Energy certification SL-HDR

Abstract

The method includes obtaining (140) reconstructed SDR data and metadata representing a first inverse tone mapping function that converts the reconstructed SDR data into HDR data with a dynamic range having a first peak luminance; using the metadata to derive (141) a second tone mapping function that converts the SDR data into HDR data with a dynamic range having a second peak luminance that is lower than the first peak luminance; and using the second tone mapping function to reconstruct (143) the HDR data intended to be displayed on a display device, the second peak luminance being lower than a third peak luminance supported by the display device.

Description

[Technical Field]

[0001] At least one embodiment relates generally to the field of displaying high dynamic range (HDR) video, and more particularly to methods and devices for controlling energy consumed in displaying HDR video. [Background technology]

[0002] This application claims priority to European Patent Application No. 23305093.9, filed January 25, 2023, the entire contents of which are incorporated herein by reference.

[0003] Recent advances in display technology provide an expanded dynamic range of color, brightness, and contrast for displayed images. The term image here refers to image content, which can be, for example, moving images, still images, or images.

[0004] High dynamic range video (HDR video) refers to video with a wider dynamic range than standard dynamic range video (SDR video). HDR video-based applications include capture, production, content / encoding, and display. HDR capture and display devices can produce brighter whites and deeper blacks. To accommodate this, HDR encoding standards provide for a higher maximum luminance using at least 10 bits of dynamic range (compared to the 8-bit (non-professional) and 10-bit (professional) dynamic range of SDR video) to maintain accuracy across this expanded range.

[0005] HDR technology offers a better viewing experience (or Quality of Experience (QoE)) for video content, but at the cost of significantly increased energy consumption compared to SDR. In fact, displaying HDR video consumes twice as much energy as SDR video. With the trend toward reducing energy consumption in many fields, it is desirable to overcome these drawbacks.

[0006] There is a particular need to propose solutions that can control or reduce energy consumption when displaying HDR video while maintaining the improved QoE achieved by HDR technology and the artistic intent of the content creator as much as possible. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 illustrates a schematic diagram of an example context in which various embodiments may be implemented. [Figure 2A] FIG. 1 illustrates a tone mapping curve. [Figure 2B] FIG. 10 shows an inverse tone mapping curve without display adjustments. [Figure 2C] FIG. 10 shows an inverse tone mapping curve with display adjustments. [Figure 3] FIG. 1 illustrates energy consumption in different types of scenes, such as bright, medium, and dark. [Figure 4A] FIG. 1 illustrates a schematic example of a hardware architecture of a processing module in which various aspects and embodiments may be implemented. [Figure 4B] FIG. 1 is a block diagram illustrating an example of a first system in which various aspects and embodiments may be implemented. [Figure 4C] FIG. 10 is a block diagram illustrating a second example system in which various aspects and embodiments may be implemented. [Figure 5] FIG. 10 is a diagram illustrating a post-processing process for controlling the energy consumed by a display device when displaying HDR video. DETAILED DESCRIPTION OF THE INVENTION

[0008] In a first aspect, one or more of the present embodiments provide a method including obtaining reconstructed SDR data and metadata representing a first inverse tone mapping function that converts the reconstructed SDR data into HDR data with a dynamic range having a first peak luminance; using the metadata to derive a second tone mapping function that converts the SDR data into HDR data with a dynamic range having a second peak luminance that is lower than the first peak luminance; and using the second tone mapping function to reconstruct the HDR data to be displayed on a display device, wherein the second peak luminance is lower than a third peak luminance supported by the display device.

[0009] In one embodiment, the information representing the second peak luminance is provided by a user.

[0010] In one embodiment, the information representative of the second peak luminance is an energy consumption reduction target or an energy consumption profile selected from a plurality of energy consumption profiles.

[0011] In one embodiment, the energy consumption reduction target is converted to the second peak luminance based on a piecewise linear or parametric curve and information that determines the reduction factor to be applied to the third peak luminance.

[0012] In one embodiment, the control points defining the linear curve, or the parameters defining the parametric curve, were obtained offline using a number of video sequences.

[0013] In one embodiment, the information determining the reduction factor, the control points defining the piecewise linear curve, or the parameters defining the parametric curve was obtained from metadata.

[0014] In one embodiment, the metadata is dynamic metadata provided for each image of the SDR data, a group of images of the SDR data, between two scene cuts of the SDR data, for each program of the SDR data, for each period of the SDR data, for each duration of the SDR data, or for each temporal layer of the SDR data.

[0015] In one embodiment, the metadata further includes information determining a reduction factor for multiple types of display devices, at least one of control points defining a piecewise linear curve or parameters defining a parametric curve, information representing the average luminance of the image, information representing spatiotemporal events, and information representing the type of content represented by the SDR data.

[0016] In one embodiment, the second peak luminance of the current image is obtained as a result of smoothing based on the second peak luminance value of the image preceding the current image.

[0017] In one embodiment, the second peak luminance is greater than or equal to the minimum value.

[0018] In one embodiment, the content adaptive process determines whether to use a second tone mapping function for the reconstruction of the HDR data.

[0019] In one embodiment, the content adaptive process uses a value that indicates the potential of the current image to reduce energy consumption.

[0020] In a second aspect, one or more of the present embodiments provide a method including: obtaining SDR data and first metadata representing a first inverse tone mapping function that converts the SDR data into HDR data in a dynamic range having a first peak luminance; generating second metadata that estimates energy consumed by a display device to display the HDR data having a second peak luminance; and encoding the SDR data together with the first and second metadata into video data, wherein the second peak luminance is lower than a third peak luminance supported by the display device.

[0021] In one embodiment, the second metadata is information determining a reduction factor to be applied to the third peak luminance to obtain the second peak luminance, and represents a piecewise linear curve representing energy consumption versus peak luminance, or represents a parametric curve representing energy consumption versus peak luminance.

[0022] In one embodiment, the information represented by the second metadata depends on the content represented by the HDR data.

[0023] In a third aspect, one or more of the present embodiments provide an apparatus comprising electronic circuitry configured to: acquire reconstructed SDR data and metadata representing a first inverse tone mapping function that converts the reconstructed SDR data into HDR data with a dynamic range having a first peak luminance; use the metadata to derive a second tone mapping function that converts the SDR data into HDR data with a dynamic range having a second peak luminance that is lower than the first peak luminance; and reconstruct the HDR data using the second tone mapping function, where the HDR data is intended to be displayed on a display device, and the second peak luminance is lower than a third peak luminance supported by the display device.

[0024] In one embodiment, the information representing the second peak luminance is provided by a user.

[0025] In one embodiment, the information representative of the second peak luminance is an energy consumption reduction target or an energy consumption profile selected from a plurality of energy consumption profiles.

