JP2019220968A - Method performed in reproducing apparatus and reproducing apparatus - Google Patents

Abstract

To achieve further improvement.SOLUTION: A display device comprises: a first remap part for receiving a video signal having a first luminance range, and for performing EOTF (Electro-Optical Transfer Function) conversion corresponding to the first luminance range to a code value indicated by a luminance signal included in the video signal to calculate a first luminance value, and for converting the first luminance value into a second luminance value corresponding to a second luminance range having the maximum value different from the first luminance range; a second remap part for receiving a graphics signal having the first luminance range, and for performing EOTF conversion corresponding to the first luminance range to a code value indicated by the luminance signal included in the graphics signal to calculate the first luminance value; a synthesis part for synthesizing the video signal whose luminance value has been converted by the first remap part with the graphics signal whose luminance value has not been converted by the second remap part; and a display part for displaying a signal synthesized by the synthesis part.SELECTED DRAWING: Figure 5B

Description

  The present disclosure relates to a data reproducing method and a reproducing apparatus.

  2. Description of the Related Art Conventionally, an image signal processing device for improving a displayable luminance level has been disclosed (for example, see Patent Document 1).

JP 2008-167418 A

  The method executed by the playback device according to an aspect of the present disclosure obtains graphics in a first luminance range including a menu or subtitles from a recording medium, and displays the video in the first luminance range. Using the color conversion table for the first luminance range to generate the first graphics for the graphics in the first luminance range, superimposing the video and the first graphics in the first luminance range When outputting to a display and displaying the video in a second luminance range wider than the first luminance range, the color conversion table for the second luminance range is used for the graphics in the first luminance range. And generating the second graphics, and superimposing the video in the second luminance range and the second graphics and outputting to the display.

  Note that these comprehensive or specific aspects may be realized by a recording medium such as a system, a method, an integrated circuit, a computer program or a computer-readable CD-ROM, and the system, the method, the integrated circuit, and the computer program. Alternatively, it may be realized by an arbitrary combination of recording media.

FIG. 1 is a diagram for explaining the evolution of the video technology. FIG. 2 is a diagram illustrating an example of an EOTF (Electro-Optical Transfer Function). FIG. 3 is an explanatory diagram of a method of determining a code value of a luminance signal stored in a content, and a process of restoring a luminance value from the code value during reproduction. FIG. 4 is an explanatory diagram of production of a BD (Blu-ray (registered trademark, the same applies hereinafter) Disc) and a player that reproduces the BD. FIG. 5A is an example in which a BD player and a TV are connected by HDMI (registered trademark, the same applies hereinafter), and shows a case where the TV supports HDR display. FIG. 5B is an example in which a BD player and a TV are connected by HDMI, and is a diagram showing a case where the TV does not support HDR display. FIG. 6 is a block diagram illustrating a configuration of a remapping unit in the conversion device. FIG. 7 is a diagram showing a flowchart of the remapping process in the conversion device. FIG. 8 is a diagram illustrating an example of a combination of HDR and SDR in a case where one video stream and one graphics stream are included in the content. FIG. 9 is a diagram showing that a graphics master is generated by using a common EOTF with a video master. FIG. 10A is a diagram for describing a case of mapping to an SDR signal in generating a graphics master. FIG. 10B is a diagram for describing a case of mapping to an HDR signal in generating a graphics master. FIG. 11 is a block diagram illustrating a configuration of a generation unit that generates a graphics signal in authoring. FIG. 12 is a flowchart illustrating a method for generating a graphics signal in authoring. FIG. 13 is a diagram for explaining the relationship between the video production, the distribution method, and the display device when introducing a new video expression into the content. FIG. 14 is a diagram for explaining the relationship between the master, the distribution method, and the display device when HDR is introduced. FIG. 15A is a diagram for describing the SDR display processing in the SDRTV. FIG. 15B is a diagram for describing SDR display processing in an SDRTV having a peak luminance of 300 nits. FIG. 16 is a diagram for describing conversion from HDR to SDR. FIG. 17A is a diagram for describing Case 1 in which only an HDR signal corresponding to HDR is stored in the HDR disc. FIG. 17B is a diagram for explaining Case 2 in which an HDR disc stores an HDR signal corresponding to HDR and an SDR signal corresponding to SDR. FIG. 18 is a diagram for describing the conversion processing from HDR to pseudo HDR. FIG. 19A is a diagram illustrating an example of an EOTF (Electro-Optical Transfer Function) corresponding to each of HDR and SDR. FIG. 19B is a diagram illustrating an example of inverse EOTF corresponding to each of HDR and SDR. FIG. 20A is a diagram illustrating an example of a display process of converting an HDR signal and performing HDR display in HDRTV. FIG. 20B is a diagram illustrating an example of a display process of performing HDR display using an HDR-compatible playback device and SDRTV. FIG. 20C is a diagram illustrating an example of a display process of performing HDR display on an HDR-compatible playback device and an SDRTV connected to each other via a standard interface. FIG. 21 is a block diagram illustrating a configuration of the conversion device and the display device according to the embodiment. FIG. 22 is a flowchart illustrating a conversion method and a display method performed by the conversion device and the display device according to the embodiment. FIG. 23A is a diagram for describing the first luminance conversion. FIG. 23B is a diagram for describing another example of the first luminance conversion. FIG. 24 is a diagram for describing the second luminance conversion. FIG. 25 is a flowchart showing the detailed processing of the display setting. FIG. 26 is a diagram for describing the third luminance conversion. FIG. 27 is a diagram for describing the conversion processing from HDR to pseudo HDR. FIG. 28 is a diagram for explaining the reproducing operation of the dual disk. FIG. 29 is a diagram illustrating types of BDs. FIG. 30 is a diagram illustrating the types of BDs in more detail. FIG. 31 is a diagram showing an example of a combination of a video stream and a graphic stream recorded on each of the BD and dual stream discs. FIG. 32 is a diagram illustrating an example of a combination of a video stream and a graphic stream recorded on each of a BD and a dual stream disc. FIG. 33 is a diagram illustrating an example of a graphic stream. FIG. 34 is a diagram illustrating an example of a combination of a video stream and a graphic stream recorded on each of the BD and dual stream discs. FIG. 35 is a diagram illustrating an example of the graphic stream. FIG. 36 is a diagram illustrating an example of a graphic stream. FIG. 37 is a diagram illustrating an example of a combination of a video stream and a graphic stream recorded on each of a BD and a dual stream disc. FIG. 38 is a diagram illustrating an example of a graphic stream. FIG. 39 is a flowchart showing processing of the playback device.

  A data reproduction method according to an aspect of the present disclosure is a data reproduction method in which graphics are superimposed on a video in a first luminance range and displayed, wherein the reproduction device has a second luminance range smaller than the first luminance range. It is determined whether or not the first graphics has a function of converting the first graphics into the second graphics in the first luminance range. If the playback device has the function, the playback device converts the first graphics into Converting to the second graphics, displaying the second graphics superimposed on the video, and displaying the video with third graphics different from the second graphics when the playback device does not have the function. Display superimposed.

  According to this, the data reproducing method can perform different operations depending on whether or not the reproducing apparatus has a function of changing and printing the luminance range of graphics. Thereby, the data reproducing method can perform an appropriate operation according to the function of the reproducing apparatus.

  For example, when the playback device does not have the function, the third graphics may be generated using the color conversion table for the first luminance range.

  According to this, it is possible to suppress the graphics image from being difficult to visually recognize.

  For example, the third graphics may be the first graphics.

  For example, in the determination, the playback device may execute a playback control program to determine whether the playback device has the function.

  For example, in the determination, the playback control program checks whether the playback device has the function by checking a register storing information indicating whether the playback device has the function. It may be determined.

  Further, a playback device according to an aspect of the present disclosure is a playback device that superimposes graphics on a video in a first brightness range and displays the video, wherein the playback device has a second brightness range that is smaller than the first brightness range. A determining unit that determines whether or not the first graphics has a function of converting the first graphics into the second graphics in the first luminance range. A conversion unit that converts the graphics into two graphics, if the playback device has the function, displays the second graphics superimposed on the video, and if the playback device does not have the function, displays the second graphics on the video. A display unit that superimposes and displays third graphics different from the second graphics.

  According to this, the playback device can perform different operations depending on whether the playback device has a function of changing and printing the luminance range of graphics. Thereby, the playback device can perform an appropriate operation according to the function of the playback device.

  Note that these comprehensive or specific aspects may be realized by a recording medium such as a system, a method, an integrated circuit, a computer program or a computer-readable CD-ROM, and the system, the method, the integrated circuit, and the computer program. Alternatively, it may be realized by an arbitrary combination of recording media.

  Regarding the above features, mainly [5-3. Operation of Reproducing Apparatus].

  Each of the embodiments described below shows a specific example of the present disclosure. Numerical values, shapes, materials, and components shown in the following embodiments. The arrangement positions and connection forms of components, the steps, the order of the steps, and the like are merely examples, and do not limit the present disclosure. Further, among the components in the following embodiments, components not described in the independent claims indicating the highest concept are described as arbitrary components.

  Hereinafter, a reproduction method and a reproduction apparatus according to an embodiment of the present disclosure will be specifically described with reference to the accompanying drawings.

  Each of the embodiments described below shows a specific example of the present disclosure. Numerical values, shapes, materials, and components shown in the following embodiments. The arrangement positions and connection forms of components, the steps, the order of the steps, and the like are merely examples, and do not limit the present disclosure. Further, among the components in the following embodiments, components not described in the independent claims indicating the highest concept are described as arbitrary components.

(Embodiment 1)
The present disclosure relates to an HDR (High Dynamic Range) signal that is a high luminance signal having a high luminance range, a TV and a projector that correspond to an SDR (Standard Dynamic Range) signal that is a normal luminance signal of a luminance range having a maximum luminance value of 100 nits. The present invention relates to an image conversion / reproduction method and apparatus for displaying on a display device such as a tablet, a smartphone, and the like.

[1-1. background]
First, the transition of the video technology will be described with reference to FIG. FIG. 1 is a diagram for explaining the evolution of the video technology.

  Up to now, emphasis has been placed on increasing the number of display pixels in order to improve the image quality of video, and from 720 × 480 pixel video of Standard Definition (SD) to 1920 × 1080 pixel of High Definition (HD), so-called 2K. Video is widespread.

  In recent years, the introduction of so-called 4K video of 3840 × 1920 pixels of Ultra High Definition (UHD) or 4096 × 1920 pixels of 4K has been started in order to further improve the image quality of video.

  In addition to increasing the resolution of an image by introducing 4K, it is also being studied to enhance the image quality by expanding the dynamic range, expanding the color gamut, or adding or improving the frame rate.

  Among them, as for the dynamic range, the maximum luminance is used to express bright light such as specular reflection light, which cannot be expressed by the current TV signal, with more realistic brightness while maintaining the dark part gradation in the conventional video. Attention has been paid to HDR (High Dynamic Range) as a method corresponding to a luminance range in which the value is enlarged. Specifically, the method of the luminance range to which the TV signal corresponds so far is called SDR (Standard Dynamic Range), and the maximum luminance value is 100 nit, whereas the maximum luminance value is 1000 nit or more in HDR. It is assumed that the brightness value is increased. HDR is being standardized in SMPTE (Society of Motion Picture & Television Engineers) and ITU-R (International Telecommunications Union Radiocommunications Sector).

  As a specific application destination of HDR, similarly to HD and UHD, it is assumed that the HDR is used for broadcasting, package media (Blu-ray Disc, etc.), and Internet distribution.

  Hereinafter, in a video corresponding to HDR, the luminance of the video includes a luminance value in a luminance range of HDR, and a luminance signal obtained by quantizing the luminance value of the video is referred to as an HDR signal. . In an image corresponding to SDR, the luminance of the image includes luminance values in the luminance range of SDR, and a luminance signal obtained by quantizing the luminance value of the image is referred to as an SDR signal.

