JP6731627B2 - Method Performed on Playback Device and Playback Device - Google Patents

Description

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

Conventionally, an image signal processing device for improving a displayable brightness level has been disclosed (for example, refer to Patent Document 1).

JP, 2008-167418, A

A method executed by a reproducing device according to an aspect of the present disclosure, when acquiring graphics in a first brightness range including a menu or subtitles from a recording medium and displaying a video in the first brightness range, First graphics is generated for the graphics in the first luminance range by using the color conversion table for the first luminance range, and the video and the first graphics in the first luminance range are superimposed. When outputting to a display and displaying the video in a second brightness range wider than the first brightness range, the color conversion table for the second brightness range is used for the graphics in the first brightness range. Second graphics are generated, and the image in the second luminance range and the second graphics are superimposed and output 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, the computer program. Alternatively, it may be realized by any combination of recording media.

FIG. 1 is a diagram for explaining the evolution of video technology. FIG. 2 is a diagram illustrating an example of EOTF (Electro-Optical Transfer Function). FIG. 3 is an explanatory diagram of a method of determining the code value of the luminance signal stored in the content and a process of restoring the luminance value from the code value during reproduction. FIG. 4 is an explanatory diagram of a player that produces a BD (Blu-ray (registered trademark, the same applies hereinafter) Disc) and reproduces a 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 is a diagram showing 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 showing the configuration of the remap processing unit in the conversion device. FIG. 7 is a diagram showing a flowchart of remapping processing in the conversion device. FIG. 8 is a diagram showing an example of a combination of HDR and SDR in the case where one video stream and one graphics stream are included in the content. FIG. 9 is a diagram showing that the graphics master is generated by using the EOTF common to the video master. FIG. 10A is a diagram for explaining a case of mapping to an SDR signal in generation of a graphics master. FIG. 10B is a diagram for explaining a case of mapping to an HDR signal in generation of a graphics master. FIG. 11 is a block diagram showing a configuration of a generation unit that generates a graphics signal in authoring. FIG. 12 is a flowchart showing a method of 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 explaining the SDR display process in SDRTV. FIG. 15B is a diagram for explaining the SDR display process in SDRTV having a peak luminance of 300 nit. FIG. 16 is a diagram for explaining the conversion from HDR to SDR. FIG. 17A is a diagram for explaining Case 1 in which only HDR signals compatible with HDR are stored in the HDR disc. FIG. 17B is a diagram illustrating Case 2 in which an HDR disc stores an HDR signal compatible with HDR and an SDR signal compatible with SDR. FIG. 18 is a diagram for explaining the conversion process from HDR to pseudo HDR. FIG. 19A is a diagram illustrating an example of 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 HDR and SDR. FIG. 20A is a diagram illustrating an example of a display process in which HDR signals are converted and HDR display is performed in HDRTV. FIG. 20B is a diagram illustrating an example of display processing for performing HDR display using an HDR-compatible playback device and SDRTV. FIG. 20C is a diagram showing an example of a display process for performing HDR display on an HDR-compatible playback device and SDRTV that are connected to each other via a standard interface. FIG. 21 is a block diagram showing the configurations of the conversion device and the display device according to the embodiment. FIG. 22 is a flowchart showing a conversion method and a display method performed by the conversion device and the display device of the embodiment. FIG. 23A is a diagram for explaining the first luminance conversion. FIG. 23B is a diagram for explaining another example of the first luminance conversion. FIG. 24 is a diagram for explaining the second luminance conversion. FIG. 25 is a flowchart showing detailed display setting processing. FIG. 26 is a diagram for explaining the third luminance conversion. FIG. 27 is a diagram for explaining the conversion processing from HDR to pseudo HDR. FIG. 28 is a diagram for explaining the reproducing operation of the dual disc. FIG. 29 is a diagram showing types of BDs. FIG. 30 is a diagram showing 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 disc of a BD and a dual stream disc. FIG. 32 is a diagram showing an example of a combination of a video stream and a graphic stream recorded on each disc of a BD and a dual stream disc. FIG. 33 is a diagram showing an example of a graphic stream. FIG. 34 is a diagram showing an example of a combination of a video stream and a graphic stream recorded on each disc of a BD and a dual stream disc. FIG. 35 is a diagram showing an example of a graphic stream. FIG. 36 is a diagram showing an example of a graphic stream. FIG. 37 is a diagram showing an example of a combination of a video stream and a graphic stream recorded on each disc of a BD and a dual stream disc. FIG. 38 is a diagram showing an example of a graphic stream. FIG. 39 is a flowchart showing the processing of the playback device.

A data reproducing method according to an aspect of the present disclosure is a data reproducing method of displaying graphics by superimposing graphics on a video in a first luminance range, wherein a reproducing device has a second luminance range narrower than the first luminance range. It is determined whether or not the reproduction apparatus has the function of converting the first graphics into the second graphics of the first luminance range. When the reproduction apparatus has the function, the reproduction apparatus converts the first graphics into When the reproduction device does not have the function, the third graphics different from the second graphics is converted into the second graphics, and the second graphics is superimposed and displayed on the video. Overlay and display.

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. As a result, the data reproducing method can perform an appropriate operation according to the function of the reproducing device.

For example, when the reproduction 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 difficulty in visually recognizing the graphics image.

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

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

For example, in the determination, the reproduction control program checks whether or not the reproduction device has the function by checking a register in which information indicating whether the reproduction device has the function is stored. You may judge.

A reproduction device according to an aspect of the present disclosure is a reproduction device that displays graphics in a first luminance range by superimposing the graphics, wherein the reproduction device has a second luminance range narrower than the first luminance range. A determining unit that determines whether the first graphics of the first luminance range is converted into the second graphics of the first luminance range; and, if the playback device has the function, When the reproduction unit and the reproduction device have the function, the second graphic is superimposed and displayed on the image, and when the reproduction device does not have the function, the image is displayed on the image. And a display unit for displaying a third graphics different from the second graphics in an overlapping manner.

According to this, the reproducing apparatus 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 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, the computer program. Alternatively, it may be realized by any combination of recording media.

Regarding the above characteristics, mainly [5-3. Operation of Playback Device].

In addition, each of the embodiments described below shows a specific example of the present disclosure. Numerical values, shapes, materials, and constituent elements shown in the following embodiments. Arrangement positions and connection forms of components, steps, order of steps, and the like are examples, and are not intended to limit the present disclosure. Further, among the constituent elements in the following embodiments, constituent elements not described in the independent claim showing the highest concept are described as arbitrary constituent elements.

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

It should be noted that each of the embodiments described below shows a specific example of the present disclosure. Numerical values, shapes, materials, and constituent elements shown in the following embodiments. Arrangement positions and connection forms of components, steps, order of steps, and the like are examples, and are not intended to limit the present disclosure. Further, among the constituent elements in the following embodiments, constituent elements not described in the independent claim showing the highest concept are described as arbitrary constituent elements.

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

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

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

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

In addition to increasing the resolution of the image by introducing 4K, it is considered to improve the image quality by expanding the dynamic range, expanding the color gamut, or adding or improving the frame rate.

Among them, regarding the dynamic range, the maximum brightness is used to express bright light such as specular reflected light, which cannot be expressed by the current TV signal, with more realistic brightness while maintaining the dark part gradation in the conventional image. HDR (High Dynamic Range) is attracting attention as a method corresponding to a brightness range in which the value is expanded. Specifically, the method of the brightness range that the TV signal has been compatible with up to now is called SDR (Standard Dynamic Range), and the maximum brightness value is 100 nit, whereas in HDR, the maximum is up to 1000 nit or more. It is envisioned to increase the brightness value. HDR is being standardized in SMPTE (Society of Motion Picture & Television Engineers) and ITU-R (International Telecommunications Union Radio Communications Sector).