[0026] In one embodiment, the energy consumption reduction target is converted to the second peak luminance based on a piecewise linear or parametric curve, based on information that determines the reduction factor applied to the third peak luminance.

[0027] In one embodiment, the control points defining the linear curve, or the parameters defining the parametric curve, were obtained offline using a number of video sequences.

[0028] In one embodiment, the information determining the reduction factor, the control points defining the piecewise linear curve, or the parameters defining the parametric curve was obtained from metadata.

[0029] In one embodiment, the metadata is dynamic metadata provided for each image of the SDR data, for a group of images of the SDR data, between two scene cuts of the SDR data, for each program of the SDR data, for each period of the SDR data, or for each duration or time layer of the SDR data.

[0030] In one embodiment, the metadata further includes information determining a reduction factor for multiple types of display devices, at least one of control points defining a piecewise linear curve or parameters defining a parametric curve, information representing the average luminance of the image, information representing spatiotemporal events, and information representing the type of content represented by the SDR data.

[0031] In one embodiment, the second peak luminance of the current image is obtained as a result of smoothing based on the second peak luminance value of the image preceding the current image.

[0032] In one embodiment, the second peak luminance is greater than or equal to the minimum value.

[0033] In one embodiment, the content adaptive process determines whether to use a second tone mapping function for reconstructing the HDR data.

[0034] In one embodiment, the content adaptive processing uses a value that indicates the potential of the current image to reduce energy consumption.

[0035] In a fourth aspect, one or more of the present embodiments provide an apparatus comprising electronic circuitry configured to: acquire SDR data and first metadata representing a first inverse tone mapping function that converts the SDR data into HDR data in a dynamic range having a first peak luminance; generate second metadata that estimates energy consumed by a display device to display the HDR data having a second peak luminance; and encode the SDR data together with the first and second metadata into video data, wherein the second peak luminance is lower than a third peak luminance supported by the display device.

[0036] In one embodiment, the second metadata is information determining a reduction factor to be applied to the third peak luminance to obtain the second peak luminance, and represents a piecewise linear curve representing energy consumption versus peak luminance, or represents a parametric curve representing energy consumption versus peak luminance.

[0037] In one embodiment, the information represented by the second metadata depends on the content represented by the HDR data.

[0038] In a fifth aspect, one or more of the present embodiments provide a non-transitory information storage medium storing program code instructions for implementing a method according to the first or second aspect.

[0039] In a sixth aspect, one or more of the present embodiments provide a computer program comprising program code instructions for implementing a method according to the first or second aspect.

[0040] In a seventh aspect, one or more of the present embodiments provide a signal generated by a method according to the second aspect or an apparatus according to the fourth aspect.

[0041] Although display devices with HDR capabilities have appeared in recent years, some of them have limited HDR capabilities. For example, an HDR-compatible display may only be able to display a lower luminance than the luminance of the HDR signal defined by the creator of the content being displayed. For example, if the peak luminance of the reconstructed HDR signal is 1000 nits, the display may only be able to display a maximum of 500 nits.

[0042] Therefore, the reconstructed signal must be adjusted to fit the display device's capabilities. One possible solution is to clip the reconstructed signal to a range of values ​​that the display device can accept before displaying it. However, this solution does not fully preserve the artistic intent of the content creator or the QoE achieved by the HDR signal.

[0043] When talking about an image, artistic intent largely depends on how tones (i.e. shadows, mid-tones, highlights) are distributed within a scene. This is part of color grading, which an artist (i.e. content creator) does to convey the intended emotion and / or define the visual characteristics of the content.

[0044] The range of tones can be defined as follows: Shadow: corresponds to the lowest part of the color distribution of the target content (e.g., represented by the image luminance histogram). Midtones: Corresponds to the center of the color distribution of the target content. Highlight: corresponds to the highest part of the color distribution of the target content.

[0045] In addition to these three tonal zones, it is common to define the black point as the pixel with the lowest sample value in the shadows, and the white point as the pixel with the highest sample value in the highlights.

[0046] Naturally, defining these black and white points is important for artists when color grading. Increasing the black point will result in a scene where areas darker than the black point are clipped. Similarly, decreasing the white point will result in a scene where areas lighter than the white point are clipped. Clipping of highlights can cause the loss of valuable highlight detail.

[0047] A solution based on display adaptation that takes artistic intent into account has been proposed. Display adaptation adapts the reconstructed HDR signal to the luminance capabilities of the display device while achieving the best QoE and preserving the artistic intent of the HDR signal. For example, display adaptation adjusts the tones to preserve highlights that cannot be clipped.

[0048] By definition, the more the display adaptation adapts the reconstructed HDR signal to the luminance capabilities of the display device, the higher the QoE. However, this also comes at the expense of the highest energy consumption. To enable a trade-off between energy consumption and QoE, various embodiments described below propose to consider energy consumption in the display adaptation.

[0049] FIG. 1 illustrates a schematic example of a context in which various embodiments may be implemented.

[0050] 1, a source device 10, such as a camera or a streaming system that provides video content, generates video content. The source device 10 may be, for example, an SDR or HDR camera that generates SDR or HDR video content, respectively.

[0051] The video content is then provided to a pre-processing module 11. The pre-processing module 11, for example, adapts the content to the SL-HDRx standard. For example, the SL-HDRx standard is SL-HDR1. Therefore, if the video content is SDR video, the pre-processing module generates SL-HDR1 metadata based on the SDR video. If the video content is HDR video, the pre-processing module applies tone mapping (TM) to the HDR video to generate SDR video and generate SL-HDR1 metadata. HDR video has a luminance peak, called the master display peak luminance, which corresponds to the peak luminance defined by the content creator. The SL-HDR1 metadata includes information describing the inverse tone mapping and color correction functions used to obtain HDR video from SDR video. These metadata are dynamic and can be adjusted for each image or group of images.

[0052] The SDR video and SL-HDR1 metadata are provided to encoding module 12, which converts the SDR video and SL-HDR1 metadata into a bitstream suitable for encoding the SDR video and SL-HDR1 metadata using a video compression format such as AVC (ISO / CEI 14496-10 / ITU-T H.264), HEVC (ISO / IEC 23008-2 - MPEG-H Part 2, Efficiency Video Coding / ITU-T H.265), VVC (ISO / IEC 23090-3 - MPEG-I, Versatile Video Coding / ITU-T H.266), AV1, VP9, ​​or EVC (ISO / CEI 23094-1 Essential Video Coding). The output of encoding module 12 is a bitstream (i.e., video data) representing the encoded SDR video and SL-HDR1 metadata.

[0053] Encoding module 12 then provides the video data, for example, over a network, to decoding module 13. Decoding module 13 decodes the bitstream to obtain a decoded (i.e., reconstructed) version of the SDR video and SL-HDR1 metadata.

[0054] The reconstructed SDR video is provided directly to a display device 16 adapted to display SDR content.

