 in which divided images to be transmitted to the image receiving device 300 are stored, and transmit the image data via the network NW. Finally, the divided image transfer function 242 causes the network communication unit 280 to specify a storage area in the divided image storage unit 260 in which end data to be transmitted to the image receiving device 300 is stored, and transmit the image data via the network NW. When specifying a storage area for a divided image to be transmitted as image data to the network communication unit 280, the divided image transfer function 242 may specify a storage area for a plurality of divided images and transmit image data combining the plurality of divided images stored in the divided image storage unit 260. Instead of sequentially specifying to the network communication unit 280 divided images (including start data and end data) to be transmitted to the image receiving device 300, the divided image transfer function 242 may sequentially read out each divided image (including start data and end data) stored in the divided image storage unit 260, output them to the network communication unit 280, and transmit the output divided images to the image receiving device 300 as image data.

[0065] When information requesting the retransmission of specific image data (a divided image including start data and end data) is output from the network communication unit 280, the divided image transfer function 242 outputs information indicating a request for this specific image data to the LPWA communication unit 220, and causes it to be transmitted to the image transmitting device 100 (more specifically, the LPWA communication unit 180) via LPWA communication.

[0066] The network communication unit 280 communicates with the image receiving device 300 via the network NW. When a divided image (including start data and end data) to be transmitted to the image receiving device 300 is specified by the processing circuit 240 (more specifically, the divided image transfer function 242), the network communication unit 280 reads the specified divided image from the divided image storage unit 260 and transmits the read divided image to the image receiving device 300 as image data. When the divided image (including start data and end data) to be transmitted to the image receiving device 300 is output as image data by the divided image transfer function 242, the network communication unit 280 transmits this image data to the image receiving device 300.

[0067] When information requesting the retransmission of specific image data (divided images including start data and end data) is transmitted from image receiving device 300, network communication unit 280 outputs information requesting specific divided images (including start data and end data) representing the requested specific image data to processing circuitry 240. Instead of outputting the information representing the requested specific image data to processing circuitry 240, network communication unit 280 may output this information to LPWA communication unit 220.

[0068] The configuration combining the divided image transfer function 242 and the LPWA communication unit 220 is an example of a “second communication unit.” The configuration combining the divided image transfer function 242 and the network communication unit 280 is an example of a “third communication unit.”

[0069] With this configuration, the image transfer device 200 receives each divided image transmitted by the image transmission device 100 via LPWA communication, and transmits each received divided image as image data to the image reception device 300 via the network NW in response to a request from the image reception device 300.

[0070] [Configuration of image receiving device] Next, a description will be given of the configuration of the image reception device 300. The image reception device 300 includes a network communication unit 320, a processing circuit 340, and an image storage unit 360, for example.

[0071] The image storage unit 360 is a storage device that stores the reconstructed image generated by the processing circuitry 340. The image storage unit 360 may store image data transmitted by the image transfer device 200 via the network NW. The image storage unit 360 is realized by, for example, a semiconductor memory element such as a ROM, a RAM, or a flash memory, a hard disk drive (HDD), an optical disk, or the like.

[0072] 1 shows a configuration in which the image storage unit 360 is provided inside the image receiving device 300, but the image storage unit 360 may be configured outside the image receiving device 300. In this case, the image storage unit 360 may be, for example, a storage device connected to the image receiving device 300, or a storage device incorporated in a cloud computing system.

[0073] The image storage unit 360 is an example of a "third storage unit."

[0074] The network communication unit 320 communicates with the image transfer device 200 (more specifically, the network communication unit 280 included in the image transfer device 200) via the network NW. The network communication unit 320 requests the network communication unit 280 to transmit each piece of image data in accordance with control from the processing circuitry 340. The network communication unit 320 receives the image data (divided images including start data and end data) transmitted by the network communication unit 280, and outputs each piece of received image data to the processing circuitry 340. The network communication unit 320 may be configured to sequentially store each piece of received image data in the image storage unit 360, notify the processing circuitry 340 of this, and the processing circuitry 340 reads the image data stored in the image storage unit 360, thereby outputting the image data received by the network communication unit 320 to the processing circuitry 340. In this case, the network communication unit 320 may notify the processing circuit 340 of this when it stores the first image data transmitted by the network communication unit 280, i.e., the divided image of the start data, in the image storage unit 360, or when it stores the last image data transmitted by the network communication unit 280, i.e., the divided image of the end data, in the image storage unit 360, in other words, when it stores all the image data transmitted by the network communication unit 280 in the image storage unit 360.

[0075] When the processing circuit 340 requests the retransmission of specific image data (divided image including start data and end data), that is, when a request is made to retransmit image data, the network communication unit 320 transmits information requesting the transmission (retransmission) of this specific image data (divided image including start data and end data) to the network communication unit 280 via the network NW.

[0076] The network communication unit 320 is an example of a "fourth communication unit."

