Video provisioning device and video provisioning method

Abstract

This invention provides a video presentation device and video presentation method that can give users who have entrusted their vehicles to an automated valet parking system a sense of security. [Solution] The video providing device 10 is a device that provides video of an automated valet parking vehicle 20 to a user, and comprises a first memory 12, a second memory 13, and a processor 11. The first memory 12 stores onboard camera video captured by an onboard camera 21 of the vehicle 20. The second memory 13 stores surveillance camera video captured by multiple surveillance cameras 30 installed in a parking lot where automated valet parking is performed. The processor 11 is communicatively connected to the first memory 12 and the second memory 13, generates a display video to show to the user based on at least one of the onboard camera video and the surveillance camera video according to the status of the vehicle 20, and displays the display video on the user terminal 40.

Description

Technical Field

[0001] The present disclosure relates to a video providing apparatus and a video providing method for providing a user with a video of a target vehicle for automatic valet parking.

Background Art

[0002] Patent Document 1 discloses a system for performing automatic valet parking using an in-vehicle camera mounted on a vehicle and a surveillance camera disposed on a wall or a column of a parking lot. Further, Patent Document 2 discloses displaying, on a user terminal, a video captured by an in-vehicle camera in a remote operation device of a vehicle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] One concern for a user of automatic valet parking is whether the parked vehicle can safely drive automatically in the parking lot without hitting or rubbing against other vehicles or walls. As a method of reassuring a user with such a concern, it is conceivable to allow the user to view, on a user terminal, a video of a vehicle traveling in the parking lot. As an example thereof, mention may be made of the technique of displaying, on a user terminal, a video of an in-vehicle camera disclosed in Patent Document 2.

[0005] However, it's not enough for users to simply be able to see video of the vehicle in motion. Depending on the video displayed on the user's device, it could alleviate the user's concerns and greatly reassure them, or conversely, fail to alleviate their concerns and instead make them more anxious.

[0006] This disclosure has been made in view of the above-mentioned issues. One of the purposes of this disclosure is to provide a video provision device and video provision method that can give users who have entrusted their vehicles to an automated valet parking service a sense of security. [Means for solving the problem]

[0007] According to one embodiment of the present disclosure, a first video providing device is provided for achieving the above objective. The first video providing device is a device that provides video of a vehicle subject to automated valet parking to a user, and comprises a first memory, a second memory, and a processor configured as follows. The first memory is configured to store a first video related to the vehicle, captured by one or more on-board cameras of the vehicle. The second memory is configured to store a second video related to the vehicle, captured by multiple surveillance cameras installed in a parking lot where automated valet parking is performed. The processor is communicatively coupled to the first memory and the second memory, and is configured to generate a display video to show to the user based on at least one of the first video and the second video according to the status of the vehicle, and to display the display video on the user's terminal.

[0008] In one embodiment of this disclosure, the processor may further be configured to assess the risks to the target vehicle as it continues to drive and to generate a display image according to the status and risks of the target vehicle. The processor may also be configured to perform processing on the display image to protect the privacy of vehicles or people present in the vicinity of the target vehicle. The processor may also be configured to acquire a video request from the user and to generate a display image according to the status of the target vehicle and the video request. In one embodiment of this disclosure, generating a display image may also include generating a composite image by combining a first image and a second image according to the status of the target vehicle.

[0009] According to one embodiment of the present disclosure, a first video provision method for achieving the above objective is provided. The first video provision method is a method for providing a user with video of a vehicle subject to automated valet parking, and includes the following first to fourth steps. The first step is to acquire a first video related to the vehicle, captured by an on-board camera of the vehicle. The second step is to acquire a second video related to the vehicle, captured by a plurality of surveillance cameras installed in a parking lot where automated valet parking is performed. The third step is to generate a display video to show to the user based on at least one of the first video and the second video, according to the status of the vehicle. The fourth step is to display the display video on the user's terminal.

[0010] According to one embodiment of the present disclosure, a first program for achieving the above objective is provided. The first program is a program that can be stored in a computer-readable storage medium and includes a plurality of instructions for causing a computer processor to perform a first video presentation method including the first to fourth steps described above.

