Electronic device and its control method

Abstract

Electronic device (100) comprising a detection unit (113) for detecting an orientation of the electronic device (100) and a display control unit (101) for performing control to display an area of ​​a part of VR content as a display area on a display unit and to change a position of the display area according to an orientation detected by the detection unit (113), wherein if a part of the VR content is a non-video area, and the non-video area is narrower than a certain amount, the display control unit (101), after the display area has reached an end of a video area of ​​the VR content in the video area according to a change of orientation in a certain direction of rotation of the electronic device (100), changes the display area from one end to another end of the video area according to a further change of orientation in the certain direction of rotation of the electronic device (100),and if part of the VR content is a non-video area and the non-video area is not narrower than the specified amount, the display control unit (101), after the display area has reached one end of a video area of ​​the VR content in the video area according to a change of orientation in the specified direction of rotation of the electronic device (100), does not change the display area from one end to the other end of the video area even if there is a further change of orientation in the specified direction of rotation of the electronic device (100).

Description

Technical FieldThe present invention relates to an electronic device, a control method of the electronic device, a program, and a storage medium, and more particularly to a control method for displaying an image having a wide video range.Background ArtIn recent years, image capturing devices capable of photographing an image including a video wider than a human viewing angle, such as an omnidirectional image or full skyball image, have become popular. There are also known methods for performing display with a strong feel of dive or a strong feel of realism, in which a part of an image including such a wide area video is displayed on a display device, and a range of the video to be displayed on the display device (a display area) is changed so as to follow a change in orientation of an image capturing apparatus.PTL 1 proposes a video display system that, when viewing a video captured by a full-skyball camera by a head-mounted display device (HMD), captures a line-of-sight direction of a user and displays video data of a predetermined area according to the line-of-sight direction.List of Citer ListsPatent LiteraturePTL 1: Japanese Patent Application Laid-Open JP 2017-22665 AWO 2016 / 013 272 A1 discloses an information processing apparatus that processes a wide-angle image displayed on a screen fixed to the head or face of the user. When the display view angle reaches the boundary of the original wide-angle image, an indicator is added to a clear view image to indicate that the boundary has been reached. The indicator is displayed such that the portion of the clear view image that touches or protrudes beyond the boundary of the wide angle image is represented as a solid black edge. Upon observing such an indicator, the user intuitively understands that the display area has reached the boundary of the wide-angle image.Summary of the InventionTechnical TaskIn the generation of video content to be displayed on an HMD or the like, various photographic viewing angles may be used by an image capturing device when photographing the content, and the viewing angle may be changed when editing the content. Therefore, the video content may not include a full 360 degree (omnidirectional) scope video, and may only include a video in a sub-range thereof (e.g., 120 degrees vertical or 220 degrees horizontal). Since a valid video area of such video content is not continuous over 360 degrees of circumference, ends are present in an area where the video is present (the valid video area), and a region exceeding the ends constitutes a non-video area. Conceivable methods for displaying a part of such video content as a display area include moving a display area beyond an end of a valid video area, displaying a non-video area in the process of moving, and displaying the valid video area on a side of another end when the display area is moved in the same direction.However, when displaying the non-video area beyond the one end of the valid video area, it is difficult for a user to distinguish whether a video is not displayed because the video is included in the non-video area or a video is not displayed due to some kind of irregularity in the display process, regarding a portion corresponding to the non-video area. In addition, when the non-video area is to be hidden beyond the one end of the valid video area, it is difficult for a user to distinguish whether a display area is not changed because an end of the valid video area has been reached or because some kind of abnormality has occurred in the display process.In a video content including a video having a range other than a human viewing angle, a non-video range is often positioned rearward or immediately below when it is assumed that a center of the valid video range is forward, and positioned in a direction in which it is difficult for a user who directly views the center of the valid video range to direct his line of sight. However, in order to display the valid video area at the other end after displaying the non-video area beyond the one end as described above, the non-video area needs to be displayed for a long period of time when the non-video area is wide. Display of the non-video area over a long period of time creates a problem in that a posture where aiming of a line of sight is difficult has to be assumed over a long period of time and a problem in that discrimination is difficult which area is being displayed. Rather, moving the display area in the opposite direction and displaying the valid video area at the other end may make it easier to distinguish which area is being displayed and at the same time may be performed more easily.In view of this, the present invention provides an electronic device, a control method of the electronic device, a program, and a storage medium that enable more appropriate display to be performed when content having a wide video range includes a non-video range.Solution of the ProblemAn electronic device according to the invention is specified in the appended claims.Advantageous Effects of the InventionAccording to the present invention, when content having a wide video area includes a non-video area, more appropriate display can be performed.Brief Description of the DrawingsFIG. 1 shows a schematic block diagram of an electronic device 100. FIG. 2 shows an external view of the electronic device 100. FIG. 3 shows an external view of a VR smart glasses to which the electronic device 100 can be attached. FIG. 4 is a flowchart of a VR display process. FIG. 5 shows a positional relationship and a display example of a display area in the VR display process. FIG. 6 shows a positional relationship and a display example of a display area in the VR display process. FIG. 7 is a flowchart showing another example of the VR display process.DESCRIPTION OF THE EMBODIMENTSFIG. 1 shows an example of a configuration of an electronic device 100 as an example of a display control device to which the present invention is applicable. The electronic device 100 may be configured using a display device such as a smartphone.Referring to FIG. 1, a CPU 101, a memory 102, a nonvolatile memory 103, an image processing unit 104, a display 105, an operation unit 106, a storage medium I / F 107, an external I / F 109, and a communication I / F 110 are connected to an internal bus 150. In addition, an audio output unit 112 and an orientation detection unit 113 are also connected to the internal bus 150. The respective units connected to the internal bus 150 are configured to be capable of exchanging data with each other via the internal bus 150.The CPU 101 is a control unit that controls the entire electronic device 100, and is constituted by at least one processor. The memory 102 is constituted by, for example, a RAM (such as a volatile memory using a semiconductor element). The CPU 101 controls the respective units of the electronic device 100 using, for example, the memory 102 as a working memory according to a program stored in the nonvolatile memory 103. The nonvolatile memory 103 stores image data and audio data, other data, various programs that enable the operation of the CPU 101, and the like. The nonvolatile memory 103 is formed by, for example, a flash memory or a ROM.Under the control of the CPU 101, the image processing unit 104 performs various image processings on images stored in the nonvolatile memory 103 or the storage medium 108, video signals acquired via the external I / F 109, images acquired via the communication I / F 110, and the like. Image processing performed by the image processing unit 104 includes an A / D conversion process and a D / A conversion process, and a coding process, compression process, decoding process, enlargement / reduction process (resizing), noise reduction process, color conversion process, and the like of image data. The image processing unit 104 also performs various image processings such as panoramic development, imaging process, and conversion of omnidirectional images or wide-range images with data of a wide range when the non-omnidirectional range is not performed. The image processing unit 104 may be constituted by a dedicated circuit block for performing the specific image processing. In addition, depending on the type of image processing, the CPU 101 may perform the image processing without using the image processing unit 104 according to a program.The display device 105 displays images, a GUI (Graphic User Interface) screen constituting a GUI, and the like under the control of the CPU 101. The CPU 101 controls the respective units of the electronic apparatus 100 to generate a display control signal according to the program and generate a video signal to be displayed on the display device 105 and output the video signal to the display device 105. The display device 105 displays a video based on an output video signal. Alternatively, components of the electronic apparatus 100 itself may be limited to an interface for outputting a video signal to be displayed by the display