Image communication system, image capturing device, communication terminal, and mode switching method

1. An image communication system comprising:

a first communication terminal configured to acquire an image captured by an image capturing device; and

a second communication terminal configured to receive the image from the first communication terminal via a network and display the image on a screen of a display,

the first communication terminal including first circuitry configured to

in response to receipt of an operation of switching a view mode related to viewing of the image, transmit the image and first viewable area information to the second communication terminal, the first viewable area information being related to a viewable area of the image to be displayed on the screen by the second communication terminal, and

the second communication terminal including second circuitry configured to

receive the image and the first viewable area information, and

display the viewable area of the image on the screen based on the received first viewable area information,

wherein, in addition to the first viewable area information, the first circuitry of the first communication terminal transmits to the second communication terminal a notification indicating that the view mode is a mode for displaying the viewable area of the image on the screen based on the first viewable area information, and

wherein, in response to receipt of the notification, the second circuitry of the second communication terminal displays the viewable area of the image on the screen based on the first viewable area information.

2. The image communication system of claim 1 , wherein

the first circuitry of the first communication terminal is configured to transmit the image, without the first viewable area information, and

in response to receipt of the image without the first viewable area information, the second circuitry of the second communication terminal displays on the screen an area determined by a user of the second communication terminal.

3. The image communication system of claim 1 , wherein the second communicating terminal shares the viewable area of the image with another communication terminal that transmits second viewable area information, and

wherein the second circuitry of the second communication terminal

receives, in addition to the first viewable area information and the image, a first priority value from the first communication terminal,

receives the second viewable area information and a second priority value from the another communication terminal, and

displays the viewable area of the image on the screen based on one of the first viewable area information and the second viewable area information having a higher priority value.

4. The image communication system of claim 1 , further comprising an image capturing device configured to capture the image, the image capturing device being included in or separated from the first communication terminal,

wherein the first viewable area information is determined by an imaging direction of the image capturing device, the imaging direction being identified by attitude information of the image capturing device that captures the image.

5. The image communication system of claim 4 , wherein the image capturing device

defines a point of interest in the image, and

converts the defined point of interest into the first viewable area information in accordance with the attitude information of the image capturing device.

6. The image communication system of claim 5 , wherein the image capturing device

executes zenith correction on the image with the attitude information, and

converts the defined point of interest into the first viewable area information with a result of the zenith correction.

7. The image communication system of claim 6 , wherein the image capturing device includes an imaging element, and the image capturing device

executes zenith correction on a conversion table with the attitude information, the conversion table being used to convert coordinate values of the imaging element into coordinate values in a spherical coordinate system,

determines the defined point of interest as the coordinate values of the imaging element, and

converts the defined point of interest into coordinate values in a spherical coordinate system with the conversion table subjected to the zenith correction with the attitude information.

8. The image communication system of claim 6 , wherein the image capturing device includes an imaging element, and the image capturing device

executes the zenith correction to match an upper side of the image with an upper side of an actual space irrespective of an attitude of the image capturing device, and

defines the point of interest as coordinate values of the imaging element corresponding to an image of an object pointed by an upper side in a longitudinal direction of the image capturing device.

9. The image communication system of claim 1 , wherein the first circuitry of the first communication terminal

displays the image on a screen of a display,

determines the viewable area of the image based on an operation performed on the image displayed on the screen, and

determines the first viewable area information based on the determined viewable area of the image.

10. A communication terminal communicable with a counterpart communication terminal, the communication terminal comprising circuitry configured to

acquire an image captured by an image capturing device, and

in response to receipt of an operation of switching a view mode related to viewing of the image, transmit first viewable area information to the counterpart communication terminal, the first viewable area information being related to a viewable area of the image to be displayed on a screen of a display by the counterpart communication terminal,

transmit to the counterpart communication terminal a notification indicating that the view mode is a mode for displaying the viewable area of the image on the screen based on the first viewable area information.

11. A mode switching method executed by a communication terminal communicable with a counterpart communication terminal, the mode switching method comprising:

acquiring an image captured by an image capturing device;

in response to receipt of an operation of switching a view mode related to viewing of the image, transmitting first viewable area information to the counterpart communication terminal, the first viewable area information being related to a viewable area of the image to be displayed on a screen of a display by the counterpart communication terminal; and

transmitting to the counterpart communication terminal a notification indicating that the view mode is a mode for displaying the viewable area of the image on the screen based on the first viewable area information.

12. The method of claim 11 , further comprising:

transmitting the image, without the first viewable area information.

13. The method of claim 11 , further comprising:

capturing the image using the image capturing device, wherein the first viewable area information is determined by an imaging direction of the image capturing device, the imaging direction being identified by attitude information of the image capturing device that captures the image.

14. The method of claim 13 , further comprising:

defining, by the image capturing device, a point of interest in the image, and

converting, by the image capturing device, the defined point of interest into the first viewable area information in accordance with the attitude information of the image capturing device.

15. The method of claim 14 , further comprising:

executing, by the image capturing device, zenith correction on the image with the attitude information, and

converting, by the image capturing device, the defined point of interest into the first viewable area information with a result of the zenith correction.

16. The method of claim 11 , further comprising:

displaying the image on a screen of a display,

determining the viewable area of the image based on an operation performed on the image displayed on the screen, and

determining the first viewable area information based on the determined viewable area of the image.