[0011] According to one embodiment of the present disclosure, a second video providing device is provided for achieving the above objective. The second video providing device is a device that provides video of a vehicle subject to automated valet parking to a user, and comprises a first memory, a second memory, and a processor configured as follows. The first memory is configured to store a first video related to the vehicle, captured by an on-board camera of the vehicle. The second memory is configured to store a second video related to the vehicle, captured by a plurality of surveillance cameras installed in a parking lot where automated valet parking is performed. The processor is communicatively coupled to the first memory and the second memory, generates a composite video by combining the first video and the second video, and is configured to display the composite video on the user's terminal.

[0012] According to one embodiment of the present disclosure, a second video provision method is provided for achieving the above objective. The second video provision method is a method for providing a user with video of a vehicle subject to automated valet parking, and includes the following first to fourth steps. The first step is to acquire a first video related to the vehicle, captured by an on-board camera of the vehicle. The second step is to acquire a second video related to the vehicle, captured by a plurality of surveillance cameras installed in a parking lot where automated valet parking is performed. The third step is to generate a composite video by combining the first video and the second video. The fourth step is to display the composite video on the user's terminal.

[0013] According to one embodiment of the present disclosure, a second program is provided for achieving the above objective. The second program is a program that can be stored in a computer-readable storage medium and includes a plurality of instructions for causing a computer processor to perform a second video presentation method, which includes the first to fourth steps described above. [Effects of the Invention]

[0014] In one embodiment of this disclosure, according to the first video providing device, the first video providing method, and the first program, video of the vehicle during automatic valet parking is acquired from both an in-vehicle camera and a surveillance camera, and a display video is generated for the user to see according to the vehicle's status, and the generated display video is shown on the user terminal. During automatic valet parking, the user is concerned about the moving vehicle and its surroundings. Since what the user is concerned about differs depending on the vehicle's status, it is not easy or even troublesome for the user to select a satisfactory video from the available video feeds. According to the first video providing device, the first video providing method, and the first program, a video suitable for the user to see what they are concerned about can be automatically generated and displayed on the user terminal, thereby giving the user a sense of security.

[0015] In one embodiment of this disclosure, according to the second video providing device, the second video providing method, and the second program, images of a vehicle during automatic valet parking are acquired from both an in-vehicle camera and a surveillance camera, the images from the in-vehicle camera and the surveillance camera are combined, and the combined image is displayed on the user terminal. The images from the in-vehicle camera and the surveillance camera each have areas that are clearly visible and areas that are not clearly visible or are difficult to see, and they are complementary to each other. Therefore, the user may not be able to see what they want to see in either the image, and the user may remain anxious. According to the first video providing device, the first video providing method, and the first program, the images from the complementary in-vehicle camera and the surveillance camera are combined, and the user can see what they are concerned about in the combined image, thus giving the user a sense of security. [Brief explanation of the drawing]

[0016] [Figure 1] This diagram shows an overview of the video delivery system configuration. [Figure 2] This diagram shows the hardware configuration of the video delivery system. [Figure 3] This diagram shows the flow of information within the video delivery system. [Figure 4]It is a flowchart showing the flow of a series of processes executed by a processor of an image providing device.

Embodiments of the Invention

[0017] 1. Configuration of the Image Providing System FIG. 1 is a diagram showing an overview of the configuration of an image providing system 2 according to the present embodiment. The image providing system 2 is introduced into a parking lot that provides automatic valet parking, and provides images of a vehicle 20 parked in the parking lot, particularly images of the vehicle 20 traveling in the parking lot, to a user.

[0018] The vehicle 20 has functions necessary for automatic valet parking including an automatic driving function, and is a target vehicle for automatic valet parking. The automatic driving of the vehicle 20 in the parking lot is controlled by, for example, a vehicle management system that uses a surveillance camera 30. Alternatively, the automatic driving of the vehicle 20 may be controlled by, for example, cooperation between a vehicle management system and a control system mounted on the vehicle 20. The vehicle 20 may be an autonomous driving vehicle capable of autonomous driving outside the parking lot.

[0019] The image providing system 2 includes a plurality of in-vehicle cameras 21 provided on the vehicle 20. The in-vehicle camera 21 is a camera for a multi-around view monitor provided inside the vehicle 20. The in-vehicle cameras 21 are provided at the front end, the rear end, and both side mirrors of the vehicle 20, and they form a set. The in-vehicle camera 21 may include a camera for an advanced driver assistance system (ADAS).