[0055] The SDR video and SL-HDR1 metadata are also provided to a post-processing module 14, which applies an inverse tone mapping (ITM) step and a color correction step to the SDR video to obtain an HDR video.

[0056] Color correction involves calculating a lookup table (LUT) lutCC() from the SL-HDR1 metadata, which is used to reconstruct the HDR color difference signals for HDR video.

[0057] For both constant luminance (CL) and non-constant luminance (NCL) modes, lutCC(Y) = f(Y).(1 / Y), where f(Y) = 1 / (R.sgf(1 / Y)), Y is a value representing luminance. The function sgf(1 / Y) corresponds to the color correction function encoded in the SL-HDR1 metadata.

[0058] In NCL mode, f(Y) is a constant function, i.e., f(Y)=Ω, so lutCC(Y)=Ω.(1 / Y).

[0059] In CL mode, f(Y) is not a constant function.

[0060] The ITM step involves deriving the LUT lutMapY() from the SL-HDR1 metadata, which is then used to inverse tone map the luma signal of the SDR video and reconstruct the HDR luma signal of the HDR video.

[0061] When display adjustment is required (i.e., when the display peak luminance (hereinafter referred to as the target display peak luminance) is lower than the master display peak luminance to support HDR displays), the target display peak luminance is taken into account during inverse tone mapping. The following three cases are considered: The target display peak luminance is identical to the master display peak luminance. In this case, the ITM curve is the inverse of the TM curve applied by the pre-processing module 11. Therefore, the LUT lutMapY() is derived directly from the SL-HDR1 metadata. When the target display peak luminance is 100 nits (i.e., the HDR display 15 is an SDR display), the ITM curve becomes an identity function in the linear region. In other words, when the target display peak luminance is 100 nits, the luminance of the reconstructed HDR signal is equal to the luminance of the reconstructed SDR signal. This is true in NCL mode, but not in CL mode. - When the target display peak luminance is between 100 nits and the master display peak luminance, the ITM curve is between the identity and inverse tone mapping curve specified in the SL-HDR1 metadata.

[0062] FIG. 2A shows the TM curves used by the pre-processing module 11 to generate SDR video from the original HDR video.

[0063] Figure 2B shows the ITM curve, which is the inverse of the TM curve in Figure 2A. Applying the TM curve in Figure 2A and the ITM curve in Figure 2B in sequence will (theoretically) restore the original HDR video.

[0064] FIG. 2C shows several ITM curves derived from the TM curve of FIG. 2A when a display adjustment process is applied.

[0065] An example of a process for deriving the LUT lutMapY() when the target display peak luminance is 100 nits and the master display peak luminance is 100 nits is described in Appendix E of ETSI TS 103 433-1 V1.2.1 (High-Performance Single Layer High Dynamic Range (HDR) System for use in Consumer Electronics devices; Part 1: Directly Standard Dynamic Range (SDR) Compatible HDR System (SL-HDR1)), and will be referred to simply as SL-HDR1 hereinafter. Essentially, this process consists of applying the process shown in Figure 4 of Section 7.2.3.1.2 of Document SL-HDR1 to calculate a first LUT lutMapY'() that represents the ITM curve without display adjustments (i.e., the first LUT lutMapY'() provides for the conversion of the reconstructed SDR signal to an HDR signal with a peak luminance equal to the master display peak luminance), and then calculating a second LUT lutMapY''() to convert the HDR signal with a peak luminance equal to the master display peak luminance to an HDR signal with a peak luminance equal to the target display peak luminance. The LUT lutMapY() is a combination of the first LUT lutMapY'() and the second LUT lutMapY''(). In Appendix E of Document SL-HDR1, the target display peak luminance is referred to as the maximum luminance of the presentation display and is defined as the variable L pdisp It is expressed as:

[0066] One of the advantages of the display adjustment process in Annex E of document SL-HDR1 is that it preserves as much as possible the artistic intent defined by the content creator.

[0067] The reconstructed HDR video is provided to an HDR display 15.

[0068] Figure 3 shows the energy consumption for various scenes corresponding to bright, medium, and dark scene luminance. Energy consumption depends on the peak luminance, expressed in nits. In this example, the target display peak luminance of the OLED display used for testing is 1000 nits. Therefore, this value uses the full capacity of the display, resulting in the highest energy consumption. Reducing the peak luminance of the displayed content reduces energy consumption. Interestingly, the amount of reduction is highly dependent on the scene luminance.

[0069] FIG. 4A shows a schematic example of the hardware architecture of a processing module 40 used, for example, in the pre-processing module 11 or the post-processing module 14. The processing module 40 includes a processor or CPU (Central Processing Unit) 400, including one or more microprocessors, general-purpose computers, special-purpose computers, processors based on multi-core architectures, etc., connected by a communication bus 405, a random access memory (RAM) 401, a read-only memory (ROM) 402, a storage unit 403, which may include non-volatile and / or volatile memory, including, but not limited to, electrically erasable programmable read-only memory (EEPROM), read-only memory (ROM), programmable read-only memory (PROM), random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), flash, magnetic and / or optical disk drives, or storage readers, such as SD (Secure Digital) card readers and / or hard disk drives (HDDs) and / or network-accessible storage devices, and at least one communication interface 404 for exchanging data with other modules, devices, systems, or devices. The communication interface 404 may include, but is not limited to, a transceiver configured to transmit and receive data over the communication network 41. The communication interface 704 may include, but is not limited to, a modem or a network card.

[0070] For example, the communication interface 404 may enable the processing module 40 to receive HDR or SDR data and output the HDR or SDR data along with SL-HDR1 metadata, for example.

[0071] The processor 400 can execute instructions loaded into the RAM 401 from the ROM 402, an external memory (not shown), a storage medium, or a communication network. When the processing module 40 is powered on, the processor 400 can read and execute instructions from the RAM 401. If the processing module 40 is included in the pre-processing module 11, these instructions form a computer program that causes the processor 400 to implement, for example, a TM process (when the source module generates HDR video). If the processing module 40 is included in the post-processing module 14, these instructions form a computer program that causes the processor 400 to implement, for example, an ITM process, including display adjustments according to embodiments of the present disclosure described below.

[0072] All or part of the algorithms and steps of the above processes may be implemented in software form by a programmable machine, such as a DSP (Digital Signal Processor) or a microcontroller, executing a series of instructions, or in hardware form by a machine or dedicated component, such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). Microprocessors, DSPs, FPGAs, and ASICs are considered to be electronic circuits.

[0073] FIG. 4C is a block diagram illustrating an example of a system A implementing a post-processing module in which various aspects and embodiments are implemented.

