Transmission device, transmission method, reception device, and reception method

1. A transmission device, comprising:

circuitry configured to:

obtain transmission video data having a second level range narrower than a first level range by applying a predetermined level mapping curve to input video data having the first level range; and

transmit the transmission video data together with auxiliary information for performing a level conversion on a reception side,

wherein the auxiliary information is level mapping curve information for obtaining an inverse conversion characteristic of the level conversion by the predetermined level mapping curve and electro-optical conversion characteristic information, or the electro-optical conversion characteristic information in which the level mapping curve information for obtaining the inverse conversion characteristic of the level conversion by the predetermined level mapping curve is reflected,

the predetermined level mapping curve is a level-mapping curve selected, based on the auxiliary information, from at least three level-mapping curves, each level-mapping curve being composed of at least three respective linear segments in the same at least three different ranges, the same at least three different ranges in the plurality of level mapping curves including the three linear segments with different slopes, wherein for each range of the at least three different ranges, a different one of the level mapping curves has a particular linear segment having a slope greater than the slopes of the two other linear segments within the range,

wherein two of the at least three level-mapping curves cross one another, and

the electro-optical conversion characteristic information includes information on a plurality of electro-optical conversion characteristics including an electro-optical conversion characteristic selectively used depending on brightness of a viewing environment to perform an electro-optical conversion on the reception side.

2. The transmission device according to claim 1 , wherein the circuitry is further configured to transmit a video stream obtained by encoding the transmission video data, wherein the auxiliary information is inserted into a layer of the video stream.

3. The transmission device according to claim 1 , wherein

the first level range is a level range of from 0% to N %, where N is a number greater than 100, and the second level range is from 0% to P %, where P is a number greater than or equal to 100 and less than N.

4. A transmission method, comprising:

obtaining, by circuitry, transmission video data having a second level range narrower than a first level range by applying a predetermined level mapping curve to input video data having the first level range; and

transmitting, by the circuitry, the transmission video data together with auxiliary information for performing a level conversion on a reception side, wherein

the auxiliary information is level mapping curve information for obtaining an inverse conversion characteristic of the level conversion by the predetermined level mapping curve and electro-optical conversion characteristic information, or the electro-optical conversion characteristic information in which the level mapping curve information for obtaining the inverse conversion characteristic of the level conversion by the predetermined level mapping curve is reflected,

the predetermined level mapping curve is a level-mapping curve selected, based on the auxiliary information, from at least three level-mapping curves, each level-mapping curve being composed of at least three respective linear segments in the same at least three different ranges, the same at least three different ranges in the plurality of level mapping curves including the three linear segments with different slopes, wherein for each range of the at least three different ranges, a different one of the level mapping curves has a particular linear segment having a slope greater than the slopes of the two other linear segments within the range,

wherein two of the at least three level-mapping curves cross one another, and

the electro-optical conversion characteristic information includes information on a plurality of electro-optical conversion characteristics including an electro-optical conversion characteristic selectively used depending on brightness of a viewing environment to perform an electro-optical conversion on the reception side.

5. A reception device, comprising: circuitry configured to: receive transmission video data having a second level range narrower than a first level range obtained by applying a predetermined level mapping curve to input video data having the first level range, and convert a level of the transmission video data based on auxiliary information received together with the transmission video data, wherein the auxiliary information is level mapping curve information for obtaining an inverse conversion characteristic of a level conversion by the predetermined level mapping curve and electro-optical conversion characteristic information, or the electro-optical conversion characteristic information in which the level mapping curve information for obtaining the inverse conversion characteristic of the level conversion by the predetermined level mapping curve is reflected,

the predetermined level mapping curve is a level-mapping curve selected, based on the auxiliary information, from at least three level-mapping curves, each level-mapping curve being composed of at least three respective linear segments in the same at least three different ranges, the same at least three different ranges in the plurality of level mapping curves including the three linear segments with different slopes, wherein for each range of the at least three different ranges, a different one of the level mapping curves has a particular linear segment having a slope greater than the slopes of the two other linear segments within the range,

wherein two of the at least three level-mapping curves cross one another, and

the electro-optical conversion characteristic information includes information on a plurality of electro-optical conversion characteristics including an electro-optical conversion characteristic selectively used depending on brightness of a viewing environment to perform an electro-optical conversion on the reception side.