[0020] The video providing system 2 includes a plurality of surveillance cameras 30 installed in the parking lot. The surveillance cameras 30 are arranged along the driving route of the vehicle 20 in the parking lot. During the automatic driving by the automatic valet parking, the vehicle 20 enters the shooting range of at least one surveillance camera 30. The surveillance cameras 30 are arranged at high places such as the ceiling, wall, and columns, and shoot the vehicle 20 from above. The angle of the surveillance camera 30 may be adjusted to shoot the vehicle 20 directly from above, or may be adjusted to shoot the vehicle 20 from diagonally in front, diagonally behind, or diagonally sideways.

[0021] The video providing system 2 includes at least one video providing device 10. The video providing device 10 acquires an in-vehicle camera video (first video) 101 related to the vehicle 20 shot by the in-vehicle camera 21. Further, the video providing device 10 acquires a surveillance camera video (second video) 102 related to the vehicle 20 shot by the surveillance camera 30. The video providing device 10 generates a display video 103 based on at least one of the in-vehicle camera video 101 and the surveillance camera video 102.

[0022] The video providing system 2 includes a user terminal 40 held by a user who has parked the vehicle 20 in the parking lot. The display video 103 generated by the video providing device 10 is transmitted to the user terminal 40. The user terminal 40 is, for example, a smartphone installed with an application having a display function for the display video 103. The display video 103 is displayed on the display screen 41 of the user terminal 40.

[0023] Among the above elements constituting the video providing system 2, the surveillance camera 30 switches to other surveillance cameras 30 according to the position of the vehicle 20 in the parking lot. Since the in-vehicle camera 21 and the user terminal 40 are linked to the vehicle 20, if the vehicle 20 targeted for automatic valet parking changes, the in-vehicle camera 21 and the user terminal 40 constituting the video providing system 2 also change to another in-vehicle camera 21 and user terminal 40. In the video providing system 2, only the video providing device 10 exists as a fixed and unchanged element.

[0024] Figure 2 shows the hardware configuration of the video provision system 2. The video provision device 10 and each surveillance camera 30 are connected via a wired LAN through the parking center computer 50. The video provision device 10 and the in-vehicle camera 21 are connected via a wireless LAN through the in-vehicle communication device 22 installed in the vehicle 20. The video provision device 10 and the user terminal 40 are connected via a mobile network over the internet. Two-way communication takes place between the video provision device 10 and the user terminal 40.

[0025] The video output device 10 is a computer that constitutes the automated valet parking system. The video output device 10 may be the same computer as the vehicle management system that uses the surveillance camera 30 to control the movement of the vehicle 20, or it may be a different computer.

[0026] The video providing device 10 includes a processor 11. The processor 11 is a processing circuit that performs various processing, including video processing and arithmetic processing. Examples of the processor 11 include a CPU, GPU, TPU, NPU, FPGA, ASIC, DSP, and combinations thereof. The processor 11 is communicatively coupled to other elements that constitute the video providing device 10. The video providing device 10 has a program memory (not shown), and the computer functions as the video providing device 10 when the video providing program stored in the program memory is executed by the processor 11.

[0027] The video providing device 10 includes one or more memories. The memories provided by the video providing device 10 include a first memory 12 and a second memory 13. The first memory 12 is a memory that stores in-vehicle camera images acquired from the vehicle 20. The second memory 13 is a memory that stores surveillance camera images acquired from the parking center computer 50. The first memory 12 and the second memory 13 are, for example, FIFO memories. The first memory 12 and the second memory 13 may be physically different memories, or they may be different storage areas allocated in one or more memories.

[0028] The video provisioning device 10 includes a wired communication module 14 and a wireless communication module 15. The wired communication module 14 is used for communication with the parking center computer 50 using a wired LAN. The wired communication module 14 is also used for communication with the user terminal 40 via the internet. The wireless communication module 15 is used for communication with the in-vehicle communication device 22 using a wireless LAN.

[0029] 2. Processing performed by the video provision system Figure 3 is a diagram showing the flow of information within the video provision system 2. This diagram will be used to explain the processes performed in the video provision system 2.