[0074] System A can be configured as a device including various components or modules and configured to generate HDR-capable video. Examples of such systems include, but are not limited to, various electronic systems, such as a personal computer, a laptop computer, a smartphone, a tablet, a television, or a set-top box. The components of System A can be configured, singly or in combination, as a single integrated circuit (IC), multiple ICs, and / or discrete components. For example, in at least one embodiment, System A includes a processing module 40 that implements post-processing module 14. In various embodiments, System A is communicatively coupled to one or more other systems or other electronic devices, for example, via a communication bus or dedicated input and / or output ports.

[0075] Input to processing module 40 can be provided through various input modules, as shown in block 42. Such input modules include, but are not limited to, (i) an RF module for receiving RF signals transmitted, e.g., wirelessly, by a broadcast station, (ii) a component (COMP) input module (or set of COMP input modules), (iii) a universal serial bus (USB) input module, and / or (iv) a high-definition multimedia interface (HDMI) input module. Other examples, not shown in FIG. 4C, include composite video.

[0076] In various embodiments, the input modules of block 42 are associated with respective input processing elements known in the art. For example, the RF module can be associated with elements suitable for (i) selecting a desired frequency (also referred to as signal selection or bandlimiting a signal to a particular frequency band), (ii) downconverting the selected signal, (iii) bandlimiting again to a narrower frequency band to select a signal frequency band, which in certain embodiments may be referred to as a channel, (iv) demodulating the downconverted and bandlimited signal, (v) performing error correction, and (vi) demultiplexing to select a desired stream of data packets. The RF module of various embodiments includes one or more elements for performing these functions, such as a frequency selector, signal selector, bandlimiter, channel selector, filter, downconverter, demodulator, error corrector, and demultiplexer. The RF section can include a tuner that performs some of these functions, for example, to convert a received signal to a lower frequency (e.g., an intermediate frequency or near-fundamental frequency) or to the fundamental frequency. In various embodiments, the order of the above (and other) elements is rearranged, some of these elements are removed, and / or other elements with similar or different functionality are added. Adding elements can include inserting elements between existing elements, such as inserting an amplifier or an analog-to-digital converter. In various embodiments, the RF module includes an antenna.

[0077] Additionally, the USB and / or HDMI modules may include respective interface processors for connecting System A to other electronic devices via USB and / or HDMI connections. It should be understood that various aspects of input processing, such as Reed-Solomon error correction, may be implemented, for example, in a separate input processing IC or processing module 40, as desired. Similarly, aspects of USB or HDMI interface processing may be implemented, as desired, in a separate interface IC or processing module 40. The demodulated, error corrected, and demultiplexed streams are provided to processing module 40.

[0078] The various elements of System A may be provided within a single integrated housing, where the various elements may be interconnected and data may be transmitted therebetween using any suitable connection means known in the art, such as an Inter-IC (I2C) bus, wiring, and a printed circuit board. For example, in System A, processing module 40 is interconnected with the other elements of System A by bus 405.

[0079] The communication interface 404 of the processing module 40 allows the system A to communicate over a communication network 41. The communication network 41 can be implemented, for example, in a wired and / or wireless medium.

[0080] In various embodiments, data is streamed or otherwise provided to system A using a wireless network, such as a Wi-Fi network, e.g., an IEEE 802.11 (IEEE refers to the Institute of Electrical and Electronics Engineers). The Wi-Fi signal in these embodiments is received through communication network 41 and communication interface 404, which are Wi-Fi enabled. Communication network 41 in these embodiments is typically connected to an access point or router that provides access to external networks, including the Internet, to enable streaming applications and other over-the-top communications. Yet another embodiment provides streaming data to system A using the RF connection of input block 42. As mentioned above, various embodiments provide data in a non-streaming manner, for example, when system A is a smartphone or tablet. Additionally, various embodiments use wireless networks other than Wi-Fi, such as a cellular network or a Bluetooth network.

[0081] System A can provide output signals to various output devices using communication network 41 or bus 405. For example, system A can provide reconstructed HDR video.

[0082] System A can provide output signals to various output devices, including an HDR display 15, speakers 46, and other peripherals 47. The HDR display 15 of various embodiments includes, for example, one or more of a touchscreen display, an organic light-emitting diode (OLED) display, a curved display, and / or a foldable display. The HDR display 15 can be for a television, a tablet, a laptop, a cell phone, or other device. The HDR display 15 can be integrated with other components (e.g., a smartphone) or separate (e.g., an external monitor for a laptop). In various example embodiments, other peripherals 47 include one or more standalone digital video discs (or digital versatile discs) (DVRs, both terms), a disc player, a stereo system, and / or a lighting system. Various embodiments use one or more peripherals 47 that provide functionality based on the output of System A. For example, a disc player performs playback functions for the output of System A.

[0083] In various embodiments, control signals are communicated between system A and HDR display 15, speakers 46, or other peripheral devices 47 using signaling such as AV.Link, Consumer Electronics Control (CEC), or other communication protocols that enable control between devices with or without user intervention. Output devices can be communicatively connected to system A via dedicated connections by respective interfaces 43, 44, and 45. Alternatively, output devices can be connected to system A using communications network 41 via communications interface 404. HDR display 15 and speakers 46 can be integrated into a single unit with other components of system A, for example, in an electronic device such as a television. In various embodiments, display interface 43 includes a display driver, for example, a timing controller (T Con) chip.

[0084] HDR display 15 and speakers 46 may alternatively be separate from the other component or components, for example, if the RF module of block 42 is part of a separate set-top box. In various embodiments in which HDR display 15 and speakers 46 are external components, the output signal may be provided via a dedicated output connection, such as, for example, an HDMI port, a USB port, or a COMP output.

[0085] FIG. 4B is a block diagram illustrating an example of a system B adapted to implement a pre-processing module 11 in which various aspects and embodiments may be implemented.

[0086] System B may be configured as an apparatus including the various components and modules described above and configured to carry out one or more aspects and embodiments described herein.

[0087] Examples of such devices include, but are not limited to, various electronic devices such as personal computers, laptop computers, cameras, smartphones, servers, etc. The elements or modules of System B can be configured, singly or in combination, as a single integrated circuit (IC), multiple ICs, and / or individual components. For example, in at least one embodiment, System B includes one processing module 40 that implements pre-processing module 11. In various embodiments, System B is communicatively coupled to one or more other systems or other electronic devices, for example, via a communication bus or dedicated input and / or output ports.

[0088] Input to processing module 40 is provided through various input modules, as shown in block 42 previously described in FIG. 4C.

[0089] The various elements of System B may be provided within an integrated housing, where the various elements may be interconnected and transmit data therebetween using any suitable connection arrangement known in the art, including, for example, an Inter-IC (I2C) bus, wiring, and a printed circuit board. For example, in System B, processing module 40 is interconnected to the other elements of System B by bus 405.

[0090] The communication interface 404 of the processing module 40 allows the system B to communicate over a communication network 41. The communication network 41 can be implemented, for example, in a wired and / or wireless medium.

