JP2018029309A - Imaging device and transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device and a transmission method that can reduce a calculation cost for processing to add mosaic on a dynamic image picked up by an imaging part and transmit the image to an external device.SOLUTION: A mosaic processing part detects a predetermined object included in a decoded reference frame, executes mosaic processing on the predetermined object, and estimates a movement locus of the predetermined object on the basis of a result of detection of the predetermined object. An exchange processing part selects, from a difference frame, of encoded frames, on which interframe encoding is performed and including motion vectors of partial areas obtained through division of the frames, the partial areas on the movement locus, and executes exchange processing to exchange the motion vectors of the partial areas between the selected partial areas. A transmission part encodes the reference frame on which the mosaic processing is performed and transmits, to an external device, the encoded reference frame and the difference frame on which the exchange processing is performed.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an imaging apparatus and a transmission method.

  An imaging device such as a monitoring camera performs privacy protection processing on a captured image obtained by imaging the monitoring area by the imaging unit, and the captured image that has been subjected to the privacy protection processing is transmitted to an external device such as a server. There is a system to send. Here, the privacy protection process is a process of detecting a predetermined object from the captured image and executing a mosaic process on the predetermined object.

JP 2007-164275 A International Publication No. 2006/115156 JP 2009-33738 A

  However, in the above-described system, there is a possibility that the calculation time required for privacy protection processing in the imaging device may be long, and it may be difficult to realize in a system that provides captured images in real time.

  The imaging device according to the embodiment includes an imaging unit, an encoder, a decoder, a mosaic processing unit, a replacement processing unit, and a transmission unit. The encoder encodes a frame included in a moving image obtained by imaging of the imaging unit. The decoder decodes a reference frame on which intra-frame coding has been performed among the coded frames. The mosaic processing unit detects a predetermined object included in the decoded reference frame, performs a mosaic process on the predetermined object, and estimates a movement trajectory of the predetermined object based on a detection result of the predetermined object. The replacement processing unit selects a partial region on the movement trajectory from the difference frame including the motion vector of each partial region in which the inter-frame encoding is performed and the frame is divided among the encoded frames, and the selected portion An exchange process for exchanging motion vectors of the partial areas between the areas is executed. The transmission unit encodes the reference frame on which the mosaic process has been performed, and transmits the encoded reference frame and the difference frame on which the replacement process has been performed to the external device.

FIG. 1 is a diagram illustrating an example of a configuration of a communication system according to the present embodiment. FIG. 2 is a diagram illustrating an example of a configuration of a vehicle included in the communication system according to the present embodiment. FIG. 3 is a diagram illustrating an example of a configuration of a cockpit of a vehicle included in the communication system according to the present embodiment. FIG. 4 is a diagram illustrating an example of a hardware configuration of an in-vehicle device included in the vehicle of the communication system according to the present embodiment. FIG. 5 is a diagram for explaining an example of a captured image transmission process by the in-vehicle device included in the vehicle of the communication system according to the present embodiment. FIG. 6 is a diagram illustrating an example of a functional configuration of the in-vehicle device included in the vehicle of the communication system according to the present embodiment. FIG. 7 is a diagram for explaining an example of encoding of a moving image by an in-vehicle device included in the vehicle of the communication system according to the present embodiment. FIG. 8 is a diagram for explaining an example of shuffle processing by the in-vehicle device included in the vehicle of the communication system according to the present embodiment. FIG. 9 is a flowchart illustrating an example of a flow of moving image transmission processing by the in-vehicle device included in the communication system according to the present embodiment.

  Hereinafter, a communication system to which an imaging apparatus and a transmission method according to the present embodiment are applied will be described with reference to the accompanying drawings.

  FIG. 1 is a diagram illustrating an example of a configuration of a communication system according to the present embodiment. FIG. 2 is a diagram illustrating an example of a configuration of a vehicle included in the communication system according to the present embodiment. As shown in FIG. 1, the communication system according to the present embodiment includes a vehicle 1, a center server 2, a client terminal 3, and a base station 4. As shown in FIG. 2, the vehicle 1 is equipped with an in-vehicle device 101 that is a drive recorder or the like and can communicate with an external device such as the center server 2. The vehicle 1 is equipped with an imaging unit 102, a communication antenna 103, and the like.