[0030] Vehicle 20 transmits onboard camera footage 101 and vehicle information 104 to the video supply device 10. The vehicle information 104 includes information about the motion of vehicle 20, such as vehicle speed, acceleration, and steering angle, acquired by sensors mounted on vehicle 20.

[0031] The parking center computer 50 transmits surveillance camera footage 102 and automated valet parking information (AVP information) 105 to the video supply device 10. The AVP information 105 includes information necessary for automated valet parking, such as the location information of the vehicle 20, route information, vehicle type information, site map information, and obstacle information including other vehicles. The location information is information about the location of the vehicle 20 within the parking lot as recognized by the surveillance camera 30. The route information is information about the route within the parking lot that the vehicle 20 will automatically travel on by automated valet parking. The vehicle type information is information about the vehicle type, including the specifications of the vehicle 20 such as vehicle width and vehicle length. The site map information is information about a map showing the layout of roads and facilities within the parking lot. The obstacle information is information about objects that may obstruct the vehicle 20 from traveling along the route, and objects that may cause accidents such as collisions. Such objects include pillars, walls, other parked vehicles, other vehicles in motion, etc.

[0032] In the video providing device 10, the in-vehicle camera video 101 is stored in the first memory 12, and the surveillance camera video 102 is stored in the second memory 13. The processor 11 generates a display video 103 based on the in-vehicle camera video 101 stored in the first memory 12 and the surveillance camera video 102 stored in the second memory 13. Examples of display videos 103 include overhead views and oblique overhead views generated from the in-vehicle camera video 101, images of the surveillance camera video 102 enlarged or reduced to match the size of the vehicle 20, images with a changed viewpoint, and composite images created by combining the in-vehicle camera video 101 and the surveillance camera video 102. In generating the display video 103, the processor 11 refers to vehicle information 104 and AVP information 105.

[0033] The processor 11 determines the status of the vehicle 20 based on the AVP information 105. Examples of the status of the vehicle 20 include the vehicle 20 being in motion, the vehicle 20 about to enter an intersection, the vehicle 20 passing through an intersection, and the vehicle 20 having just started moving from its parking spot.

[0034] The processor 11 evaluates the risk of vehicle 20 based on vehicle information 104 and AVP information 105. The risk of vehicle 20 here refers to the risk to vehicle 20 while it is driving, for example, the risk of vehicle 20 being damaged by hitting or scraping against other vehicles or walls while it is being automatically valet parked. Examples of indicators that represent the type and magnitude of the risk of vehicle 20 include TTC (time to collision with an obstacle (wall, parked vehicle, etc.)), vehicle speed, acceleration in the forward, backward, left, and right directions, road gradient, and clearance from the surroundings. The risk of vehicle 20 is greater the smaller the TTC, greater the vehicle speed, greater the acceleration in the forward, backward, left, and right directions, greater the road gradient, and greater the clearance from the surroundings.

[0035] The processor 11 generates display images 103 according to the situation of the vehicle 20. For example, when the vehicle 20 is driving on a straight road with no obstacles around it, the processor 11 generates an image from the surveillance camera 102 showing the vehicle 20 and its surroundings from a predetermined direction, and uses this as the display image 103. Also, for example, when the vehicle 20 is reversing into a parking space, the processor 11 generates an image from the in-vehicle camera 101 showing the area behind and to the sides of the vehicle 20, and uses this as the display image 103. Also, for example, when the vehicle 20 is passing through an intersection, the processor 11 generates an image showing the area in front of and to both sides of the vehicle 20, and uses this as the display image 103. This image may be generated from the surveillance camera 102, or it may be a composite image of the in-vehicle camera 101 and the surveillance camera 102. Furthermore, for example, when vehicle 20 turns a corner with a small radius, processor 11 generates an image that shows the distance between vehicle 20 and an object located inside the corner, and uses this as the display image 103. This image may be generated from surveillance camera footage 102, from in-vehicle camera footage 101, or a composite image of these.