[0077] The processing circuitry 340 requests the image transfer device 200 to transmit image data (divided images including start data and end data) at predetermined time intervals. The processing circuitry 340 performs processing to generate a reconstructed image (an image that reproduces the original image captured by the camera C) based on the image data (divided images including start data and end data) output by the network communication unit 320. The processing circuitry 340 executes processes such as an image data determination function 342 and an image reconstruction function 344. The processing circuitry 340 realizes each function such as the image data determination function 342 and the image reconstruction function 344 by, for example, a hardware processor executing a program (software) stored in a memory (not shown) (which may be the image storage unit 360). The memory (not shown) may be realized by, for example, a semiconductor memory element such as a ROM, RAM, or flash memory, a hard disk drive (HDD), an optical disk, or the like.

[0078] A hardware processor refers to a circuit such as a CPU, GPU, LSI, SOC, application-specific integrated circuit (ASIC), or programmable logic device (e.g., simple programmable logic device (SPLD) or complex programmable logic device (CPLD), or field programmable gate array (FPGA)). Instead of storing a program in a memory (not shown), the program may be directly embedded in the circuit of the hardware processor. In this case, the hardware processor realizes each function by reading and executing the program embedded in the circuit. The hardware processor is not limited to being configured as a single circuit, but may be configured as a single hardware processor by combining multiple independent circuits to realize each function. Multiple components may be integrated into a single hardware processor to realize each function. Multiple components may be incorporated into a single dedicated LSI to realize each function. Here, the program (software) may be stored in advance in a storage device (non-transitory storage device (which may be the image storage unit 360)) such as a semiconductor memory element such as a ROM, RAM, or flash memory, or a HDD, or may be stored in a removable storage medium (non-transitory storage medium) such as a DVD or CD-ROM, and may be installed in the storage device of the image receiving device 300 by inserting the storage medium into a drive device of the image receiving device 300. The program (software) may be downloaded in advance from another computer device including a server device or storage device incorporated in a cloud computing system via a network (which may be a network NW) (not shown), and installed in the storage device of the image receiving device 300 (which may be the image storage unit 360). The program (software) installed in the storage device of the image receiving device 300 may be transferred to the processing circuit 340 of the image receiving device 300 and executed.

[0079] The image data determination function 342 determines whether the number of image data (divided images including start data and end data) output by the network communication unit 320 is sufficient for the information indicating the number of divided images included in the image data of the start data, i.e., whether the amount of image data necessary to generate a reconstructed image is sufficient. This determination is made by determining whether there are any gaps in the consecutive serial numbers (which may include consecutive image numbers) added to each piece of image data from the start data to the end data output by the network communication unit 320, i.e., the serial numbers added to each divided image of the same original image captured by camera C. More specifically, when each piece of image data received from the network communication unit 320 is output sequentially, or when each piece of received image data is stored sequentially in the image storage unit 360 and notified, the image data determination function 342 determines whether the consecutive serial numbers added to each piece of image data are in order. On the other hand, when the image data determination function 342 is notified that all image data received from the network communication unit 320 has been stored in the image storage unit 360, it determines whether all of the consecutive serial numbers attached to each piece of image data stored in the image storage unit 360 are present.

[0080] If there are no gaps in the serial numbers added to the image data, the image data determination function 342 determines that the amount of image data necessary to generate a reconstructed image is complete. In this case, the image data determination function 342 outputs information indicating this to the image reconstruction function 344. On the other hand, if there are gaps in the serial numbers added to the image data, the image data determination function 342 determines that the amount of image data necessary to generate a reconstructed image is not complete. In this case, the image data determination function 342 outputs information indicating this and information about the missing serial numbers to the image reconstruction function 344. In the following description, information indicating whether the amount of image data necessary to generate a reconstructed image is complete (including information about the missing serial numbers if there are gaps in the serial numbers added to the image data) is referred to as "missing information."

[0081] When the image data determination function 342 determines that the amount of image data necessary to generate a reconstructed image is not available, it outputs information requesting the transmission (retransmission) of specific image data (divided images including start data and end data) including the serial number (which may include the image number) of the missing image data and a request to retransmit the image data with this serial number to the network communication unit 320. As a result, the network communication unit 320 transmits information requesting the transmission (retransmission) of specific image data (divided images including start data and end data) to the network communication unit 280, i.e., the image transfer device 200, via the network NW.

[0082] Image data determination function 342 is an example of a "determination unit." Information (information on the serial number (which may include the image number) of the missing image data and a request to resend the image data of this serial number) that image data determination function 342 outputs to network communication unit 320 and that network communication unit 320 transmits to network communication unit 280, requesting transmission (retransmission) of specific image data (divided image including start data and end data), is an example of a "first retransmission request." The specific image data (divided image including start data and end data) is an example of a "specific third image."