[1-2. About EOTF]
Here, the EOTF will be described with reference to FIG.

  FIG. 2 is a diagram illustrating an example of EOTF (Electro-Optical Transfer Function) corresponding to each of HDR and SDR.

  The EOTF is generally called a gamma curve, indicates the correspondence between a luminance value and a code value, and quantizes the luminance value and converts it into a code value. That is, the EOTF is relationship information indicating a correspondence relationship between a luminance value and a plurality of code values. For example, when the luminance value of an image corresponding to SDR is represented by an 8-bit gradation code value, the luminance value in a luminance range up to 100 nits is quantized and mapped to 256 integer values of 0 to 255. Is done. That is, by performing quantization based on the EOTF, a luminance value in a luminance range up to 100 nit (a luminance value of a video corresponding to SDR) is converted into an SDR signal that is an 8-bit code value. In the EOTF corresponding to HDR (hereinafter, referred to as “HDR EOTF”), it is possible to express a higher luminance value than the EOTF corresponding to SDR (hereinafter, referred to as “SDR EOTF”). For example, in FIG. 2, the maximum value of the luminance (peak luminance) is 1000 nits. That is, the HDR luminance range includes the entire SDR luminance range, and the HDR peak luminance is larger than the SDR peak luminance. The HDR luminance range is a luminance range in which the maximum value is expanded from the maximum value of the SDR luminance range, for example, 100 nit to 1000 nit. The HDR signal is expressed, for example, with a 10-bit gradation.

[1-3. How to use EOTF]
FIG. 3 is an explanatory diagram of a method of determining a code value of a luminance signal stored in a content, and a process of restoring a luminance value from the code value during reproduction.

  The luminance signal indicating the luminance in this example is an HDR signal corresponding to HDR. The graded image is quantized by an inverse function of HDR EOTF, and a code value corresponding to the luminance value of the image is determined. Image coding and the like are performed based on the code values, and elementary streams for video and graphics are generated. At the time of reproduction, the luminance value of each pixel is restored by inversely quantizing the decoding result of the elementary stream based on the HDR EOTF.

[1-4. BD Stream Configuration]
As mentioned above, there is a possibility that the HDR may be used in an optical disc such as a BD or in a broadcast. Hereinafter, a BD as an example of a medium using HDR will be described with reference to FIG.

  FIG. 4 is an explanatory diagram of a BD production and a player that reproduces the BD.

  As shown in FIG. 4, the production process includes authoring of Blu-ray content, creation of a BD storing the authored Blu-ray content, and the like. The Blu-ray content includes, besides video and audio, graphics data for generating subtitles and menus, and scenario data for providing interactivity in menu display and user operation. The scenario data includes a format called HDMV (High Definition Movie) controlled by a prescribed command and a format called BD-J (Blu-ray Disc Java) controlled by a Java (registered trademark, hereinafter the same) program. I do. In the authoring, video and audio are encoded, and their encoded streams and graphics data indicating subtitles, menus, and the like are multiplexed into an M2TS format transport stream, and playback of playlists and EP maps is performed. Generate management information required for control. Then, the data generated by the authoring is stored in the BD.

  The BD player refers to the management information, separates and decodes video and audio elementary streams required for reproduction, and graphics data, and outputs them. Here, the video and graphics such as subtitles and menus are output after synthesizing each other's planes. When the resolution of the video is different from the resolution of the graphics, the graphics are up-converted in accordance with the resolution of the video, and then the video and the graphics are combined.

[1-5. Configuration of the device)]
When reproducing HDR-compatible content (video), a display such as a TV receives and displays an output signal from a reproduction device such as a BD player. Hereinafter, the display of the video corresponding to HDR is referred to as “HDR display”, and the display of the video corresponding to SDR is referred to as “SDR display”. At this time, if the display supports the HDR display, the output signal output by the playback device may be the HDR signal corresponding to the HDR. On the other hand, when the display does not support HDR display, the playback device converts the output signal into an SDR signal corresponding to SDR and outputs the signal. The case where the display does not support the HDR display is the case where the display supports only the SDR display.

  5A and 5B are examples in which the BD player 200 and the TVs 300 and 310 are connected by HDMI, respectively. FIG. 5A shows a case where the TV 300 supports the HDR display, and FIG. 5B shows a case where the TV 310 displays the HDR display. Indicates the case where it is not supported. Although the configuration of the BD player 200 in FIG. 5A is different from that of the BD player 200 in FIG. 5B, FIG. 5A shows a case where remapping, which will be described later, is not performed. The illustration of the configuration of 210 is omitted.

  In FIG. 45, the BD player 200 reads video and graphics from the medium 100 and decodes them. Then, the BD player 200 combines the decoded HDR data of video and graphics, and outputs an HDR signal generated by combining the HDR data to the HDR display-compatible TV 300 by HDMI.

  On the other hand, in FIG. 5B, since the TV 310 does not support HDR display, the BD player 200 uses the HDR EOTF and the SDR EOTF before synthesizing the video and graphics, and Each is remapped to SDR data. Then, the BD player 200 combines the remapped video and graphics SDR data, and outputs the SDR signal generated by the combination to the TV 310 that does not support HDR display by HDMI.

  Note that remapping is a process of converting a first code value in the first EOTF into a second code value in the second EOTF when two types of EOTFs, a first EOTF and a second EOTF, are present. In the case of FIG. 5B, remapping is a process of converting the HDR EOTF code value into the SDR EOTF code value in the conversion from HDR to SDR.

  That is, in the case of FIG. 5B, the BD player 200 uses an acquisition unit that acquires a first luminance signal (HDR signal) corresponding to the first luminance range (HDR), an EOTF of HDR, and an EOTF of SDR. From the code value indicated by the first luminance signal acquired by the acquiring unit, a code value associated by quantization for the second luminance range (SDR) is determined as a converted code value, and the first luminance signal is converted And a conversion unit for converting to a second luminance signal indicating a code value. More specifically, in the conversion into the second luminance signal, the conversion unit uses the first EOTF and the second EOTF to determine a corresponding second value from the code value indicated by the first luminance signal acquired by the acquisition unit. The code value is determined as the converted code value. Note that the BD player 200 performs a conversion method for performing steps corresponding to each unit of the conversion device 210. Although FIG. 5B illustrates a case where the conversion device 210 converts an HDR signal into an SDR signal and outputs the converted signal, the conversion device 210 may convert the SDR signal into an HDR signal and output the converted signal as described later.

  Since the luminance exceeding 100 nit cannot be expressed in the SDR, at least the luminance exceeding 100 nit in the HDR signal and the SDR code value corresponding to the luminance in the conversion processing from the HDR to the SDR performed by the conversion device 210. It is necessary to perform the attachment based on a predefined conversion table or an adaptive process according to the luminance distribution of the image in the content. In the conversion process, it is assumed that different conversion rules are required for data whose luminance value is discrete, such as subtitles, and for video. In addition, since remapping occurs in units of frames, the processing amount is large especially for high-resolution images such as 4K. Further, since the luminance value changes before and after the remap, the image after the remap may have an impression different from the creator's intention.

  When converting an HDR signal of an HDR-compatible video (content) into an SDR signal and outputting the SDR signal, graphics require the same remapping as video. By performing remapping on both video and graphics, the amount of processing required for the remapping is increased, and there is also a problem that a luminance value may be converted into a luminance value not intended by the creator.

[1-6. Conversion method and conversion device]
FIG. 6 is a block diagram illustrating a configuration of a remapping unit in the conversion device.

  The remapping unit 220 is included in the conversion device 210. As illustrated in FIG. 6, the remapping unit 220 temporarily stores the EOTF determination unit 221, the processing target determination unit 222, the variable brightness value remapping unit 223, the fixed brightness value remapping unit 224, and the content (video) stream. And a storage unit 225 for temporarily storing.

  The EOTF determination unit 221 determines that the EOTF corresponding to the signal of the content (video and graphics) read from the medium 100 corresponds to the EOTF corresponding to the output signal to be output to a display such as the TV 300 or 310 that displays the video. It is determined whether or not is different. Here, the EOTF to which the output signal corresponds is the EOTF of the output signal which can be displayed by a display such as a TV.

  The processing target determination unit 222 determines whether the processing target is a video (graphics).

  The brightness value variable remapping unit 223 converts the stream signal stored in the storage unit 225 into a signal corresponding to the EOTF of the output signal by a brightness value variable remapping (second remapping).

  The fixed brightness value remapping unit 224 converts the stream signal stored in the storage unit 225 into a signal corresponding to the EOTF of the output signal by a fixed brightness value remapping (first remapping).

  FIG. 7 is a diagram showing a flowchart of the remapping process in the conversion device.

  As shown in FIG. 7, in the remapping process, first, the EOTF determining unit 221 corresponds to the EOTF corresponding to the signal of the acquired content (video and graphics) and the output signal to be output to the display. It is determined whether or not the EOTF is different (step 101). If “yes” is determined in step 101, the processing of step 102 to step 104 is performed to convert the method of the luminance range corresponding to the content signal to the EOTF corresponding to the output signal. On the other hand, if "No" is determined in step 101, the remapping process is terminated, and the signal of the content is output without remapping. As described above, by performing step 101, the format of the output signal is determined based on whether or not a display such as a TV for displaying video is compatible with HDR display. The format of the output signal may be determined so as to match the main video such as the main part.

  Next, the processing target determination unit 222 determines whether the processing target is a video (graphics) (step 102). If "yes" is determined in step 102, the variable brightness value remapping unit 223 converts the content signal into a signal corresponding to the EOTF of the output signal by using a variable brightness value remapping (second remapping) (step 103).

  On the other hand, if “No” is determined in step 102, the brightness value fixed remapping unit 224 converts the output signal into a signal corresponding to the EOTF of the output signal by the brightness value fixed remapping (first remapping) (step 104).

  As described above, when the content (video) is video, the second remap is performed, and when the content (video) is graphics, the first remap is performed.

  In the brightness value variable remapping in step 103 and the brightness value fixed remapping in step 104, tables indicating the correspondence between the HDR and SDR brightness values are prepared in advance. In this table, in the HDR EOTF and the SDR EOTF, the correspondence between the luminance values where the code values exist may be described. By doing so, since there is always a code value corresponding to the luminance value of the EOTF after the remapping, if there is no code value corresponding to the luminance value, the code value having the luminance value closest to the luminance value is changed. No need to search.

  In the brightness value variable remapping (second remapping), a plurality of tables are adaptively switched based on a brightness distribution in an image or for each scene, or an optimal table is sequentially created for each content. May be. That is, for example, in the determination of the second luminance value which is the luminance value after the remapping, the video information is obtained from a plurality of pieces of relation information (table) indicating the relation between the luminance value in the first luminance range and the luminance value in the second luminance expression. May be selected, and the second luminance value may be determined from the determined first luminance value using the selected relation information.

  In the brightness value variable remapping in step 103, processing is performed in the following procedure. In this case, the first luminance signal corresponding to the first EOTF is converted to a second luminance signal corresponding to the second EOTF.

  (1) A first luminance value (luminance value before remapping) corresponding to the code value of the first EOTF is determined.

  (2) A second luminance value (luminance value after remapping) of the second EOTF corresponding to the first luminance value determined in (1) is determined.

  (3) The code value of the second EOTF corresponding to the second luminance value determined in (2) is determined.

  In the brightness value fixed remapping in step 104, processing is performed in the following procedure. In this case, the first luminance signal corresponding to the first EOTF is converted to a second luminance signal corresponding to the second EOTF.

  (1) A luminance value corresponding to the code value of the first EOTF is determined.