[0036] Furthermore, the processor 11 generates the display image 103 according to the risk of the vehicle 20. For example, if the vehicle 20 is driving on a straight road and the gap between it and an object on the left becomes narrower than the gap between it and an object on the right, the processor 11 switches the display image 103 from an image of the vehicle 20 and its surroundings viewed from a predetermined direction, generated from the surveillance camera image 102, to an image focused on the left side of the vehicle 20, generated from the in-vehicle camera image 101. The image focused on the left side of the vehicle 20 may also be a composite image of the in-vehicle camera image 101 and the surveillance camera image 102. Also, for example, if the vehicle 20 is reversing into a parking slot, the processor 11 may use the image generated from the surveillance camera image 102 as the display image 103 until the TTC to the object behind is below a predetermined value, and then switch the display image 103 to the image generated from the in-vehicle camera image 101. However, in generating the display video 103, the status of the vehicle 20 may be a mandatory condition, while the risks associated with the vehicle 20 may be an optional condition.

[0037] The synthesis of the in-vehicle camera image 101 and the surveillance camera image 102 by the processor 11 includes supplementing the blind spots of the in-vehicle camera image 101 with the surveillance camera image 102, and supplementing the blind spots of the surveillance camera image 102 with the in-vehicle camera image 101. The synthesis of the in-vehicle camera image 101 and the surveillance camera image 102 also includes creating a 3D spatial image by combining the in-vehicle camera image 101 and the surveillance camera image 102. Various methods can be used to create the 3D spatial image, such as the multi-view stereo method, the structure reconstruction method from motion (SfM), and the deep learning-based 3D reconstruction method. The synthesized image generated by the processor 11 includes an image in which the surveillance camera image 102 is spliced ​​onto the in-vehicle camera image 101. The synthesized image generated by the processor 11 also includes a picture-in-picture image in which the other is displayed within either the in-vehicle camera image 101 or the surveillance camera image 102.

[0038] The processor 11 receives a video request 106 from the user terminal 40 and generates a display video 103. The video request 106 may simply be a request to transmit video, or it may be a request regarding the content of the video. However, the content requested in the video request 106 is general, such as a video of the vehicle 20 viewed from above, or a video of the vehicle 20 viewed from the side. The processor 11 determines the detailed content of the display video 103 according to the status of the vehicle 20, or according to the status and risks of the vehicle 20.

[0039] Furthermore, the processor 11 performs image processing on the display image 103 for privacy protection. Such image processing includes blurring the license plates of surrounding vehicles, the surrounding vehicles themselves, or the surrounding people that are visible in the surveillance camera image 102.

[0040] The display video 103 generated by the processor 11 is real-time video. However, since users may want replays, the video provider 10 may also have a recording and playback function. In that case, the display video 103 transmitted from the video provider 10 to the user terminal 40 will be a recorded video stored in the video provider 10. The user can specify the playback period of the recorded video in the application on the user terminal 40.

[0041] Figure 4 is a flowchart showing the flow of a series of processes executed by the processor 11, among the processes executed by the video provisioning system 2. This flowchart also illustrates the video provisioning method according to this embodiment. The video provisioning program stored in the program memory includes a plurality of instructions for causing the processor 11 to execute the video provisioning method shown in this flowchart.

[0042] In step S1 of this flowchart, the processor 11 determines whether or not it has received a video request 106 from the user. Until it receives the video request 106, the processor 11 skips the processing in steps S2-S5 and terminates the flow. Then, upon receiving the video request 106, the processor 11 executes the processing in step S2.

[0043] In step S2, the processor 11 first identifies the vehicle 20 associated with the user terminal 40 based on the user terminal information included in the video request 106. The association between the user terminal 40 and the vehicle 20 is performed when the user registers for use of the parking lot. The processor 11 obtains the AVP information 105 of the identified vehicle 20 from the parking lot center computer 50 and determines the status of the vehicle 20 based on the AVP information 105. After executing the process in step S2, the processor 11 executes the process in step S3.

[0044] In step S3, the processor 11 obtains vehicle information 104 from the vehicle 20 and evaluates the risk of the vehicle 20 based on the vehicle information 104 and the AVP information 105. After executing the process in step S3, the processor 11 executes the process in step S4. Note that the order of the processes in steps S3 and S2 may be reversed, or they may be executed in parallel. Also, since the evaluation of the risk of the vehicle 20 is optional, the process in step S3 may be omitted, and the process in step S4 may be executed after the process in step S2.

[0045] In step S4, the processor 11 generates a display image 103 based on at least one of the in-vehicle camera image 101 stored in the first memory 12 and the surveillance camera image 102 stored in the second memory 13. The processor 11 generates the display image 103 according to the status of the vehicle 20, or according to the status and risks of the vehicle 20. After executing the process in step S4, the processor 11 executes the process in step S5.