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

Note that, in the following, in a video corresponding to HDR, the brightness of the video is composed of brightness values in the HDR brightness range, and a brightness signal obtained by quantizing the brightness value of the video is called an HDR signal. .. In a video corresponding to SDR, the brightness of the video is composed of brightness values in the brightness range of SDR, and a brightness signal obtained by quantizing the brightness value of the video is called an SDR signal.

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

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

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

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

The luminance signal indicating the luminance in this example is an HDR signal compatible with HDR. The image after grading is quantized by the inverse function of HDR EOTF, and the code value corresponding to the luminance value of the image is determined. Image coding or the like is performed based on this code value, and elementary streams of video and graphics are generated. At the time of reproduction, the luminance value for each pixel is restored by dequantizing the decoded result of the elementary stream based on HDR EOTF.

[1-4. BD stream configuration]
It was mentioned above that HDR may be used in optical discs such as BD, or in broadcasting. Hereinafter, a BD as an example of a medium in which HDR is used will be described with reference to FIG.

FIG. 4 is an explanatory diagram of a player that produces a BD and 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, in addition to video and audio, graphics data for generating subtitles and menus, and scenario data for providing interactivity in displaying menus and user operations. The scenario data has a format called HDMV (High Definition Movie) which is controlled by a prescribed command and a format called BD-J (Blu-ray Disc Java) which is controlled by a Java (registered trademark, the same applies below) program. To do. In authoring, video and audio are encoded, and those encoded streams and graphics data indicating subtitles, menus, etc. are multiplexed into a transport stream of M2TS format, and a playlist, EP map, etc. are reproduced. 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 the video and audio elementary streams required for reproduction from the graphics data, decodes them, and outputs them. Here, the video and graphics such as subtitles and menus are output after synthesizing the planes of each other. When the video resolution and the graphics resolution are different, the graphics are up-converted to match the video resolution, and then the video and the graphics are combined.

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

5A and 5B are examples in which the BD player 200 and the TVs 300 and 310 are connected by HDMI. FIG. 5A shows a case where the TV 300 supports HDR display, and FIG. 5B shows the TV 310 in HDR display. The case where it is not supported is shown. Note that the BD player 200 in FIG. 5A and the BD player 200 in FIG. 5B have different configurations, but in the case of FIG. The configuration of 210 is omitted in the drawing.

In FIG. 45, the BD player 200 reads video and graphics from the medium 100 and decodes them. Then, the BD player 200 synthesizes the decoded video and graphics HDR data, and outputs the HDR signal generated by the synthesis to the TV 300 compatible with HDR display 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 to combine the video and graphics HDR data before combining the video and graphics. Remap each to SDR data. Then, the BD player 200 synthesizes the SDR data of the remapped video and graphics, and outputs the SDR signal generated by the synthesis to the TV 310 that does not support HDR display by HDMI.

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

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

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

When converting an HDR signal of a video (content) compatible with HDR into an SDR signal and outputting the SDR signal, the remap similar to that of the video is required for graphics. By performing remapping on both video and graphics, the processing amount required for remapping increases and there is also a possibility that the brightness may be converted to a brightness value that is not intended by the creator.

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

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

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

The processing target determination unit 222 determines whether or not the processing target is a video (graphics).

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

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

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

As shown in FIG. 7, in the remapping process, first, the EOTF determination unit 221 corresponds the EOTF to which the acquired content (video and graphics) signal corresponds 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 processes in steps 102 to 104 are performed in order to convert the method of the luminance range to which the content signal corresponds to the EOTF to which the output signal corresponds. On the other hand, if “No” is determined in step 101, the remapping process is terminated and the content signal 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 that displays 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 or not the processing target is a video (graphics) (step 102). If YES is determined in step 102, the brightness value variable remapping unit 223 converts the content signal into a signal corresponding to the EOTF of the output signal by the brightness value variable remap (second remap) (step 103).

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

Thus, when the content (video) is video, the second remapping is performed, and when the content (video) is graphics, the first remapping is performed.

In the brightness value variable remap of step 103 and the brightness value fixed remap of step 104, tables showing the correspondence relationship between the brightness values of HDR and SDR are prepared in advance. In this table, the correspondence relationship between the brightness values in which the code value exists may be described in the HDR EOTF and the SDR EOTF. By doing so, the code value corresponding to the brightness value of the EOTF after remapping always exists, and therefore, when the code value corresponding to the brightness value does not exist, the code value having the brightness value closest to the brightness value concerned is selected. No need to search.

In the variable brightness value remapping (second remapping), a plurality of tables are adaptively switched based on the brightness distribution in each image or each scene, or an optimum table is sequentially created for each content. You may. That is, for example, in the determination of the second luminance value which is the luminance value after remapping, the image is extracted from a plurality 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. Alternatively, the second brightness value may be determined from the determined first brightness value by selecting the relationship information according to the scene.

In the brightness value variable remap of step 103, the processing is performed in the following procedure. In this case, it is assumed that the first luminance signal corresponding to the first EOTF is converted into the second luminance signal corresponding to the second EOTF.

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

(2) The 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 brightness value determined in (2) is determined.

In the luminance value fixed remap of step 104, the processing is performed in the following procedure. In this case, it is assumed that the first luminance signal corresponding to the first EOTF is converted into the second luminance signal corresponding to the second EOTF.

(1) The brightness value corresponding to the code value of the first EOTF is determined.

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

* In the case of the fixed luminance value remapping, the luminance value does not change before and after the remapping, and thus the process (2) in step 103 is not necessary.

After the remapping process of step 103 and step 104 is completed, the conversion device 210 synthesizes the video and graphics and outputs the synthesized image. That is, the conversion device 210 may further perform the first remapping and the second remapping to combine and output the video and graphics converted into the second luminance signal.

Further, the conversion device 210 may further transmit information for identifying the EOTF of the output signal as meta information when outputting to the display via an interface such as HDMI. That is, the conversion device 210 may further output the second brightness signal converted from the acquired first brightness signal together with the 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 in HDR or SDR depending on whether or not the output destination of the video is HDR, and the video is output in accordance with the output format. The graphics are remapped from SDR to HDR or from HDR to SDR. For graphics, fixed luminance remapping processing in which the luminance value does not change before and after remapping is applied, and for video, luminance variable remapping processing in which the luminance value can change before and after remapping is applied.

As for the graphics, since the brightness does not change before and after the remapping, the image quality intended by the creator can be maintained. Further, it is not necessary to associate the brightness values between the EOTFs before and after the conversion, and the processing amount related to the remapping can be reduced.

(Embodiment 2)
[2-1. Content generation method]
In creating a video or graphics master, the brightness and hue of each pixel is corrected in a digital image taken with a camera or a scanned image of film so as to reflect the intention of the creator. A grading process is required, which requires advanced know-how for grading and enormous man-hours. Therefore, it is desirable to minimize the number of masters generated. On the other hand, since HDR and SDR have different peak luminances, it is generally necessary to generate different masters for each. FIG. 8 is a diagram showing an example of a combination of HDR and SDR in the case where one video stream and one graphics stream are included in the content. In this example, there are four combinations, requiring HDR and SDR masters for video and graphics, respectively.

On the other hand, HDR is most effective in video contents in videos such as the main part of a movie, and graphics such as subtitles are considered to be less effective than videos. Nevertheless, even for graphics, creating a master for HDR and SDR as with video has a problem that the load of content production is heavy.