6. The reception device according to claim 5 , wherein the circuitry is further configured to convert the transmission video data having the second level range to output video data having a third level range greater than or equal to the second level range based on the level mapping curve information.

7. The reception device according to claim 6 , wherein

the first level range is a level range of from 0% to N %, where N is a number greater than 100, the second level range is from 0% to P %, where P is a number greater than or equal to 100 and less than N, and the third level range is from 0% to Q %, where Q is a number greater than or equal to 100 and less than or equal to N.

8. The reception device according to claim 6 , wherein a maximum level of the third level range is determined based on maximum displayable level information.

9. The reception device according to claim 5 , wherein the circuitry is further configured to, based on the electro-optical conversion characteristic information, obtain output video data by performing an electro-optical conversion on the transmission video data having the second level range, or video data having a third level range greater than or equal to the second level range obtained by performing the level conversion on the transmission video data based on the level mapping curve information.

10. The reception device according to claim 5 , wherein the circuitry is further configured to select one electro-optical conversion characteristic used from the plurality of electro-optical conversion characteristics.

11. The reception device according to claim 10 , wherein the circuitry is further configured to select one electro-optical conversion characteristic used from the plurality of electro-optical conversion characteristics based on an output of a brightness sensor or a user operation input.

12. A reception method, comprising:

receiving, by circuitry, transmission video data having a second level range narrower than a first level range obtained by applying a predetermined level mapping curve to input video data having the first level range; and

converting, by the circuitry, a level of the transmission video data based on auxiliary information received together with the transmission video data, wherein

the auxiliary information is level mapping curve information for obtaining an inverse conversion characteristic of a level conversion by the predetermined level mapping curve and electro-optical conversion characteristic information, or the electro-optical conversion characteristic information in which the level mapping curve information for obtaining the inverse conversion characteristic of the level conversion by the predetermined level mapping curve is reflected,

the predetermined level mapping curve is a level-mapping curve selected, based on the auxiliary information, from at least three level-mapping curves, each level-mapping curve being composed of at least three respective linear segments in the same at least three different ranges, the same at least three different ranges in the plurality of level mapping curves including the three linear segments with different slopes, wherein for each range of the at least three different ranges, a different one of the level mapping curves has a particular linear segment having a slope greater than the slopes of the two other linear segments within the range,

wherein two of the at least three level-mapping curves cross one another, and

the electro-optical conversion characteristic information includes information on a plurality of electro-optical conversion characteristics including an electro-optical conversion characteristic selectively used depending on brightness of a viewing environment to perform an electro-optical conversion on the reception side.

13. The method according to claim 12 , further comprising:

converting the transmission video data having the second level range to output video data having a third level range greater than or equal to the second level range based on the level mapping curve information.

14. The method according to claim 13 , wherein the first level range is a level range of from 0% to N %, where N is a number greater than 100, the second level range is from 0% to P %, where P is a number greater than or equal to 100 and less than N, and the third level range is from 0% to Q %, where Q is a number greater than or equal to 100 and less than or equal to N.

15. The method according to claim 13 , further comprising:

determining a maximum level of the third level range based on maximum displayable level information.

16. The method according to claim 12 , further comprising:

based on the electro-optical conversion characteristic information, obtaining output video data by performing an electro-optical conversion on the transmission video data having the second level range, or video data having a third level range greater than or equal to the second level range obtained by performing the level conversion on the transmission video data based on the level mapping curve information.

17. The method according to claim 12 , further comprising:

selecting one electro-optical conversion characteristic used from the plurality of electro-optical conversion characteristics.

18. The method according to claim 17 , further comprising:

selecting one electro-optical conversion characteristic used from the plurality of electro-optical conversion characteristics based on an output of a brightness sensor or a user operation input.

19. The transmission device of claim 1 , wherein one of the at least three level-mapping curves, from which the predetermined level mapping curve is selected by the circuitry, has a same slope in each of the at least three ranges.

20. The transmission device of claim 1 , wherein each of the at least three level-mapping curves, from which the predetermined level mapping curve is selected by the circuitry, has, in each of the same at least three different ranges, the single linear segment.