  (2) The code value of the second EOTF corresponding to the luminance value determined in (1) is determined.

  * In the case of the fixed brightness value remapping, the brightness value does not change before and after the remapping, so that the process (2) in step 103 becomes unnecessary.

  After the completion of the remapping process in step 103 and step 104, the conversion device 210 combines and outputs the video and graphics. That is, the conversion device 210 may further combine the video and graphics converted into the second luminance signal by performing the first remapping and the second remapping, and output the combined signal.

  Further, when outputting to a display through an interface such as HDMI, the conversion device 210 may further transmit information for identifying the EOTF of the output signal as meta information. That is, the conversion device 210 may further output the second luminance signal converted from the acquired first luminance signal together with meta information for identifying the second EOTF.

[1-7. Effects etc.]
In the first embodiment, in reproducing the content, it is determined whether to output the video in HDR or SDR according to whether the output destination of the video is HDR-compatible. Remap graphics from SDR to HDR or from HDR to SDR. For graphics, a fixed brightness remap process in which the brightness value does not change before and after the remap is applied, and for a video, a brightness variable remap process in which the brightness value can change before and after the remap is applied.

  Regarding graphics, since the luminance does not change before and after remapping, the image quality intended by the creator can be maintained. Further, it is not necessary to associate a luminance value between the EOTFs before and after the conversion, and the amount of processing related to remapping can be reduced.

(Embodiment 2)
[2-1. Content generation method]
In the creation of a video or graphics master, the brightness and hue of each pixel is modified for digital images taken with a camera or scanned images of film to reflect the intentions of the creator, as shown in FIG. A grading process is required, and grading requires a high level of know-how and the required man-hours are enormous. Therefore, it is desirable that the number of masters to be generated be minimized. On the other hand, since the peak brightness differs between HDR and SDR, it is generally necessary to generate different masters for each. FIG. 8 is a diagram illustrating an example of a combination of HDR and SDR in a case where one video stream and one graphics stream are included in the content. In this example, there are four combinations, and HDR and SDR masters are required for video and graphics, respectively.

  On the other hand, the highest effect of HDR in video content is video such as a main part of a movie, and it is considered that graphics such as subtitles are less effective than video. Nevertheless, even for graphics, creating HDR and SDR masters as in the case of video has a problem that the load of content production is large.

  Therefore, in the generation of the graphics master according to the present disclosure, as shown in FIG. 9, the SDR and HDR masters are shared. FIG. 9 is a diagram showing that a graphics master is generated by using a common EOTF with a video master. For this purpose, the luminance range of the graphics master is made to match the luminance range of the SDR. That is, the peak luminance in the graphics master is equal to or less than the upper limit of the luminance range of the SDR. When mapping graphics data in content to an SDR signal corresponding to SDR, a code value for each pixel is determined based on the EOTF of SDR, and when mapping to an HDR signal corresponding to HDR, , HDR EOTF is used to determine a code value for each pixel.

  FIG. 10A is a diagram for describing a case of mapping to an SDR signal in generating a graphics master. In this case, since the luminance range of the SDR matches the luminance range of the graphics master, the domain of the code values in the EOTF of the SDR is all valid.

  FIG. 10B is a diagram for describing a case of mapping to an HDR signal in generating a graphics master. In this case, only a code value equal to or less than the code value corresponding to the peak luminance of the SDR is valid.

  When the graphics master is mapped to the HDR signal, identification information indicating that the peak luminance is within the luminance range of the SDR may be stored in management information such as an elementary stream or a playlist. . In the above-described remapping process, it is possible to determine whether to apply the fixed brightness value remapping or the variable brightness value remapping based on the identification information. Further, when outputting through an interface such as HDMI, this identification information may be stored as meta information of the output interface.

  The EOTF of graphics can be determined according to the video. That is, if the video is HDR, the graphics data is also HDR, and if the video is SDR, the graphics data is also SDR. Alternatively, the graphics data may always be in SDR.

  Note that the same concept can be applied when a plurality of videos exist. For example, if there is a sub video to be superimposed on or displayed side by side with the main video, the EOTF of the sub video can be adjusted to the main video.

[2-2. Data generation method and device]
FIG. 11 is a block diagram illustrating a configuration of a generation unit that generates a graphics signal in authoring.

  The generation section 400 includes a GFX grading section 410, a determination section 420, an HDR signal generation section 430, and an SDR signal generation section 440.

  The GFX grading unit 410 grades the graphics master so that the luminance value is equal to or less than the peak luminance of SDR.

  The determination unit 420 determines whether the video displayed simultaneously with the graphics is HDR.

  When the determination unit 420 determines that the video displayed simultaneously with the graphics is HDR, the HDR signal generation unit 430 converts the luminance value of the graphics into a code value using the HDR EOTF.

  When the determination unit 420 determines that the video displayed simultaneously with the graphics is not HDR (that is, SDR), the SDR signal generation unit 440 converts the luminance value of the graphics into a code value using the EOTF of the SDR. I do.

  FIG. 12 is a flowchart illustrating a method for generating a graphics signal in authoring.

  First, the GFX grading unit 410 grades the graphics master so that the luminance value is equal to or less than the peak luminance of the SDR (step 201).

  Next, the determination unit 420 determines whether or not the video displayed simultaneously with the graphics is HDR (step 202).

  If “Yes” is determined in step 202, the HDR signal generation unit 430 converts the graphics luminance value into a code value using the HDR EOTF (step 203).

  If “No” is determined in step 202, the SDR signal generation unit 440 converts the luminance value of the graphics into a code value using the EOTF of SDR (step 204).

  In step 202, it is determined whether the graphics are displayed simultaneously with the video. If the graphics are subtitles, for example, the video on which the subtitles are superimposed is determined. For graphics such as menus that are not displayed simultaneously with the video, the determination may be made based on whether or not the main video is HDR. Since the same graphics as the conventional 2K format are used, the graphics are always converted using the EOTF of SDR, and the processing of step 204 may be always performed without performing the determination processing of step 202. .

  As described above, by setting the luminance range of the graphics to be equal to or less than the peak luminance of the SDR, there is an advantage that the luminance value fixed remapping can be performed without changing the luminance value before and after the remapping.

  It is possible to grade data other than graphics so that the brightness of the HDR master is within the SDR range. In particular, in graphics such as subtitles, the merit of using a luminance value higher than the peak luminance of the SDR is small. Therefore, in the remapping from SDR to HDR, a fixed brightness value remapping may be applied regardless of whether the grading is within the range of SDR.

[2-3. Effects etc.]
In the generation device and the generation method according to the second embodiment, when authoring a content including video data such as graphics in addition to video, a common master is used for HDR and SDR for video data other than video. use. For this reason, grading is performed so that the peak luminance in the master falls within the luminance range of SDR.

  Thereby, since masters other than video can be shared by HDR and SDR, the man-hour related to master generation can be reduced.

(Other embodiments)
As described above, the embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which changes, replacements, additions, omissions, and the like are made as appropriate. Further, it is also possible to form a new embodiment by combining the components described in the above embodiment.

  Therefore, other embodiments will be exemplified below.

  For example, in each of the above-described embodiments, two types of HDR and SDR have been described as the format of the output signal output from the conversion device 210. When outputting to an HDMI or the like, the signal is output using either HDR or SDR as a standard. For example, when a BD player is built in a TV, a broadcast is received and reproduced by a TV, or a tablet is used. For example, when viewing the OTT service, it is possible to output a signal directly from the conversion device 210 to the display device.

  At this time, if the peak luminance according to the HDR standard is different from the peak luminance that can be displayed on the display device, the remapping process according to the EOTF of the display device may be performed on the data in the content corresponding to the HDR. Good. Also, for the SDR or HDR signal input to the display device by HDMI, remapping may be performed again on the EOTF according to the peak luminance of the display device. That is, in this case, the conversion to the second luminance signal is performed by setting the acquired first luminance signal to the first EOTF and the luminance range that can be displayed on the display device to which the second luminance signal is output to the second luminance range. This may be performed using the second EOTF.

  Although not described in each of the above embodiments, in the BD authoring, video, audio, or graphics to be reproduced for each play item in the playlist can be specified. As described above, when video, audio, or graphics to be reproduced in play item units is specified, in an interface such as HDMI, when HDR and SDR are switched in play item units, reset processing is performed at the boundary of play items. And playback may not be seamless. Therefore, when the HDR and the SDR are switched between the play items connected seamlessly, the remapping process is performed in the conversion device provided in the BD player or the like so that the EOTF of the output signal is the same as the immediately preceding play item. May go. Alternatively, switching between EOTFs may be prohibited between play items that are connected seamlessly, and identification information indicating that EOTFs are not switched may be stored in management information such as a playlist.

  Further, the authoring or conversion method of each of the above embodiments can be applied not only to package media such as optical disks, but also to broadcasting and OTT (Over The Top) services. For example, in broadcasting, in addition to a main part of a broadcast program, a data broadcast transmitted by broadcasting or a content acquired via a communication network can be superimposed on a main part video. At this time, it is expected that the HDR program and the SDR program will be mixed in the main part of the video, and the limitation of the peak luminance by the method described above will be applied to the graphics and the video in the content acquired separately from the main part. Alternatively, a remapping process can be performed.

(Embodiment 3)
[3-1. Relationship between master generation, distribution method, and display device]
FIG. 13 is a diagram for explaining the relationship between the video production, the distribution method, and the display device when introducing a new video expression into the content.

  When introducing a new image expression (such as an increase in the number of pixels) to improve the image quality of an image, as shown in FIG. 13, (1) it is necessary to change the master for home entertainment on the image production side. . Accordingly, it is necessary to update (2) the distribution method of broadcasting, communication, package media, and the like, and (3) the display device such as a TV and a projector for displaying the video.

[3-2. Relationship between master, distribution method, and display device when HDR is introduced]
In order for a user to enjoy content (for example, high-brightness video content (HDR content)) corresponding to a new video expression at home, it is necessary to newly introduce both an HDR-compatible distribution method and an HDR-compatible display device. . That is, in order to enjoy the content corresponding to the new video expression at home, the user needs to prepare a distribution method and a display device corresponding to the new video expression. This should be avoided even when new video expressions are introduced, such as when SD video is replaced with HD video, HD video is replaced with 3D video, and HD video is replaced with UHD (4K) video. Could not.

  For this reason, it is expensive, it is not easy to replace even in terms of size and weight, it is necessary to replace the TV, and the change to a new video expression depends on the spread of display devices (for example, TV) having new functions. Will do. At the outset, neither the media side nor the content side can make a large investment, so that the spread of new video expressions has often slowed down.

  Therefore, as shown in FIG. 14, in order to make full use of the HDR original video expression, a TV (hereinafter, referred to as “HDR display”) corresponding to HDR (hereinafter, referred to as “HDR display”) is also used for HDR. It is anticipated that a replacement by “HDRTV” will be required.

[3-3. SDRTV]
To a TV (hereinafter, referred to as “SDRTV”) corresponding to only display of an image corresponding to SDR (hereinafter, referred to as “SDR display”), an input signal having a luminance value of up to 100 nit is normally input. For this reason, the SDRTV is sufficient to express the luminance value of the input signal if the display capability is 100 nit. However, the SDRTV actually has a function of reproducing an image having an optimal luminance value according to a viewing environment (dark room: cinema mode, bright room: dynamic mode, etc.), and is capable of expressing an image of 200 nit or more. There are many that have. In other words, such an SDRTV can display an image up to the maximum brightness (for example, 300 nit) of the display capability by selecting a display mode according to the viewing environment.

  However, in the SDR system input signal input to the SDRTV, since the upper limit of the luminance of the input signal is set to 100 nits, as long as the SDR system input interface is used as usual, the high brightness video exceeding 100 nits of the SDRTV has to be used. It is difficult to use the playback capability for HDR signal playback (see FIGS. 15A and 15B).