  The imaging unit 102 is provided so as to be able to capture the surroundings of the vehicle 1 such as the front of the vehicle 1. The in-vehicle device 101 stores a captured image obtained by imaging the outside of the vehicle 1 or the like by imaging of the imaging unit 102. The in-vehicle device 101 receives a GPS signal from a GPS satellite ST via a GPS (Global Positioning System) antenna 303 (see FIG. 3) described later, and the position of the in-vehicle device 101 is based on the received GPS signal. To get. The in-vehicle device 101 controls the communication antenna 103 and receives a transmission instruction from the center server 2 via the base station 4.

  When receiving the transmission instruction, the in-vehicle device 101 controls the communication antenna 103 to transmit various information such as a captured image obtained by imaging the outside of the vehicle 1 and the like via the base station 4 to the center server 2 and the like. Send to external device. In the present embodiment, when the in-vehicle device 101 transmits a captured image to an external device such as the center server 2, the position information indicating the position of the in-vehicle device 101 is added to the captured image, and the center server 2 or the like. To the external device. Thereby, the center server 2 can detect which position is the captured image obtained by imaging. Further, the in-vehicle device 101 can also transmit a captured image obtained by imaging the outside of the vehicle 1 or the like to the center server 2 without receiving a transmission instruction from the center server 2.

  The base station 4 can wirelessly communicate with the in-vehicle device 101 mounted on the vehicle 1. In the present embodiment, the base station 4 transfers the transmission instruction transmitted from the center server 2 to the in-vehicle device 101. Further, the base station 4 receives various types of information of the captured image from the in-vehicle device 101 and transfers the received various types of information to the center server 2 via a network such as the Internet.

  The client terminal 3 instructs the transmission of captured images for the purpose of obtaining monitoring information related to the monitoring area, such as congestion of stores and bus stops, watching school routes, tracking criminals, night tours, and grasping disaster situations. The transmission condition to be transmitted is transmitted to the center server 2. Here, the transmission condition is information indicating a monitoring position where the monitoring information is acquired. Then, the client terminal 3 receives the captured image at the monitoring position from the center server 2.

  The center server 2 receives a captured image from the in-vehicle device 101. The center server 2 receives the transmission condition from the client terminal 3 of the user who has contracted for the service provided by the center server 2. The center server 2 then captures the captured image to which the position information that matches the monitoring position indicated by the transmission condition received from the client terminal 3 among the captured images received from the in-vehicle device 101 (that is, the vehicle that travels through the monitoring position). Captured image received from one in-vehicle device 101) to the client terminal 3. Thereby, the user of the client terminal 3 can recognize the status of the monitoring position by looking at the captured image of the monitoring position. For example, the user of the client terminal 3 can recognize the situation of the area where the monitoring camera or the like is not installed.

  In this embodiment, although the center server 2 demonstrates the example which transmits the captured image received from the vehicle-mounted apparatus 101 to the client terminal 3, it is not limited to this, For example, it installs in the roadside of a building, a road, etc. A captured image obtained by imaging a monitoring position such as a roadside of a building or a road by an imaging unit such as a camera that is included in the surveillance camera or a mobile terminal 304 (see FIG. 3) described later is transmitted to the client terminal 3 Is also possible.

  FIG. 3 is a diagram illustrating an example of a configuration of a cockpit of a vehicle included in the communication system according to the present embodiment. As shown in FIG. 3, the cockpit of the vehicle 1 included in the communication system according to the present embodiment is provided with an in-vehicle device 101, imaging units 301 and 302, a GPS antenna 303, and a portable terminal 304. . The imaging units 301 and 302 are included in the imaging unit 102 and are provided so as to be capable of imaging a preceding vehicle traveling in front of the vehicle 1 from different angles. In the present embodiment, the imaging units 301 and 302 are provided symmetrically with respect to the center console.

  The GPS antenna 303 is provided so as to be able to receive a GPS signal transmitted from the GPS satellite ST in order to acquire the position of the vehicle 1. The portable terminal 304 is configured by a smartphone, a tablet terminal, or the like, and can perform data communication with the center server 2 via the base station 4. In the present embodiment, the mobile terminal 304 has an imaging unit that can image the surroundings of the vehicle 1 and the like. And the portable terminal 304 will transmit the picked-up image obtained by imaging the circumference | surroundings of the vehicle 1 by an imaging part to the center server 2 via the base station 4, if the transmission instruction | indication is received from the center server 2. FIG.