device 105, and the display device 105 may be formed by an external monitor (such as a TV set).The operation unit 106 is an input device for accepting a user operation, examples of which include a character information input device such as a keyboard, a pointing device such as a mouse or an touch panel, a button, a dial, a joystick, a touch sensor, and a touch panel. In this case, a touch panel refers to a display device configured planarly so as to overlap the display device 105 and output coordinate information according to a touched position.The storage medium I / F 107 is configured such that a storage medium 108 such as a memory card, a CD, or a DVD can be mounted thereon, and the storage medium I / F 107 reads data from the mounted storage medium 108 and writes data into the mounted storage medium 108 under the control of the CPU 101. The external I / F 109 is an interface to be connected to an external device using a cable or wirelessly to perform input and output of video signals and audio signals. The communication I / F 110 is an interface for communicating with an external device, the Internet 111, and the like to transmit and receive various kinds of data such as files and commands.The audio output unit 112 outputs sound of moving pictures and music data, keyboard clicks, call sounds, various notification sounds, and the like. Although it is assumed that the audio output unit 112 includes an audio output terminal 112 ato which a headphone or the like is to be connected and a speaker 112 b, the audio output may alternatively be performed by radio communication or the like.The orientation detection unit 113 detects an orientation of the electronic device 100 relative to the gravity direction. Based on an orientation detected by the orientation detection unit 113, it may be determined whether the electronic device 100 is held horizontally, held vertically, directed upward, directed downward, or assumed to be an oblique orientation. As the orientation detection unit 113, an acceleration sensor, a gyro sensor, a geo-magnetic sensor, an orientation sensor, or the like may be used, or a plurality of the sensors may be used in combination.The operation unit 106 includes an operation interactive panel 106 a. The CPU 101 can grasp the following operations with respect to the operation panel 106 aor the following states of the operation panel 106 a, respectively.• A state in which a finger or pen that was not previously in contact with the operation panel 106a newly touches the operation panel 106a, and a start of a touch (hereinafter referred to as a touch-down state), respectively• A state in which the touch panel 106a is touched by a finger or a pen (hereinafter referred to as a touch-on state)• A state in which a finger or pen moves while touching the touch panel 106 a(hereinafter referred to as a touch-move state)• A state in which a finger or a pen that has previously touched the operation panel 106 aseparates from the operation panel 106 a, or an end of a touch (hereinafter referred to as a touch-up state), respectively• A state in which nothing touches the touch panel 106 a(hereinafter referred to as a touch-off state)When a touch-down state is detected, a touch-on state is simultaneously detected. After a touch-down state, a touch-on state is normally continuously detected if no touch-up state is detected. When a touch-move state is detected, a touch-on state is simultaneously detected. Even if a touch-on state is detected, a touch-move state is not detected when the touch position does not move. A touch-off state is detected upon detection of a touch-up state of all fingers or a pen that have / have touched previously.The CPU 101 is informed of the above-described operations and a position coordinate where a finger or pen touches the touch panel 106 avia an internal bus, and the CPU 101 determines what kind of operation (touch operation) is performed on the touch panel 106 abased on the notified information. Regarding a touch-move state, a moving direction of a finger or a stylus moving on the touch panel 106 amay be determined for a vertical component and a horizontal component on the touch panel 106 a, respectively, based on a change in the position coordinate. When a touch-move state of a predetermined distance or more is detected, it is determined that a slide operation is performed. An operation that includes a rapid movement of a finger on the touch panel 106 aover a certain distance while the finger remains in contact with the touch panel 106 a, and the finger is then released is referred to as wiping. That is, wiping is an operation in which a finger pulls the touch panel 106 alike as if he would wear on the touch panel 106 a. A determination that swiping is performed may be performed (a determination that swiping has occurred after a slide operation may be performed) when detection of a touch-move state over a predetermined distance or more at a predetermined speed or more is followed by detection of a touch-up state. A touch operation including touching a plurality of locations (for example, from two points) at the same time and bringing the respective touch positions close to each other is referred to as pinching, while a touch operation in which the respective touch positions are separated from each other is referred to as pinching. Clipping and clamping are collectively referred to as a clamping operation (or simply clamping). As the touch panel 106 a, a touch panel using any of various systems including a resistive layer system, a capacitance system, a surface acoustic wave system, an infrared system, an electromagnetic induction system, a vision system, and an optical sensor system may be used. Any system may be employed in which a touch is detected when contact is made with the touch panel, or in which a touch is detected when a finger or pen approaches the touch panel.FIG. 2 shows an example of an external view of the electronic device 100. The display device 105 is a display unit that displays images and various kinds of information. The display device 105 is integrally constructed with the touch panel 106 aas described above, and is configured to be capable of detecting a touch operation on a display surface of the display device 105. As illustrated, the operation unit 106 includes operation units 106 b, 106 c, 106 d, and 106 e. The operation unit 106 bis a power supply button for accepting an operation for switching between on and off of a power supply to the electronic device 100. The operation unit 106 cand the operation unit 106 dare volume keys for increasing and decreasing a volume of audio output from the audio output unit 112. The operation unit 106 eis a home button for causing a home screen to be displayed on the display device 105.FIG. 3 shows an external view of a VR glasses (a head mount adapter) to which the electronic device 100 can be attached. By attaching the electronic device 100 to the VR glasses, the electronic device 100 can be used as a head-mounted display. An insertion opening 301 is an insertion opening into which the electronic device 100 can be inserted. The entire electronic device 100 can be inserted into the VR glasses by orienting the display surface of the display device 105 to one side of a head band 302 (i.e., oriented toward the user) to fix the VR glasses to the head of a user. By wearing the VR glasses to which the electronic device 100 is mounted in this manner, the user can view the display device 105 of the electronic device 100 in a state in which the VR glasses are worn on the head of the user without holding the electronic device 100 in the hand. In this case, when the user moves his head or whole body, the orientation of the electronic device 100 also changes. The orientation detection unit 113 detects a change in the orientation of the electronic device 100 at this time, and the CPU 101 performs a VR display process (to be described below) based on the change in the orientation. In this case, the detection of the orientation of the electronic device 100 by the orientation detection unit 113 is equivalent to detection of an orientation of the head of the user (a direction in which a line of sight of the user is oriented).The electronic device 100 may perform VR display of a VR image (VR content) on the display 105.It is assumed that a VR image is an image for which VR display can be performed. It is assumed that VR images include an omnidirectional image (a full-sky-sphere image) captured by an omnidirectional camera (a full-sky-sphere camera) and a panoramic image having a further video range (a valid video range) as a display range that can be displayed on a display unit at a time. In addition to images photographed by a camera, it is assumed that VR images (VR contents) even include images generated using computer graphics (CD) as long as the VR display of the images can be performed. VR images include moving images and live view images (images acquired in near real time from a camera) in addition to still images. A VR image has a maximum video range (valid video range) corresponding to a field of view of 360 degrees in the vertical direction (vertical angle, angle from the apex, elevation, angle of depression or angle of elevation) and 360 degrees in the horizontal direction (horizontal angle or azimuth). In addition, it is assumed that VR images include images having a wide angle of view (field of view) wider than an angle of view that can be photographed by a general camera or images having a wider video range (valid video range) than a display range that can be displayed on a display unit at once even if the field of view of the images is less than 360 degrees in the vertical direction and less than 360 degrees in the horizontal direction. An image photographed by a full-sky-sphere camera that can photograph an object corresponding to a field of view (angle of view) of 360 degrees in the horizontal direction (horizontal angle or azimuth) and 210 degrees in the vertical direction from the vertex is, for example, a kind of VR image. That is, an image having a video range corresponding to a field of view of 180 degrees (±90 degrees) or more in both the vertical direction and the horizontal direction and a video range other than a range that can be seen by a human at a time is a kind of VR image. By performing VR display of the VR image, changing an orientation in the horizontal rotation direction enables seamless observation of an omnidirectional video in the horizontal