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

FIG. 10A is a diagram for explaining a case of mapping to an SDR signal in generation of a graphics master. In this case, since the luminance range of SDR and the luminance range of the graphics master match, the domain of the code value in EOTF of SDR is all valid.

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

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

The graphics EOTF 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 SDR. Alternatively, the graphics data may always be SDR.

The same idea can be applied when there are multiple videos. For example, when there is a sub video to be superimposed on the main video or displayed side by side, 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 showing a configuration of a generation unit that generates a graphics signal in authoring.

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

The GFX grading unit 410 grades the graphics master so that the brightness value becomes equal to or lower than the peak brightness 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 HDR EOTF.

If the determination unit 420 determines that the video displayed at the same time as the graphics is not HDR (that is, SDR), the SDR signal generation unit 440 converts the brightness value of the graphics into a code value using the EOTF of SDR. To do.

FIG. 12 is a flowchart showing a method of generating a graphics signal in authoring.

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

Next, the determination unit 420 determines whether the video displayed simultaneously with the graphics is HDR (step 202).

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

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

Although it is determined in step 202 whether or not the graphics are displayed simultaneously with the video, if the graphics is a subtitle, for example, the video on which the subtitle is superimposed is determined. In addition, graphics such as menus that are not displayed at the same time as the video may be determined based on whether or not the main video is HDR. Since the same graphics format as the conventional 2K format is used, the conversion may always be performed using the EOTF of SDR, and the determination processing of step 202 may not be performed, and the processing of step 204 may always be performed. ..

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

Note that grading the luminance of the HDR master to fall within the SDR range is possible for data other than graphics. Also, especially in graphics such as subtitles, the advantage of using a luminance value higher than the peak luminance of SDR is small. Therefore, in the remapping from SDR to HDR, the fixed luminance value remapping may be applied regardless of whether the grading is within the range of SDR.

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

As a result, since masters other than video can be shared by HDR and SDR, man-hours 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 technique in the present disclosure is not limited to this, and is also applicable to the embodiment in which changes, replacements, additions, omissions, etc. are appropriately made. Further, it is possible to combine the respective constituent elements described in the above-described embodiment to form a new embodiment.

Therefore, other embodiments will be exemplified below.

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

At this time, if the peak luminance according to the HDR standard and the peak luminance that can be displayed on the display device are different, the remapping processing according to the EOTF of the display device is performed on the data in the content corresponding to the HDR. Good. Further, the SDR or HDR signal input to the display device by HDMI may be remapped again to the EOTF corresponding to the peak luminance of the display device. That is, in this case, in the conversion into the second luminance signal, the obtained first luminance signal is set to the first EOTF and the luminance range that can be displayed on the display device to which the second luminance signal is output is set to the second luminance range. It may be performed using the second EOTF.

Although not mentioned in each of the above-described embodiments, in authoring a BD, it is possible to specify video, audio, or graphics to be reproduced in units of play items in the playlist. In this way, when video, audio, or graphics to be played in units of play items are designated, in interfaces such as HDMI, when HDR and SDR are switched in units of play items, reset processing is performed at boundaries of play items. However, it may not be played back seamlessly. Therefore, when HDR and SDR are switched between seamlessly connected play items, remapping processing is performed in the conversion device provided in the BD player or the like so that the EOTF of the output signal becomes the same as the immediately preceding play item. You can go. Alternatively, switching of EOTFs may be prohibited between play items that are seamlessly connected, and further, 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-described embodiments can be applied not only to a package medium such as an optical disc, but also to broadcasting and OTT (Over The Top) service. For example, in broadcasting, in addition to the main part of a broadcast program, a data broadcast sent by the broadcast or content acquired via a communication network can be superimposed and displayed on the main part video. At this time, it is expected that HDR and SDR programs will coexist in the main part video, and the peak luminance limitation by the method described so far is applied to the graphics and video in the content acquired separately from the main part. Alternatively, remapping processing 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 (increase in the number of pixels, etc.) to improve the image quality of the 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) broadcasting, communication, package media, and other distribution methods, and (3) display devices such as TVs and projectors that display the video.

[3-2. Relationship between master, distribution method, and display device when introducing HDR]
In order for the user to enjoy content (eg, high-luminance video content (HDR content)) compatible with a new video expression at home, it is necessary to newly introduce both the HDR compatible distribution method and the 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 system and a display device corresponding to the new video expression. This should be avoided even when a new image expression is introduced, such as when the SD image is changed to the HD image, the HD image is changed to the 3D image, and the HD image is changed to the UHD (4K) image. I couldn't.

For this reason, it is expensive, it is not easy to replace it in terms of size and weight, it is necessary to replace the TV, and changes to new video expressions depend on the spread of display devices (eg TV) having new functions. Will be done. Initially, neither the medium side nor the content side could make a large investment, so the spread of new video expression was often delayed.

Therefore, as shown in FIG. 14, also for HDR, in order to fully utilize the original video expression of HDR, a TV (hereinafter, referred to as “HDR display”) that supports display of video compatible with HDR (hereinafter, referred to as “HDR display”). It is expected that a replacement by purchase to "HDRTV" will be required.

[3-3. SDRTV]
An input signal having a brightness value up to 100 nit is normally input to a TV (hereinafter, referred to as "SDRTV") that is compatible only with the display of video corresponding to SDR (hereinafter, referred to as "SDR display"). Therefore, SDRTV is sufficient to represent the luminance value of the input signal if the display capability is 100 nit. However, SDRTV actually has a function of reproducing an image with an optimum brightness value according to the viewing environment (dark room: cinema mode, bright room: dynamic mode, etc.), and is capable of expressing images of 200 nits or more. Many have. That is, such an SDRTV can display an image up to the maximum brightness (for example, 300 nit) of the display capability by selecting the display mode according to the viewing environment.

However, in the SDR input signal input to SDRTV, the upper limit of the brightness of the input signal is set to 100 nits. Therefore, as long as the SDR input interface is used as usual, a high-luminance image exceeding 100 nit of SDRTV is provided. It is difficult to use the reproduction capability for reproducing the HDR signal (see FIGS. 15A and 15B).

[3-4. HDR to SDR conversion]
High-luminance video content (hereinafter referred to as “HDR content”) distributed by a distribution method such as HDR-compatible broadcasting, video distribution via a communication network, or HDR-compatible package media (for example, HDR-compatible Blu-ray Disc). It is assumed that the “HDR video” is output by SDRTV via an HDR-compatible playback device (eg, communication STB (Set Top Box), Blu-ray device, IPTV playback device). .. When HDR content is played back with SDRTV, "HDR → SDR conversion" is implemented to convert the HDR signal corresponding to HDR into an SDR signal in the SDR luminance range with a maximum value of 100 nit so that the video can be displayed correctly with SDRTV. To do. Accordingly, SDRTV can display the SDR video obtained by converting the HDR video using the converted SDR signal (see FIG. 16 ).

However, even in this case, even if the user purchases the HDR compatible content (for example, Blu-ray Disc, HDR IPTV content) and the HDR compatible reproducing device (for example, Blu-ray device, HDR compatible IPTV reproducing device). Regardless, in SDRTV, images can be enjoyed only in SDR image representation (SDR representation). In other words, even if the HDR content and the playback device compatible with HDR are prepared, if there is no display device compatible with HDR (for example, HDRTV) and there is only SDRTV, an image is displayed in HDR image representation (HDR representation). I can't watch.

Therefore, the user cannot understand the value of HDR (that is, superiority to SDR due to the high image quality of HDR) even if the user purchases the HDR content or the transmission medium (reproduction device) unless the HDRTV is prepared. As described above, the user cannot know the value of HDR without HDRTV. Therefore, it can be said that the widespread use of HDR content and the HDR-compatible distribution method depends on the widespread speed of HDRTV.