  FIG. 4 is a diagram illustrating an example of a hardware configuration of an in-vehicle device included in the vehicle of the communication system according to the present embodiment. As illustrated in FIG. 4, the in-vehicle device 101 includes a control unit 401, a communication I / F 402, a storage unit 403, and an external storage device 404. The control unit 401 controls the entire in-vehicle device 101. In the present embodiment, the control unit 401 is configured by a microcomputer including an MPU (Micro Processing Unit) or the like.

  When receiving a transmission instruction from the center server 2, the control unit 401 acquires a captured image obtained by imaging the surroundings of the vehicle 1 by the imaging unit 102 from the imaging unit 102 via the communication I / F 402. Then, the control unit 401 transmits the acquired captured image to the center server 2 via the communication antenna 103. The communication I / F 402 can communicate with the imaging unit 102, the communication I / F 402, the GPS antenna 303, the mobile terminal 304, and the like. The storage unit 403 is used as a ROM (Read Only Memory) that stores various programs and the like used for controlling the in-vehicle device 101 by the control unit 401 in a nonvolatile manner, and a work area when executing the various programs stored in the ROM. A RAM (Random Access Memory), a flash ROM that stores setting data set in the vehicle 1 in a nonvolatile manner, a VRAM that stores a captured image obtained by imaging of the imaging unit 102, and the like. The external storage device 404 is configured by a large-capacity storage device such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

  Next, a transmission process of a captured image by the in-vehicle device 101 according to the present embodiment will be described using FIG. 5 and FIG. FIG. 5 is a diagram for explaining an example of a captured image transmission process by the in-vehicle device included in the vehicle of the communication system according to the present embodiment. FIG. 6 is a diagram illustrating an example of a functional configuration of the in-vehicle device included in the vehicle of the communication system according to the present embodiment.

  In the present embodiment, as illustrated in FIG. 6, the control unit 401 executes a program stored in the storage unit 403, whereby an encoder 601, a decomposition unit 602, a decoder 603, a mosaic processing unit 604, and a shuffle processing unit 605. And the video reconstruction unit 606 are realized. When receiving a transmission instruction from the center server 2 via the communication antenna 103, the control unit 401 controls the imaging unit 102 to start imaging around the vehicle 1. The encoder 601 acquires a moving image obtained by imaging the surroundings of the vehicle 1 by the imaging unit 102. Then, the encoder 601 encodes each frame included in the acquired moving image. Specifically, the encoder 601 is H.264. Each frame included in the moving image is encoded according to a standard such as H.264.

  The disassembling unit 602 divides each frame of the moving image encoded by the encoder 601 into a frame subjected to intra-frame encoding (hereinafter referred to as a reference frame), inter-frame encoded, and divided the frame. The frame is decomposed into frames (hereinafter referred to as difference frames) including motion vectors (movement vectors) of each intra block (an example of a partial region). Here, intraframe coding is a method of coding a frame without using interframe prediction. In other words, intraframe coding encodes a frame without using other frames. Specifically, intra-frame encoding predicts the value of a target pixel that is a pixel to be encoded from the values of two adjacent pixels, and encodes the difference between the predicted value and the actual value of the target pixel. . Also, interframe coding is a method of coding a frame using interframe prediction. In the present embodiment, the decomposition unit 602 decomposes each frame of the moving image encoded by the encoder 601 into an I frame as a reference frame and P and B frames as difference frames. Then, the decomposition unit 602 outputs a reference frame (for example, an I frame) decomposed from the moving image frame to the decoder 603. Also, the decomposition unit 602 outputs the difference frames (for example, P and B frames) decomposed from the moving image frame to the shuffle processing unit 605.

  The decoder 603 decodes the reference frame input from the decomposition unit 602. Then, the decoder 603 outputs the decoded reference frame to the mosaic processing unit 604.

  The mosaic processing unit 604 detects a predetermined object included in the reference frame decoded by the decoder 603. In the present embodiment, the mosaic processing unit 604 detects a predetermined object included in the reference frame by performing pattern recognition processing or the like on the decoded reference frame. In the present embodiment, as shown in FIG. 5, the mosaic processing unit 604 detects a privacy-protected object such as a person, a vehicle, a license plate, or a face as the predetermined object O from the reference frame.

  Next, the mosaic processing unit 604 estimates the movement trajectory of the predetermined object based on the detection result of the predetermined object from the plurality of reference frames. In the present embodiment, it is assumed that the mosaic processing unit 604 estimates the movement trajectory of the predetermined object based on the detection result of the predetermined object from two time-series reference frames. For example, the mosaic processing unit 604 estimates a straight line connecting the positions of predetermined objects detected from two time-series reference frames as the movement locus of the predetermined object.