[3-4. HDR → SDR conversion]
High-luminance video content (hereinafter referred to as “HDR content”) distributed by a distribution method such as HDR-compatible broadcasting, moving image distribution via a communication network, or HDR-compatible package media (for example, HDR-compatible Blu-ray Disc) Or, also referred to as “HDR video”), it is assumed that the video is output by SDRTV via a HDR-compatible playback device (for example, a communication STB (Set Top Box), a Blu-ray device, or an IPTV playback device). . When playing HDR content on SDRTV, "HDR-> SDR conversion" is performed to convert the HDR signal corresponding to HDR into an SDR signal in an SDR luminance range with a maximum value of 100 nits so that the video can be displayed correctly on SDRTV. I do. This allows the SDRTV to display the SDR video obtained by being converted from the HDR video using the converted SDR signal (see FIG. 16).

  However, even in this case, even if the user purchases an HDR-compatible content (eg, Blu-ray Disc, HDR IPTV content) and an HDR-compatible playback device (eg, Blu-ray device, HDR-compatible IPTV playback device). Regardless, in SDRTV, a video can be enjoyed only in an SDR video expression (SDR expression). In other words, even if HDR content and a playback device compatible with HDR are prepared, if there is no display device (eg, HDRTV) compatible with HDR and only SDRTV, the video can be displayed in HDR video expression (HDR expression). Can't watch.

  Therefore, if the user cannot prepare HDRTV, the value of HDR (that is, superiority over SDR due to high image quality of HDR) will not be understood even if the user purchases HDR content or a transmission medium (playback device). As described above, since the user does not know the value of HDR without HDRTV, it can be said that the spread of HDR contents and HDR-compatible distribution methods is determined according to the diffusion speed of HDRTV.

[3-5. Two methods for realizing HDR → SDR conversion]
When sending an HDR signal to a TV using a Blu-ray Disc (BD), two cases can be assumed as shown in FIGS. 17A and 17B below. FIG. 17A is a diagram for describing Case 1 in which only HDR signals corresponding to HDR are stored in an HDR-compatible BD. FIG. 17B is a diagram for explaining Case 2 in which an HDR-compatible BD stores an HDR signal corresponding to HDR and an SDR signal corresponding to SDR.

  As shown in FIG. 17A, in case 1, when displaying an image obtained by playing back a BD on a Blu-ray device on the HDRTV, even when a HDR-compatible BD (hereinafter, referred to as “HDRBD”) is played, the SDR is used. Even when a corresponding BD (hereinafter, referred to as “SDRBD”) is reproduced, the Blu-ray device outputs the luminance signal stored in the BD to the HDRTV without conversion. The HDRTV can display both the HDR signal and the SDR signal. Therefore, the HDRTV performs a display process according to the input luminance signal, and displays the HDR video or the SDR video.

  On the other hand, in case 1, when displaying an image of a BD played on a Blu-ray device on the SDRTV, when the HDRBD is played, the Blu-ray device performs a conversion process of converting an HDR signal into an SDR signal. Then, the SDR signal obtained by the conversion process is output to SDRTV. When the SDRBD is reproduced, the Blu-ray device outputs the SDR signal stored in the BD to the SDRTV without conversion. As a result, the SDRTV displays the SDR video.

  In addition, as shown in FIG. 17B, in case 2, when displaying an image obtained by playing back a BD with a Blu-ray device on an HDRTV, the process is the same as in case 1.

  On the other hand, in case 2, when displaying an image in which a BD is reproduced on a Blu-ray device on the SDRTV, the Blu-ray device is stored in the BD regardless of whether the HDRBD is reproduced or the SDRBD is reproduced. The converted SDR signal is output to SDRTV without conversion.

  In both Case 1 and Case 2, if you buy a Blu-ray device that supports HDRBD and HDR, you can only enjoy SDR video without HDRTV. Therefore, in order for the user to view HDR video, HDRTV is required, and it is expected that it will take time to spread HDR-compatible Blu-ray devices or HDRBD.

[3-6. HDR → pseudo HDR conversion]
From the above, it can be said that in order to promote the spread of HDR, it is important to promote the commercialization of HDR contents and distribution methods without waiting for the spread of HDRTV. To this end, if the existing SDRTV can make the HDR signal viewable not as an SDR video but as an HDR video or a pseudo HDR video that is closer to the HDR video than the SDR video, the user can use the HDRTV. Even if you don't buy it, you can watch higher quality video, which is clearly different from SDR video and close to HDR video. In other words, if the user can view the pseudo HDR video on the SDRTV, the user can view the video with higher quality than the SDR video only by preparing the HDR content or the HDR distribution device without preparing the HDRTV. . In short, making the pseudo HDR video viewable on the SDRTV can be a motivation for the user to purchase the HDR content and the HDR distribution device (see FIG. 18).

  In order to realize the display of the pseudo HDR video on the SDRTV, in the configuration where the SDRTV is connected to the HDR distribution method, when the HDR content is reproduced, the HDR signal is output so that the HDR content video can be correctly displayed on the SDRTV. Instead of converting to an SDR video signal, a pseudo HDR signal for displaying a video having the maximum brightness of the display capability of the SDRTV, for example, 200 nit or more, is generated by using the input of a video signal having a maximum value of 100 nits of SDRTV. Then, it is necessary to realize “HDR → pseudo HDR conversion processing” that enables the generated pseudo HDR signal to be sent to SDRTV.

[3-7. About EOTF]
Here, the EOTF will be described with reference to FIGS. 19A and 19B.

  FIG. 19A is a diagram illustrating an example of an EOTF (Electro-Optical Transfer Function) corresponding to each of HDR and SDR.

  The EOTF is generally called a gamma curve, indicates a correspondence between a code value and a luminance value, and converts a code value into a luminance value. That is, the EOTF is relationship information indicating a correspondence between a plurality of code values and a luminance value.

  FIG. 19B is a diagram illustrating an example of inverse EOTF corresponding to each of HDR and SDR.

  The inverse EOTF indicates the correspondence between the luminance value and the code value. The inverse EOTF quantizes the luminance value and converts it into a code value, contrary to the EOTF. That is, the inverse EOTF is relationship information indicating the correspondence between the luminance value and the plurality of code values. For example, when a luminance value of an image corresponding to HDR is expressed by a code value of a 10-bit gradation, luminance values in an HDR luminance range of up to 10,000 nits are quantized to 1024 luminance values of 0 to 1023. Is mapped to an integer value. That is, by performing quantization based on the inverse EOTF, a luminance value (luminance value of a video corresponding to HDR) in a luminance range up to 10,000 nit is converted into an HDR signal which is a 10-bit code value. In the EOTF corresponding to HDR (hereinafter, referred to as “HDR EOTF”) or the inverse EOTF corresponding to HDR (hereinafter, referred to as “HDR inverse EOTF”), the EOTF corresponding to SDR (hereinafter, “SDR EOTF”) is used. ) Or an inverse EOTF corresponding to SDR (hereinafter referred to as “inverse EOTF of SDR”). For example, in FIG. 19A and FIG. The value (peak luminance) is 10,000 nit. That is, the HDR luminance range includes the entire SDR luminance range, and the HDR peak luminance is larger than the SDR peak luminance. The HDR luminance range is a luminance range obtained by expanding the maximum value from 100 nit, which is the maximum value of the SDR luminance range, to 10,000 nit.

  For example, the HDR EOTF and the HDR inverse EOTF are, for example, SMPTE 2084 standardized by the American Society of Motion Picture and Television Engineers (SMPTE).

  In the following description, a luminance range from 0 nit to 100 nit which is the peak luminance described in FIGS. 19A and 19B may be described as a first luminance range. Similarly, the luminance range from 0 nit to 10,000 nit which is the peak luminance described in FIGS. 19A and 19B may be described as a second luminance range.

[3-8. Necessity of pseudo HDR]
Next, the necessity of the pseudo HDR will be described with reference to FIGS. 20A to 20C.

  FIG. 20A is a diagram illustrating an example of a display process of converting an HDR signal and performing HDR display in HDRTV.

  As shown in FIG. 20A, when displaying an HDR video, the maximum value of the HDR luminance range (HPL (HDR Peak Luminance: example: 1500 nit)) is displayed as it is even when the display device is an HDRTV. May not be possible. In this case, the linear signal after the inverse quantization using the HDR EOTF is adjusted to the maximum value of the luminance range of the display device (peak luminance (DPL (Display Peak Immunity): example 750 nit)). Performs luminance conversion. Then, by inputting the video signal obtained by performing the brightness conversion to the display device, it is possible to display an HDR video that matches the maximum brightness range which is the limit of the display device.

  FIG. 20B is a diagram illustrating an example of display processing for performing HDR display using an HDR-compatible playback device and SDRTV.

  As shown in FIG. 20B, when displaying an HDR image, if the display device is an SDRTV, the maximum value (peak luminance (DPL: example 300 nit)) of the luminance range of the SDRTV to be displayed exceeds 100 nits. 20B is the maximum value of the “HDR EOTF conversion” and the luminance range of SDRTV performed in HDRTV in “HDR → pseudo HDR conversion processing” in the HDR-compatible playback device (Blu-ray device) in FIG. 20B. If the signal obtained by performing "brightness conversion" using DPL (eg, 300 nit) and performing "brightness conversion" can be directly input to the "display device" of SDRTV, the same effect as that of HDRTV can be obtained by using SDRTV. Can be realized.

  However, SDRTV cannot be realized because there is no means for directly inputting such a signal from outside.

  FIG. 20C is a diagram illustrating an example of display processing for performing HDR display using an HDR-compatible playback device and an SDRTV connected to each other via a standard interface.

  As shown in FIG. 20C, it is usually necessary to input a signal capable of obtaining the effect of FIG. 20B to the SDRTV using an input interface (HDMI or the like) provided in the SDRTV. In SDRTV, a signal input via an input interface sequentially passes through “EODR conversion of SDR”, “luminance conversion for each mode”, and “display device”, and an image matched to the maximum luminance range of the display device. Is displayed. For this reason, in the HDR-compatible Blu-ray device, a signal (pseudo HDR signal) that passes immediately after the input interface by SDRTV and that can cancel “EODR conversion of SDR” and “luminance conversion for each mode” is output. Generate. In other words, in the HDR-compatible Blu-ray device, immediately after “HDR EOTF conversion” and “luminance conversion” using SDRTV peak luminance (DPL), “inverse luminance conversion for each mode” and “inverse SDR EOTF conversion ", the same effect as when the signal immediately after the" luminance conversion "is input to the" display device "(broken line arrow in FIG. 20C) is pseudo-realized.

[3-9. Conversion device and display device]
FIG. 21 is a block diagram illustrating a configuration of the conversion device and the display device according to the embodiment. FIG. 22 is a flowchart illustrating a conversion method and a display method performed by the conversion device and the display device according to the embodiment.

  As shown in FIG. 21, the conversion apparatus 500 includes an HDR EOTF converter 501, a luminance converter 502, an inverse luminance converter 503, and an inverse SDR EOTF converter 504. The display device 600 includes a display setting unit 601, an SDR EOTF conversion unit 602, a luminance conversion unit 603, and a display unit 604.

  A detailed description of each component of the conversion device 500 and the display device 600 will be given in the description of the conversion method and the display method.

[3-10. Conversion Method and Display Method]
A conversion method performed by the conversion device 500 will be described with reference to FIG. The conversion method includes steps S101 to S104 described below.