direction (the horizontal rotation direction). Although seamless omnidirectional video can be viewed in the vertical direction (a vertical rotation direction in a range of ±105 degrees directly from above (the vertex), a range exceeding 105 degrees directly from above constitutes a blank region in which no video is present. A VR image can be described as "an image whose video area is at least a part of a virtual space (a VR space)).A VR display refers to a display method for displaying a video of a field of view area according to an orientation of the electronic device 100 detected by the orientation detection unit 113 from a VR image, and in which a display area can be changed. When viewing the electronic device 100 mounted on the VR eyeglasses, a video of a field of view is to be displayed according to an orientation of the user's head. For example, it is assumed that a video having a viewing angle (viewing angle) centered at 0 degrees in the horizontal direction (a certain azimuth such as north) and centered at 90 degrees in the vertical direction (90 degrees from the vertex) is displayed at a certain time in a VR image. When reversing from this state front and back of the orientation of the electronic device 100 (for example, when changing a display surface from looking to south to looking to north), the display area is changed to a video having a viewing angle centered at 180 degrees in the horizontal direction (an opposite azimuth such as south) and 90 degrees in the vertical direction (the horizontal) in the same VR image. That is, in a case where the user views the electronic device 100 mounted on the VR glasses, when the user turns his head from north to south (that is, when the user turns), the video displayed on the electronic device 100 also changes from a video to north to a video to south. Such a VR display enables the user to feel as if the user were visually within the VR image (within the VR space).FIG. 4 is a flowchart of a VR display process performed by the electronic device 100. This process is realized when the CPU 101 applies a program recorded in the nonvolatile memory 103 to the memory 102 and executes the program. The process shown in FIG. 4 is started when the power supply of the electronic device 100 is turned on, a VR image (a VR content) is selected from images recorded on the storage medium 108 and images acquired from a communication target, and the display is set by VR display among a plurality of display methods.In S 401, the CPU 101 loads a VR image to be a display target from the storage medium 108 or from a communication target via the communication I / F. In addition, the CPU 101 acquires information on a video area (a valid video area) attached as attribute information of the VR image. The valid video range information refers to information describing angle ranges in the vertical direction and the horizontal direction of a valid video included in the VR image. The information on a valid video range only needs to be information that enables determination of a valid video range of the VR image, and may be angle information representing a viewpoint, viewing angle, azimuth, elevation, depression angle, elevation angle, steradian, or the like, or position information such as the number of vertical and horizontal pixels or coordinates. Alternatively, the information on a valid video area may be model information of the camera used for capturing the VR image (a photographable area may be determined by specifying a model), information on zoom during photography, and the like. When the CPU 101 acquires the information on a valid video range, the CPU 101 also identifies (calculates) an invalid video range (a non-video range) based on differences from vertical and horizontal 360 degrees. On the other hand, information on an invalid video area may be acquired from the attribute information of the VR image, and a valid video area may be calculated from the information on the invalid video area, or both information on a valid video area and information on an invalid video area may be acquired from the attribute information of the VR image.In S 402, the CPU 101 acquires an orientation (orientation information) acquired by the orientation acquisition unit 113.In S 403, based on the orientation acquired in S 402, the CPU 101 preliminarily calculates a display area indicating an area to be displayed from the VR image (calculates a preliminary display area). In the subsequent processes, a determination must be made as to whether or not a video of the provisional display area calculated in S 403 should actually be displayed.In S 404, the CPU 101 determines whether a distance from the temporary display area to the invalid video area is within a predetermined distance (within a predetermined amount) that is a threshold value. When the distance is within the predetermined distance, the process goes to S 406, but when the distance is larger than the predetermined distance, the process goes to S 405. The process of S 404 will be described with reference to FIG. 5( a 1). In FIG. 5 (a1), a valid video area 501 represents an entire valid video area in a VR image mapped to a two-dimensional plane. An invalid video area 502 shown in gray indicates a region that is not a valid video area (a non-video area) in the VR image with respect to an entire horizontal area (all directions) of 360 degrees and a vertical area of 180 degrees. This region does not contain video, and an attempt to display the region results in monochromatic display of the region as a blank region in black, gray or the like. A display area 503 indicates an area currently displayed on the display device 105 with respect to the VR image (before the orientation change). When the display area 503 is located at a position shown in FIG. 5(a1), display such as that shown in FIG. 5(a2) is performed on the display device 105. A preliminary display area 504 represents a viewing angle moved by an amount of change in the orientation detected by the orientation detection unit 113 from the display area 503. The distance from the preliminary display area to the invalid video area as determined in S404 includes the following values.• A distance a1 between a right end of the temporary display area 504 and a right end of the valid video area 501• A distance a2 between an upper end of the preliminary display area 504 and a lower end of the valid video area 501• A distance a3 between a left end of the preliminary display area 504 and a left end of the valid video area 504• A distance a4 between a lower end of the preliminary display area 504 and a lower end of the valid video area 501Note that an end of the valid video area 501 is a portion in contact with a boundary between the valid video area 501 and the invalid video area 502. If any one of the distances a 1 to a 4 is less than or equal to a distance Ath that is a threshold, the process goes to S 406, but otherwise the process goes to S 405. The threshold Ath is, for example, a length of about 30% of a width of the display area 503 in the lateral direction, and any one of the distances a 1 to a 4 that is equal to or smaller than the threshold Ath indicates that an end of the valid video area is reached shortly when the display area moves further in the same direction. Although an example of comparing a distance with a threshold has been described as the process of S 404, because a two-dimensional planar view is used as an example, the process of S 404 is not limited thereto. It is only necessary to make a determination as to whether ends of a provisional display area 504 and the valid video area 501 approach each other, and an angle difference between an angle indicating the end of the valid video area 501 and an angle indicating the end of the provisional display area 504 may be compared with a threshold value. Although an example in which all the distances a 1 to a 4 are compared with the distance Ath that is a threshold has been described, this example is not a limitation. For example, only a shortest distance among the distances a 1 to a 4 may be compared with the distance Ath, and the process may proceed to S 406 if the shortest distance is less than or equal to the distance Ath, but on the other hand, the process proceeds to S 405.According to a moving direction from the display area 503 before the orientation change to the provisional display area 504 calculated after the orientation change, a distance in a direction in which the end of the provisional display area 504 separates from the end of the valid video area among the distances a 1 to a 4 cannot be used for the determination. In the illustrated example, the distance a 3 may not be compared to the threshold Ath. Further, instead of comparing all the distances a 1 to a 4 with the same threshold, each of the distances a 1 to a 3 may be compared with different thresholds. For example, the distances a 1 and a 3 in the horizontal direction may be compared with a distance Ath 1, and the process may proceed to S 406 when the distances a 1 and a 3 are equal to or less than the distance Ath 1. The distances a 2 and a 4 in the vertical direction may be compared with a distance Ath 2 (<Ath 1), and the process may proceed to S 406 when the distances a 2 and a 4 are equal to or less than the distance Ath 2. Otherwise, the process may proceed to S 406. In the following processes, the attention of the user is turned earlier to the fact that the display area is about to reach an end of the valid video area in a case of horizontally directional orientation change representing a direction in which a person can turn his head more easily than in the case of vertically directional orientation change.In S 405, the CPU 101 updates the display area to the provisional display area calculated in S 403, and displays a video of the updated display area on the display device 105. In addition, since this situation is a case where it is not determined in S 404 that the distance to the invalid video area is within the predetermined distance, no area guidance is displayed. If the area guidance before the orientation change has been displayed, the CPU 101 hides the area guidance. The area guidance will be described later.FIG. 5( a 1) shows a positional relationship of the display area 503 in a VR image in the situation of S 405 and FIG. 5( a 2) shows a display example in this case. The provisional display area 504 illustrated in FIG. 5( a 1) is an example of a provisional display area calculated when there is another