  Further, the mosaic processing unit 604 performs mosaic processing on a predetermined object included in the reference frame. In the present embodiment, the mosaic processing unit 604 executes a mosaic process for replacing a predetermined object included in the reference frame, but the present invention is not limited to this, as long as the predetermined object included in the reference frame is made invisible. good. For example, the mosaic processing unit 604 may execute a mosaic process for blurring or blackening a predetermined object included in the reference frame. In the present embodiment, the mosaic processing unit 604 performs reversible mosaic processing on a predetermined object included in the reference frame. However, the present invention is not limited to this. For example, the mosaic processing unit 604 may perform mosaic processing of irreversible conversion on a predetermined object included in the reference frame.

  The shuffle processing unit 605 (an example of a replacement processing unit) selects an intra block on the movement locus estimated by the mosaic processing unit 604 from the difference frame decomposed by the decomposition unit 602. In the present embodiment, the shuffle processing unit 605 selects an intra block that overlaps the movement locus and an intra block near the movement locus from the difference frame. Then, the shuffle processing unit 605 executes shuffle processing (an example of replacement processing) for exchanging motion vectors of the intra blocks between the selected intra blocks.

  In the present embodiment, the shuffle processing unit 605 exchanges the motion vectors of the intra blocks between the selected intra blocks based on a preset rule. Here, the preset rule is a rule for exchanging motion vectors of intra blocks by lossless transformation. For example, as illustrated in FIG. 5, the shuffle processing unit 605 performs a reversible mosaic processing on the intra blocks constituting the selected predetermined object O (number plate). In the present embodiment, the shuffle processing unit 605 performs a reversible transformation mosaic process on the intra blocks constituting the predetermined object. However, the shuffle processing unit 605 performs the irreversible mosaic processing on the intra blocks constituting the predetermined object. Processing may be executed.

  The video reconstruction unit 606 (an example of a transmission unit) encodes the reference frame on which the mosaic processing is performed by the mosaic processing unit 604. In the present embodiment, the video reconstruction unit 606 performs intra-frame coding on the reference frame on which mosaic processing has been performed. In addition, the video reconstruction unit 606 transmits the encoded reference frame and the difference frame subjected to the shuffle process to the center server 2 (an example of an external device). As a result, when a moving image obtained by imaging by the imaging unit 102 is subjected to mosaic and transmitted to the center server 2, it is not necessary to execute processing for detecting a predetermined object from the difference frame. It is possible to reduce the calculation cost of the process of applying a mosaic to the obtained moving image and transmitting it to the center server 2. In the present embodiment, the imaging unit 102 and the in-vehicle device 101 function as an example of an imaging device. However, by realizing the functional configuration illustrated in FIG. 6 in the mobile terminal 304, the monitoring camera, or the like, the mobile terminal 304, the monitoring camera, or the like. Can be made to function as an example of an imaging apparatus.

  Next, the flow of a moving image transmission process performed by the in-vehicle device 101 of the vehicle 1 of the communication system according to the present embodiment will be described with reference to FIGS. FIG. 7 is a diagram for explaining an example of encoding of a moving image by an in-vehicle device included in the vehicle of the communication system according to the present embodiment. FIG. 8 is a diagram for explaining an example of shuffle processing by the in-vehicle device included in the vehicle of the communication system according to the present embodiment. FIG. 9 is a flowchart illustrating an example of a flow of moving image transmission processing by the in-vehicle device included in the communication system according to the present embodiment.

  In the present embodiment, the encoder 601 encodes a frame constituting a moving image obtained by imaging the surroundings of the vehicle 1 by the imaging unit 102. The decomposition unit 602 selects two reference frames at different times from among the encoded reference frames. Specifically, as shown in FIG. 7, the decomposition unit 602, among the encoded reference frames, the reference frame at the first time and the reference frame at the second time after the first time (that is, the time frame). Select two reference frames in the sequence. Next, as illustrated in FIG. 7, the decomposition unit 602 calculates a difference frame (for example, three difference frames) between the reference frame at the first time and the reference frame at the second time among the encoded difference frames. One set (an example of a frame group) is assumed.