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

As shown in FIG. 17A, in case 1, in the case of displaying an image of a BD reproduced on a Blu-ray device on HDRTV, even if a BD compatible with HDR (hereinafter referred to as “HDRBD”) is reproduced, SDR is performed. 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 HDRTV without conversion. Since HDRTV can display and process both the HDR signal and the SDR signal, it performs display processing according to the input luminance signal and displays HDR video or SDR video.

On the other hand, in case 1, in the case of displaying the image of the BD reproduced by the Blu-ray device on SDRTV, when the HDRBD is reproduced, the Blu-ray device performs the conversion process of converting the HDR signal into the SDR signal. Then, the SDR signal obtained by the conversion processing 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, SDRTV displays the SDR video.

Further, as shown in FIG. 17B, in case 2, in the case of displaying an image of a BD reproduced by a Blu-ray device on HDRTV, the same as in case 1.

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

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

[3-6. HDR to pseudo HDR conversion]
From the above, in order to promote the spread of HDR, it can be said that it is important to be able to promote the commercialization of HDR contents and distribution methods without waiting for the spread of HDRTV. To this end, if the HDR signal can be viewed by the existing SDRTV as not the SDR video but the 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 without having to buy it, it is possible to view a higher quality image similar to the HDR image, which is clearly different from the SDR image. In other words, if the user can view the pseudo HDR video with SDRTV, he/she can watch a video having a higher image quality than the SDR video by preparing the HDR content and the HDR distribution device without preparing the HDRTV. .. In short, allowing the pseudo HDR video to be viewed on SDRTV can be a motivation for the user to purchase the HDR content or the HDR distribution device (see FIG. 18 ).

In order to display the pseudo HDR video on the SDRTV, the HDR signal is transmitted so that the video of the HDR content can be correctly displayed on the SDRTV when the HDR content is played back with the configuration in which the SDRTV is connected to the HDR distribution method. Instead of converting to an SDR video signal, a video signal input having a maximum value of 100 nit of SDRTV is used to generate a pseudo HDR signal for displaying a video of maximum brightness of SDRTV, for example, 200 nit or more. However, it is necessary to realize the “HDR→pseudo HDR conversion process” that enables the generated pseudo HDR signal to be sent to SDRTV.

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

FIG. 19A 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, shows the correspondence between the code value and the brightness value, and converts the code value into the brightness value. That is, EOTF is relationship information indicating a correspondence relationship between a plurality of code values and brightness values.

Further, FIG. 19B is a diagram showing an example of inverse EOTF corresponding to HDR and SDR.

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

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

In the following specification, the luminance range from 0 nit shown in FIGS. 19A and 19B to 100 nit which is the peak luminance may be described as the 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 the second luminance range.

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

FIG. 20A is a diagram illustrating an example of a display process in which HDR signals are converted and HDR display is performed in HDRTV.

As shown in FIG. 20A, when displaying an HDR image, even if the display device is HDRTV, the maximum value of the HDR brightness range (peak brightness (HPL (HDR Peak Luminance): Example 1500 nit)) should be displayed as it is. May not be possible. In this case, in order to match the linear signal after the inverse quantization using HDR EOTF to the maximum value (peak brightness (DPL (Display Peak Immance): Example 750 nit)) of the brightness range of the display device. Perform brightness conversion. Then, by inputting the video signal obtained by performing the brightness conversion to the display device, it is possible to display the HDR video in accordance with 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 HDR video is displayed, if the display device is SDRTV, the maximum value of the brightness range of SDRTV to be displayed (peak brightness (DPL: example 300 nit)) exceeds 100 nits. 20B is the maximum value of the “HDR EOTF conversion” and the brightness range of SDRTV performed in HDRTV by “HDR→pseudo HDR conversion process” in the HDR-compatible playback device (Blu-ray device). If the signal obtained by performing "luminance conversion" using DPL (example: 300 nit) and performing "luminance conversion" can be directly input to the "display device" of SDRTV, the same effect as HDRTV can be obtained using SDRTV. Can be realized.

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

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

As shown in FIG. 20C, it is usually necessary to use an input interface (HDMI or the like) included in SDRTV to input a signal capable of obtaining the effect of FIG. 20B to SDRTV. In SDRTV, the signal input through the input interface passes through “SDR EOTF conversion”, “brightness conversion for each mode”, and “display device” in order, and an image matched to the maximum brightness range of the display device is displayed. Is displayed. Therefore, a signal (pseudo HDR signal) that can cancel the “SDR EOTF conversion” and the “brightness conversion for each mode” passing immediately after the input interface by SDRTV in the HDR-compatible Blu-ray device is provided. To generate. That is, in the HDR-compatible Blu-ray device, immediately after the “EODR conversion of HDR” and the “luminance conversion” using the peak luminance (DPL) of SDRTV, “inverse luminance conversion for each mode” and “inverse SDR” are performed. By performing "EOTF conversion of", pseudo-realization of the same effect as when the signal immediately after "luminance conversion" is input to the "display device" (broken line arrow in FIG. 20C).

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

As illustrated in FIG. 21, the conversion device 500 includes an HDR EOTF conversion unit 501, a luminance conversion unit 502, an inverse luminance conversion unit 503, and an inverse SDR EOTF conversion unit 504. The display device 600 also includes a display setting unit 601, an SDR EOTF conversion unit 602, a brightness 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 device 500 acquires an HDR video that has undergone inverse HDR EOTF conversion. The HDR EOTF conversion unit 501 of the conversion device 500 performs HDR EOTF conversion on the acquired HDR signal of the HDR video (S101). As a result, the HDR EOTF converter 501 converts the acquired HDR signal into a linear signal indicating a luminance value. HDR EOTF is, for example, SMPTE 2084.

Next, the brightness conversion unit 502 of the conversion device 500 performs the first brightness conversion for converting the linear signal converted by the HDR EOTF conversion unit 501 using the display characteristic information and the content brightness information (S102). .. In the first luminance conversion, the luminance value corresponding to the HDR luminance range (hereinafter referred to as “HDR luminance value”) is converted to the 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 the HDR signal as the first luminance signal indicating the code value obtained by quantizing the luminance value of the video. In addition, the HDR EOTF conversion unit 501 and the brightness conversion unit 502 determine the code value indicated by the HDR signal acquired by the acquisition unit based on the brightness range of the display (display device 600). It functions as a conversion unit that converts into a display brightness value corresponding to a display brightness range having a maximum value (DPL) smaller than the value (HPL) and larger than 100 nit.

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

Further, in step S102, the brightness conversion unit 502 determines, for the HDR brightness value determined in step S101, a display brightness value that is associated with the brightness value of the HDR in advance and that corresponds to the brightness range of the display. The first luminance conversion for converting the HDR luminance value corresponding to the luminance range of 1 to the display luminance value corresponding to the display luminance range is performed.

Further, the conversion device 500, prior to step S102, content luminance information including at least one of a maximum luminance value (CPL: Content Peak luminance) of an image (content) and an average luminance value (CAL: Content Average Luminance) of the image. Is acquired as information regarding the HDR signal. The CPL (first maximum brightness value) is, for example, the maximum value of the brightness values for a plurality of images forming an HDR video. Further, CAL is, for example, an average brightness value that is an average of brightness values for a plurality of images that form an HDR video.

Further, the conversion device 500 acquires the display characteristic information of the display device 600 from the display device 600 before step S102. The display characteristic information includes the maximum value (DPL) of the brightness that the display device 600 can display, the display mode of the display device 600 (see later), the input/output characteristic (EOTF corresponding to the display device) of the display device 600, and the like. This is information indicating display characteristics.