[0083] The image reconstruction function 344 performs a predetermined reconstruction process on the image data (divided images including start data and end data) output by the network communication unit 320 to generate a reconstructed image. The reconstruction process is the reverse of the process performed by the image division function 142 in the processing circuit 140 of the image transmission device 100 to divide the image data output by the camera C. More specifically, the image reconstruction function 344 first complements, in the header data to be added to the reconstructed image to be generated, information that was deleted when the image transmission device 100 transmitted the divided images to the image transfer device 200. For example, the image reconstruction function 344 complements predetermined fixed information as information to be included in the header data to be added to the reconstructed image to be generated. Then, the image reconstruction function 344 recreates data representing the subject captured by the camera C in the reconstructed image to be generated based on the missing information output by the image data determination function 342. At this time, if the missing information indicates that the amount of image data necessary to generate a reconstructed image is complete, the image reconstruction function 344 reproduces data representing the subject by sequentially arranging the divided image data based on the serial numbers (which may include image numbers) attached to each piece of image data. On the other hand, if the missing information indicates that the amount of image data necessary to generate a reconstructed image is not complete, the image reconstruction function 344 also sequentially arranging the divided image data based on the serial numbers attached to each piece of image data, but reproduces data representing the subject by substituting predetermined dummy image data for the missing image data. The dummy image data is image data in which all data is a predetermined value (e.g., "0"). In other words, the image reconstruction function 344 reproduces data representing the subject by complementing and substituting the missing image data with the dummy image data. The image reconstruction function 344 stores the reconstructed image generated in this manner in the image storage unit 360.

[0084] When the image data determination function 342 determines that the amount of image data required to generate a reconstructed image is not available, the image data with the missing serial number requested is retransmitted, and the retransmitted image data is output from the network communication unit 320, the image reconstruction function 344 replaces the complemented dummy image data with the retransmitted image data and performs the reconstruction process again. This allows the image reconstruction function 344 to generate a reconstructed image with all the image data available, that is, a reconstructed image that reproduces one image captured by the camera C.

[0085] The image reconstruction function 344 is an example of a "generator." The dummy image data is an example of a "substitute image."

[0086] With this configuration, the image receiving device 300 receives each image data (divided images including start data and end data) transmitted by the image transfer device 200 via the network NW, and generates an image (reconstructed image) captured by the camera C from the received image data. The image receiving device 300 then stores the generated reconstructed image in the image storage unit 360. As a result, the image receiving device 300 can display the reconstructed image stored in the image storage unit 360 as an image captured by the camera C, for example, on a display device (not shown), and provide it to a monitor or the like.

[0087] [Overall processing flow in the image transmission system] Next, an example of the overall processing flow in the image transmission system 1 will be described. Fig. 2 is a sequence diagram showing an example of the overall processing flow in the image transmission system 1 according to an embodiment of the present invention. The sequence diagram shown in Fig. 2 shows the flow of each process when the image receiving device 300 communicates with the image transmission device 200 via the network NW and starts generating a reconstructed image while the image transmission device 100 is transmitting segmented images corresponding to one image captured by the camera C to the image transmission device 200 via LPWA communication. In the following description, for ease of explanation, the LPWA communication between the image transmission device 100 and the image transmission device 200 and the communication via the network NW between the image transmission device 200 and the image reception device 300 will be omitted as appropriate. Furthermore, in the following description, for ease of explanation, it is assumed that the image acquisition unit 120 included in the image transmitting device 100 stores data of an image captured by the camera C in the image storage unit 160, the LPWA communication unit 220 included in the image transferring device 200 receives the divided image transmitted by the image transmitting device 100 and stores (accumulates) it in the divided image storage unit 260, and the network communication unit 320 included in the image receiving device 300 receives the image data transmitted by the image transferring device 200 and stores it in the image storage unit 360. Furthermore, the notification by each component to the corresponding processing circuit that data has been stored in the corresponding storage unit will be omitted as appropriate.

[0088] In the image transmitting device 100, the image acquiring unit 120 acquires an image output by the camera C (step S100). As a result, the processing circuit 140 generates divided images by dividing the image acquired by the image acquiring unit 120 using the image dividing function 142. Then, the processing circuit 140 starts transmitting each of the divided images generated by the image dividing function 142 to the image transfer device 200 using the divided image transmitting function 144 (step S101).

[0089] When the divided image transmission function 144 starts transmitting the divided images to the image transfer device 200, it first outputs start data as divided images to the LPWA communication unit 180, and causes the image transfer device 200 to transmit the start data (step S102). As a result, in the image transfer device 200, the LPWA communication unit 220 receives the start data transmitted by the LPWA communication unit 180, and starts receiving the divided images transmitted by the LPWA communication unit 180 (step S200). The LPWA communication unit 220 stores (accumulates) the received start data (divided images) in the divided image storage unit 260.

[0090] The divided image transmission function 144 checks whether there is a retransmission request for the specific divided image from the image transfer device 200 (step S103). If it is confirmed in step S103 that there is no retransmission request for the specific divided image from the image transfer device 200, the divided image transmission function 144 proceeds to step S105.

[0091] The divided image transmission function 144 outputs the first divided image generated by the image division function 142 to the LPWA communication unit 180, causing the first divided image to be transmitted to the image transfer device 200 (step S105). As a result, the LPWA communication unit 220 receives the divided image transmitted by the LPWA communication unit 180, and stores (accumulates) the received divided image in the divided image storage unit 260 (step S201).

[0092] In the image receiving device 300, the processing circuit 340 checks whether it is the predetermined timing to acquire image data from the image transfer device 200 (step S300). If it is confirmed in step S300 that it is not the predetermined timing to acquire image data, the processing circuit 340 repeats the processing of step S300.