  Next, the decoder 603 decodes two time-series reference frames. As illustrated in FIG. 7, the mosaic processing unit 604 detects a predetermined object (for example, a preceding vehicle) from each of the reference frame at the first time and the reference frame at the second time. The mosaic processing unit 604 performs mosaic processing on a predetermined object detected from each reference frame. In addition, the mosaic processing unit 604 uses a straight line connecting the position of the predetermined object in the reference frame at the first time and the position of the predetermined object in the reference frame at the second time to determine the predetermined object between the first time and the second time. A movement trajectory is estimated (step S901). For example, the mosaic processing unit 604 estimates a straight line connecting the position of the predetermined object in the reference frame at the first time and the position of the predetermined object in the reference frame at the second time as the movement locus of the predetermined object.

  Next, the shuffle processing unit 605 corrects the movement locus based on the motion vector of the intra block on the movement locus among the intra blocks included in the difference frame output from the decoder 603 (step S902). Specifically, the shuffle processing unit 605 sets the movement locus so that the movement direction of the predetermined object indicated by the movement locus approaches the direction of the motion vector of the intra block on the movement locus among the intra blocks included in the difference frame. to correct. Thereby, since the intra block for which the shuffle processing unit 605 performs the shuffle process can be brought close to the intra block of the predetermined object included in the difference frame, the shuffle process can be performed with high accuracy on the predetermined object included in the difference frame. .

  Next, the shuffle processing unit 605 selects an intra block (for example, a black intra block in FIG. 8) on a movement locus in a plurality of difference frames included in one set (step S903). Then, the shuffle processing unit 605 executes shuffle processing for exchanging motion vectors of the intra blocks between the selected intra blocks (step S904). That is, the shuffle processing unit 605 executes shuffle processing for exchanging motion vectors of the intra block between the intra blocks on the movement locus in the plurality of difference frames included in one set. Thereby, since the motion vector of the intra block can be more complicatedly exchanged between intra blocks on the movement trajectory in one difference frame, the intensity of the mosaic for the difference frame can be increased.

  In the present embodiment, the shuffle processing unit 605 can also change the strength of the mosaic with respect to the difference frame by changing a rule for exchanging motion vectors of the intra block between the selected intra blocks.

  Thereafter, the video reconstruction unit 606 re-encodes the time-series reference frames for which the mosaic processing unit 604 has performed the mosaic processing. Then, the video reconstruction unit 606 rearranges the encoded reference frame and the difference frame subjected to the shuffle processing by the shuffle processing unit 605 in time series and transmits them to the center server 2 (step S905). When a moving image obtained by imaging by the imaging unit 102 is mosaiced and transmitted to the center server 2, it is not necessary to execute processing for detecting a predetermined object from the difference frame, and thus a moving image obtained by imaging by the imaging unit 102 It is possible to reduce the calculation cost of processing for mosaicing an image and transmitting it to the center server 2.

  In the present embodiment, the video reconstruction unit 606 transmits the reference frame and the difference frame to an external device such as the center server 2, but the position where the mosaic processing is executed in the reference frame (that is, the predetermined frame detected from the reference frame). Information (for example, coordinate information) indicating the position of the object may be transmitted to the center server 2 together with the reference frame and the difference frame. Thereby, when canceling the mosaic executed on the reference frame in an external device such as the center server 2, the position where the mosaic processing is executed on the reference frame can be easily specified.

  In addition, the video reconstruction unit 606 may transmit information indicating the estimated movement locus to the center server 2 together with the reference frame and the difference frame. Thereby, when canceling the mosaic executed on the difference frame in an external device such as the center server 2, it is possible to easily identify the intra block on which the shuffle process is executed on the difference frame.

  As described above, according to the in-vehicle device 101 according to the present embodiment, it is possible to reduce the calculation cost of the process of applying the mosaic to the moving image obtained by the imaging of the imaging unit 102 and transmitting it to the center server 2.

  Note that the program executed by the in-vehicle device 101 of the present embodiment is provided by being incorporated in advance in a ROM or the like. The program executed in the in-vehicle device 101 of the present embodiment is a file in an installable format or an executable format, and is a computer such as a CD-ROM, a flexible disk (FD), a CD-R, a DVD (Digital Versatile Disk). You may comprise so that it may record and provide on a readable recording medium.

  Furthermore, the program executed by the in-vehicle device 101 according to the present embodiment may be configured to be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. The program executed by the in-vehicle device 101 of the present embodiment may be configured to be provided or distributed via a network such as the Internet.