Further, the conversion device 500 may transmit recommended display setting information (see later, hereinafter also referred to as “setting information”) to the 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. As a result, the inverse brightness conversion unit 503 performs the second brightness conversion for converting the brightness value corresponding to the display brightness range into the brightness value corresponding to the SDR brightness range (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 the third luminance value corresponding to the luminance range of the SDR having the maximum value of 100 nit, which is associated with the display luminance value in advance. Luminance value corresponding to SDR (hereinafter referred to as "SDR luminance value") The luminance value of SDR is determined, and the display luminance value corresponding to the luminance range of the display is changed to the luminance value of SDR corresponding to the luminance range of SDR. A second luminance conversion is performed.

Then, the inverse SDR EOTF conversion unit 504 of the conversion device 500 performs inverse SDR EOTF conversion to generate a pseudo HDR video (S104). That is, the inverse SDR EOTF conversion unit 504 is an inverse EOTF (Electro-Optical) of SDR (Standard Dynamic Range) that is third relationship information that associates a brightness value in the HDR brightness range with a plurality of third code values. Transfer Function) is used to quantize the determined SDR luminance value, determine the third code value obtained by the quantization, and indicate the SDR luminance value corresponding to the SDR luminance range as the third code value. The pseudo HDR signal is generated by converting the SDR signal as the third luminance signal. It should be noted that 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 image using the inverse EOTF of the SDR in which the luminance value in the luminance range of the SDR and the code values of the plurality of SDRs are associated with each other. It is represented by a code value. Then, the conversion device 500 outputs the pseudo HDR signal (SDR signal) generated in step S104 to the display device 600.

The conversion device 500 generates the SDR brightness value corresponding to the pseudo HDR by performing the first brightness conversion and the second brightness conversion on the HDR brightness value obtained by dequantizing the HDR signal. Then, the SDR luminance value is quantized using the SDR EOTF to generate an SDR signal corresponding to pseudo HDR. The SDR brightness value is a numerical value within the brightness range of 0 to 100 nit corresponding to SDR, but since conversion is performed based on the brightness range of the display, the EOTF and SDR of HDR are compared with the brightness value of HDR. Is a numerical value different from the luminance value within the luminance range of 0 to 100 nit corresponding to the SDR obtained by performing the luminance conversion using 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 the display setting of the display device 600 using the setting information acquired from the conversion device 500 (S105). Here, the display device 600 is SDRTV. The setting information is information indicating display settings recommended for the display device, and information indicating how to perform EOTF of the pseudo HDR video and which setting should display a beautiful video (that is, This is information for switching the display setting of the display device 600 to the optimum display setting). The setting information includes, for example, a gamma curve characteristic at the time of output on the display device, a display mode such as a living mode (normal mode) and a dynamic mode, and a numerical value of a backlight (brightness). Further, a message prompting the user to manually change the display settings of the display device 600 may be displayed on the display device 600 (hereinafter, also referred to as “SDR display”). Details will be described later.

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

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

Next, the SDR EOTF conversion unit 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 dequantizes the SDR signal (pseudo HDR signal) using the SDR EOTF. As a result, the SDR EOTF conversion unit 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 in the display device 600. Thereby, 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]). The third brightness conversion is performed (S107). Details will be described later.

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

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

Then, in the conversion into the display luminance value, in step S107, the display luminance value corresponding to the luminance range of the display, which is associated in advance with the determined SDR luminance value, is determined, and the SDR corresponding to the SDR luminance range is determined. A third brightness conversion is performed to convert the brightness value into a display brightness value corresponding to the brightness 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 brightness 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 the first brightness conversion for converting the linear signal (HDR brightness value) obtained in step S101 using the display characteristic information and the HDR video content brightness information. .. The first brightness conversion converts the HDR brightness value (input brightness value) into a display brightness value (output brightness value) that does not exceed the display peak brightness (DPL). The DPL is determined using the maximum brightness and display mode of the SDR display, which is the display characteristic information. The display mode is mode information such as a theater mode in which an SDR display is displayed darkly and a dynamic mode in which it is displayed brightly. 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 brightness value) is the maximum value of brightness that can be displayed in the display mode in which the SDR display is currently set. That is, in the first luminance conversion, the DPL as the second maximum luminance value is determined using the display characteristic information that is the 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, the luminance values near CAL and below are the same before and after the conversion, and the luminance value is changed only for the luminance values near CPL and above. To do. That is, as shown in FIG. 23A, in the first brightness conversion, when the brightness value of the HDR is CAL or less, the brightness value of the HDR is not converted, and the brightness value of the HDR is determined as the display brightness value, When the luminance value of the HDR is CPL or more, the DPL as the second maximum luminance value is determined as the display luminance value.

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

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

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

Through the above process, the second brightness conversion converts the display brightness value (input brightness value) in the display brightness range into the SDR brightness value (output brightness value) in the SDR brightness range.

In the second luminance conversion, the conversion formula is switched depending on 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 into a direct proportional value which is directly proportional to the display luminance value. In the second luminance conversion, when the display mode of the SDR display is a dynamic mode in which high-luminance pixels are brighter and low-luminance pixels are darker than in the normal mode, the inverse function is used to reduce the low-luminance pixels. The SDR luminance value is converted to a value higher than the direct 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 the direct 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 associated with the display luminance value using the luminance relation information according to the display characteristic information that is the information indicating the display characteristic of the SDR display. The brightness value is determined as the brightness value of the SDR, and the brightness conversion processing is switched according to the display characteristic information. Here, the brightness-related information according to the display characteristic information is, for example, as shown in FIG. 24, the display brightness value (input brightness value) and the SDR of the display brightness value (input brightness value) determined for each display parameter (display mode) of the SDR display. This is information that is associated with the brightness value (output brightness 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 detailed display setting processing.

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

First, the display setting unit 601 uses the setting information to determine whether the EOTF set in the SDR display (EOTF 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 (EOTF matching the pseudo HDR video) (Yes in S201), the EOTF for SDR display is set to the system It is determined whether the switching is possible on the side (S202).

When the display setting unit 601 determines that switching is possible, 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 setting of display settings (S105), the EOTF set in the SDR display is set to the recommended EOTF according to the acquired setting information. Further, as a result, in step S106 performed after step S105, the recommended EOTF can be used to determine the luminance value of the SDR.

When it is determined that the system is not switchable (No in S202), a message prompting the user to manually change the EOTF is displayed on the screen (S204). For example, the message "Please set the display gamma to 2.4" is displayed on the screen. That is, when the EOTF set in the SDR display cannot be switched in the display setting setting (S105), the display setting unit 601 switches the EOTF set in the SDR display (EODR for SDR display) to the recommended EOTF. A message for prompting the user to do so is displayed on the SDR display.

Next, on the SDR display, the pseudo HDR video (SDR signal) is displayed. Before the display, the setting information is used to determine whether the display parameters of the SDR display match the setting information (S205).

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

When the display setting unit 601 determines that the display parameter of the SDR display can be switched (Yes in S206), the display setting unit 601 switches the display parameter of the SDR display according to the setting information (S207).

From step S204 to step S207, in the setting of display setting (S105), the display parameter set in the SDR display is set to the recommended display parameter according to the acquired setting information.

When it is determined that the system is not switchable (No in S206), a message prompting the user to manually change the display parameter set in the SDR display is displayed on the screen (S208). For example, the message "Please set the display mode to the dynamic mode and maximize the backlight" is displayed on the screen. That is, in the setting (S105), if the display parameter set in the SDR display cannot be switched, a message prompting the user to switch the display parameter set in the SDR display to the recommended display parameter is displayed. 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 explaining 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]) into (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 of S103.