[0046] In step S5, the processor 11 sends the display video 103 generated in step S4 to the user terminal 40. If the user sends a new video request 106, for example, if the user requests video with a different viewpoint, the processor 11 again executes the processes in steps S2-S5 and sends the display video 103 generated according to the status of the vehicle 20 at that time, or according to the status and risks of the vehicle 20 at that time, to the user terminal 40.

[0047] 3. Effectiveness of the video distribution system During automated valet parking, users are concerned about the moving vehicle 20 and its surroundings. Since the user's concerns vary depending on the vehicle 20's condition, it is not easy or even cumbersome for the user to select a satisfactory image from the available images. In this regard, the image provision system 2 automatically generates images 103 suitable for the user to see what they are concerned about and displays them on the user terminal 40. This allows the user to feel at ease.

[0048] Furthermore, both the in-vehicle camera footage 101 and the surveillance camera footage 102 have areas that are clearly visible and areas that are not clearly visible or are difficult to see, and they are complementary to each other. Therefore, if a user cannot see what they want to see in either the footage, they may remain anxious. In this regard, the video provision system 2 combines the complementary in-vehicle camera footage 101 and the surveillance camera footage 102, allowing the user to view the areas of concern in the combined image. This gives the user a sense of security. [Explanation of Symbols]

[0049] 2. Video Provision System 10. Video provisioning device 11 processors 12 First Memory 13. Second Memory 20 vehicles (applicable vehicles) 21 In-car cameras 22. In-vehicle communication device 30 surveillance cameras 30 Remote Cockpit 40 User terminals 41 screens 50 Parking Center Computer

Claims

1. A video providing device that provides users with video footage of vehicles subject to automated valet parking, A first memory that stores first video footage related to the target vehicle, captured by one or more in-vehicle cameras of the target vehicle, A second memory that stores second video footage related to the target vehicle, captured by multiple surveillance cameras installed in the parking lot where the automated valet parking is performed, A processor is provided which is communicatively coupled to the first memory and the second memory, The aforementioned processor, The display video shown to the user is generated based on at least one of the first video and the second video according to the status of the target vehicle. The system is configured to display the aforementioned display video on the user's terminal. A video provisioning device characterized by the following features.

2. In the video providing device according to claim 1, The aforementioned processor further, The risks to the aforementioned vehicle continuing to operate were assessed, The system is configured to generate the display image according to the aforementioned circumstances and risks. A video provisioning device characterized by the following features.

3. In the video providing device according to claim 1, Generating the display video includes generating a composite video by combining the first video and the second video, according to the circumstances. A video provisioning device characterized by the following features.

4. In the video providing device according to claim 1, The aforementioned processor further, The system is configured to perform processing on the display image to protect the privacy of vehicles or people present in the vicinity of the target vehicle. A video provisioning device characterized by the following features.

5. In the video providing device according to claim 1, The aforementioned processor further, The video request from the aforementioned user is obtained, The system is configured to generate the display video in response to the aforementioned circumstances and the video request. A video provisioning device characterized by the following features.

6. A method for providing video footage to a user of a vehicle subject to automated valet parking, To acquire a first video related to the subject vehicle, captured by the in-vehicle camera of the subject vehicle, To acquire a second video related to the target vehicle, captured by multiple surveillance cameras installed in the parking lot where the automated valet parking is performed, The display video shown to the user is generated based on at least one of the first video and the second video according to the status of the target vehicle, This includes displaying the aforementioned display video on the user's terminal. A video provision method characterized by the following features.

7. The method for providing video according to claim 6 includes a plurality of instructions for causing a computer processor to execute the video provision method. A program characterized by the following features.

8. A video providing device that provides users with video footage of vehicles subject to automated valet parking, A first memory that stores a first video related to the subject vehicle, captured by the vehicle's onboard camera, A second memory that stores second video footage related to the target vehicle, captured by multiple surveillance cameras installed in the parking lot where the automated valet parking is performed, A processor is provided which is communicatively coupled to the first memory and the second memory, The aforementioned processor, A composite image is generated by combining the first image and the second image. The system is configured to display the synthesized image on the user's terminal. A video provisioning device characterized by the following features.

Images