Method for correcting SDR picture in SL-HDR1 system

Abstract

A method for correcting SDR video in an SL-HDR1 system, comprising: identifying SDR picture samples whose chroma component values are at risk of being clipped during an SL-HDR1 process; and before generating the HDR picture from the SDR picture, correcting the identified samples to prevent clipping.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of European application number EP22305441.2 filed on April 4, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0003] At least one of the present embodiments generally relates to the field of production of high dynamic range (HDR) video, and more specifically to a method, device and apparatus for generating HDR content from SDR content in a system with variable levels of precision in computation and data representation. Background Art

[0004] Recent advances in display technology are beginning to allow an extended dynamic range of color, brightness and contrast in images to be displayed.The term image herein refers to image content, which may be, for example, a video or a still picture or image.

[0005] High dynamic range video (HDR video) describes video whose dynamic range is greater than that of standard dynamic range video (SDR video). HDR video involves capture, production, content / encoding, and display. HDR capture and display devices are able to display brighter whites and deeper blacks. To accommodate this, the HDR encoding standard allows for higher maximum luminance and uses at least 10 bits of dynamic range (compared to 8 bits for non-professional SDR video and 10 bits for professional SDR video) to maintain accuracy across this extended range.

[0006] HDR production is a new field, and there will be a transition phase during which both HDR content and SDR content coexist. During this coexistence phase, the same live content will be produced in both HDR and SDR versions and distributed to devices that support SDR and HDR via an SDR / HDR distribution system. Users can then display either the HDR or SDR version of the content depending on their preference or capabilities.

[0007] The SDR / HDR distribution system consists of various modules, including a production system, a post-production module, a pre-processor module, an encoding module, a decoding module, a post-processor module, and a display module. For example, the production module can be an HDR or SDR camera. The post-production module can be a module for color grading, special effect insertion, tone mapping, or inverse tone mapping. The pre-processor module can adapt the content to the SL-HDRx (x is 1, 2, or 3) standard, for example, by generating SDR video content with SL-HDRx metadata. The encoding module can encode the SDR video content and metadata into a video compression format such as HEVC or VVC. The decoding module decodes the encoded SDR video content and metadata. The post-processor module can generate HDR video content from the SDR video content and SL-HDRx metadata. The display module is responsible for displaying the decoder SDR video or the generated HDR video.

[0008] In such an SDR / HDR distribution system, each module can be managed by a different entity. For example, a first entity can manage a production module, a post-production module, a pre-processor module, and an encoding module, and a second entity can manage a decoding module, a post-processor module, and a display module. Each entity cannot control the implementation of the various modules managed by another entity. Therefore, even if each entity complies with the same standard, such as SL-HDRx, each entity is free to define at what level of precision to perform the internal calculations of the module it is responsible for. For example, one entity may decide to perform the calculations of a pre-processing module in floating point mode, while another entity may decide to perform the calculations performed by the post-processing module in integer mode, using a given bit depth precision and within a given value range. This drift in the precision of internal calculations between modules may cause unacceptable errors in the displayed HDR video, which is generally due to clipping of some values ​​during calculations.

[0009] It would be desirable to overcome the above-mentioned disadvantages.

[0010] It is particularly desirable to propose a system that allows display errors due to clipping to be avoided or limited. Summary of the invention

[0011] In a first aspect, one or more of the present embodiments provide a method comprising: obtaining a chroma component from a current sample of an input SDR picture using a color correction function; estimating a clipping factor based on the obtained chroma component and based on a first range; representing each obtained chroma component as a product of a first sub-portion of a luminance component of a sample of the input SDR picture and a second sub-portion of a corresponding chroma component of the sample of the input SDR picture, and obtaining a first ratio of a correction factor to be applied to the first sub-portion and a second ratio of a correction factor to be applied to the second sub-portion, the correction factor being based on the clipping factor; obtaining a luminance value of a sample of a corrected SDR picture corresponding to the sample of the input SDR picture by dividing the first sub-portion by a power of the correction factor equal to the first ratio; and obtaining, for each chroma component, a chroma value of a sample of the corrected SDR picture corresponding to the sample of the input SDR picture by dividing the second sub-portion of the chroma component by a power of the correction factor equal to the second ratio.

[0012] In an embodiment, the first ratio and the second ratio depend on a characteristic of the current sample, the characteristic comprising a value representing the brightness of the current sample and / or a value representing the saturation of the current sample.

[0013] In a second aspect, one or more of the present embodiments provide a method wherein the method of the first aspect is applied to all samples of an input SDR picture, and wherein the first ratio and the second ratio are fixed for all samples of the input SDR picture and depend on characteristics of the input SDR picture, the characteristics comprising a value representing the brightness of the input SDR picture and / or a value representing the saturation of the input SDR picture.

[0014] In a third aspect, one or more of the present embodiments provide a method wherein the method of the first aspect is applied to all samples of an input SDR picture of an SDR video, and wherein the first ratio and the second ratio are fixed for all samples of all SDR pictures of the SDR video.

[0015] In an embodiment of the first, second or third aspect, the first ratio and the second ratio depend on a single value.