In the third luminance conversion, the conversion formula is switched depending on 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 brightness value is converted into a direct proportional value that is directly proportional to the SDR brightness 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 in the normal mode, the display luminance value of the low-luminance pixels is SDR. The display brightness value of the high-brightness pixel is converted into a value lower than a direct proportional value that is directly proportional to the brightness value, and a value higher than a direct proportional value that is directly proportional to the SDR brightness value. That is, in the third brightness conversion, the brightness value associated with the brightness value of the SDR determined in step S106 is associated with the brightness value of the SDR using the brightness relationship information according to the display parameter indicating the display setting of the SDR display. The value is determined as the display brightness value, and the brightness conversion process is switched according to the display parameter. Here, the brightness-related information according to the display parameter is, for example, as shown in FIG. 26, the SDR brightness value (input brightness value) and the display brightness which are determined for each display parameter (display mode) of the SDR display. It is the information in which the value (output brightness value) is associated.

[3-15. Effects, etc.]
A normal SDRTV has an input signal of 100 nit, but has an ability to express an image of 200 nit or more according to the viewing environment (dark room: cinema mode, bright room: dynamic mode, etc.). However, since the upper limit of the brightness of the input signal to SDRTV was set to 100 nit, the ability could not be directly used.

When displaying HDR video in SDRTV, the peak brightness of SDRTV to be displayed exceeds 100 nits (usually 200 nits or more), and rather than converting the HDR video into SDR video of 100 nits or less, brightness exceeding 100 nit The “HDR→pseudo HDR conversion process” is performed so as to maintain a certain range of gradation. Therefore, it can be displayed on SDRTV as a pseudo HDR image close to the original HDR.

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

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

An HDR signal sent by broadcasting, package media such as Blu-ray, or Internet distribution such as OTT is converted into a pseudo HDR signal by performing HDR-pseudo HDR conversion processing. As a result, the HDR signal can be displayed as a pseudo HDR video on the existing SDRTV.

(Embodiment 4)
As described above, the first embodiment has been described as an example of the technique disclosed in the present application. However, the technique of the present disclosure is not limited to this, and can be applied to the first embodiment in which changes, replacements, additions, omissions, etc. are appropriately made. Further, it is also possible to combine the constituent elements described in the first embodiment to form a new embodiment.

Therefore, in the following, another embodiment will be exemplified as the second embodiment.

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

The conversion device 500 (HDR→pseudo HDR conversion processing unit) may be present inside a disc player, a disc recorder, a set top box, a television, a personal computer, or a smartphone. The conversion device 500 may exist inside a server device on the Internet.

The display device 600 (SDR display unit) is, for example, a television, a personal computer, or 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 be the display characteristic information included in the model information of the display device 600 or the like via the Internet. Alternatively, the user may manually perform the operation to set the display characteristic information in the conversion device 500. Further, the display characteristic information of the conversion apparatus 500 may be acquired immediately before the pseudo HDR video generation (steps S101 to S104), or at the time of initial setting of the device or the timing of connecting the display. For example, the display characteristic information may be acquired immediately before the conversion into the display brightness value, or may be performed at the timing when the conversion device 500 is first connected to the display device 600 with the HDMI cable.

Further, one CPL or CAL of HDR video may be provided for each content, or may be present for each scene. That is, in the conversion method, the first maximum luminance value that is the luminance information corresponding to each of the plurality of scenes of the video and is the maximum value of the luminance values for the plurality of images that configure the scene for each scene. 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, and in the first luminance conversion, for each of the plurality of scenes, The display brightness value may be determined according to the brightness information corresponding to the scene.

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

Further, in the first luminance conversion (HPL→DPL) of the conversion device 500, fixed values may be used without using CPL, CAL, and display peak luminance (DPL). Further, the fixed value may be changeable from the outside. Further, CPL, CAL, and DPL may be switched in several types, for example, DPL may be set to only three types of 200 nit, 400 nit, and 800 nit, or a value closest to the display characteristic information is used. You may do so.

Also, the HDR EOTF need not be SMPTE 2084, and other types of HDR EOTFs may be used. Further, the maximum luminance (HPL) of the HDR image may not be 10,000 nit, and may be 4,000 nit or 1,000 nit, for example.

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

Further, the inverse SDR EOTF conversion is determined from the display characteristic information, but a fixed conversion function (which can be changed externally) may be used. The inverse SDR EOTF conversion is performed by, for example, Rec. ITU-R BT. The function defined by 1886 may be used. Further, the types of inverse SDR EOTF conversion may be narrowed down to several types, and the one closest to the input/output characteristics of the display device 600 may be selected and used.

The display mode may be a fixed mode or may not be included in the display characteristic information.

Further, the conversion device 500 does not have to transmit the setting information, and the 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 the image is a pseudo HDR image. For example, when the image is a pseudo HDR image, the setting may be changed to display the brightest image. That is, in the display setting setting (S105), when the acquired setting information indicates that the signal indicates the pseudo HDR video converted by using the DPL, the brightness setting of the display device 600 is set to the brightest display. You may switch to.

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

Here, L represents a luminance value normalized to 0 to 1, and S1, S2, a, b, and M are values set based on CAL, CPL, and DPL. In is a natural logarithm. V is a luminance value after conversion normalized to 0 to 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, and up to CAL + 50 nit is not converted. It will be a value like this.

S1 = 350/10000
S2 = 2000/10000
M = 750/10000
a = 0.023
b=S1-a*ln(S1)=0.112105

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

By converting the HDR video using information such as the content peak brightness and the average content brightness of the HDR video, the conversion formula can be changed according to the content, and the conversion can be performed so as to keep the HDR gradation as much as possible. Becomes In addition, it is possible to suppress adverse effects such as being too dark and being too bright. Specifically, by mapping the content peak luminance of the HDR video to the display peak luminance, the gradation is kept as much as possible. Also, by not changing the pixel values near the average brightness, the overall brightness is kept unchanged.

In addition, by converting the HDR image 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 there is an HDR feeling according to the performance of the SDR display. An image (pseudo HDR image) can be displayed with the same gradation and brightness as the original HDR image. Specifically, by determining the display peak brightness according to the maximum brightness of the SDR display and the display mode and converting the HDR video so that the peak brightness value is not exceeded, the HDR video is displayed at the brightness that can be displayed on the SDR display. The gradation value is displayed with almost no reduction, and the brightness value that cannot be displayed is lowered to the displayable brightness level.

As described above, it becomes possible to reduce the non-displayable brightness information, display the gradation of the displayable brightness, and display it in a form close to the original HDR image. For example, for a display having a peak brightness of 1,000 nit, the brightness is changed depending on the display mode of the display by converting the pseudo HDR image with the peak brightness of 1,000 nit to maintain the overall brightness. Therefore, the conversion formula of the brightness is changed according to the display mode of the display. If a brightness higher than the peak brightness of the display is allowed in the pseudo HDR image, the high brightness may be replaced with the peak brightness on the display side and displayed, and in that case, it is darker than the original HDR image. Become. On the contrary, if the 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 entire HDR image becomes brighter. Moreover, since it is smaller than the peak brightness on the display side, the performance related to the gradation of the display is not used to the maximum.

Also, on the display side, it is possible to better display the pseudo HDR video by switching the display setting using the setting information. For example, when the brightness is set to be dark, high-luminance display cannot be performed, so that the HDR feeling is lost. In that case, the display setting is changed or a message prompting the change is displayed to maximize the performance of the display and display a high gradation image.