[0093] On the other hand, if it is confirmed in step S300 that it is the predetermined timing to acquire image data, the processing circuitry 340 outputs a request for the image data to the network communication unit 320, which transmits the request to the image transfer device 200 (step S301). In the image transfer device 200, the network communication unit 280 receives the request for the image data transmitted by the network communication unit 320, and notifies the processing circuitry 240. As a result, the processing circuitry 240 outputs the divided images stored in the divided image storage unit 260 by the divided image transfer function 242 to the network communication unit 280, which transmits the divided images to the image receiving device 300 as image data (step S202).

[0094] In the image receiving device 300, the network communication unit 320 receives the image data transmitted by the network communication unit 280, and the processing circuit 340 uses the image data determination function 342 to determine the received image data (step S302). The image data determination function 342 determines whether or not there is a gap in the image data by determining whether or not there is a gap in the serial number added to each piece of received image data (step S303). If it is determined in step S303 that there is no gap in the image data, the image data determination function 342 proceeds to step S305.

[0095] On the other hand, if it is determined in step S303 that a gap has occurred in the image data, the image data determination function 342 outputs the gap information to the image reconstruction function 344. Furthermore, the image data determination function 342 outputs information on the serial number of the missing image data and a retransmission request to the network communication unit 320, causing the image transfer device 200 to transmit a request to retransmit the missing image data (specific image data) (step S304). As a result, in the image transfer device 200, the network communication unit 280 receives the retransmission request for the specific image data transmitted from the network communication unit 320, and the LPWA communication unit 220 transmits a retransmission request for the specific divided image to the LPWA communication unit 180 (step S203).

[0096] In step S103, when it is confirmed that there is a retransmission request for a specific divided image from the image transfer device 200, the divided image transmission function 144 outputs the divided image for which the retransmission request has been made to the LPWA communication unit 180, and causes it to be transmitted to the image transfer device 200 (step S104). As a result, the image transfer device 200 stores (accumulates) the divided image for which the retransmission request has been made in the divided image storage unit 260 (step S201).

[0097] In step S103, after confirming that there is no request from the image transfer device 200 to resend a specific divided image, or after having the image transfer device 200 transmit the divided image for which a resend request has been made in step S104, the divided image transmission function 144 checks whether transmission of all divided images corresponding to one image to the image transfer device 200 has been completed (step S106).

[0098] If it is confirmed in step S106 that transmission of all divided images corresponding to one image to the image transfer device 200 has not been completed, the divided image transmission function 144 returns the process to step S103. In this way, the divided image transmission function 144 repeats the processes of steps S103 to S106, and while checking whether there is a retransmission request for a specific divided image from the image transfer device 200, sequentially outputs all divided images corresponding to one image to the LPWA communication unit 180 and causes them to be transmitted to the image transfer device 200.

[0099] On the other hand, if it is confirmed in step S106 that transmission of all divided images corresponding to one image to the image transfer device 200 has been completed, the divided image transmission function 144 outputs the end data as divided images to the LPWA communication unit 180, which transmits the divided images to the image transfer device 200 (step S107). Then, the image transfer device 100 ends transmission of divided images corresponding to the image currently acquired by the image acquisition unit 120 from camera C to the image transfer device 200 (step S108). Then, the image transfer device 100 returns the process to step S100.

[0100] In the image transfer device 200, the LPWA communication unit 220 receives the end data transmitted by the LPWA communication unit 180, and stores (accumulates) the received end data (divided images) in the divided image storage unit 260. Then, in the image transfer device 200, reception of the divided images transmitted by the LPWA communication unit 180 ends (step S204).

[0101] After determining in step S303 that no gaps have occurred in the image data, or after causing the image transfer device 200 to transmit a request to retransmit the missing image data (specific image data) in step S304, the processing circuitry 340 generates a reconstructed image using the image reconstruction function 344. At this time, the image reconstruction function 344 generates a reconstructed image by sequentially combining the image data currently obtained (by combining dummy image data in place of the image data indicated by the gap information). Then, the image reconstruction function 344 stores (saves) the reconstructed images generated up to this point in time in the image storage unit 360 (step S305).

[0102] Thereafter, the image data determination function 342 determines whether or not the received image data includes end data (step S306). If it is determined in step S306 that the received image data does not include end data, the image data determination function 342 returns the process to step S301, outputs a request for image data to the network communication unit 320, and causes it to be transmitted to the image transfer device 200. In other words, the image receiving device 300 continues to obtain image data from the image transfer device 200.

[0103] On the other hand, if it is determined in step S306 that the received image data includes end data, the processing circuitry 340 ends the generation of the current reconstructed image and the storage (saving) of the image in the image storage unit 360. Then, the processing circuitry 340 returns the process to step S300 and waits until a predetermined timing for acquiring image data corresponding to the next image captured by the camera C from the image transfer device 200.