[0016] In one embodiment, the methods of the first, second and third aspects are performed in a process for generating SDR pictures or in a process for capturing SDR pictures.

[0017] In a fourth aspect, one or more of the present embodiments provide a device comprising an electronic circuit configured to: obtain a chroma component from a current sample of an input SDR picture using a color correction function; estimate a clipping factor based on the obtained chroma component and based on a first range; represent each obtained chroma component as a product of a first sub-portion of a luminance component of a sample of the input SDR picture and a second sub-portion of a corresponding chroma component of the sample of the input SDR picture, and obtain a first ratio of a correction factor to be applied to the first sub-portion and a second ratio of a correction factor to be applied to the second sub-portion, the correction factor being based on the clipping factor; obtain a luminance value of a sample of a corrected SDR picture corresponding to the sample of the input SDR picture by dividing the first sub-portion by a power of the correction factor equal to the first ratio; and obtain, for each chroma component, a chroma value of a sample of the corrected SDR picture corresponding to the sample of the input SDR picture by dividing the second sub-portion of the chroma component by a power of the correction factor equal to the second ratio.

[0018] In an embodiment, the first ratio and the second ratio depend on a characteristic of the current sample, the characteristic comprising a value representing the brightness of the current sample and / or a value representing the saturation of the current sample.

[0019] In a fifth aspect, one or more of the present embodiments provide a device comprising an electronic circuit adapted to process each sample of an input SDR picture in the following manner: obtain a chroma component from a current sample of the input SDR picture using a color correction function; estimate a clipping factor based on the obtained chroma component and based on a first range; represent each obtained chroma component as a product of a first sub-portion of a luminance component of the sample of the input SDR picture and a second sub-portion of a corresponding chroma component of the sample of the input SDR picture, and obtain a first ratio of the correction factor to be applied to the first sub-portion and a second ratio of the correction factor to be applied to the second sub-portion. ratio, the correction factor being based on the clipping factor; obtaining luminance values ​​of samples of the corrected SDR picture corresponding to samples of the input SDR picture by dividing a first sub-portion by the correction factor raised to a power equal to the first ratio; and obtaining, for each chrominance component, chrominance values ​​of samples of the corrected SDR picture corresponding to samples of the input SDR picture by dividing a second sub-portion of the chrominance component by the correction factor raised to a power equal to a second ratio; and wherein the first ratio and the second ratio are fixed for all samples of the input SDR picture and depend on a characteristic of the input SDR picture, the characteristic comprising a value representing the luminance of the input SDR picture and / or a value representing the saturation of the input SDR picture.

[0020] In a sixth aspect, one or more of the present embodiments provide a device comprising an electronic circuit adapted to process each sample of an input SDR picture of an SDR video in the following manner: obtaining a chroma component from a current sample of the input SDR picture using a color correction function; estimating a clipping factor based on the obtained chroma component and based on a first range; representing each obtained chroma component as a product of a first sub-portion of a luminance component of a sample of the input SDR picture and a second sub-portion of a corresponding chroma component of the sample of the input SDR picture, and obtaining a first ratio of a correction factor to be applied to the first sub-portion and a second ratio of a correction factor to be applied to the second sub-portion, the correction factor being based on the clipping factor; obtaining a luminance value of a sample of a corrected SDR picture corresponding to the sample of the input SDR picture by dividing the first sub-portion by a power of the correction factor equal to the first ratio; and for each chroma component, obtaining a chroma value of a sample of a corrected SDR picture corresponding to the sample of the input SDR picture by dividing the second sub-portion of the chroma component by a power of the correction factor equal to the second ratio; and wherein the first ratio and the second ratio are fixed for all samples of all SDR pictures of the SDR video.

[0021] In an embodiment of the fourth, fifth and sixth aspects, the first ratio and the second ratio depend on a single value.

[0022] In one embodiment, the apparatus of the fourth, fifth and sixth aspects is used to generate SDR pictures or to capture SDR pictures.

[0023] In a seventh aspect, one or more of the present embodiments provides a computer program comprising program code instructions for implementing the method according to the first, second or third aspect.

[0024] In an eighth aspect, one or more of the present embodiments provide a non-transitory information storage medium storing program code instructions for implementing the method according to the first, second or third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 schematically illustrates examples of scenarios in which various embodiments may be implemented;

[0026] Figure 2 Illustration of the post-processing process that allows the generation of an HDR picture from an SDR picture;

[0027] Figure 3 Diagram showing the reconstruction process from SDR to HDR;

[0028] Figure 4An example of a post-processing process that allows an HDR picture to be generated from an SDR picture according to an embodiment is illustrated;

[0029] Figure 5 illustrates the correction process applied to an SDR picture;

[0030] Figure 6 The details of the correction process are illustrated;

[0031] Fig. 7A schematically illustrates an example of a hardware architecture of a processing module capable of implementing various aspects and embodiments;

[0032] Figure 7B illustrates a block diagram of an example of a first system in which various aspects and embodiments are implemented; and,

[0033] Figure 7C A block diagram of an example of a second system in which various aspects and embodiments are implemented is illustrated. DETAILED DESCRIPTION

[0034] Figure 1 Examples of scenarios in which various embodiments are implemented are schematically illustrated.