In contents such as Blu-ray, video signals and graphics signals such as subtitles and menus are multiplexed as independent data. At the time of reproduction, each is individually decoded, and the decoded results are combined and displayed. Specifically, the subtitle and menu planes are superimposed on the video plane.

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

(A) When performing HPL→DPL conversion after synthesizing graphics 1. The graphics EOTF is converted from the SDR EOTF to the HDR EOTF.
2. The graphics after EOTF conversion are combined with the video.
3. HPL→DPL conversion is performed on the combined result.

(B) When performing HPL→DPL conversion before graphics composition 1. The graphics EOTF is converted from the SDR EOTF to the HDR EOTF.
2. Perform HPL→DPL conversion on the video.
3. The graphics after EOTF conversion and the video after DPL conversion are combined.

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

In either of the methods (a) and (b), the peak luminance of graphics is 100 nit. However, if the DPL has a high luminance such as 1000 nits, the luminance of graphics cannot be 100 nits. , The brightness of graphics may be reduced for a video after HPL→DPL conversion. Especially, it is expected that the subtitles superimposed on the video will be dark. Therefore, the brightness of graphics may be converted according to the value of DPL. For example, with respect to the brightness of the subtitle, it is possible to predefine what percentage of the DPL value is set, and to convert based on the set value. Graphics other than subtitles such as menus can be processed in the same manner.

In the above, the reproduction operation of the HDR disc in which only the HDR signal is stored has been described.

Next, the multiplexed data stored in the dual disc in which both the HDR signal and the SDR signal are stored will be described with reference to FIG. FIG. 28 is a diagram for explaining multiplexed data stored in the dual disc.

In the dual disc, as shown in FIG. 28, the HDR signal and the 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 system called M2TS. These multiplexed streams are referred to by playback control metadata such as playlists, and are played by the player analyzing the metadata at the time of playback, or a separate language stored in the multiplexed stream. Select the data of. This example shows a case in which playlists for HDR and SDR are individually stored, and each playlist refers to the HDR signal or the SDR signal. Further, identification information indicating that both the HDR signal and the SDR signal are stored may be separately shown.

Both the HDR signal and the SDR signal can be multiplexed in the same multiplexed stream, but they are multiplexed 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 having a high bit rate within a predetermined data read rate. Therefore, it is desirable to separate the multiplexed stream.

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

According to the conversion method of the present disclosure, when displaying HDR video in SDRTV, HDR video is converted into SDR video of 100 nit or less by utilizing that the peak luminance of SDRTV to be displayed exceeds 100 nit (normally 200 nit or more). Instead, the "HDR->pseudo HDR conversion process" can be realized in which the gradation of the area exceeding 100 nit is converted to some extent and converted into a pseudo HDR image close to the original HDR and can be displayed on SDRTV.

In the conversion method, the conversion method of “HDR→pseudo HDR conversion processing” may be switched depending on the display characteristics (maximum brightness, input/output characteristics, and display mode) of SDRTV.

Display characteristic information can be acquired by (1) automatic acquisition through HDMI or a network, (2) generation by allowing a user to input information such as manufacturer name and product number, and (3) manufacturer name and product number. It is conceivable to obtain the information from the cloud using the information of.

Further, the acquisition timing of the display characteristic information of the conversion device 500 includes (1) acquisition immediately before the pseudo HDR conversion, and (2) the first connection with the display device 600 (SDRTV or the like) (when the connection is established). ) Can be obtained.

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

For example, as the method of acquiring the brightness information of the HDR video of the conversion device 500, (1) acquisition as meta information associated with the HDR video, (2) acquisition by allowing the user to input the title information of the content, And (3) it is conceivable to obtain the information from the cloud or the like by using the input information made available to the user.

Further, as the details of the conversion method, (1) conversion is performed so as not to exceed DPL, (2) conversion is performed so that CPL becomes DPL, and (3) brightness at and below the CAL is not changed, 4) Convert using natural logarithm, and (5) perform clip processing with DPL.

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

(Embodiment 5)
[5-1. Disc type]
The third embodiment will be described below. As described above, the display device has a higher resolution and a higher brightness range, thereby providing a plurality of types of Blu-ray Discs according to the specifications of the display device. FIG. 29 is a diagram showing types of BDs. FIG. 30 is a diagram showing the types of BDs in more detail. The playback device (Blu-ray device) plays back the content recorded in the inserted BD and displays it on the display device. As shown in FIGS. 29 and 30, in Embodiment 3 below, a BD on which a video signal having a resolution of the first resolution and a luminance range of the first luminance range is recorded is a 2K_SDR compatible BD. It is described ((a) of FIG. 30). A video signal whose resolution is the first resolution and whose luminance range is the first luminance range is stored in the BD as a stream. 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 having a resolution of the second resolution and a luminance range of the first luminance range is recorded is described 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 in the BD as a stream. 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 recorded is described as a 2K_HDR compatible BD. A video signal whose resolution is the first resolution and whose luminance range is the second luminance range is stored in the BD as a stream. This stream is described as a 2K_HDR stream ((d) in FIG. 30).

A BD on which a video signal having a resolution of the second resolution and a luminance range of the second luminance range is recorded is described 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 in the BD as a stream. This stream is described as a 4K_HDR stream ((e) in FIG. 30).

The first resolution is, for example, a so-called 2K (1920x1080, 2048x1080) resolution, but may be any resolution including such a resolution. In the third embodiment, the first resolution may be simply described as 2K.

The second resolution is a so-called 4K (3840x2160, 4096x2160) resolution, but may be any resolution including such a resolution. The second resolution is a resolution having more pixels than the first resolution.

The first brightness range is, for example, the SDR described above (the brightness range in which the peak brightness is 100 nit). The second brightness range is, for example, the HDR described above (a brightness range in which the peak brightness exceeds 100 nit). The second brightness range includes the entire first brightness range, and the peak brightness of the second brightness range is larger than the peak brightness of the first brightness 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 can be considered. 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 different resolutions and/or luminance ranges are recorded.

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

The dual stream disc shown in (c) of FIG. 30 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 showing an example of a combination of a video stream and a graphic stream recorded on each disc for each BD including a dual stream disc.

In FIG. 31, in consideration of the time and effort required for producing the content, the graphic stream is recorded with a resolution of 2K and a luminance range of SDR regardless of the resolution and luminance range of the corresponding video stream. The 2K_SDR stream, the 4K_SDR stream, the 2K_HDR stream, and the 4K_HDR stream can all share the graphic 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 both executed 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 are no restrictions 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 also used for the HDR video stream. In this case, all functions including the Java drawing command (Java Drawing) are not restricted. Specifically, since the Blu-ray device performs conversion from SDR to HDR, there are no restrictions on the Java side and all functions can be used.

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

In FIG. 34, the graphic stream is recorded at a resolution of 2K regardless of the resolution of the corresponding video stream in consideration of the time and effort required for producing the content (BD). The graphic stream can be shared by the 2K_SDR stream and the 4K_SDR stream. However, the graphic stream is recorded in a brightness range that matches the brightness range of the corresponding video stream. When the video stream is HDR, the HDR graphics stream is recorded. When the video stream is SDR, an SDR graphics stream 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 SDR graphic stream and the HDR graphic stream have the same basic specifications of the graphic stream, but in the HDR graphic stream, the Java color space (BT 2020 for 4K), EOTF (EOTF for HDR), etc. There are restrictions. Therefore, the Java drawing command cannot be used as it is.

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

In the specification of color and luminance values, the Java drawing command can be used by specifying the values assuming the results of EOTF conversion (SDR->HDR), color space (BT709->BT2020) conversion, and the like. It is possible.