[0091] In various embodiments, data is streamed or otherwise provided to system B using a wireless network, such as a Wi-Fi network, for example, an IEEE 802.11 (IEEE refers to the Institute of Electrical and Electronics Engineers) network. The Wi-Fi signal in these embodiments is received through communication network 41 and communication interface 404, which are adapted to support Wi-Fi communications. Communication network 41 in these embodiments is typically connected to an access point or router that provides access to external networks, including the Internet, to enable streaming applications and other over-the-top communications. Yet another embodiment provides streamed data to system B using the RF connection of input block 42. As discussed above, various embodiments provide data in a non-streaming manner.

[0092] Where a figure is shown as a flow diagram, it should be understood that the figure also illustrates a block diagram of the corresponding apparatus. Similarly, where a figure is shown as a block diagram, it should be understood that the figure also illustrates a flow diagram of the corresponding method / process.

[0093] The embodiments and aspects described herein may be implemented as, for example, a method or process, an apparatus, a software program, a data stream, or a signal. Even if described in the context of a single embodiment (e.g., described only as a method), the described embodiment of the features may also be implemented in other forms (e.g., an apparatus or a program). An apparatus may be implemented, for example, in appropriate hardware, software, and firmware. A method may be implemented in a processor, which refers to general processing equipment such as a computer, a microprocessor, an integrated circuit, or a programmable logic device. Processors also include communication equipment such as computers, cell phones, portable / personal digital assistants (PDAs), smartphones, tablets, and other devices that facilitate communication of information between end users.

[0094] The use of "one embodiment," "embodiment," or "one implementation," or "implementation," and other variations thereof, means that a particular feature, structure, characteristic, etc. described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," or "one implementation," and other variations thereof, in various places in this application are not necessarily all referring to the same embodiment.

[0095] Additionally, this application may refer to "determining" various pieces of information. Determining information may include, for example, one or more of estimating information, calculating information, predicting information, retrieving information from memory, or retrieving information from other devices, modules, users, etc.

[0096] Additionally, this application may refer to "accessing" various information, which may include one or more of receiving information, retrieving information (e.g., from memory), storing information, moving information, copying information, calculating information, determining information, predicting information, inferring information, etc.

[0097] Additionally, this application may refer to "receiving" various pieces of information. Receiving, like "accessing," is a broad term. Receiving information may include, for example, one or more of accessing information or retrieving information (e.g., from memory). Furthermore, "receiving" typically involves some form of, for example, storing information, processing information, transmitting information, moving information, copying information, erasing information, calculating information, determining information, predicting information, or inferring information.

[0098] The use of " / ", "and / or", "at least one", "one or more" below, as in "A / B", "A and / or B", "at least one of A and B", "one or more of A and B", etc., should be understood to mean selecting only the first listed option (A), only the second listed option (B), or both. As a further example, the terms "A, B, and / or C" and "at least one of A, B, and C", "one or more of A, B, and C" refer to the first listed option (A) only, the second listed option (B) only, the third listed option (C), the first and second listed options (A and B) only, the first and third listed options (A and C) only, the second and third listed options (B and C) only, or all three options (A, B, and C). This can be expanded depending on the number of items listed, as would be apparent to one of ordinary skill in this and related arts.

[0099] As will be apparent to one skilled in the art, implementations or embodiments can generate various signals formatted to carry information that can be stored or transmitted, for example. This information can include, for example, instructions for performing a method or data generated by any of the described implementations or embodiments. For example, a signal can be formatted to carry the SDR images or video sequences of the described embodiments and SL-HDRx metadata. Such a signal can be formatted, for example, as electromagnetic waves (e.g., using the radio frequency portion of the spectrum) or as a baseband signal. The format can include, for example, encoding the SDR images or video sequences with a stream encoded with SL-HDR1 metadata and modulating a carrier with the encoded stream. The information carried by the signal can be, for example, analog or digital information. The signal can be transmitted via various known wired or wireless links. The signal can be stored on a processor-readable medium.

[0100] As described above, display adjustment allows the artistic intent of the content creator to be maintained while displaying HDR video that conforms to the target display peak luminance, which corresponds to the peak luminance supported by the display device displaying the HDR video, provided that in this case the energy consumed by the display device to display the HDR video is the maximum energy that the display device can consume to display the HDR video.

[0101] A common objective of the various embodiments described below is to reduce the power consumption of a display device when displaying HDR video relative to this maximum energy. Therefore, in the display adaptation process, instead of the target display peak luminance, a peak luminance lower than the target display peak luminance and corresponding to an energy reduction target or an appropriate profile selected by the end user, hereinafter referred to as "energy consumption-based peak luminance," is used. Using an energy consumption-based peak luminance lower than the target display peak luminance has a direct effect on reducing energy consumption.

[0102] FIG. 5 illustrates a post-processing process that provides control over the power consumption of a display device when displaying HDR video.

[0103] 5 is performed by processing module 40 of system A, for example, when this processing module 40 implements post-processing module 14. It is assumed that system A receives encoded video data from system B. Decoding module 13 of system A then decodes the encoded video data to generate reconstructed SDR data and SL-HDR1 metadata. Post-processing module 14 then obtains the reconstructed SDR data and SL-HDR1 metadata from decoding module 13.

[0104] The following description will be given using SL-HDR1 as an example. However, the various embodiments described below also apply to other HDR delivery technologies that use dynamic metadata, such as SL-HDR2, SL-HDR3, Dolby Vision, and HDR10+. In addition, various implementations use a modified version of the display adjustment process described in Appendix E of SL-HDR1. However, the display adjustment process described in Appendix E of SL-HDR1 is only an example, and other display adjustment processes may also be used.

[0105] In step 140, the processing module 40 of the post-processing module 14 obtains metadata representing the reconstructed SDR data and a first inverse tone mapping function that converts the reconstructed SDR data into HDR data with a dynamic range having a first peak luminance. In the example of Figure 5, the metadata is the SL-HDR1 metadata generated by the pre-processing module 11. The first peak luminance is a master display peak luminance that corresponds to a peak luminance defined by the content creator.

[0106] In step 141, processing module 40 uses the metadata to derive a second tone mapping function that converts the SDR data into HDR data with a dynamic range having a second peak luminance that is lower than the first peak luminance. The second peak luminance is typically the peak luminance based on the energy consumption discussed above. To do this, processing module 40 applies the display adjustment process described, for example, in Appendix E of document SL-HDR1, and derives a variable L representing the target display peak luminance (i.e., the maximum luminance of the display). pdisp , the variable L representing the peak brightness based on energy consumption. energyConso The calculation of the first LUT lutMapY'(), which represents the ITM curve without display adjustments, is unchanged. pdisp L energyConso , which maps the HDR signal whose peak luminance is equal to the master display peak luminance to an HDR signal whose peak luminance is equal to the energy consumption-based peak luminance. energyConso The LUT lutMapY() is given by the first LUT lutMapY'() and the second LUT lutMapY'' energyConso It is a combination of ().