[0104] According to this processing flow, in the image transmission system 1, the image transmitting device 100 sequentially transmits divided images obtained by dividing an image captured by the camera C to the image transmitting device 200. Then, in the image transmission system 1, the image transmitting device 200 transmits each divided image transmitted by the image transmitting device 100 to the image receiving device 300 as image data in response to a request from the image receiving device 300. Furthermore, in the image transmission system 1, the image receiving device 300 generates an image captured by the camera C (reconstructed image) based on each image data (divided image including start data and end data) transmitted by the image transmitting device 200, and stores (saves) the generated reconstructed image in the image storage unit 360. In this way, the image receiving device 300 can provide the reconstructed image stored in the image storage unit 360 to a monitor or the like by displaying it, for example, on a display device (not shown) as an image captured by the camera C.

[0105] [Overall processing flow in the image transmission system] Next, an example of another overall processing flow in the image transmission system 1 will be described. FIG. 3 is a sequence diagram showing an example of another overall processing flow in the image transmission system 1 according to an embodiment of the present invention. The sequence diagram shown in FIG. 3 illustrates the flow of each processing when, after the image transmitting device 100 has finished transmitting segmented images corresponding to one image captured by camera C to the image transmitting device 200 via LPWA communication, the image receiving device 300 communicates with the image transmitting device 200 via the network NW and starts generating a reconstructed image. In the following description, similar to the description of the sequence diagram shown in FIG. 2, for ease of explanation, the LPWA communication between the image transmitting device 100 and the image transmitting device 200 and the communication via the network NW between the image transmitting device 200 and the image receiving device 300 will be omitted as appropriate. Furthermore, in the following description, similar to the description of the sequence diagram shown in FIG. 2, for ease of explanation, each component will be assumed to store (accumulate) data in a corresponding storage unit, and notification of this to a corresponding processing circuit will be omitted as appropriate.

[0106] The sequence diagram shown in Fig. 3 includes processes similar to those in the sequence diagram shown in Fig. 2. Therefore, in the following explanation, the same step numbers are assigned to processes similar to those in the sequence diagram shown in Fig. 2, and detailed explanations of the same processes will be omitted. Furthermore, for ease of explanation, the sequence diagram shown in Fig. 3 omits the process (steps S103 and S104) of checking whether or not there is a retransmission request for a specific divided image from the image transfer device 200 when the image transfer device 100 sequentially transmits all divided images corresponding to one image to the image transfer device 200, which was performed by the image transmission device 100 in the process of the sequence diagram shown in Fig. 2.

[0107] 3, as in the sequence diagram shown in FIG. 2, in the image transmitting device 100, the image acquiring unit 120 acquires an image output by the camera C (step S100), the processing circuit 140 uses the image dividing function 142 to generate divided images by dividing the image acquired by the image acquiring unit 120, and the divided image transmitting function 144 starts transmitting each divided image to the image transferring device 200 (step S101). Then, the divided image transmitting function 144 first causes the image transferring device 200 to transmit start data as divided images (step S102). Thus, in the sequence diagram shown in FIG. 3 as well, the LPWA communication unit 220 of the image transferring device 200 receives the transmitted start data and starts receiving the divided images (step S200), and stores (accumulates) the received start data (divided images) in the divided image storage unit 260.

[0108] The divided image transmission function 144 outputs the first divided image generated by the image division function 142 to the LPWA communication unit 180, causing the first divided image to be transmitted to the image transfer device 200 (step S113). As a result, the LPWA communication unit 220 receives the divided image transmitted by the LPWA communication unit 180, and stores (accumulates) the received divided image in the divided image storage unit 260 (step S201).

[0109] The divided image transmission function 144 checks whether or not transmission of all divided images corresponding to one image to the image transfer device 200 has been completed (step S114). If it is confirmed in step S114 that transmission of all divided images corresponding to one image to the image transfer device 200 has not been completed, the divided image transmission function 144 returns the process to step S114, repeats the processes of steps S113 and S114, and sequentially outputs all divided images corresponding to one image to the LPWA communication unit 180 to transmit them to the image transfer device 200.

[0110] On the other hand, if it is confirmed in step S114 that transmission of all divided images corresponding to one image to the image transfer device 200 has been completed, the divided image transmission function 144 outputs the end data as divided images to the LPWA communication unit 180, which transmits the divided images to the image transfer device 200 (step S115). Then, the image transfer device 100 ends transmission of divided images corresponding to the image currently acquired by the image acquisition unit 120 from camera C to the image transfer device 200 (step S116). Then, the image transfer device 100 returns the process to step S100.

[0111] In the image transfer device 200, the LPWA communication unit 220 receives the end data transmitted by the LPWA communication unit 180, and stores (accumulates) the received end data (divided images) in the divided image storage unit 260. Then, in the image transfer device 200, reception of the divided images transmitted by the LPWA communication unit 180 ends (step S212).

[0112] As a result of this processing flow, in the sequence diagram shown in Figure 3, it is assumed that all divided images corresponding to one image captured by camera C have been transmitted to the image transfer device 200 and stored (accumulated) in the divided image storage unit 260.

[0113] 3, as in the sequence diagram shown in Fig. 2, in the image receiving device 300, the processing circuit 340 checks whether it is a predetermined timing to acquire image data from the image transfer device 200 (step S300). In the sequence diagram shown in Fig. 3, if it is confirmed in step S300 that it is not a predetermined timing to acquire image data, the processing circuit 340 repeats the processing of step S300.