clockwise orientation change from a display area 503 displayed in S 405. Therefore, in S 405 it is assumed that the provisional display region 504 is not acquired at the position illustrated in FIG. 5( a 1). The distance between the right end of the display area 503 and the right end of the valid video area 501 is larger than the threshold Ath and is a long distance (the same applies to the other distances). FIG. 5( a 2) is a display example in a case where VR display of a position corresponding to the display region 503 in FIG. 5( a 1) is performed on the display device 105. Since no area guide 510 (to be described below) is displayed, the visual recognition of the VR image is not obstructed.In S 406, the CPU 101 determines whether or not one of the ends (one of the sides) of the provisional display area 504 has reached an end of the valid video area. That is, this is a determination as to whether any one of the distances a 1 to a 4 has become zero. When one of the ends (one of the sides) of the temporary display area 504 has reached the one end of the valid video area, the process goes to S 408, but otherwise the process goes to S 407.In S 407, the CPU 101 updates the display area to the provisional display area calculated in S 403, and displays a video of the updated display area on the display device 105. In addition, since this situation is a case where it is determined in S404 that the invalid video range distance is within the predetermined distance, the CPU 101 displays range guidance as notifying the fact that the invalid video range distance is now within the predetermined distance.FIG. 5( b 1) shows a positional relationship of the display area 503 in a VR image in the situation of S 407, and FIG. 5( b 2) shows a display example in this case. The display area 503 has moved further to the right end of FIG. 5( a 1), and although the display area 503 has not reached an end of the valid video area 501, the distance between the right end of the display area 503 and the right end of the valid video area 501 is less than or equal to the threshold Ath and is a short distance. FIG. 5 ( b 2) is a display example in a case where VR display of a position corresponding to the display region 503 in FIG. 5( b 1) is performed on the display device 105. The area guide 510 is displayed superimposed on the VR display of an image. The area guide 510 indicates, from a 360 degree scope, a valid video area (dotted line portion 511), a display area (white portion 512) whose VR display is being performed, and an invalid video area (black portion 513). By viewing the area guide 510, the user can recognize which area (positional relationship) in the entire VR image the currently displayed area (display area) occupies. In the example shown in FIG. 5( b 2), the white portion 512 is located near the black portion 513, indicating that the invalid video area is reached shortly when the line of sight (the display area) is moved further to the right.The area guide 510 in FIG. 5( b 2) shows a valid video area, an invalid video area, and a display area of 360 degrees in the horizontal direction. In addition, an area guide showing a valid video area, an invalid video area, and a display area of 360 degrees or 180 degrees in the vertical direction may be displayed separately. That is, both the horizontal direction range guide 510 and a vertical direction range guide may be displayed. Since displaying both the range guides hinders the visual recognition of the image of which VR display is performed, the range guide 510 for the horizontal direction and the range guide for the vertical direction can be dynamically switched according to a direction of an immediately preceding change in orientation to display one of the range guides or none of the range guides. For example, when the distance a 1 or the distance a 3 each being a direction in the horizontal direction between the display area 503 and the valid video area 501 becomes equal to or less than the threshold Ath due to an immediately preceding change in orientation, the area guide 510 for the horizontal direction may be displayed, and the area guide for the vertical direction may be hidden. In addition, when the distance a 2 or the distance a 3 each being a direction in the vertical direction between the display area 503 and the valid video area 503 becomes equal to or less than the threshold Ath due to an immediately preceding change in orientation, the area guide for the vertical direction may be displayed and the area guide 510 for the horizontal direction may be hidden. The user can thus understand a positional relationship of a region (display region) currently being viewed with respect to a direction in which an end of a valid video region is nearly reached. Alternatively, a component of a motion vector in the horizontal direction and a component of the motion vector in the vertical direction from an immediately preceding orientation may be compared with each other, and a range guidance of the larger motion component may be displayed.In S 408, the CPU 101 determines whether or not an amount by which the provisional display area 504 exceeds the valid video area 501 is greater than a threshold value Bth (a predetermined amount). FIG. 5( c 1) shows an example of a positional relationship in a case where the provisional display area 504 exceeds the valid video area 501. In S 408, the CPU 101 determines whether or not a distance b representing an amount by which the provisional display area 504 exceeds the valid video area 501 is greater than the threshold Bth. When the distance b exceeds the threshold value Bth, the process goes to S 410 and otherwise the process goes to S 409. The amount by which the provisional display area 504 exceeds the valid video area 501 (an amount of exceeding from an end of the valid video area 501) refers specifically to the following.• When the right end of the preliminary display area 504 exceeds the right end of the valid video area 501 (i.e., when a1<0): the distance between the right end of the preliminary display area 504 and the right end of the valid video area 501• When the top end of the preliminary display area 504 exceeds the top end of the valid video area 501 (i.e., when a2<0): the distance between the top end of the preliminary display area 504 and the top end of the valid video area 501• When the left end of the preliminary display area 504 exceeds the left end of the valid video area (i.e., when a3<0): the distance between the left end of the preliminary display area 504 and the left end of the valid video area 501• When the bottom end of the preliminary display area 504 exceeds the bottom end of the valid video area 501 (i.e., when a4<0): the distance between the bottom end of the preliminary display area 504 and the bottom end of the valid video area 501The threshold value Bth is a variable determined by a width of the invalid video area (a width of the valid video area), and is assumed to be a sum of the width of the invalid video area and a width of the display area in the moving direction of the display area. That is, when the excess amount reaches the threshold value Bth, the provisional display area becomes an area in contact with an end of the exactly opposite side of the valid video area.While a determination is made in S 408 as to whether or not an amount by which the provisional display area 504 exceeds the valid video area 501 is greater than the threshold Bth (a predetermined amount), this is equivalent to a determination as to whether or not an amount of orientation change exceeds a threshold. That is, the determination is equivalent to determining whether a change in orientation of the electronic device 100 in a certain rotational direction has occurred from a state in which the display area 503 is in contact with an end of the valid video area 501 with an amount of change that causes the excess amount to reach Bth. A change in the orientation in the determined rotation direction is a change that causes the temporary display area 504 to move in a direction where the temporary display area 504 exceeds the valid video area. The determination of S 408 may therefore be a determination made based on the orientation.In S 409, the CPU 101 updates the display area to an area in contact with an end of the valid video area 501 in a direction toward the provisional display area calculated in S 403 from the display area before the movement, and not to the provisional display area calculated in S 403. In addition, the CPU 101 displays a video of the updated display area from the VR image on the display device 105. Further, since this situation is a case where it is determined in S 404 that the distance to the invalid video area is within the predetermined distance, the CPU 101 displays area guidance.FIG. 5( c 1) shows a positional relationship of the display area 503 in a VR image in the situation of S 409, and FIG. 5( c 2) shows a display example on the display device 105 in this case. The display area 503 has moved further to the right of FIG. 5( b 1) and has reached an end of the valid video area 501, and the right end of the display area 503 and the right end of the valid video area 501 are in contact with each other. As shown in FIG. 5( c 1), while the temporary display area 504 extends out of the valid video area 501 due to an immediately preceding change in orientation of the electronic device 100, the display area 503 is set to an area in contact with the right end of the valid video area 501 and not set to the temporary display area 504. That is, even if the user changes the orientation of the electronic device for moving the display area 503 to the right, the display area 503 temporarily stops at a position where the display area 503 abuts against the right end of the valid video area 501, and the display area does not move any further unless Yes determinations are made in S 408 and S410. For example, when the user views the electronic device 100 mounted on the VR glasses, the display area may move right to right by rotating the user's head (a right side of the VR image may be viewed).However, the movement of the display area (scrolling the video to the left) stops temporarily when the display area reaches the right end of the valid video area, and the display area does not change even if the head of the user is further rotated to the right unless Yes determinations are made in S 408 and S 410.FIG. 5( c 2) shows a display example in a case where VR display of a