  First, the HDR EOTF conversion unit 501 of the conversion apparatus 500 acquires an HDR video on which inverse HDR EOTF conversion has been performed. The HDR EOTF conversion unit 501 of the conversion device 500 performs HDR EOTF conversion on the obtained HDR video HDR signal (S101). As a result, the HDR EOTF converter 501 converts the obtained HDR signal into a linear signal indicating a luminance value. The HDR EOTF is, for example, SMPTE 2084.

  Next, the luminance conversion unit 502 of the conversion device 500 performs a first luminance conversion for converting the linear signal converted by the HDR EOTF conversion unit 501 using the display characteristic information and the content luminance information (S102). . In the first luminance conversion, a luminance value corresponding to the HDR luminance range (hereinafter, referred to as “HDR luminance value”) is changed to a luminance value corresponding to the display luminance range (hereinafter, referred to as “display luminance value”). Convert. Details will be described later.

  From the above, the HDR EOTF conversion unit 501 functions as an acquisition unit that acquires an HDR signal as a first luminance signal indicating a code value obtained by quantizing a video luminance value. The HDR EOTF conversion unit 501 and the luminance conversion unit 502 determine the code value indicated by the HDR signal acquired by the acquisition unit based on the luminance range of the display (display device 600). It functions as a conversion unit for converting into a display luminance value corresponding to a display luminance range that is a maximum value (DPL) smaller than the value (HPL) and larger than 100 nit.

  More specifically, the HDR EOTF conversion unit 501 uses the obtained HDR signal and the HDR EOTF in step S101 to determine the HDR code value as the first code value indicated by the obtained HDR signal. The HDR luminance value associated with the HDR code value in the HDR EOTF is determined. Note that the HDR signal is obtained by quantizing the luminance value of a video (content) using an inverse EOTF of HDR that associates a luminance value in an HDR luminance range with a plurality of HDR code values. Shows the HDR code value.

  In step S102, the luminance conversion unit 502 determines a display luminance value corresponding to the luminance range of the display, which is related to the luminance value of the HDR determined in step S101 in advance, and The first brightness conversion is performed to convert the HDR brightness value corresponding to the brightness range of the display into a display brightness value corresponding to the brightness range of the display.

  Further, before step S102, conversion device 500 has content luminance information including at least one of the maximum value (CPL: Content Peak Luminance) of the video (content) and the average luminance value (CAL: Content Average Luminance) of the video. Is obtained as information on the HDR signal. The CPL (first maximum luminance value) is, for example, the maximum value of the luminance values for a plurality of images constituting the HDR video. CAL is, for example, an average luminance value that is an average of luminance values of a plurality of images constituting an HDR video.

  In addition, the conversion device 500 has acquired the display characteristic information of the display device 600 from the display device 600 before step S102. Note that the display characteristic information includes the maximum value (DPL) of the luminance that can be displayed by the display device 600, the display mode (see below) of the display device 600, and the input / output characteristics (EOTF corresponding to the display device). This is information indicating display characteristics.

  Further, conversion device 500 may transmit recommended display setting information (see below, also referred to as “setting information” hereinafter) to display device 600.

  Next, the inverse luminance conversion unit 503 of the conversion device 500 performs inverse luminance conversion according to the display mode of the display device 600. Thereby, the inverse luminance conversion unit 503 performs the second luminance conversion for converting the luminance value corresponding to the luminance range of the display into the luminance value corresponding to the luminance range of SDR (0 to 100 [nit]) (S103). . Details will be described later. That is, the inverse luminance conversion unit 503 sets the display luminance value obtained in step S102 as a third luminance value that is related to the display luminance value in advance and corresponds to the luminance range of the SDR having a maximum value of 100 nits. A luminance value corresponding to the SDR (hereinafter, referred to as “SDR luminance value”) is determined, and the display luminance value corresponding to the display luminance range is changed to the SDR luminance value corresponding to the SDR luminance range. A second luminance conversion is performed.

  Then, the inverse SDR EOTF conversion unit 504 of the conversion device 500 generates the pseudo HDR video by performing the inverse SDR EOTF conversion (S104). That is, the inverse SDR EOTF conversion unit 504 generates an inverse EOTF (Electro-Optical) of SDR (Standard Dynamic Range), which is the third relation information that associates the luminance value in the HDR luminance range with a plurality of third code values. Using Transfer Function), the determined SDR luminance value is quantized, a third code value obtained by the quantization is determined, and the SDR luminance value corresponding to the SDR luminance range is indicated by the third code value. A pseudo HDR signal is generated by converting the signal into an SDR signal as a third luminance signal. The third code value is a code value corresponding to SDR, and is hereinafter referred to as “SDR code value”. That is, the SDR signal is obtained by quantizing the luminance value of the video using the inverse EOTF of the SDR that associates the luminance value in the luminance range of the SDR with the code values of the plurality of SDRs. It is represented by a code value. Then, conversion device 500 outputs the pseudo HDR signal (SDR signal) generated in step S104 to display device 600.

  The conversion device 500 generates the SDR luminance value corresponding to the pseudo HDR by performing the first luminance conversion and the second luminance conversion on the HDR luminance value obtained by dequantizing the HDR signal. Then, an SDR signal corresponding to the pseudo HDR is generated by quantizing the SDR luminance value using the SDR EOTF. Note that the SDR luminance value is a numerical value within a luminance range of 0 to 100 nit corresponding to the SDR, but since the conversion based on the luminance range of the display is performed, the HDR EOTF and the SDR Is a numerical value different from the luminance value in the luminance range of 0 to 100 nit corresponding to the SDR obtained by performing the luminance conversion using the EOTF.

  Next, a display method performed by the display device 600 will be described with reference to FIG. The display method includes steps S105 to S108 described below.

  First, the display setting unit 601 of the display device 600 sets display settings of the display device 600 using the setting information acquired from the conversion device 500 (S105). Here, the display device 600 is an SDRTV. The setting information is information indicating a display setting recommended for the display device, and information indicating how to perform EOTF on the pseudo HDR image and display with which setting a beautiful image can be displayed (that is, Information for switching the display setting of the display device 600 to the optimal display setting). The setting information includes, for example, gamma curve characteristics at the time of output on the display device, display modes such as a living mode (normal mode) and a dynamic mode, and numerical values of a backlight (brightness). Further, a message that prompts the user to change the display settings of the display device 600 by manual operation may be displayed on the display device 600 (hereinafter, also referred to as “SDR display”). Details will be described later.

  Note that the display device 600 acquires an SDR signal (pseudo HDR signal) and setting information indicating display settings recommended for the display device 600 when displaying an image before step S105.

  The display device 600 may acquire the SDR signal (pseudo HDR signal) before step S106, or may acquire it after step S105.

  Next, the SDR EOTF converter 602 of the display device 600 performs SDR EOTF conversion on the acquired pseudo HDR signal (S106). That is, the SDR EOTF conversion unit 602 performs inverse quantization on the SDR signal (pseudo HDR signal) using the SDR EOTF. As a result, the SDR EOTF converter 602 converts the SDR code value indicated by the SDR signal into an SDR luminance value.

  Then, the brightness conversion unit 603 of the display device 600 performs brightness conversion according to the display mode set for the display device 600. Accordingly, the brightness conversion unit 603 converts the SDR brightness value corresponding to the SDR brightness range (0 to 100 [nit]) into the display brightness value corresponding to the display brightness range (0 to DPL [nit]). Is performed (S107). Details will be described later.

  From the above, in steps S106 and S107, the display device 600 calculates the third code value indicated by the acquired SDR signal (pseudo HDR signal) using the setting information acquired in step S105, and sets the display luminance range ( 0 to DPL [nit]).

  More specifically, in the conversion from the SDR signal (pseudo HDR signal) to the display luminance value, in step S106, an EOTF that associates the luminance value in the luminance range of the SDR with a plurality of third code values is used. For the SDR code value indicated by the acquired SDR signal, the luminance value of the SDR associated with the SDR code value by the EOTF of the SDR is determined.

  Then, in the conversion to the display brightness value, in step S107, a display brightness value corresponding to the display brightness range, which is related to the determined SDR brightness value in advance, is determined, and the SDR corresponding to the SDR brightness range is determined. A third luminance conversion is performed to convert the luminance value to a display luminance value corresponding to a luminance range of the display.

  Finally, the display unit 604 of the display device 600 displays the pseudo HDR video on the display device 600 based on the converted display luminance value (S108).

[3-11. First luminance conversion]
Next, details of the first luminance conversion (HPL → DPL) in step S102 will be described with reference to FIG. 23A. FIG. 23A is a diagram for describing an example of the first luminance conversion.

  The brightness conversion unit 502 of the conversion device 500 performs a first brightness conversion for converting the linear signal (HDR brightness value) obtained in step S101 using display characteristic information and HDR video content brightness information. . The first luminance conversion converts the HDR luminance value (input luminance value) into a display luminance value (output luminance value) that does not exceed the display peak luminance (DPL). The DPL is determined using the maximum brightness and the display mode of the SDR display, which are display characteristic information. The display mode is, for example, mode information such as a theater mode for displaying a dark image on the SDR display and a dynamic mode for displaying a bright image. When the display mode is, for example, the maximum brightness of the SDR display is 1,500 nit and the display mode is a mode in which the brightness is 50% of the maximum brightness, the DPL is 750 nit. Here, the DPL (second maximum luminance value) is the maximum value of the luminance that can be displayed in the currently set display mode of the SDR display. That is, in the first luminance conversion, the DPL as the second maximum luminance value is determined using display characteristic information that is information indicating the display characteristic of the SDR display.

  Also, in the first luminance conversion, CAL and CPL of the content luminance information are used, luminance values below CAL are the same before and after the conversion, and luminance values are changed only for luminance values above CPL. I do. That is, as shown in FIG. 23A, in the first luminance conversion, when the luminance value of the HDR is equal to or less than CAL, the luminance value of the HDR is not converted, and the luminance value of the HDR is determined as a display luminance value. When the luminance value of the HDR is equal to or higher than the CPL, DPL as the second maximum luminance value is determined as the display luminance value.

  In the first luminance conversion, the peak luminance (CPL) of the HDR video in the luminance information is used, and when the luminance value of the HDR is CPL, DPL is determined as the display luminance value.

  In the first luminance conversion, as shown in FIG. 23B, the linear signal (the luminance value of HDR) obtained in step S101 may be converted so as to be clipped to a value not exceeding DPL. By performing such luminance conversion, the processing in the conversion device 500 can be simplified, and the device can be reduced in size, the power consumption can be reduced, and the processing speed can be increased. FIG. 23B is a diagram for describing another example of the first luminance conversion.

[3-12. Second luminance conversion]
Next, details of the second luminance conversion (DPL → 100 [nit]) in step S103 will be described with reference to FIG. FIG. 24 is a diagram for describing the second luminance conversion.

  The inverse luminance conversion unit 503 of the conversion device 500 performs inverse luminance conversion according to the display mode on the display luminance value of the display luminance range (0 to DPL [nit]) converted by the first luminance conversion in step S102. Apply. In the reverse brightness conversion, when the brightness conversion process (step S107) according to the display mode by the SDR display is performed, the display brightness value of the display brightness range (0 to DPL [nit]) after the process of step S102 is obtained. This is a process for making it possible. That is, the second luminance conversion is an inverse luminance conversion of the third luminance conversion.

  By the above processing, the second luminance conversion converts a display luminance value (input luminance value) in the display luminance range into an SDR luminance value (output luminance value) in the SDR luminance range.