[0114] 3, when it is confirmed in step S300 that it is the predetermined timing to acquire image data, the processing circuitry 340 outputs a request for image data to the network communication unit 320, which transmits the image data to the image transfer device 200 (step S311). In the image transfer device 200, the network communication unit 280 receives the request for image data transmitted by the network communication unit 320 and notifies the processing circuitry 240, and the processing circuitry 240 sequentially outputs the divided images stored in the divided image storage unit 260 by the divided image transfer function 242 to the network communication unit 280, which transmits the divided images as image data to the image receiving device 300 (step S223).

[0115] In the image receiving device 300, the network communication unit 320 receives each piece of image data transmitted by the network communication unit 280, and the processing circuit 340 uses the image data determination function 342 to determine each piece of received image data (step S312). The image data determination function 342 determines whether or not each piece of received image data contains end data (step S313). If it is determined in step S313 that the received image data does not contain end data, the image data determination function 342 returns the process to step S311 and outputs a request for image data to the network communication unit 320, which then transmits the request to the image transferring device 200. In other words, the image receiving device 300 continues to obtain image data from the image transferring device 200.

[0116] On the other hand, if it is determined in step S313 that the received image data includes end data, the image data determination function 342 determines whether or not there is a gap in the image data by determining whether or not there is a gap in the serial number added to each piece of received image data (step S314). The image data determination function 342 outputs gap information indicating the result of the determination in step S314 to the image reconstruction function 344. Then, if it is determined in step S314 that there is no gap in the image data, the image data determination function 342 proceeds to the process in step S316.

[0117] On the other hand, if it is determined in step S314 that a gap has occurred in the image data, the image data determination function 342 outputs the gap information to the image reconstruction function 344. Furthermore, the image data determination function 342 outputs information on the serial number of the missing image data and a retransmission request to the network communication unit 320, causing the image transfer device 200 to transmit a request to retransmit the missing image data (specific image data) (step S315). As a result, in the image transfer device 200, the network communication unit 280 receives the retransmission request for the specific image data transmitted from the network communication unit 320, and the LPWA communication unit 220 transmits a retransmission request for the specific divided image to the LPWA communication unit 180 (step S224).

[0118] After determining in step S314 that no gaps have occurred in the image data, or after causing the image transfer device 200 to send a request to resend the missing image data (specific image data) in step S315, the processing circuitry 340 generates a reconstructed image using the image reconstruction function 344. At this time, the image reconstruction function 344 generates a reconstructed image by sequentially combining the image data currently obtained (by combining dummy image data in place of the image data indicated by the gap information). Then, the image reconstruction function 344 stores (saves) the reconstructed images generated up to this point in time in the image storage unit 360 (step S316).

[0119] In the image transmitting device 100, after completing transmission of all divided images corresponding to one image to the image transferring device 200, the processing circuit 140 checks whether it is a predetermined timing to confirm a retransmission request for a specific divided image from the image transferring device 200 (step S127). If it is confirmed in step S127 that it is not the predetermined timing to confirm a retransmission request for a specific divided image, the processing circuit 140 repeats the processing of step S127.

[0120] On the other hand, if it is confirmed in step S127 that it is the predetermined timing to confirm a resend request for the specific divided image, the divided image sending function 144 checks whether or not there is a resend request for the specific divided image from the image transfer device 200 (step S128). If it is confirmed in step S128 that there is no resend request for the specific divided image from the image transfer device 200, the divided image sending function 144 returns the process to step S127.

[0121] In step S128, when it is confirmed that there is a retransmission request for a specific divided image from the image transfer device 200, the divided image transmission function 144 outputs the divided image for which the retransmission request has been made to the LPWA communication unit 180, and causes it to be transmitted to the image transfer device 200 (step S129). As a result, the image transfer device 200 stores (accumulates) the divided image for which the retransmission request has been made in the divided image storage unit 260 (step S235).

[0122] In the image receiving device 300, the processing circuitry 340 checks whether a predetermined time has elapsed since the image transmitting device 200 transmitted a request to retransmit the missing image data (specific image data) in the process of step S315 (step S327). If it is confirmed in step S327 that the predetermined time has not elapsed, the processing circuitry 340 repeats the process of step S327.

[0123] On the other hand, if it is confirmed in step S327 that the predetermined time has elapsed, the processing circuitry 340 outputs a request for image data to the network communication unit 320, causing it to transmit to the image transfer device 200 (step S328). In the image transfer device 200, the network communication unit 280 receives the request for image data transmitted by the network communication unit 320 and notifies the processing circuitry 240, and the processing circuitry 240 outputs, via the divided image transfer function 242, the divided images transmitted by the image transmitting device 100 in response to the retransmission request and stored (accumulated) in the divided image storage unit 260 to the network communication unit 280, causing it to transmit as image data to the image receiving device 300 (step S236).

[0124] In the image receiving device 300, the network communication unit 320 receives the image data requested for retransmission, transmitted by the network communication unit 280, and the processing circuitry 340 generates a reconstructed image using the image reconstruction function 344. At this time, the image reconstruction function 344 regenerates a reconstructed image by replacing the portion of the reconstructed image generated in step S316 where dummy image data was used instead of image data with the image data received in response to the retransmission request. The image reconstruction function 344 then stores (saves) the reconstructed image in the image storage unit 360 (step S329). In other words, the image reconstruction function 344 replaces the reconstructed image currently stored (saved) in the image storage unit 360 with the reconstructed image.