position corresponding to the display region 503 in FIG. 5( c 1) is performed on the display device 105. The area guide 510 is displayed superimposed on the VR display of an image. In the area guide 510, the white portion indicates a display area in contact with the black portion indicating an invalid video area, thereby enabling the fact that the display area has reached an end of the valid video area to be recognized. The CPU 101 also displays an end indication 520 on a right side of FIG. 5( c 2) corresponding to a right side that is one side in contact with the valid video area 501 of four sides of the display area 503. The end indication 520 is a semi-transmissive or non-transmissive display object displayed in a region along an end of a VR image whose VR display is being performed (an end of a display region of the display 105). The end indication 520 means that at least a part of a page on which the end indication 520 is displayed has reached an end of the valid video range. By viewing the end indicator 520 in the example shown in FIG. 5( c 2), the user can recognize that there is no video even if the display area is moved further to the right. As described above, even when the orientation of the electronic device 100 is changed, the movement of the display area (leftward scrolling of the video) stops temporarily at the end of the valid video area. In this case, when only the displayed video (image) is viewed, there is a possibility that the user erroneously interprets that the movement of the display area has stopped due to any process abnormality, such as frame dropping due to insufficient processing performance or an error. In addition, even if the movement of the display area at an end of the valid video area is not temporarily stopped, it is difficult for the user to determine whether display of an empty region occurs due to an invalid video area being included or occurs due to an occurrence of a region in which a part cannot be displayed due to a kind of abnormality in the display process. However, in this embodiment, since the end indication 520 is displayed in this case, the user can correctly recognize that the display of the blank region is not a process abnormality but a normal operation that occurs due to the display area having reached an end of the valid video range. Further, since no blank state corresponding to the invalid video area is displayed (a black portion or the like having no relation with the valid video area is not displayed), a quality of the VR display at a high level can be maintained. The display of an empty state (display of a black portion or the like that has no relation to the valid video area) involves a risk that the feel of the virtual reality is narrowed down for a viewer of the empty state, and can prevent the feel of the user being immersed. In contrast, in this embodiment, since a region corresponding to an invalid video area is not displayed even if the invalid video area is present, the feel of dipping can be prevented from being prevented.Note that the message displayed when the display area reaches an end of the valid video area is not limited to displaying the end indication 520. When the display area reaches an end of the valid video area, a display form of the area guide 510 may be changed (by flickering the display or changing colors), a message may be displayed such as "You have reached the end", or other display items may be displayed (for example, a notification icon may be displayed). In addition, the fact that an end of the valid video range has been reached may be notified by not displaying the range guide 510 until the display range reaches the end of the valid video range, and displaying the range guide 510 once the display range reaches the end of the valid video range. From the viewpoint of preventing the user's getting-in feeling from being prevented, notification by changing the display shape of the area guide or displaying another display element that does not cover a page is more appropriate than displaying a display object such as the end indicator 520 that covers a page. Since the fact that the display area has reached an end of the valid video area can also be detected by the area guide 510, an additional display object such as the end indicator 520 cannot be displayed only because an end is reached. On the other hand, from the viewpoint of explicitly notifying a reason for stopping the movement of the display area, the end indication 520 may be displayed, and the display of the end indication 520 may be changed according to an excess amount of the valid video area by the provisional display area, for example, the greater the excess amount, the larger an area of the end indication 520. Exceeding the temporary display area occurs in a case where the display area reaches an end of the valid video area, and further an instruction to change the display area to a region exceeding the end is issued (an instruction due to orientation change, user operation, or the like). The notification that an end is reached, such as the end indication 520, may not be performed simply when the display area reaches an end of the valid video area, but may be performed when the preliminary display area exceeds the end of the valid video area, or in other words, when there is a change in orientation to display a region exceeding the end. In this case, when the orientation does not change and is stable even when the display area has reached an end of the valid video area, notification that the end is reached is not performed by the end indicator 520 or the like.In S 410, the CPU 101 determines whether or not a width of the invalid video area in the moving direction to the provisional display area calculated in S 403 from the pre-moving display area is less than a threshold Cth (a certain amount). While the width of the invalid video area is expressed by the number of pixels, a length or a distance when the VR image is mapped on a two-dimensional plane, the width of the invalid video area may also be expressed by angle information in the form of a view angle, a view angle, azimuth, elevation, a depression angle, elevation angle, steradians or the like. The threshold Cth used in the determination of S 410 may therefore be a threshold Cth of the number of pixels, a length or a distance, or a threshold Cth of angle information. The threshold value Cth is assumed to be, for example, a width of the display area in the moving direction. If the width of the invalid video area is smaller than the threshold value Cth, the process goes to S 411 and otherwise the process goes to S 409.FIGS. 6( a 1) and 6( b 1) show a width of the invalid video range when the moving direction of the display range is rightward, and a comparative example of a width of the display range as an example of the threshold Cth. Figs. 6(a1) and 6(b1) both show a VR image mapped on a two-dimensional plane with the invalid video area at the center. Figs. 6(a1) and 6(b1) are different from each other in the valid video area in the horizontal direction of the VR pictures, and the VR picture shown in Fig. 6(a1) is assumed to have a wider valid video area (narrower invalid video area) than the VR picture shown in Fig. 6(b1). A width c in Figs. 6(a1) and 6(b1) represents a width (length) in the horizontal direction of the invalid video area. In FIG. 6( a 1), the width c of the invalid video area in the horizontal direction is narrower than a width X 1 (=Cth) of the display area 503 in the horizontal direction. Therefore, when an area corresponding to the display area 503 shown in FIG. 6( a 1) is displayed on the display device 105, as shown in FIG. 6( a 2), at least a part of the valid video area is displayed, and a situation in which an entire screen becomes an empty region does not occur. In this case, a determination of Yes is made in S410. In FIG. 6( a2), on the other hand, the width c of the invalid video area in the horizontal direction is wider than the width X1 (=Cth) of the display area 503 in the horizontal direction. When an area corresponding to the display area 503 shown in FIG. 6( b1) is displayed on the display device 105, the entire screen becomes an empty region as shown in FIG. 6( b2). In this case, a determination of No is made in S410.When the determination in S 410 is No, the process does not proceed to S 411 and the display area does not move to an opposite end of the valid video area no matter how far the provisional display area moves to the right. That is, no matter how much the user changes the orientation of the electronic device 100 in the same direction, the opposite end of the valid video range is not displayed. To display the opposite end of the valid video range, the orientation of the electronic device 100 must be changed in the opposite direction. Regarding an example of the case where the electronic device 100 is mounted on VR smart glasses, the display area does not exceed a right end of the valid video area no matter how much the head is rotated rightward. To view a region on a left side of the valid video range, the head must be rotated to the left. The reason for this is that since the width of the invalid video area is wide in the horizontal direction, continuity (relevance) of videos on a right side and a left side of the valid video area is small on both sides of the invalid video area. For example, a side further to the right of an object shown at a right end of the valid video area (in the example shown in FIG. 6( b 1), a building having a white wall) is not shown at a left end of the valid video area, and is cut off. In this case, switching a display from a right end area to a left end area of the valid video area according to an orientation change including turning the head to the right results in the display of a low relevance video (in the example shown in FIG. 6( b 1), another building) for the object shown at the right end of the valid video area. When the user views such a display change, there is a possibility that the user cannot realize that the displayed video of the left end portion of the change amount is a video of a page further to the right of the video of the right end portion viewed by the user immediately before, and may feel a feeling of discomfort such as a feeling of reduced dipping. Therefore, in this embodiment, when the width of the invalid video area in the moving direction is wide, the display area is not changed from the one end to the opposite end of the valid video area. While an