  In the second luminance conversion, the conversion formula is switched according to the display mode of the SDR display. For example, when the display mode of the SDR display is the normal mode, the luminance is converted to a directly proportional value that is directly proportional to the display luminance value. In the second luminance conversion, when the display mode of the SDR display is the dynamic mode in which the high luminance pixels are brighter and the low luminance pixels are darker than the normal mode, the inverse function is used to obtain the low luminance pixels. Is converted to a value higher than a directly proportional value directly proportional to the display luminance value, and the SDR luminance value of the high luminance pixel is converted to a value lower than a directly proportional value directly proportional to the display luminance value. That is, in the second luminance conversion, the display luminance value determined in step S102 is related to the display luminance value using the luminance relation information corresponding to the display characteristic information that is the information indicating the display characteristic of the SDR display. The luminance value is determined as the luminance value of the SDR, and the luminance conversion processing is switched according to the display characteristic information. Here, the luminance-related information according to the display characteristic information includes, for example, a display luminance value (input luminance value) determined for each display parameter (display mode) of the SDR display and an SDR This is information relating a luminance value (output luminance value).

[3-13. Display Settings]
Next, details of the display setting in step S105 will be described with reference to FIG. FIG. 25 is a flowchart showing the detailed processing of the display setting.

  In step S105, the display setting unit 601 of the SDR display performs the following processes of steps S201 to S208.

  First, the display setting unit 601 uses the setting information to determine whether the EOTF set for the SDR display (EODR for SDR display) matches the EOTF assumed when the pseudo HDR video (SDR signal) is generated. A determination is made (S201).

  If the display setting unit 601 determines that the EOTF set in the SDR display is different from the EOTF indicated by the setting information (the EOTF matching the pseudo HDR video) (Yes in S201), the display setting unit 601 converts the EOTF for the SDR display into a system. It is determined whether switching is possible on the side (S202).

  When determining that the display can be switched, the display setting unit 601 switches the EOTF for SDR display to an appropriate EOTF using the setting information (S203).

  From step S201 to step S203, in the display setting (S105), the EOTF set on the SDR display is set to the recommended EOTF according to the acquired setting information. In this way, in step S106 performed after step S105, the luminance value of SDR can be determined using the recommended EOTF.

  If the system determines that the switching is not possible (No in S202), a message prompting the user to manually change the EOTF is displayed on the screen (S204). For example, a message “Please set the display gamma to 2.4” is displayed on the screen. That is, if the EOTF set on the SDR display cannot be switched in the display setting setting (S105), the display setting unit 601 switches the EOTF set on the SDR display (EODR for SDR display) to the recommended EOTF. Is displayed on the SDR display.

  Next, on the SDR display, a pseudo HDR video (SDR signal) is displayed. Before displaying the pseudo HDR video, it is determined whether the display parameters of the SDR display match the setting information using the setting information (S205).

  When the display setting unit 601 determines that the display parameters set in the SDR display are different from the setting information (Yes in S205), the display setting unit 601 determines whether the display parameters of the SDR display can be switched (S206). .

  When the display setting unit 601 determines that the display parameters of the SDR display can be switched (Yes in S206), the display setting unit 601 switches the display parameters of the SDR display in accordance with the setting information (S207).

  In steps S204 to S207, in the display setting (S105), the display parameters set in the SDR display are set to the recommended display parameters according to the acquired setting information.

  If the system determines that the switching is not possible (No in S206), a message is displayed on the screen that prompts the user to manually change the display parameters set in the SDR display (S208). For example, a message “Please change the display mode to the dynamic mode and maximize the backlight” is displayed on the screen. That is, in the setting (S105), when the display parameters set in the SDR display cannot be switched, a message for prompting the user to switch the display parameters set in the SDR display to the recommended display parameters is displayed on the SDR display. To display.

[3-14. Third luminance conversion]
Next, details of the third luminance conversion (100 → DPL [nit]) in step S107 will be described with reference to FIG. FIG. 26 is a diagram for describing the third luminance conversion.

  The brightness conversion unit 603 of the display device 600 converts the SDR brightness value in the SDR brightness range (0 to 100 [nit]) to (0 to DPL [nit]) according to the display mode set in step S105. . This processing is performed so as to be an inverse function of the inverse luminance conversion for each mode in S103.

  In the third brightness conversion, the conversion formula is switched according to the display mode of the SDR display. For example, when the display mode of the SDR display is the normal mode (that is, when the set display parameter is a parameter corresponding to the normal mode), the display luminance value is converted to a directly proportional value that is directly proportional to the SDR luminance value. . In the third luminance conversion, when the display mode of the SDR display is the dynamic mode in which the high-luminance pixels are brighter and the low-luminance pixels are darker than the normal mode, the display luminance value of the low-luminance pixels is equal to that of the SDR. The display luminance value of the high luminance pixel is converted into a value higher than the direct proportional value directly proportional to the SDR luminance value to a value lower than the direct proportional value directly proportional to the luminance value. In other words, in the third luminance conversion, the luminance value of the SDR determined in step S106 is determined by using the luminance relation information corresponding to the display parameter indicating the display setting of the SDR display, and the luminance value previously associated with the luminance value of the SDR. The value is determined as the display luminance value, and the luminance conversion processing is switched according to the display parameter. Here, the luminance-related information corresponding to the display parameters includes, for example, an SDR luminance value (input luminance value) determined for each display parameter (display mode) of the SDR display and a display luminance as shown in FIG. This is information that is associated with a value (output luminance value).

[3-15. Effects etc.]
A normal SDRTV has an input signal of 100 nits, but has a capability of expressing a video of 200 nits or more in accordance with a viewing environment (dark room: cinema mode, bright room: dynamic mode, etc.). However, since the upper limit of the luminance of the input signal to the SDRTV was set to 100 nit, the ability could not be used directly.

  When displaying an HDR video in SDRTV, the HDR video is converted to an SDR video of 100 nit or less by utilizing the fact that the peak luminance of the displayed SDRTV exceeds 100 nit (usually 200 nit or more). The “HDR → pseudo HDR conversion process” is performed so as to maintain the range of gradations to some extent. For this reason, it is possible to display the pseudo HDR video close to the original HDR on the SDRTV.

  When this “HDR → pseudo HDR conversion” technology is applied to Blu-ray, as shown in FIG. 27, only HDR signals are stored in an HDR disc, and when an SDRTV is connected to a Blu-ray device, The -ray device performs “HDR → pseudo HDR conversion processing”, converts the HDR signal into a pseudo HDR signal, and sends the signal to SDRTV. Accordingly, the SDRTV can display a video having a pseudo HDR effect by converting the received pseudo HDR signal into a luminance value. As described above, even when there is no HDR-compatible TV, if a HDR-compatible BD and an HDR-compatible Blu-ray device are prepared, a pseudo HDR video with higher image quality than an SDR video can be displayed even with an SDRTV. it can.

  Therefore, it has been considered that an HDR-compatible TV is required to watch an HDR video, but a pseudo HDR video that can realize an HDR-like effect can be viewed on an existing SDRTV. As a result, the spread of HDR-compatible Blu-ray can be expected.

  The HDR signal transmitted by broadcast, package media such as Blu-ray, or Internet distribution such as OTT is converted into a pseudo HDR signal by performing an HDR-pseudo HDR conversion process. As a result, the HDR signal can be displayed as a pseudo HDR video on an existing SDRTV.

(Embodiment 4)
As described above, the first embodiment has been described as an example of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to the first embodiment in which changes, replacements, additions, omissions, and the like are made as appropriate. Further, it is also possible to form a new embodiment by combining the components described in the first embodiment.

  Therefore, another embodiment will be described below as a second embodiment.

  The HDR video is, for example, a Blu-ray Disc, a DVD, a video distribution site on the Internet, a broadcast, or a video in an HDD.

  The conversion device 500 (the HDR → pseudo HDR conversion processing unit) may exist inside a disk player, a disk recorder, a set-top box, a television, a personal computer, and a smartphone. The conversion device 500 may exist inside a server device in the Internet.

  The display device 600 (SDR display unit) is, for example, a television, a personal computer, and a smartphone.

  The display characteristic information acquired by the conversion device 500 may be acquired from the display device 600 via an HDMI cable or a LAN cable using HDMI or another communication protocol. The display characteristic information acquired by the conversion device 500 may acquire the display characteristic information included in the model information or the like of the display device 600 via the Internet. Alternatively, the user may perform a manual operation to set the display characteristic information in the conversion device 500. Further, the acquisition of the display characteristic information of the conversion device 500 may be performed immediately before the generation of the pseudo HDR video (steps S101 to S104), or may be performed at the time of initial setting of the device or at the time of connecting the display. For example, the acquisition of the display characteristic information may be performed immediately before the conversion to the display luminance value, or may be performed at the timing when the conversion device 500 is first connected to the display device 600 via the HDMI cable.

  In addition, one HDR video CPL or CAL may be provided for one content, or may be present for each scene. That is, in the conversion method, the first maximum luminance value, which is luminance information corresponding to each of a plurality of scenes of a video and is the maximum value among luminance values for a plurality of images forming the scene, for each of the scenes And luminance information (CPL, CAL) including at least one of an average luminance value that is an average of luminance values for a plurality of images forming the scene. In the first luminance conversion, for each of the plurality of scenes, The display luminance value may be determined according to the luminance information corresponding to the scene.

  Also, the CPL and the CAL may be included in the same medium (Blu-ray Disc, DVD, etc.) as the HDR video, or may be obtained from a location different from the HDR video, such as the conversion device 500 obtaining from the Internet. May be. That is, luminance information including at least one of CPL and CAL may be acquired as video meta information, or may be acquired via a network.

  Further, in the first luminance conversion (HPL → DPL) of conversion device 500, a fixed value may be used without using CPL, CAL, and display peak luminance (DPL). Further, the fixed value may be externally changeable. Further, CPL, CAL, and DPL may be switched in several types. For example, DPL may be set to only three types, 200 nit, 400 nit, and 800 nit, and a value closest to the display characteristic information may be used. You may make it.

  Also, the HDR EOTF may not be SMPTE 2084, and another type of HDR EOTF may be used. Also, the maximum luminance (HPL) of the HDR video need not be 10,000 nits, but may be, for example, 4,000 nits or 1,000 nits.

  The bit width of the code value may be, for example, 16, 14, 12, 10, or 8 bits.

  In addition, although the inverse SDR EOTF conversion is determined from the display characteristic information, a fixed conversion function (which can be changed from outside) may be used. The inverse SDR EOTF conversion is performed, for example, in Rec. ITU-R BT. The function specified in 1886 may be used. Alternatively, the types of inverse SDR EOTF conversion may be reduced to several types, and the type closest to the input / output characteristics of the display device 600 may be selected and used.

  The display mode may use a fixed mode, and may not be included in the display characteristic information.

  Further, conversion device 500 does not need to transmit the setting information, and display device 600 may have a fixed display setting, or may not change the display setting. In this case, the display setting unit 601 becomes unnecessary. The setting information may be flag information indicating whether or not the image is a pseudo HDR image. For example, if the image is a pseudo HDR image, the setting may be changed to a setting for displaying the brightest image. That is, in the setting of the display setting (S105), when the acquired setting information indicates a signal indicating a pseudo HDR video converted using the DPL, the brightness setting of the display device 600 is set to be the brightest. May be switched.

  Further, the first luminance conversion (HPL → DPL) of the conversion device 500 is performed by, for example, the following equation.

  Here, L indicates a luminance value normalized to 0 to 1, and S1, S2, a, b, and M are values set based on CAL, CPL, and DPL. ln is the natural logarithm. V is the converted luminance value normalized to 0-1. As in the example of FIG. 23A, CAL is set to 300 nits, CPL is set to 2,000 nits, DPL is set to 750 nits, conversion is not performed up to CAL + 50 nits, and conversion is performed for 350 nits or more. It becomes such a value.

S1 = 350/10000
S2 = 2000 / 10,000
M = 750/10000
a = 0.023
b = S1−a * ln (S1) = 0.112105

  That is, in the first luminance conversion, when the luminance value of the SDR is between the average luminance value (CAL) and the first maximum luminance value (CPL), the luminance value of the HDR corresponds to the luminance value of the HDR using the natural logarithm. Determine the display brightness value.