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

That is, as shown in FIG. 36, it is easier to author and easier for the user to prohibit the use of other than the subtitle (PG). However, in this case, it is not possible to perform normal display using Java and to issue the Popup menu that is displayed overlaid on the video during playback of the video stream.

Further, as shown in FIG. 37, in the case of 2K_HDR Graphics Stream, only the caption (PG) is stored because the Java side is restricted.

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 by the IG. As a result, the Popup menu using Java cannot be displayed, but the Popup menu can be displayed by the IG using HDMV mode.

[5-3. Playback device operation]
Hereinafter, a case where there are two types of reproducing devices (data reproducing devices), a type having a function of converting graphics of an SDR signal into graphics of an HDR signal and outputting the same and a type not having the function, will be described. Such a reproducing apparatus handles an HDR signal as a video image, but handles an SDR signal or an HDR signal with respect to graphics such as menus and subtitles to be superimposed on the video.

In this case, in a reproducing apparatus (player) of a type that does not have a conversion output function, for example, graphics are processed with the SDR signal as it is. As a result, the quality of the reproduced video becomes low, or the brightness of the menu or subtitle becomes different from the intention of the content creator, which may cause a problem that it is difficult for the user to visually recognize it. In order to solve this problem, it is conceivable that the content creator prepares both the graphics content of the HDR signal and the graphics content of the SDR signal and provides it as a Blu-ray disc.

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

FIG. 39 is a flowchart showing the processing of the playback device. The playback device reads a playback control program written in a playback control programming language called BD-J (BD-Java) or HDMV stored in the 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 the menu and presents the reproduction selection menu of the main video to the user. Here, when the user specifies the reproduction of the main part video of the HDR signal, the reproduction control program determines whether the reproduction device is compatible with HDR graphics (has a function of processing HDR graphics) (S401). ).

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

On the other hand, when the playback device does not support HDR graphics (No in S401), the playback control program determines whether the playback device has the function of converting the graphics of the SDR signal into the graphics of the HDR signal. Is determined (S402). Specifically, the reproduction control program confirms the register value of the reproduction device. For example, the player register number 25 (a 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 reproduction control program determines whether or not the reproducing device has the conversion output function by confirming the value of this register.

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 graphics. As a result, the playback device outputs the graphics of the converted HDR signal while converting the graphics of the SDR signal into the graphics of the HDR signal (S404).

On the other hand, in a reproducing apparatus having no conversion output function (No in S402), the reproduction control program reproduces the playlist #B including the pseudo HDR signal graphics signal prepared so that this conversion process is unnecessary. Specifically, the playback device plays the subtitles and the HDMV menu using the CLUT prepared for the HDR signal (S405).

Here, in a 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 played according to the presence/absence of the conversion output function, in a playlist for a playback device without the conversion output function, a subtitle (Presentation Graphics) and a menu (Interactive Graphics) by HDMV are used. CLUT (color conversion table in which the correspondence between index numbers and colors and luminances is defined) is devised. Specifically, the playback device uses the CLUT prepared for the SDR signal when outputting the graphics of the SDR signal, and prepares the HDR signal when outputting the graphics of the HDR signal. Another CLUT is used. In other words, Java cannot easily support HDR due to the limitation of the color space, but the CLUT for HDR can be used for the HDR luminance range in the menu including subtitles and HDMV. This makes it possible to inexpensively avoid the problem that the graphics image of the menu and subtitles is hard to be visually recognized in the reproducing device that cannot convert the SDR signal graphics into the HDR signal graphics.

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

Does the reproducing device have a function of converting the first graphics in the second luminance range (SDR) narrower than the first luminance range (HDR) into the second graphics in the first luminance range (HDR). It is determined whether or not (S402). Specifically, the playback device executes the playback control program to determine whether or not the playback device has the above function. In addition, the reproduction control program determines whether or not the reproduction device has the above-mentioned function by checking the register in which the information indicating whether the reproduction device has the above-mentioned function is stored. In addition, the playback device obtains the video in the first luminance range (HDR), the first graphics in the second luminance range (SDR), and the playback control program from the disc.

When the playback device has the above function, the playback device converts the first graphics into the second graphics and displays the second graphics by superimposing it 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 reproducing device generates the third graphics by 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 the brightness value that is not included in the second brightness range (SDR) and is included in the first brightness range.

If the playback device does not have the above function, the playback device may display the image by superimposing the first graphics in the second luminance range (SDR) on the video without performing the graphics conversion process. .. 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, and 4K and HDR video. This necessitates complicated authoring work and internal processing in the playback device.

Further, in the case of a Blu-ray that stores HDR video, if subtitles and menu graphics, Java graphics, Java rendering processing, etc. are processed as HDR content, Java cannot be displayed because there is no HDR color space definition. Are subject to various restrictions.

In the present embodiment, a case where the playback device (player) has a function of converting graphics from SDR to HDR and a case where the playback device does not have it are divided into all the graphics related cases when the playback device has a conversion function. Is processed with an SDR signal, the result is converted from SDR to HDR, and the obtained HDR graphics are combined with the HDR video. As a result, all processing using Java or the like becomes possible and high quality graphics can be provided.

On the other hand, if the playback device does not have the conversion function, Java processing cannot be performed in HDR, and thus processing such as Popup menu cannot be performed. Therefore, by calling the HDMV mode from Java and processing the HDR graphics (subtitles, Popup menu, etc.) in the HDMV mode, even HDR video can have the same user experience as SDR with a simple authoring process. realizable.

In addition, in each of the above-described 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 in a recording medium such as a hard disk or a semiconductor memory.

Although the conversion method and the conversion device according to one or more aspects of the present disclosure have been described above based on the embodiments, the present disclosure is not limited to the embodiments. As long as it does not depart from the gist of the present disclosure, various modifications that a person skilled in the art can think of in the present embodiment, a configuration constructed by combining components in different embodiments, and the like are also included It may be included in the range of the aspect.

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

100 media 200 BD player 210 conversion device 220 remap processing unit 221 determination unit 222 processing target determination unit 223 brightness value 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 inverse SDR EOTF conversion unit 600 display device 601 display setting unit 602 SDR EOTF converter 603 Luminance converter 604 Display

Claims (3)

From the recording medium, obtain the graphics in the first brightness range including the menu or subtitles,
When displaying an image in the first luminance range, first graphics are generated for the graphics in the first luminance range using a color conversion table for the first luminance range, and the first luminance range is generated. Superimposing the image and the first graphics of the above, and outputting to the display,
When displaying the image in a second luminance range wider than the first luminance range, a second graphics is used for the graphics in the first luminance range by using the color conversion table for the second luminance range. Is generated, and the image in the second luminance range and the second graphics are superimposed and output to the display.
Is the method performed on the playback device,
The first brightness range is SDR (Standard Dynamic Range), and the second brightness range is HDR (High Dynamic Range).
The method performed on the playback device. The color conversion table for the second brightness range represents brightness values that are not included in the first brightness range but are included in the second brightness range.
The method of claim 1. A playback device having one or more memories and a processor,
From the recording medium, obtain the graphics in the first brightness range including the menu or subtitles,
When displaying an image in the first luminance range, first graphics are generated for the graphics in the first luminance range using a color conversion table for the first luminance range, and the first luminance range is generated. wherein by superimposing the image and the first graphics output to de Isupurei of
When displaying the image in a second luminance range wider than the first luminance range, a second graphics is used for the graphics in the first luminance range by using the color conversion table for the second luminance range. Is generated, and the image in the second luminance range and the second graphics are superimposed and output to the display.
Is a playback device,
The first brightness range is SDR (Standard Dynamic Range), and the second brightness range is HDR (High Dynamic Range).
Playback device.

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