example in which an amount corresponding to the width of the display area is used as the threshold Cth has been described, an amount corresponding to a fixed angle, such as an amount corresponding to 270 degrees or an amount corresponding to 180 degrees, may be used instead. In addition, the width of the valid video area may be used as the threshold Cth, such as comparing the invalid video area with the width of the valid video area and preventing the display area from exceeding an end of the valid video area when the width of the invalid video area is wider.In S 411, the CPU updates the display area in the valid video area to an area in contact with an end on an opposite side to the end with which the display area was in contact before the movement, and displays a video of the updated display area of the VR image on the display device 105. When a sum of the width of the invalid video area and the width of the display area in the moving direction is used as the threshold Bth, the area in contact with the end on the opposite side to the end with which the display area before the moving is in contact is equivalent to a provisional display area set with an excess amount equal to the threshold Bth. Since this situation represents a case where it is determined in S 404 that the distance to the invalid video area is within the predetermined distance, the CPU 101 displays area guidance.FIG. 5( d 1) shows a positional relationship of the display area 503 in a VR image in the situation of S 411, and FIG. 5( d 2) shows a display example on the display device 105 in this case. While the display area 503 in FIG. 5( c 1) was in contact with the right end of the valid video area 501, the display area 503 in FIG. 5( d 1) became an area in contact with a left end (opposite end of the right end) of the valid video area 501 as a result of an orientation change in which the orientation of the electronic device 100 caused the display area to move further to the right. FIG. 5( d 2) is a display example in a case where VR display of a position corresponding to the display region 503 in FIG. 5( d 1) is performed on the display device 105. The area guide 510 is displayed superimposed on the VR display of an image. In the area guide 510, the white portion indicating a display area is in contact with the black portion indicating an invalid video area in a reversed positional relationship with respect to the example shown in FIG. 5( c 2), thereby enabling the fact that the display area has been moved to an opposite end of the valid video area to be recognized. In addition, the end indication 520 is not displayed. The reason for this is that the immediately preceding change in orientation was not a change that caused the display area to move in a direction where the left end of the valid video area is exceeded.An animation display informing that the display area has moved to the opposite end of the valid video area may be performed at a point after a determination is made in S 408 that the excess amount has exceeded the threshold value Bth and before the display of FIG. 5( d 2) is performed in S 411. For example, as shown in FIG. 6( a2), display may be performed such that a video 601 of the display area before movement, a blank region 602, and a video 603 of the display area after movement are rapidly moved to the left (scroll), and the video 603 of the display area after movement appears by moving from the right. The insertion of such a display enables the user to more easily recognize that the display area has moved to the opposite end. Note that, at this point, since the display area passes through the invalid video area, the display area overlaps the invalid video area in the area guide 510. The overlapped area is displayed with a display shape that enables the overlapped area to be distinguished from a non-overlapped area (in the illustrated example, the overlapped area is displayed gray, and is neither white nor black).According to the above-described VR process, when the user changes the orientation of the electronic device for moving the display area 503 to the right, the display area 503 moves in a sequence of FIGS. 5( a 1), 5( b 1), 5( c 1), and 5( d 1). In this moving process, while the display area changes smoothly according to the change in orientation of FIGS. 5( a 1), 5( b 1) to 5( c 1), the movement of the display area of FIG. 5( c 1) to 5( d 1) is temporarily stopped even if the change in orientation continues. At a time point when the excess amount of the provisional display area thereafter reaches the threshold value Bth, the display area 503 moves from FIG. 5( c 1) to FIG. 5( d 1).While an example has been described in the above-described VR display process in which the area guide 510 is displayed in a case where the display area is within a predetermined distance from an end of the valid video area, the area guide 510 may alternatively be displayed when the invalid video area is present in the VR image which is a display target but is hidden when the invalid video area is not present. That is, switching between displaying and concealing the area guide 510 may be performed according to whether or not there is an invalid video area in the VR image that is a display target.In addition, while an example has been described in the above-described VR display process in which the area guide 510 is displayed in a case where the display area is within a predetermined distance from an end of the valid video area, the area guide 510 may alternatively be displayed regardless of whether or not the display area is within a predetermined distance from an end of the valid video area. That is, the area guide 510 may be displayed even when the display area is apart from an end of the valid video area by more than the predetermined distance. When the area guide 510 is displayed even if the display area is apart from an end of the valid video area by more than the predetermined distance, it is better to notify that the display area reaches an end of the valid video area by another method when the display area moves from the end to a predetermined distance. For example, a display element other than the area guide 510, such as a icon, a message, or a symbol, may be displayed according to the movement of the display area into a predetermined distance from an end of the valid video area. Alternatively, according to the movement of the display area to a predetermined distance from an end of the valid video area, the display shape of the originally displayed area guide 510 may be changed from a first display shape to a second display shape (for example, by blinking or changing color).In the above-described VR display process, an example has been further described in which, when the display area reaches an end of the valid video area, the fact that the display area reaches the end is notified by maintaining the display area in a state where the display area is in contact with the end and subsequently displaying the end indication 520. However, this example is not a limitation, and instead of the process of S 409, the fact that an end of the valid video range is reached may be notified by moving the display range beyond the end of the valid video range up to a part of the invalid video range, but the invalid video range is not displayed by more than a predetermined amount (an amount corresponding to Bmax, which will be described later).Fig. 6(c1) shows a positional relationship between the valid video area and the display area in this case. FIG. 6( c 1) illustrates an example of a positional relationship in a case where there is a change in orientation of the electronic device 100, and the excess amount b of the provisional display area 504 from the valid video area 501 has exceeded a maximum width Bmax of the invalid video area included in the display area 503. FIG. 6( c 2) shows a display example of a VR display on the display device 105 in a case where the display region 503 is located at a position shown in FIG. 6( c 1). Until the provisional display area 504 exceeds the maximum width Bmax, the display area is updated by an area including the invalid video area according to the provisional display area, and a video of the updated display area is displayed. A blank region (a region exceeding an end of the valid video range) corresponding to the invalid video range included in the display range is displayed by filling the blank region with a single color or the like. That is, according to an orientation change of the electronic device 100, an empty region having a width corresponding to an orientation change amount is displayed until the provisional display region 504 exceeds the maximum width Bmax. When the provisional display area 504 exceeds the maximum width Bmax, instead of displaying the display area according to the provisional display area, the display area is held in an area where the maximum width Bmax is not exceeded, as shown in FIG. 6( c 1), and an area where the excess amount from the valid video area 501 is the maximum width Bmax is displayed as the display area 503. It is assumed that the maximum width Bmax is set to a value smaller than the width of the display area 503. When the excess amount b of the temporary display area 504 from the valid video area 501 has exceeded the maximum width Bmax of the invalid video area included in the display area 503, but still needs to exceed the threshold value Bth, the display area 503 shown in FIG. 6( c 1) is maintained, and display such as that shown in FIG. 6( c 2) is performed. Such display enables the user to intuitively understand that a region that exceeds an end of the currently displayed video is an empty region and that no video is present in the empty region. Since the display area at this point partially overlaps the invalid video area, the display area overlaps the invalid video area in the area guide 510. The overlapped area is displayed with a display shape that enables the overlapped area to be distinguished from a non-overlapped area (in the illustrated example, the overlapped area is displayed gray, neither white nor black). When the excess amount b of the provisional display area 504 from the valid video area 501 exceeds Bth, the process described earlier is performed.While an example in which the area guide is displayed in a case where the display area is within a predetermined distance from an end of the valid video area has been described in the above-described VR display process, the area guide may alternatively