[0107] In step 143, processing module 40 reconstructs the HDR data to be displayed on HDR display 15 using a second tone mapping function (i.e., LUT lutMapY()).

[0108] Note that the energy-based peak luminance is lower than the target display peak luminance, which represents the peak luminance that HDR display 15 supports.

[0109] Optionally, if the SDR data includes chroma components, the SL-HDR1 metadata includes information describing a color correction function, and processing module 40 derives the color correction function in step 142 as described in document SL-HDR1. In step 143, processing module 40 applies the color correction function to the SDR data to obtain the chroma components of the HDR data.

[0110] In a first embodiment of step 141, the end user defines an energy consumption reduction target. The energy consumption reduction target can be a simple scalar value Δ selected by the end user within a predefined range, for example, from 0 to 50%, that reflects the energy reduction the end user wishes to achieve relative to the energy consumption that would result from applying a display adjustment with a target peak luminance equal to the target peak luminance.

[0111] In a first variation of the first embodiment, the scalar value is converted to a reduction factor γ = 1 - Δ. For example, if Δ = 10%, then γ = 1 - 0.1 = 0.9. The reduction factor is then applied to the target display peak luminance value TargetDisplayPeakLum to obtain the energy consumption-based peak luminance value EnergyConsoPeakLum as follows:

[0112]

number

[0113] In a first variant of the first embodiment, it is assumed that energy consumption increases proportionally to the peak luminance value (i.e., the light emitted). This assumption is not always correct, and the relationship between energy consumption and peak luminance value is generally better represented by a piecewise linear or parametric curve. A piecewise linear curve can be represented by multiple control points. For example, two consecutive control points of a piecewise linear curve are C display|peakLuminance1 and C display|peakLuminance2 The first control point C display|peakLuminance1 defines the energy consumption for a particular peak luminance value, peakLuminance1. The second control point, C display|peakLuminance2defines the energy consumption for a smaller peak luminance value peakLuminance2 (peakLuminance1>peakLuminance2). A piecewise linear curve can be represented by a minimum of two control points. The calculation of the peak luminance value of the energy consumption based on the expected energy consumption reduction value is done by performing linear interpolation between the two control points of the piecewise linear curve.

[0114] In a second variation of the first embodiment, processing module 40 implements a converter that converts the energy consumption reduction value into an energy-based peak luminance value using a piecewise linear curve defined by a number of control points. The control points defining this curve were obtained offline, for example, by applying the display calibration process of Annex E of SL-HDR1 to a number of video sequences with various energy-based peak luminance values ​​and measuring the energy consumption of the display device.

[0115] The first and second variants of the first embodiment estimate the energy consumption-based peak luminance based on the energy consumption reduction value without prior knowledge of the content represented by the HDR data. Without prior knowledge of the content represented by the HDR data, it may be difficult to convert the energy consumption reduction value into the energy consumption-based peak luminance value. Therefore, while the first and second variants achieve energy reduction, they may not achieve the expected energy consumption reduction.

[0116] In a third variation of the first embodiment, system B (e.g., preprocessing module 11 or encoding module 12 of system B) estimates the energy consumed to display the original HDR data and converts this energy consumption information into new additional energy-aware metadata that is embedded in the video data sent to system A. The energy-aware metadata provides, for example, an estimate of the energy consumed by a display device to display the HDR data at a peak luminance equal to a peak luminance based on an energy consumption defined by an end user.

[0117] An advantage of this embodiment is that the converter that converts the energy consumption reduction value to an energy consumption based peak brightness value takes into account the information represented by the energy-aware metadata to improve the accuracy of the conversion.

[0118] In one embodiment, the energy-aware metadata is information calculated by system B (e.g., preprocessing module 11 or encoding module 12 of system B) as information representing the actual energy consumption or an estimate of the energy consumption for displaying the content represented by the HDR data for a given display type.

[0119] In one embodiment, the information is a single value C that represents the actual energy consumed to display content on a given display device. display|peakLuminance is.

[0120] The energy consumption based peak luminance value, EnergyConsoPeakLum, is calculated as follows:

[0121]

number

[0122] where targetConsumption is the information C display|peakLuminance represents the target energy consumption, which can be defined as a percentage of the peak brightness (i.e., the energy consumption reduction target), where the percentage is specified by the end user. Again, we assume that the energy consumption increases linearly with the peak brightness value.

[0123] As already indicated above, piecewise linear or parametric curves generally better represent the relationship between energy consumption and peak luminance value.

[0124] In another embodiment, the energy-aware metadata includes information representing a number of control points (or parameters of a parametric curve) that allow for constructing a curve representing peak luminance values ​​as a function of energy consumption adapted to the content represented by the HDR data, for example.

[0125] Energy-aware metadata is dynamic metadata that can be displayed at different temporal granularities: they can be provided in a variety of ways, such as per image, per group of images, between scene changes, per program, per period, per duration, per time layer, etc.

[0126] In addition to data for converting between energy consumption reduction values ​​and peak luminance values, the energy-aware metadata can include the following information to improve the accuracy of the conversion: Data representing transformation curves (piecewise linear or parametric) for multiple types of display devices (LCD screens (e.g., reference models, Abaqus), RGB OLED screens (e.g., black point, parametric curves), RGBW OLED screens (e.g., black point, parametric curves)). Percentage of maximum consumption of the current image at a specific time resolution Average brightness of the image -Information representing spatiotemporal events such as scene cuts and fades Information indicating the type of content (sports, news, documentaries, movies, etc.)

[0127] Energy-aware metadata can be embedded in metadata associated with the encoded video data, such as proprietary fields in SL-HDR1 (SL-HDR2, SL-HDR3, Dolby Vision, HDR10+) metadata, or in dedicated SEI (Supplemental Enhancement Information) messages defined in AVC, HEVC, and VVC.

[0128] In a second embodiment of step 141, the energy consumption reduction target is an energy consumption profile selected from among predefined energy consumption profiles by the end user. In this case, for each profile, the value of peak brightness based on energy consumption is known. For example, the following profiles are defined: High Energy: Display calibration mode uses a target peak luminance equal to the target display peak luminance. Energy consumption is not reduced and QoE is maximized (i.e., the display calibration of Appendix E of SL-HDR1 is applied without modification). Standard Energy: The display calibration processing mode uses a target peak luminance equal to the peak luminance based on the first predefined energy consumption (i.e., the display calibration process of Annex E of SL-HDR1 is applied using the peak luminance based on the first predefined energy consumption). Energy consumption is reduced, but QoE remains high. Low Energy: The display adaptation processing mode uses a second predefined energy consumption-based peak luminance that is lower than the first predefined energy consumption-based peak luminance as the target peak luminance (i.e., the display adjustment process of Annex E of SL-HDR1 is applied using the second predefined energy consumption-based peak luminance). Energy consumption is reduced, and QoE is degraded.