  The program executed by the in-vehicle device 101 according to the present embodiment has a module configuration including the above-described units (encoder 601, decomposition unit 602, decoder 603, mosaic processing unit 604, shuffle processing unit 605, and video reconstruction unit 606). As actual hardware, a CPU (Central Processing Unit) reads out a program from the ROM and executes it, so that the above-described units are loaded onto the main storage device, and an encoder 601, a decomposing unit 602, a decoder 603, a mosaic A processing unit 604, a shuffle processing unit 605, and a video reconstruction unit 606 are generated on the main storage device.

  Although the embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment is included in the scope and gist of the invention, and is also included in the invention described in the claims and the equivalent scope thereof.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Center server 3 Client terminal 4 Base station 101 In-vehicle apparatus 102,301,302 Imaging part 103 Communication antenna 401 Control part 402 Communication I / F
403 Storage unit 404 External storage device 601 Encoder 602 Decomposition unit 603 Decoder 604 Mosaic processing unit 605 Shuffle processing unit 606 Video reconstruction unit

Claims (14)

An imaging unit;
An encoder that encodes a frame included in a moving image obtained by imaging of the imaging unit;
A decoder that decodes a reference frame that has been subjected to intra-frame encoding among the encoded frames;
A mosaic processing unit that detects a predetermined object included in the decoded reference frame, performs a mosaic process on the predetermined object, and estimates a movement locus of the predetermined object based on a detection result of the predetermined object; ,
The partial area on the movement trajectory is selected from the difference frame including the motion vector of each partial area obtained by performing inter-frame encoding among the encoded frames and dividing the frame, and the selected partial area A replacement processing unit that executes replacement processing for replacing the motion vectors of the partial area,
A transmitter that encodes the reference frame on which the mosaic processing has been performed, and transmits the encoded reference frame and the difference frame on which the replacement processing has been performed to an external device;
An imaging apparatus comprising:   The imaging apparatus according to claim 1, wherein the mosaic processing unit detects a privacy protection target object as the predetermined object from the decoded reference frame. The difference frame between two reference frames in time series is defined as one frame group,
2. The imaging according to claim 1, wherein the replacement processing unit executes the replacement process of replacing the motion vectors of the partial areas between the partial areas on the movement locus in the difference frames included in the frame group. apparatus.   The imaging apparatus according to claim 1, wherein the replacement processing unit corrects the movement locus based on the motion vector of the partial region on the movement locus.   The imaging apparatus according to claim 1, wherein the replacement processing unit replaces the motion vectors of the partial areas based on a preset rule between the selected partial areas.   The imaging apparatus according to claim 5, wherein the preset rule is a rule for exchanging the motion vectors of the partial regions by reversible transformation.   The imaging apparatus according to claim 1, further comprising a decomposing unit that decomposes the encoded frame into an I frame as the reference frame and P and B frames as the difference frames. Encode a frame included in a moving image obtained by imaging of the imaging unit,
Decoding a reference frame subjected to intra-frame encoding among the encoded frames;
Detecting a predetermined object included in the decoded reference frame;
Mosaic processing is performed on the predetermined object included in the reference frame,
Based on the detection result of the predetermined object, the movement trajectory of the predetermined object is estimated,
Selecting the partial region on the movement trajectory from the difference frame including the motion vector of each partial region in which the inter-frame encoding is performed and the frame is divided among the encoded frames;
Performing a replacement process for replacing the motion vectors of the partial areas between the selected partial areas;
Encoding the reference frame on which the mosaic processing has been performed;
Transmitting the encoded reference frame and the difference frame subjected to the replacement process to an external device;
A transmission method including that.   The transmission method according to claim 8, wherein an object subject to privacy protection is detected as the predetermined object from the decoded reference frame. The difference frame between two reference frames in time series is defined as one frame group,
The transmission method according to claim 8, wherein the replacement process of exchanging the motion vectors of the partial areas is performed between the partial areas on the movement trajectory in the difference frames included in the frame group.   The transmission method according to claim 8, wherein the movement trajectory is corrected based on the motion vector of the partial region on the movement trajectory.   The transmission method according to claim 8, wherein the motion vectors of the partial areas are exchanged between the selected partial areas based on a preset rule.   The transmission method according to claim 12, wherein the preset rule is a rule for exchanging the motion vectors of the partial regions by reversible transformation.   9. The transmission method according to claim 8, further comprising: decomposing the encoded frame into an I frame as the reference frame and P and B frames as the difference frames.

Images