  By converting the HDR video using information such as the content peak luminance and the average content luminance of the HDR video, the conversion formula can be changed according to the content and the HDR video can be converted to keep the HDR gradation as much as possible. It becomes. Further, adverse effects such as too dark and too bright can be suppressed. Specifically, by mapping the content peak luminance of the HDR video to the display peak luminance, the gradation is kept as much as possible. In addition, by keeping the pixel values below the average luminance unchanged, the overall brightness is not changed.

  Also, by converting the HDR video using the peak luminance value and the display mode of the SDR display, the conversion formula can be changed according to the display environment of the SDR display, and the HDR image can be changed according to the performance of the SDR display. The video (pseudo HDR video) can be displayed with the same gradation and brightness as the original HDR video. Specifically, the display peak luminance is determined according to the maximum luminance and the display mode of the SDR display, and the HDR image is converted so as not to exceed the peak luminance value. The display is performed with almost no reduction in gradation, and the brightness value that cannot be displayed is reduced to a displayable brightness.

  As described above, undisplayable brightness information is reduced, and it is possible to display in a form close to the original HDR video without lowering the displayable brightness gradation. For example, for a display with a peak luminance of 1,000 nits, the overall brightness is maintained by converting to a pseudo HDR image with a peak luminance of 1,000 nits, and the luminance value changes depending on the display mode of the display. For this reason, the conversion formula of the luminance is changed according to the display mode of the display. If a luminance higher than the peak luminance of the display is allowed in the pseudo HDR image, the large luminance may be replaced with the peak luminance on the display side and displayed. In this case, the whole image is darker than the original HDR image. Become. Conversely, if a luminance smaller than the peak luminance of the display is converted as the maximum luminance, the small luminance is replaced with the peak luminance on the display side, and the whole becomes brighter than the original HDR video. Moreover, since the brightness is smaller than the peak brightness on the display side, the performance regarding the gradation of the display is not used to the utmost.

  On the display side, by switching the display setting using the setting information, it is possible to display the pseudo HDR video better. For example, when the brightness is set to be dark, high-luminance display cannot be performed, and the HDR feeling is impaired. In this case, by changing the display setting or displaying a message urging the user to change the display setting, the performance of the display is maximized and a high-gradation image can be displayed.

  In content such as Blu-ray, a video signal and a graphics signal such as a caption or a menu are multiplexed as independent data. At the time of reproduction, each is individually decoded, and the decoding results are combined and displayed. Specifically, a subtitle or menu plane is superimposed on a video plane.

  Here, even if the video signal is HDR, graphics signals such as subtitles and menus may be SDR. In the HPL to DPL conversion of a video signal, the following two types of conversions (a) and (b) are possible.

(A) When HPL → DPL conversion is performed after graphics are synthesized The graphics EOTF is converted from the SDR EOTF to the HDR EOTF.
2. The graphics after the EOTF conversion are combined with the video.
3. HPL → DPL conversion is performed on the synthesis result.

(B) Performing HPL → DPL conversion before combining graphics The graphics EOTF is converted from the SDR EOTF to the HDR EOTF.
2. HPL → DPL conversion is performed on the video.
3. The graphics after the EOTF conversion and the video after the DPL conversion are combined.

  In the case of (b), the order of 1 and 2 may be interchanged.

  In either of the methods (a) and (b), the graphics peak luminance is 100 nits. For example, when the DPL is high luminance such as 1000 nits, the graphics luminance remains at 100 nits. , The luminance of graphics may decrease with respect to the video after the HPL → DPL conversion. In particular, adverse effects such as darkening of subtitles superimposed on video are assumed. Therefore, the brightness of graphics may be converted according to the value of DPL. For example, the subtitle luminance may be set in advance to what percentage of the DPL value, and may be converted based on the set value. Graphics other than subtitles such as menus can be processed in a similar manner.

  The operation of reproducing an HDR disc storing only HDR signals has been described above.

  Next, multiplexed data stored on a dual disc storing both the HDR signal and the SDR signal will be described with reference to FIG. FIG. 28 is a diagram for describing multiplexed data stored on a dual disk.

  In a dual disc, as shown in FIG. 28, an HDR signal and an SDR signal are stored as different multiplexed streams. For example, in an optical disc such as a Blu-ray, data of a plurality of media such as video, audio, subtitles, and graphics is stored as one multiplexed stream by an MPEG-2 TS-based multiplexing method called M2TS. These multiplexed streams are referred to from playback control metadata such as a playlist, and at the time of playback, a multiplexed stream reproduced by a player by analyzing the metadata, or a separate language stored in the multiplexed stream. Select the data of. This example shows a case where playlists for HDR and SDR are individually stored, and each playlist refers to an HDR signal or an SDR signal. Also, identification information indicating that both the HDR signal and the SDR signal are stored may be separately indicated.

  Although it is possible to multiplex both the HDR signal and the SDR signal in the same multiplexed stream, the multiplexing is performed so as to satisfy a buffer model such as T-STD (System Target Decoder) defined in MPEG-2 TS. In particular, it is difficult to multiplex two videos with a high bit rate within a predetermined data read rate range. For this reason, it is desirable to separate the multiplexed stream.

  Data such as audio, subtitles, and graphics need to be stored for each multiplexed stream, and the data amount increases as compared to the case of multiplexing into one stream. However, an increase in the amount of data can reduce the amount of video data by using a video encoding scheme with a high compression rate. For example, by changing MPEG-4 AVC used in the conventional Blu-ray to HEVC (High Efficiency Video Coding), a 1.6 to 2 times improvement in compression ratio is expected. In addition, to store data on a dual disk, a combination of 2K HDR and SDR, a combination of 4K SDR and 2K HDR, such as two 2K or a combination of 2K and 4K, By prohibiting the storage of two, only combinations that fit in the capacity of the optical disk may be allowed.

  According to the conversion method of the present disclosure, when displaying an HDR video in SDRTV, the HDR video is converted into an SDR video of 100 nit or less by using the fact that the peak luminance of the displayed SDRTV exceeds 100 nit (normally 200 nit or more). Instead, the “HDR → pseudo HDR conversion processing” that can be converted so as to maintain the gradation of an area exceeding 100 nit to some extent, converted to a pseudo HDR video close to the original HDR, and displayed on the SDRTV is realized.

  In the conversion method, the conversion method of “HDR → pseudo HDR conversion processing” may be switched according to the display characteristics (the highest luminance, the input / output characteristics, and the display mode) of the SDRTV.

  The display characteristic information can be acquired by (1) automatically acquiring the information through HDMI or a network, (2) generating the information by allowing the user to input information such as a manufacturer name and a product number, and (3) producing a manufacturer name and a product number. It is conceivable that the information is obtained from the cloud or the like using the information of the cloud.

  In addition, the acquisition timing of the display characteristic information of the conversion device 500 includes (1) acquisition immediately before performing the pseudo HDR conversion, and (2) first connection with the display device 600 (such as SDRTV) (when connection is established). ).

  In the conversion method, the conversion method may be switched according to the luminance information (CAL, CPL) of the HDR video.

  For example, as a method of acquiring the luminance information of the HDR video by the conversion device 500, (1) acquiring as the meta information attached to the HDR video, (2) acquiring by inputting the title information of the content to the user, And (3) It is conceivable to acquire from a cloud or the like using input information that is influential to the user.

  The details of the conversion method include (1) conversion so as not to exceed DPL, (2) conversion so that CPL becomes DPL, and (3) brightness not changing CAL and its surroundings. 4) Conversion is performed using natural logarithm, and (5) clip processing is performed by DPL.

  Further, in the conversion method, in order to enhance the effect of the pseudo HDR, display settings such as a display mode of SDRTV and display parameters can be transmitted to the display device 600 to be switched, and for example, the user is prompted for the display settings. The message may be displayed on the screen.

(Embodiment 5)
[5-1. Disc type]
Hereinafter, Embodiment 3 will be described. As described above, by increasing the resolution and the luminance range of the display device, a plurality of types of Blu-ray Discs that meet the specifications of the display device are provided. FIG. 29 is a diagram illustrating types of BDs. FIG. 30 is a diagram illustrating the types of BDs in more detail. The playback device (Blu-ray device) plays back the content recorded on the inserted BD and displays it on the display device. As shown in FIG. 29 and FIG. 30, in the following third embodiment, a BD on which a video signal whose resolution is the first resolution and whose luminance range is the first luminance range is a 2K_SDR-compatible BD (FIG. 30 (a)). A video signal whose resolution is the first resolution and whose luminance range is the first luminance range is stored as a stream on the BD. This stream is described as a 2K_SDR stream. The 2K_SDR compatible BD is a conventional BD.

  A BD on which a video signal whose resolution is the second resolution and whose luminance range is the first luminance range is recorded is referred to as a 4K_SDR compatible BD. A video signal whose resolution is the second resolution and whose luminance range is the first luminance range is stored as a stream on the BD. This stream is described as a 4K_SDR stream ((b) in FIG. 30).

  Similarly, a BD on which a video signal whose resolution is the first resolution and whose luminance range is the second luminance range is described as a 2K_HDR compliant BD. A video signal whose resolution is the first resolution and whose luminance range is the second luminance range is stored as a stream on the BD. This stream is described as a 2K_HDR stream ((d) in FIG. 30).

  A BD on which a video signal whose resolution is the second resolution and whose luminance range is the second luminance range is recorded is referred to as a 4K_HDR-compatible BD. A video signal whose resolution is the second resolution and whose luminance range is the second luminance range is stored as a stream on the BD. This stream is described as a 4K_HDR stream ((e) in FIG. 30).

  The first resolution is, for example, a so-called 2K (1920 × 1080, 2048 × 1080) resolution, but may be any resolution including such a resolution. In the third embodiment, the first resolution may be simply described as 2K.

  Further, the second resolution is a so-called 4K (3840 × 2160, 4096 × 2160) resolution, but may be any resolution including such a resolution. The second resolution is a resolution having a larger number of pixels than the first resolution.

  The first luminance range is, for example, the SDR (luminance range with a peak luminance of 100 nit) described above. The second luminance range is, for example, the HDR described above (a luminance range in which the peak luminance exceeds 100 nit). The second luminance range includes the entire first luminance range, and the peak luminance of the second luminance range is higher than the peak luminance of the first luminance range.

  As shown in (c), (f), (g), and (h) of FIG. 30, a dual stream disc corresponding to a plurality of video expressions with one BD is conceivable. The dual stream disc is a BD in which a plurality of video signals for reproducing the same content and a plurality of video signals having at least one of a different resolution and a different luminance range are recorded.

  Specifically, the dual stream disc shown in FIG. 30C is a BD on which a 4K_SDR stream and a 2K_SDR stream are recorded. The dual stream disc shown in (f) of FIG. 30 is a BD on which a 2K_HDR stream and a 2K_SDR stream are recorded.

  The dual stream disc shown in (g) of FIG. 30 is a BD on which a 4K_HDR stream and a 4K_SDR stream are recorded. The dual stream disc shown in (h) of FIG. 30 is a BD on which a 4K_HDR stream and a 2K_SDR stream are recorded.

  Note that the dual stream disc shown in FIG. 30C is not essential because the Blu-ray device can perform down conversion (hereinafter, also referred to as down conversion) with a resolution of 4K to 2K.

[5-2. Disc type details]
FIG. 31 is a diagram illustrating an example of a combination of a video stream and a graphic stream recorded on each BD including a dual stream disc.