[0129] In a third embodiment of step 141, the energy consumption-based peak luminance is defined by the end user directly, e.g., at the level of HDR display 15, e.g., using a user interface of the display device. In that case, HDR display 15 notifies system A (and post-processing module 14) of a supported peak luminance value that is equal to the user-defined energy consumption-based peak luminance, rather than the target display peak luminance.

[0130] The first, second, and third embodiments provide for determining the peak luminance based on the energy consumption per image. In a fourth embodiment, the peak luminance based on the determined energy consumption at instant t, EnergyConsoPeakLum(t), is temporally smoothed to prevent flicker. A simple approach using a time window of size T is described below.

[0131]

number

[0132] α i is a weighting coefficient. Weighting coefficient α i Several methods for determining are given below. Uniform weighting: α i =1 / T Exponential smoothing: Past observations are weighted at a rate that decreases exponentially with age. That is, the more recent an observation is, the more weight it receives. For example, α i =exp(-(i / σ 2 )), where σ is a factor that controls the rate of decay. σ is often set to a value between 0 and 1. A higher value causes the model to focus primarily on the most recent observations, while a lower value causes the model to take more past observations into account when making predictions.

[0133] In a fifth embodiment of step 141, a minimum value MinPeakLum is defined for the energy consumption based peak luminance EnergyConsoPeakLum to limit the impact on QoE. In this fifth embodiment, the energy consumption based EnergyConsoPeakLum is calculated as follows:

[0134]

number

[0135] Here, max(x;y) is a function that finds the larger of x and y as the maximum value.

[0136] In a sixth embodiment of step 141, the strategy for reducing energy consumption is based on a spatiotemporal event such as a scene cut. For example, before and after a scene cut, the energy consumption-based peak luminance, EnergyConsoPeakLum, is systematically reduced relative to the target display peak luminance, TargetDisplayPeakLum, using, for example, any of the first to fifth embodiments.

[0137] In step 141 of the seventh embodiment, the application of the display adjustment processes of the first to sixth embodiments is content-adaptive. In fact, applying a display adjustment process to certain content has only a small impact on energy consumption. For example, for dark content, any display adjustment process will only have a small effect on energy reduction. For such content, the total luminance per image can be calculated, and if it is lower than a predetermined threshold, the display adjustment processes of the first to sixth embodiments can be disabled. To avoid setting a strict threshold, a piecewise linear or parametric function can be used to define appropriate weighting. One method is to linearly combine the target display peak luminance, TargetDisplayPeakLum, and the peak luminance based on the energy consumption determined by the display adjustment process, EnergyConsoPeakLum, as follows:

[0138]

number

[0139] where α is a weighting factor, α=0: The display adjustment processes in the first to sixth embodiments are invalid. In this case, for example, the display adjustment process described in Appendix E of SL-HDR1 is applied without modification. ·α=1: The display adjustment processes of the first to sixth embodiments are applied.

[0140] The weighting factor α can be calculated in various ways: Hard thresholding based on predefined thresholds

[0141]

number

[0142] Soft thresholding

[0143]

number

[0144] where σ is the factor that controls the rate of exponential decay.

[0145] The potential is a positive scalar value that indicates the potential of the current image to reduce energy consumption. Dark images have a low potential, while bright images have a much higher potential. If the potential is high, α should approach 1.

[0146] In one embodiment, the positive scalar value potential of an HDR image is estimated from a normalized cumulative histogram of a reconstructed SDR image corresponding to the HDR image. Each bin of the image's cumulative histogram is associated with a first sample value (a value between 0 and 255 for an SDR image) and the number of samples in the image that have a sample value equal to or less than that sample value. The normalized cumulative histogram is obtained by dividing the number of samples in each bin by the total number of samples in the image. The positive scalar value potential is the first sample value of the cumulative histogram of the normalized number of samples in the image that are equal to or less than that sample value, and this sample value is equal to a predefined sample value β. For example, β = 0.9 indicates that 90% of the samples in the image have a sample value equal to or less than the first sample value. For example, in hard thresholding, if the threshold value is 50 and the potential is 30 (meaning that 90% of the samples in the reconstructed SDR image have a sample value equal to or less than 30), the display adjustment processes of the first to sixth embodiments are not applied.

[0147] The potential can also depend on the motion activity in the content, or more generally, can be a function of the potential masking image luminance fluctuations. Indeed, it is known that in a series of consecutive images, the greater the motion in the sequence, the less noticeable the peak luminance fluctuations are to an end user than in a static sequence. For example, the positive scalar-valued potential of an HDR frame can be calculated as the sum of the norms of the motion vectors of the blocks of the corresponding reconstructed SDR image, or as the sum of the residual values ​​of the blocks of the corresponding reconstructed SDR image. If the potential represents slow motion, the display adjustment processes of the first to sixth embodiments are not applied. Otherwise, i.e., in the case of fast motion, the display adjustment processes of the first to sixth embodiments are applied. It may be noted that information about the motion vectors or residual values ​​is provided by the decoding module 13, and the potential is calculated by the post-processing module 14. It may be noted that other encoding information can be used to determine the potential, such as information about the division of images or blocks, statistical information about blocks encoded in INTRA mode and blocks encoded in INTER mode, etc.

[0148] The above describes several embodiments. The features of these embodiments can be provided alone or in any combination. Furthermore, the embodiments can include one or more of the following features, devices, or aspects, alone or in any combination, across various claim categories and types. · Bitstreams or signals containing SDR video and energy-aware metadata, or variations thereof. · Creating and / or transmitting and / or receiving and / or decoding bitstreams or signals containing SDR video and energy-aware metadata, or variations thereof. A server, camera, television, set-top box, cell phone, tablet, personal computer, or other electronic device that executes at least one of the described embodiments. A television, set-top box, cell phone, tablet, personal computer, or other electronic device that performs at least one of the described embodiments and displays the resulting image (e.g., using a monitor, screen, or other type of display). A television, set-top box, mobile phone, tablet, personal computer, or other electronic device that tunes to a channel to receive a signal (e.g., using a tuner) that includes encoded SDR video and energy-aware metadata and that performs at least one of the described embodiments. A television, set-top box, cell phone, tablet, or other electronic device that receives a signal wirelessly (e.g., using an antenna) containing encoded SDR video and energy-aware metadata and that performs at least one of the described embodiments. A server, camera, mobile phone, tablet, personal computer, or other electronic device that tunes (e.g., using a tuner) a channel for transmitting a signal including SDR video and energy-aware metadata and that performs at least one of the described embodiments. A server, camera, mobile phone, tablet, personal computer, or other electronic device that transmits signals wirelessly (e.g., using an antenna) that include SDR video and energy-aware metadata and that executes at least one of the described embodiments.