be displayed when at least a part of the display area includes an invalid video area. Setting of a display area including only the invalid video area (a display area not including a valid video area) may be permitted, for example, when the above-described maximum width Bmax is wider than the width of the display area. In such a case, the area guide may be displayed according to the entire display area becoming the invalid video area.While an example in which the area guide 510 indicates a valid video area, a display area, and an invalid video area has been described in the above-described VR display process, alternatively, the display area may not be indicated. As long as the valid video area and the invalid video area are specified, the user can recognize that an empty region display due to the invalid video area is performed and does not present a process abnormality.ModificationsA VR display process shown in FIG. 7 may be performed instead of the VR display process described with reference to FIG. 4. The VR display process shown in FIG. 7 dispenses with the processes of S 408 and S 411 in FIG. 4, but additionally includes S 711 instead.The processes of S 401 to S 407 are similar to those described with reference to FIG. 4. When it is determined in S 406 that the provisional display area has reached an end of the valid video area, the process of S 410 is performed.In S 410, the CPU 101 determines whether or not a width of the invalid video area is narrower than the threshold Cth. When the width of the invalid video area is narrower than the threshold Cth, the process goes to S 711, but when the width of the invalid video area is equal to or wider than the threshold Cth, the process goes to S 409.In S 409, the CPU 101 performs a process similar to the process described with reference to FIG. 4. That is, the display area does not become an area exceeding an end of the valid video area, and an area exceeding the end (the invalid video area) is not displayed in the VR display.In S 711, the CPU 101 updates the display area to the provisional display area calculated in S 403, and displays a video of the updated display area on the display device 105. In this situation, the display area includes the invalid video area which is an area exceeding an end. Therefore, in this case, display such as that shown in Fig. 6(c2) and Fig. 6(a2) is performed.When the width of the invalid video area is narrower than the threshold value Cth, the movement of the display area does not stop according to the VR display process shown in FIG. 7 even if there is an orientation change in which the provisional display area exceeds an end of the valid video area. According to the VR display process shown in FIG. 7, in such a case, the display area can be smoothly moved to the valid video area at an opposite end via a display of an empty region. On the other hand, when the width of the invalid video area is equal to or more than the threshold value Cth, and when the provisional display area reaches an end of the valid video area, the movement of the display area stops even if there is another change in orientation in the same direction. As described above, the VR display process shown in FIG. 7 is different in that, according to whether or not the width of the invalid video region is narrower than the threshold Cth, either an empty region exceeding an end of the display region is displayed or the display region is stopped without displaying the empty region.Accordingly, the user wearing the VR glasses and viewing the electronic device 100, for example, notes that the display area does not move although the user turns his head to the right, quickly recognizes that an area beyond the display area is not displayed even if he further turns his head, and stops turning his head to the right. Specifically, the user realizes that an area beyond the display area is not displayed at a time point where he has further rotated his head by about 10 degrees after the display area is stopped, and thus stops rotating his head to the right. Therefore, it is possible to prevent a vender rotation operation of the head from being performed (for example, an operation of rotating the head by an additional 90 degrees after the display area is stopped).When a center of the valid video area becomes a display area when the electronic device 100 is mounted on the VR smart glasses and the user looks forward, the center of the invalid video area should be behind the user. If the invalid video area is narrow (if the width of the invalid video area is narrower than the threshold value Cth), there is also a valid video area behind the user, and it is accustomed to the user turning over. However, when the invalid video range is wide (when the width of the invalid video range is equal to or more than the threshold value Cth), it makes little sense for the user to turn over because there is no valid video range behind the user. Moreover, for diagonally left-rear viewing where the opposite end of the valid video range is displayed from a diagonal right-rear viewing state where the right end of the valid video range is displayed, it is easier for the structure of the human body to move the line of sight by turning left over front than by turning over and further moving the line of sight to the right. When the invalid video area is wide and hence there is little sense of turning over as in the process described with reference to Fig. 7, the movement of the display area is promptly stopped to direct the user not to turn over any further. Accordingly, it is possible to prevent a vendery execution of operations that are difficult to perform, such as turning, and a VR display can be viewed conveniently.In the above-described embodiment, as an example of VR display, an example of performing monocular VR display in which an image of a display area is displayed at once on a single screen has been described. However, the VR display is not limited to a monocular VR display. The present invention is also applicable to binocular VR display in which one display area is displayed in two display regions on a single screen, or two display areas that have been slightly shifted in consideration of parallax are respectively displayed in two display regions on a single screen.In addition, although an example in which the invention is applied to a VR display in which a display area moves based on an orientation of the electronic device 100 detected by the orientation detection unit 113 has been described in the above-described embodiment, the invention is not limited thereto. The present invention can also be applied to a case where, instead of moving the display area based on an orientation, the display area is moved based on a scroll instruction operation by the user. In another display mode other than a VR display mode, for example, the display area may be moved (scrolld) not according to an orientation change but according to a touch-move state with respect to the touch panel 106 aby the user or an operation with respect to a direction key such as an arrow key. Even in this case, a provisional display area corresponding to the scroll instruction operation can be obtained, and the processes from S 404 to S 411 in FIG. 4 or the processes from S 404 to S 711 in FIG. 7 described above can be performed. That is, even when the display area is moved by a touch-move state, when the display area approaches or reaches an end of the valid video area, the fact that the display area has approached or reached the end is notified. Although the display area may be scrolled beyond an end of the valid video area by a touch-move state when the width of the invalid video area is narrower than a predetermined width, a movement of the display area beyond a touch-move state does not result in the end of the valid video area being exceeded when the width of the invalid video area is equal to or wider than the predetermined width.When the display area reaches an end of the valid video area of a VR image from a position not including the end, control is performed with the above-described processes so as to display the area guide 510 or the end indication 520. As a result, it can be recognized that the reason for the display area not moving further is that the display area has reached an end of the valid video area. Therefore, false detection that the reason is another factor such as a decrease in processing performance due to a high processing load, a process abnormality, or an error can be avoided.In addition, according to the processes described above, control is performed so that the display area can be changed beyond an end of the valid video area to an opposite end when a width of the invalid video area is narrower than a predetermined width, but the display area is prevented from moving beyond the end of the valid video area when the width of the invalid video area is equal to or wider than the predetermined width. As a result, when the invalid video area is narrow, a video of the opposite end of the valid video area can be displayed by a small orientation change. On the other hand, when the invalid video range is wide, the user can be prevented from being forced to perform a difficult orientation change such as turning over and advancing the line of sight by a large amount.In a VR content including a video of a range other than a human viewing angle, a non-video range is often positioned rearward or immediately below when a center of the valid video range is assumed to be positioned on a front surface and in a direction in which it is difficult for a user who directly views the center of the valid video range to direct his line of sight. However, in order to display the valid video area at another end after displaying the non-video area beyond one end, the non-video area needs to be displayed for a long period of time when the non-video area is wide. Displaying the non-video area over a long period of time requires taking a posture over a long period of time in which it is difficult to direct a line of sight, and makes it difficult to distinguish which area is being displayed. Rather, moving the display area in an opposite direction and displaying a valid video area at the other end may make it easier to distinguish which area is being displayed and may be performed more easily at the same time. Since the display area does not move beyond an end of the valid video area according to this embodiment, when the width of the invalid video area is equal to or