  In FIG. 31, the graphic stream is recorded in the resolution of 2K and the luminance range in SDR irrespective of the resolution and luminance range of the corresponding video stream in consideration of the trouble of producing the content. The graphic stream can be shared by all of the 2K_SDR stream, the 4K_SDR stream, the 2K_HDR stream, and the 4K_HDR stream. In this case, the conversion of the resolution of the graphic stream from 2K to 4K and the conversion of the luminance range of the graphic stream from SDR to HDR are all performed by the Blu-ray device.

  In this case, as shown in FIG. 32, since the Blu-ray device performs conversion from SDR to HDR, there is no restriction on the Java side and all functions can be used.

  FIG. 33 is a diagram showing details of the graphic stream shown in FIG. In the example shown in FIG. 33, SDR graphics (PG, IG, Java Graphics, Java Drawing) are used also for the HDR video stream. In this case, all functions including the Java drawing command (Java Drawing) are not restricted. Specifically, since conversion from SDR to HDR is performed by a Blu-ray device, there is no restriction on the Java side, and all functions can be used.

  FIG. 34 is a diagram illustrating an example of a combination of a video stream and a graphic stream recorded on each BD including a dual stream disc.

  FIG. 34 shows that the graphic stream is recorded at a resolution of 2K irrespective of the resolution of the corresponding video stream in consideration of the trouble of producing the content (BD). A graphic stream can be shared between the 2K_SDR stream and the 4K_SDR stream. However, the graphic stream is recorded in a luminance range that matches the luminance range of the corresponding video stream. If the video stream is HDR, an HDR graphics stream is recorded. If the video stream is SDR, a graphics stream of SDR is recorded. The conversion of the graphic stream from SDR to HDR is performed when the content is created.

  FIG. 35 is a diagram showing details of the graphic stream shown in FIG.

  The basic specifications of the SDR graphic stream and the HDR graphic stream are the same, but in the HDR graphic stream, the Java color space (BT 2020 for 4K), EOTF (EOTF for HDR), etc. There are restrictions. For this reason, the Java drawing command cannot be used as it is.

  That is, in the 4K_SDR-compatible BD, the 2K_HDR-compatible BD, and the 4K_HDR-compatible BD, it is necessary to suppress the Java drawing command.

  In addition, in specifying the values of the color and the luminance, the Java drawing command may be used by specifying a value assuming the result of the EOTF conversion (SDR-> HDR), the color space (BT709-> BT2020) conversion, or the like. It is possible.

  In this case, it is necessary to create a different graphics stream depending on whether the video stream is SDR or HDR, or whether the color space is BT709 or BT2020, and it is difficult to produce content. Therefore, it is easier to understand that the menu is set to SDR and only the main part and subtitles are set to HDR.

  That is, as shown in FIG. 36, authoring becomes easier and the user can easily understand when the use of other than subtitles (PG) is prohibited. However, in this case, the normal display using Java and the Popup menu that is displayed by overlaying on the video during the reproduction of the video stream cannot be displayed.

  In addition, as shown in FIG. 37, in the case of 2K_HDR Graphics Stream, only captions (PG) are stored because restrictions are imposed on the Java side.

  As another example, as shown in FIG. 38, in the case of HDR video playback, the HDMV mode may be used instead of Java, and the Popup menu may be displayed on the IG. As a result, the Popup menu using Java cannot be displayed, but the Popup menu can be displayed using the IG using the HDMV mode.

[5-3. Operation of playback device]
Hereinafter, there will be described two types of playback devices (a data playback device): a type having a function of converting graphics of an SDR signal into graphics of an HDR signal and outputting the graphics, and a type having no function. In such a reproducing apparatus, while handling an HDR signal as a video image, an SDR signal or an HDR signal is handled for graphics such as menus and subtitles to be superimposed on the video.

  In this case, in a playback device (player) having no conversion output function, for example, graphics are processed as SDR signals. As a result, there may be a problem that the quality of the reproduced video is reduced, or the brightness of the menu or the caption is different from the intention of the content creator, and it is difficult for the user to visually recognize the content. In order to solve this problem, it is conceivable that the content production side prepares both the graphics content of the HDR signal and the graphics content of the SDR signal and provides them as a Blu-ray disc.

  The playback device is not limited to a player such as a BD device, but may be a display device such as a TV.

  FIG. 39 is a flowchart showing processing of the playback device. The playback device reads a playback control program described in a playback control programming language called BD-J (BD-Java) or HDMV stored in a disc, and executes the playback control program. The processing shown in FIG. 39 is executed by this reproduction control program.

  First, the reproduction control program reproduces a menu and presents a user with a reproduction selection menu for a main video. Here, when the user specifies reproduction of the main video of the HDR signal, the reproduction control program determines whether the reproduction device supports HDR graphics (has a function of processing HDR graphics) (S401). ).

  If the playback device supports HDR graphics (Yes in S401), the playback control program plays back the graphics content of the HDR signal (S403).

  On the other hand, if the playback device does not support HDR graphics (No in S401), the playback control program determines whether the playback device has a function of converting graphics of an SDR signal into graphics of an HDR signal. Is determined (S402). Specifically, the playback control program checks the register value of the playback device. For example, the 25th player register (32-bit register called PSR25) indicates whether or not there is a function of converting SDR signal graphics as HDR signal graphics and outputting the result. By checking the value of this register, the playback control program determines whether or not the playback device has a conversion output function.

  In the reproducing apparatus having the conversion output function (Yes in S402), the reproduction control program reproduces the playlist #A prepared for converting the graphics of the SDR signal into the graphics of the HDR signal and outputting the converted graphics. Thus, the playback device outputs the converted graphics of the HDR signal while converting the graphics of the SDR signal into the graphics of the HDR signal (S404).

  On the other hand, in the playback device without the conversion output function (No in S402), the playback control program plays back the playlist #B including the pseudo HDR signal graphics signal prepared so that the conversion process is unnecessary. Specifically, the playback device plays back the subtitles and the HDMV menu using the CLUT prepared for the HDR signal (S405).

  Here, on the Blu-ray Disc, there are three types of graphics: subtitles (Presentation Graphics), graphics such as BD-J menus (BD-J Graphics), and graphics such as HDMV menus (Interactive Graphics). Available. As described above, when a playlist is selected and reproduced according to the presence or absence of the conversion output function, the playlist for a playback device without the conversion output function includes subtitles (Presentation Graphics) and a menu (Interactive Graphics) using HDMV. )) (A color conversion table in which the correspondence between index numbers and colors and luminances is defined). Specifically, the playback device uses a CLUT prepared for the SDR signal when outputting graphics of the SDR signal, and prepares for the HDR signal when outputting graphics of the HDR signal. Another CLUT is used. That is, in Java, there is a limitation on the color space, so that it is not possible to easily cope with HDR. However, a subtitle and a menu based on HDMV can cope with the luminance range of HDR by using a CLUT for HDR. This makes it possible to inexpensively avoid the problem of difficulty in visually recognizing menu and subtitle graphics images in a playback device that cannot convert SDR signal graphics into HDR signal graphics.

  As described above, the playback device according to the present embodiment superimposes graphics on video in the first luminance range (HDR) and displays the video.

  Does the playback device have a function of converting the first graphics in the second brightness range (SDR) smaller than the first brightness range (HDR) to the second graphics in the first brightness range (HDR)? It is determined whether or not it is (S402). Specifically, the playback device executes the playback control program to determine whether the playback device has the above function. Also, the playback control program determines whether the playback device has the above function by checking a register storing information indicating whether the playback device has the above function. In addition, the playback device acquires the video in the first brightness range (HDR), the first graphics in the second brightness range (SDR), and the playback control program from the disc.

  If the playback device has the above function, the playback device converts the first graphics into the second graphics, and superimposes and displays the second graphics on the video (S404).

  In addition, when the playback device does not have the above function, the playback device superimposes and displays the third graphics different from the second graphics on the video. Specifically, the playback device generates the third graphics using the color conversion table for the first luminance range (S405). Here, in the color conversion table (CLUT) for the first luminance range (HDR), the corresponding color associated with each number is included in the first luminance range. In other words, the color conversion table can represent a luminance value that is not included in the second luminance range (SDR) and that is included in the first luminance range.

  When the playback device does not have the above function, the playback device may perform the graphics conversion process and display the first graphics in the second luminance range (SDR) in a superimposed manner on the video. . That is, the third graphics may be the first graphics.

  As described above, in addition to the basic 2K and SDR video, there are four cases of 4K and SDR video, 2K and HDR video, 4K and HDR video. This necessitates complicated authoring work and internal processing in the playback device.

  Furthermore, in the case of Blu-ray storing HDR video, if subtitles and graphics for menus, graphics for Java, drawing processing for Java, and the like are processed as HDR content, it cannot be displayed because Java does not have an HDR color space definition. Of various restrictions.

  In this embodiment, the case where the playback device (player) has a function of converting graphics from SDR to HDR is divided into the case where the playback device has no function. Is performed on the SDR signal, the result is converted from SDR to HDR, and the obtained HDR graphics are combined with HDR video. As a result, all processes using Java or the like can be performed, and high-quality graphics can be provided.

  On the other hand, if the playback device does not have a conversion function, HDR cannot process Java, and thus cannot process Popup menus or the like. For this reason, by calling the HDMV mode from Java and performing HDR graphics (subtitles, pop-up menus, etc.) in the HDMV mode, even in the case of HDR video, the same user experience as SDR can be obtained by a simple authoring process. realizable.

  In each of the above embodiments, each component may be configured by dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

  As described above, the conversion method and the conversion device according to one or more aspects of the present disclosure have been described based on the embodiments, but the present disclosure is not limited to the embodiments. Unless departing from the spirit of the present disclosure, various modifications conceived by those skilled in the art may be applied to the present embodiment, and a configuration constructed by combining components in different embodiments may be one or more of the present disclosure. It may be included within the scope of the embodiment.

  The present disclosure can be applied to a playback device such as a Blu-ray device.

Reference Signs List 100 media 200 BD player 210 conversion device 220 remap processing unit 221 determination unit 222 processing target determination unit 223 brightness variable remap unit 224 brightness value fixed remap unit 225 storage unit 300, 310 TV
400 generation unit 410 grading unit 420 determination unit 430 HDR signal generation unit 440 SDR signal generation unit 500 conversion device 501 EOTF conversion unit 502 luminance conversion unit 503 inverse luminance conversion unit 504 EOTF conversion unit for inverse SDR 600 display device 601 display setting unit 602 SDR EOTF converter 603 Luminance converter 604 Display

Claims (4)

Obtain graphics in a first luminance range including a menu or subtitles from a recording medium,
When displaying an image in the first luminance range, first graphics are generated using the color conversion table for the first luminance range with respect to the graphics in the first luminance range, and the first luminance range is generated. Outputting the video and the first graphics on a display in a superimposed manner,
When displaying the video in the second luminance range that is wider than the first luminance range, the graphics in the first luminance range are displayed using the color conversion table for the second luminance range. Is generated, and the video of the second luminance range and the second graphics are superimposed and output to the display.
The method performed on the playback device. The first luminance range is an SDR (Standard Dynamic Range), and the second luminance range is an HDR (High Dynamic Range).
The method of claim 1. The color conversion table for the second luminance range expresses a luminance value not included in the first luminance range but included in the second luminance range.
The method of claim 1. A playback device having one or more memories and a processor,
Obtain graphics in a first luminance range including a menu or subtitles from a recording medium,
When displaying an image in the first luminance range, first graphics are generated using the color conversion table for the first luminance range with respect to the graphics in the first luminance range, and the first luminance range is generated. Outputting the video and the first graphics to the display in a superimposed manner,
When displaying the video in the second luminance range that is wider than the first luminance range, the graphics in the first luminance range are displayed using the color conversion table for the second luminance range. Is generated, and the video of the second luminance range and the second graphics are superimposed and output to the display.
Playback device.

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