[0125] Thereafter, the processing circuitry 340 ends the generation (including regeneration) of the current reconstructed image and the storage (saving) of the image in the image storage unit 360. Then, the processing circuitry 340 returns the process to step S300 and waits until a predetermined timing for acquiring image data corresponding to the next image captured by the camera C from the image transfer device 200.

[0126] Even with this processing flow, in the image transmission system 1, the image transmitting device 100 sequentially transmits divided images obtained by dividing an image captured by camera C to the image transmitting device 200. Then, in the image transmission system 1, the image transmitting device 200 transmits each divided image transmitted by the image transmitting device 100 to the image receiving device 300 as image data in response to a request from the image receiving device 300. Furthermore, in the image transmission system 1, the image receiving device 300 generates an image captured by camera C (reconstructed image) based on each image data (divided image including start data and end data) transmitted by the image transmitting device 200, and stores (saves) the generated reconstructed image in the image storage unit 360. In this way, the image receiving device 300 can provide the reconstructed image stored in the image storage unit 360 to a monitor or the like by displaying it, for example, on a display device (not shown) as an image captured by camera C.

[0127] As described above, according to the embodiment of the present invention, the image transmitting device 100 constituting the image transmission system 1 divides an image captured by the camera C into predetermined size segments within the transmission capacity constraints of LPWA communication, and sequentially transmits each of the divided images (including start data and end data) to the image transmitting device 200 via LPWA communication. In the embodiment of the present invention, the image transmitting device 200 constituting the image transmission system 1 receives each of the divided images transmitted by the image transmitting device 100, stores (accumulates) them in the divided image storage unit 260, and transmits each of the stored (accumulated) divided images as image data to the image receiving device 300 via high-speed communication using a high-speed communication line in response to a request from the image receiving device 300. Furthermore, in the embodiment of the present invention, the image receiving device 300 constituting the image transmission system 1 generates an image (reconstructed image) that reproduces the original image captured by the camera C based on each of the image data (divided images including start data and end data) transmitted by the image transmitting device 200, and stores (saves) the generated reconstructed image in the image storage unit 360. As a result, in the image transmission system 1 of an embodiment for implementing the present invention, images captured by a camera C installed in an environment where wireless communication using high-speed communication lines is limited, such as a mountainous region, can be transmitted to a monitoring station located in an urban area several kilometers to several tens of kilometers away for confirmation.

[0128] Moreover, in the embodiment for carrying out the present invention, the image receiving device 300 constituting the image transmission system 1 determines whether or not there is a gap in the segmented image (image data) transmitted by the image transmitting device 100. Then, in the embodiment for carrying out the present invention, if the image receiving device 300 constituting the image transmission system 1 finds that there is a gap in the segmented image (image data) transmitted by the image transmitting device 100, it first generates a reconstructed image with the gap, but then requests retransmission of the segmented image (image data) with the gap. In the embodiment for carrying out the present invention, when the image receiving device 300 constituting the image transmission system 1 acquires the segmented image (image data) with the gap for which retransmission has been requested, it reconstructs the reconstructed image that was generated with the gap using the acquired segmented image (image data). As a result, in the image transmission system 1 constituting the embodiment for carrying out the present invention, it is possible to stabilize the transmission of segmented images from the image transmitting device 100 to the image transfer device 200 via LPWA communication, and it is possible to generate a reconstructed image that more appropriately reproduces the original image captured by the camera C.

[0129] The above describes an embodiment of the present invention with reference to the drawings, but the specific configuration is not limited to this embodiment, and various modifications are also included within the scope that does not deviate from the spirit of the present invention. [Explanation of symbols]

[0130] 1. Image transmission system 100 Image transmission device 120 Image acquisition unit 140 Processing circuit 142···Image division function 144···Split image sending function 160 Image storage unit 180···LPWA communication unit 200 Image transfer device 220···LPWA communication unit 240 Processing circuit 242···Split image transfer function 260...Divided image storage unit 280 Network Communications Department 300 Image receiving device 320 Network Communications Department 340 Processing circuit 342 Image data judgment function 344···Image reconstruction function 360...Image storage section C···Camera

Claims

1. The system includes at least an image sending device, an image transfer device, and an image receiving device, An image transmission system that transmits a first image captured by an imaging device, the image transmitting device generates second images by dividing the first image into predetermined capacity segments based on a transmission capacity of a first wireless communication capable of long-distance communication with low power consumption, and transmits each of the generated second images to the image transferring device via the first wireless communication; the image transfer device receives and stores the second image transmitted by the image transmission device, and transmits the stored second image as a third image to the image reception device via a second wireless communication capable of faster communication than the first wireless communication in response to a request from the image reception device; the image receiving device requests transmission of the third image, receives the third image transmitted by the image transmitting device in response to the request, and generates a fourth image that reproduces the first image based on the received third image. Image transmission system.