more than a predetermined width, the user tries to have the valid video area of the other end displayed by moving a display direction in an opposite direction. In this way, a situation in which displaying the non-video area over a long period of time requires taking a posture in which aiming of a line of sight is difficult over a long period of time and a situation in which it is difficult to distinguish which area is being displayed can be suppressed. In this way, after reaching an end of a video area included in a VR content, more appropriate display can be performed.The various control operations described above as control operations to be performed by the CPU 101 may be executed by one piece of hardware, or a plurality of pieces of hardware may control an entire device by sharing processes.In addition, although the invention has been described in detail based on a preferred embodiment, the invention is not limited to the specific embodiment, and various modes that do not constitute any departure from the scope of the invention may be included in the present inventions. Further, the above-described embodiment is merely an example of the invention, and the embodiment may be combined with other embodiments.Although an example in which the invention is applied to the electronic device 100 that is a smartphone or the like has been described in the above embodiment, the invention is not limited to this example, and may be applied to any electronic device that can perform control for displaying a portion of a VR image. Obviously, the invention can be applied to a head mounted display (HMD) in addition to a smartphone. In addition, the invention can be applied to a personal computer, a PDA, a mobile phone terminal, a mobile image viewer, a printer apparatus equipped with a display, a digital photo frame, and the like. The present invention can be further applied to a music reproduction apparatus, a game device, an electronic book reader, a tablet device, a smartphone, a projection apparatus, a household electric application, or an in-car apparatus equipped with a display device, and the like.Further Exemplary EmbodimentsThe present invention can also be achieved by supplying a program realizing one or more functions of the above-described embodiments to a system or an apparatus via a network or a storage medium, and causing one or more processors in a computer in the system or the apparatus to read and execute the program. Alternatively, the present invention may also be achieved by a circuit (e.g., an ASIC) that realizes one or more functions.List of reference characters100 Electronic Device 101 CPU 113 Orientation Detection Unit

Claims

An electronic device (100) comprising: a detection unit (113) for detecting an orientation of the electronic device (100); and a display control unit (101) for performing control for displaying a range of a part of VR content as a display area on a display unit and changing a position of the display area according to an orientation detected by the detection unit (113), wherein when a part of the VR content is a non-video area and the non-video area is narrower than a certain amount, after the display area reaches an end of a video area of the VR content in the video area according to an orientation change in a certain rotation direction of the electronic device (100), the display area changes from the one end to another end of the video area according to a further change in orientation in the specific rotation direction of the electronic device (100), and when a part of the VR content is a non-video area and the non-video area is not narrower than the specific amount, after the display area reaches an end of a video area of the VR content in the video area according to a change in orientation in the specific rotation direction of the electronic device (100), the display control unit (101) does not change the display area from the one end to the other end of the video area even if there is a further change in orientation in the specific rotation direction of the electronic device (100).An electronic device (100) comprising a display control unit (101) for performing control for displaying a portion of a part of VR content as a display portion on a display unit and changing a position of the display portion according to an operation by a user, wherein when a part of the VR content is a non-video portion and the non-video portion is narrower than a certain amount, after the display portion has reached an end of a video portion of the VR content in the video portion according to a performance of a predetermined operation, the display control unit (101) changes the display portion from the one end to another end of the video portion according to a further performance of the predetermined operation, and when a part of the VR content is a non-video portion, and the non-video area is not narrower than the predetermined amount, after the display area reaches an end of a video area of the VR content in the video area according to execution of the predetermined operation, the display control unit does not change the display area from the one end to another end of the video area even if there is further execution of the predetermined operation.The electronic device (100) of claim 1 or 2, wherein the determined amount is an amount corresponding to 180 degrees of a viewing angle.The electronic device (100) according to claim 1 or 2, wherein the determined amount is an amount corresponding to a width of the display area in a moving direction of the display area.The electronic device (100) according to claim 1 or 2, wherein the determined amount is an amount corresponding to a width of a video area of the VR content in a moving direction of the display area.The electronic device (100) according to any one of claims 1 to 5, wherein when the non-video area is narrower than the certain amount, the display control unit (101) performs control for displaying an empty region corresponding to the non-video area in the course of a change in the display area from the one end to the other end.The electronic device (100) according to claim 1, wherein even if the non-video range is narrower than the predetermined amount, the display control unit (101) does not change the display range from the one end until an amount of change of the further orientation change in the determined rotation direction of the electronic device (100) exceeds a threshold value.The electronic device (100) according to any one of claims 1 to 7, wherein when the display area reaches an end of a video area of the VR content, the display control unit (101) performs control for performing display indicating that the display area has reached the one end.The electronic device (100) according to claim 1 or 7, wherein, when there is another orientation change in the particular rotation direction of the electronic device (100) after the display area reaches an end of a video area of the VR content according to an orientation change in the particular rotation direction of the electronic device (100), the display control unit (101) changes the display area from the one end to the other end of the video area and performs control for performing display indicating that the display area has reached the one end.The electronic device (100) according to any one of claims 1 to 9, wherein the display control unit (101) performs control for displaying a display element representing a positional relationship among a video area, a non-video area, and a display area of the VR content, together with an area of a part of the VR content.A control method of an electronic device (100), comprising a detection step of detecting an orientation of the electronic device (100), and a display control step of performing control for displaying a range of a part of VR content as a display area on a display unit and changing a position of the display area according to an orientation detected in the detection step, wherein when a part of the VR content is a non-video area and the non-video area is narrower than a certain amount after the display area reaches an end of a video area of the VR content in the video area according to an orientation change in a certain rotational direction of the electronic device (100), In the display control step, the display area is changed from the one end to another end of the video area according to a further change in orientation in the specific rotation direction of the electronic device (100), and when a part of the VR content is a non-video area, and the non-video area is not narrower than the specific amount, after the display area reaches an end of a video area of the VR content in the video area according to a change in orientation in the specific rotation direction of the electronic device (100), the display area is not changed from the one end to another end of the video area in the display control step, even if there is a further change in orientation in the specific rotation direction of the electronic device (100).A control method of an electronic device (100), comprising a display control step of performing control for displaying a range of a part of VR content as a display range on a display unit and changing a position of the display range according to an operation by a user, wherein when a part of the VR content is a non-video range and the non-video range is narrower than a certain amount after the display range reaches an end of a video range of the VR content in the video range according to a performance of a predetermined operation, the display range is changed from the one end to another end of the video range according to a further performance of the predetermined operation in the display control step, and when a part of the VR content is a non-video range, and the non-video area is not narrower than the specified amount after the display area reaches an end of a video area of the VR content in the video area according to execution of the predetermined operation, the display area is not changed from the one end to another end of the video area in the display control step even if there is further execution of the predetermined operation.A program for causing a computer to operate as each unit of the electronic device according to any one of claims 1 to 10.A computer readable medium storing a program that causes a computer to operate as each unit of the electronic device according to any one of claims 1 to 10.

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