Claims

1. 1. A method comprising: Obtaining (140) reconstructed SDR data and metadata representing a first inverse tone mapping function that converts the reconstructed SDR data into HDR data in a dynamic range having a first peak luminance; deriving (141) a second tone mapping function using the metadata to convert the SDR data into HDR data with a dynamic range having a second peak luminance lower than the first peak luminance; reconstructing the HDR data using the second tone mapping function, the HDR data being intended for permanent display on a display device (143); Equipped with The method, wherein the second peak luminance is less than the third peak luminance, which is the maximum peak luminance supported by the display device.

2. The method of claim 1 , wherein the information representing the second peak luminance is provided by a user.

3. The method of claim 2 , wherein the information representing the second peak brightness is an energy consumption reduction target or an energy consumption profile selected from a plurality of energy consumption profiles.

4. 4. The method of claim 3, wherein the energy consumption reduction target is converted to a second peak luminance based on information for determining a reduction factor to be applied to the third peak luminance based on a piecewise linear curve or a parametric curve.

5. The method of claim 4 , wherein the control points defining the piecewise linear curve or the parameters defining the parametric curve are obtained offline using multiple video sequences.

6. The method of claim 3 or 4, wherein information determining a reduction factor, control points defining the piecewise linear curve, or parameters defining the parametric curve are obtained from the metadata.

7. 7. The method of claim 6, wherein the metadata is dynamic metadata provided for each image of the SDR data, for a group of images of the SDR data, for a period between two scene cuts of the SDR data, for each program of the SDR data, for each period of the SDR data, or for a period or time layer of the SDR data.

8. 7. The method of claim 6, wherein the metadata further comprises information determining a reduction factor for multiple types of display devices, control points defining the piecewise linear curve, or at least one of parameters defining the parametric curve, information representing an average luminance of an image, information representing spatiotemporal events, and information representing a type of content represented by the SDR data.

9. The method according to claim 1 , wherein the second peak luminance of the current image is obtained by smoothing based on the second peak luminance of an image preceding the current image.

10. The method of claim 1 , wherein the second peak luminance is greater than or equal to a minimum value.

11. The method of claim 1 , wherein a content adaptive process determines whether to use the second tone mapping function for the reconstruction of the HDR data.

12. The method of claim 11 , wherein the content adaptive processing uses a value indicative of the potential to reduce energy consumption of the current image.

13. 1. A method comprising: obtaining first metadata representing SDR data and a first inverse tone mapping function that converts the SDR data into HDR data with a dynamic range having a first peak luminance; generating second metadata estimating energy consumed by a display device to display the HDR data at a second peak luminance; encoding the SDR data together with the first metadata and the second metadata into video data; Equipped with The method, wherein the second peak luminance is less than a third peak luminance, and the third peak luminance is the maximum peak luminance supported by the display device.

14. 14. The method of claim 13, wherein the second metadata is information determining a reduction factor to be applied to the third peak luminance to obtain the second peak luminance, and represents a piecewise linear curve representing energy consumption as a function of peak luminance, or represents a parametric curve representing energy consumption as a function of peak luminance.

15. The method of claim 13 or 14, wherein the information represented by the second metadata depends on the content represented by the HDR data.

16. A device, Obtaining (140) reconstructed SDR data and metadata representing a first inverse tone mapping function that converts the reconstructed SDR data into HDR data in a dynamic range having a first peak luminance; deriving (141) a second tone mapping function using the metadata to convert the SDR data into HDR data with a dynamic range having a second peak luminance lower than the first peak luminance; reconstructing the HDR data using the second tone mapping function, the HDR data being intended for display on a display device (143); an electronic circuit configured for The second peak luminance is lower than the third peak luminance, which is the maximum peak luminance supported by the display device.

17. The apparatus of claim 16 , wherein the information representing the second peak brightness is provided by a user.

18. The device of claim 17 , wherein the information representing the second peak luminance is an energy consumption reduction target or an energy consumption profile selected from a plurality of energy consumption profiles.

19. 20. The device of claim 18, wherein the energy consumption reduction target is converted to a second peak luminance based on information for determining a reduction factor to be applied to the third peak luminance based on a piecewise linear curve or a parametric curve.

20. 20. The apparatus of claim 19, wherein the control points defining the piecewise linear curve or the parameters defining the parametric curve are obtained offline using multiple video sequences.

21. 21. The apparatus of claim 19 or 20, wherein information determining a reduction factor, control points defining the piecewise linear curve, or parameters defining the parametric curve is obtained from the metadata.

22. 22. The device of claim 21, wherein the metadata is dynamic metadata provided for each image of the SDR data, for a group of images of the SDR data, for a period between two scene cuts of the SDR data, for each program of the SDR data, for each period of the SDR data, or for a period or time layer of the SDR data.

23. 22. The device of claim 21, wherein the metadata further comprises, for multiple types of display devices, information determining a reduction factor, control points defining the piecewise linear curve, or at least one of parameters defining the parametric curve, information representing an average luminance of an image, information representing a spatiotemporal event, and information representing a type of content represented by the SDR data.

24. 24. The apparatus of claim 16, wherein the second peak luminance of a current image is obtained by smoothing based on a second peak luminance of an image preceding the current image.

25. 25. The apparatus of claim 16, wherein the second peak luminance is greater than or equal to a minimum value.

26. 26. The device of claim 16, wherein a content adaptation process determines whether to use the second tone mapping function for the reconstruction of the HDR data.

27. 27. The device of claim 26, wherein the content adaptive processing uses a value indicative of a potential for reducing energy consumption of a current image.

28. A device, obtaining first metadata representing SDR data and a first inverse tone mapping function that converts the SDR data into HDR data with a dynamic range having a first peak luminance; generating second metadata estimating energy consumed by a display device to display the HDR data at a second peak luminance; encoding the SDR data together with the first metadata and the second metadata into video data; an electronic circuit configured for The second peak luminance is lower than a third peak luminance, and the third peak luminance is the maximum peak luminance supported by the display device.

29. 30. The device of claim 28, wherein the second metadata is information determining a curtailment factor to be applied to the third peak luminance to obtain the second peak luminance, and represents a piecewise linear curve representing energy consumption as a function of peak luminance, or represents a parametric curve representing energy consumption as a function of peak luminance.

30. 30. The apparatus of claim 28 or 29, wherein the information represented by the second metadata depends on the content represented by the HDR data.

31. A non-transitory information storage medium storing program code instructions for implementing the method of any one of claims 1 to 15.

32. A computer program comprising program code instructions for implementing the method according to any one of claims 1 to 15.

33. A signal generated by a method according to any one of claims 13 to 15 or an apparatus according to any one of claims 28 to 30.

Images