2. The image transmitting device an acquisition unit that acquires the first image; a division unit that divides the first image to generate the second image; a first storage unit that stores the first image and the second image; a first communication unit that transmits the second image to the image transfer device through the first wireless communication; Equipped with The image transfer device a second communication unit that performs the first wireless communication with the first communication unit and receives the second image transmitted by the image transmission device; a second storage unit that stores the second image; a third communication unit that transmits the second image as the third image to the image receiving device through the second wireless communication; Equipped with The image receiving device a fourth communication unit that performs the second wireless communication with the third communication unit and receives the third image transmitted by the image transfer device; a determination unit that determines whether the third image required to generate the fourth image is complete; a generation unit that generates the fourth image by combining the third images based on the result of the determination; a third storage unit that stores the third image and the fourth image; Equipped with 2. The image transmission system according to claim 1.

3. the dividing unit generates the second images by dividing the first image for each of the predetermined capacities after deleting at least fixed information included in prefix data added to the first image; the generation unit complements the information included in the deleted prefix data to generate the fourth image.

3. The image transmission system according to claim 2.

4. the division unit generates the second image by dividing the first image for each of the predetermined capacities within the constraints of the transmission capacity.

4. The image transmission system according to claim 3.

5. The dividing unit adding information indicating the order in which the first image was divided to each of the second images; generating the second image by dividing the first image so that the capacity of the second image becomes the predetermined capacity, with information indicating the division order added; the determination unit determines whether or not there is a gap in the third image required to generate the fourth image based on the information indicating the division order; the generation unit generates the fourth image by combining the third images based on the information indicating the division order and the result of the determination.

5. The image transmission system according to claim 4.

6. When the result of the determination indicates that there is a gap in the third image required to generate the fourth image, the generation unit generates the fourth image by complementing the missing third image with a predetermined substitute image.

6. The image transmission system according to claim 5.

7. When the determination unit determines that there is a gap in the third image required to generate the fourth image, the determination unit outputs a first retransmission request to the fourth communication unit to request retransmission of the missing third image as a specific third image; the fourth communication unit transmits the first retransmission request to the third communication unit; the third communication unit receives the first retransmission request and outputs the received first retransmission request to the second communication unit; the second communication unit transmits a second retransmission request to the first communication unit, requesting retransmission of a specific second image, the specific second image being the second image corresponding to the specific third image requested by the first retransmission request; the first communication unit receives the second retransmission request and transmits the specific second image requested by the received second retransmission request to the second communication unit; the second communication unit receives the specific second image and stores the received specific second image in the second storage unit; the third communication unit transmits the specific second image stored in the second storage unit as the specific third image to the fourth communication unit in response to a request from the image receiving device; the fourth communication unit receives the specific third image; the generation unit regenerates the fourth image by replacing the substitute image in the generated fourth image with the specific third image; 7. The image transmission system according to claim 6.

8. The system includes at least an image sending device, an image transfer device, and an image receiving device, 1. An image transmission method in an image transmission system for transmitting a first image captured by an imaging device, comprising: The computer of the image transmission device generating second images by dividing the first image into predetermined capacity segments based on a transmission capacity of a first wireless communication capable of long-distance communication with low power consumption; transmitting each of the generated second images to the image transfer device via the first wireless communication; The computer of the image transfer device receiving and storing the second image transmitted by the image transmission device; In response to a request from the image receiving device, transmit the stored second image as a third image to the image receiving device via a second wireless communication capable of communication at a higher speed than the first wireless communication; The computer of the image receiving device requesting transmission of the third image; receiving the third image transmitted by the image transfer device in response to the request; generating a fourth image that reproduces the first image based on the received third image; Image transmission method.

9. The system includes at least an image sending device, an image transfer device, and an image receiving device, a computer of the image transmitting device in an image transmission system that transmits a first image captured by an imaging device, generating second images by dividing the first image into predetermined capacity segments based on a transmission capacity of a first wireless communication capable of long-distance communication with low power consumption; transmitting each of the generated second images to the image transfer device via the first wireless communication; program.

10. The system includes at least an image sending device, an image transfer device, and an image receiving device, In an image transmission system that transmits a first image captured by an imaging device, a computer of the image transfer device receiving and storing second images obtained by dividing the first image, which is generated by the image transmitting device and transmitted by a first wireless communication capable of long-distance communication with low power consumption, into predetermined capacity portions based on a transmission capacity of the first wireless communication; In response to a request from the image receiving device, the stored second image is transmitted as a third image to the image receiving device via a second wireless communication capable of communication at a higher speed than the first wireless communication. program.

11. The system includes at least an image sending device, an image transfer device, and an image receiving device, a computer of the image receiving device in an image transmission system that transmits a first image captured by an imaging device, a request for transmission of second images, which are stored in the image transfer device and generated by the image transmission device by dividing the first image into predetermined capacity segments based on a transmission capacity of a first wireless communication capable of long-distance communication with low power consumption, as third images; receiving, in response to the request, the third image transmitted by a second wireless communication capable of communication at a higher speed than the first wireless communication, by the image transfer device; generating a fourth image that reproduces the first image based on the received third image; program.

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