[0035] exist Figure 1 In the present invention, a source device 10 (such as a camera or a streaming system providing video content) generates video content. The source device 10 is, for example, an SDR or HDR camera that generates SDR or HDR video content, respectively.

[0036] The video content is then provided to the pre-processing module 11. For example, the pre-processing module 11 adapts the content to the SL-HDRx standard. For example, the SL-HDRx standard is SL-HDR1. Therefore, when the video content is an SDR video, the pre-processing module generates SL-HDR1 metadata based on the SDR video. When the video content is an HDR video, the pre-processing module applies tone mapping (TM) to the HDR video to generate an SDR video and generates SL-HDR1 metadata. The S1-HDR1 metadata includes information representing an inverse tone mapping function and a color correction function, thereby allowing an HDR video to be obtained from an SDR video.

[0037] The SDR video and SL-HDR1 metadata are then provided to an encoding module 12. The SDR video and SL-HDR1 metadata are encoded in a bitstream by the encoding module 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, High Efficiency Video Coding / ITU-T H.265), VVC (ISO / IEC 23090-3–MPEG-I, Generic Video Coding / ITU-T H.266), AV1, VP9, ​​EVC (ISO / CEI23094-1 Basic Video Coding), or any other video compression format adapted to encode the SDR video and SL-HDR1 metadata. The output of the encoding module 12 is a bitstream representing the encoded SDR video and SL-HDR1 metadata.

[0038] The encoding module 12 then provides the bitstream, for example via a network, to the decoding module 13. The decoding module 13 decodes the bitstream to obtain a decoded version of the SDR video and the SL-HDR1 metadata.

[0039] The SDR video is provided directly to a display device 16 which is adapted to display SDR content.

[0040] The SDR video and SL-HDR1 metadata are also provided to the post-processing module 14. The post-processing 14 module applies inverse tone mapping (ITM) and color correction to the SDR video to obtain HDR video using the ITM function and color correction function derived from the SL-HDR1 metadata.

[0041] The HDR video is then provided to a display device 15 which is adapted to display HDR content.

[0042] Fig. 7AAn example of a hardware architecture of a processing module 70, such as used in a pre-processing module 11 or a post-processing module 14, is schematically illustrated. The processing module 70 includes the following items connected by a communication bus 705: a processor or CPU (central processing unit) 700, as a non-limiting example, covering one or more microprocessors, general-purpose computers, special-purpose computers, and processors based on a multi-core architecture; a random access memory (RAM) 701; a read-only memory (ROM) 702; a storage unit 703, which may include non-volatile memory 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 memory, magnetic disk drive and / or optical disk drive, or storage medium reader (such as SD (Secure Digital) card reader) and / or hard disk drive (HDD) and / or network accessible storage device; at least one communication interface 704 for exchanging data with other modules, devices, systems or equipment. The communication interface 704 may include, but is not limited to, a transceiver configured to send and receive data through the communication network 71. The communication interface 704 may include, but is not limited to, a modem or a network card.

[0043] For example, the communication interface 704 enables, for example, the processing module 70 to receive HDR or SDR data and output HDR or SDR data together with SL-HDR1 metadata.

[0044] The processor 700 is capable of executing instructions loaded into the RAM 701 from the ROM 702, an external memory (not shown), a storage medium or a communication network. When the processing module 70 is powered on, the processor 700 is capable of reading instructions from the RAM 701 and executing them. When the processing module 70 is included in the pre-processing module 11, these instructions form a computer program so that, for example, the TM process is implemented by the processor 700 (when the source module generates HDR video), and in one embodiment, the TM process is implemented. Figure 5 When the processing module 70 is included in the post-processing module 14, these instructions form a computer program so that, for example, the ITM process is implemented by the processor 700 and Figure 4 In the embodiment shown in FIG. Figure 5 process.

[0045] All or some of the algorithms and steps of the process may be implemented in software by executing a set of instructions by a programmable machine such as a DSP (digital signal processor) or a microcontroller, or in hardware by a machine or dedicated components such as an FPGA (field programmable gate array) or ASIC (application-specific integrated circuit).

[0046] Figure 7C A block diagram of an example of a system A implementing a post-processing module in which various aspects and embodiments are implemented is illustrated.

[0047] System A can be embodied as a device including various components or modules and is configured to generate HDR displayable video. Examples of such systems include, but are not limited to, various electronic systems such as personal computers, laptops, smart phones, tablets, TVs, or set-top boxes. The components of system A can be embodied individually or in combination in a single integrated circuit (IC), multiple ICs, and / or discrete components. For example, in at least one embodiment, system A includes a processing module 70 that implements post-processing module 14. In various embodiments, system A is communicatively coupled to one or more other systems or other electronic devices via, for example, a communication bus or through dedicated input and / or output ports.

[0048] Input to the processing module 70 may be provided by various input modules, as indicated by block 72. Such input modules include, but are not limited to: (i) a radio frequency (RF) module that receives an RF signal transmitted over the air, for example, by a broadcaster, (ii) a component (COMP) input module (or a group of COMP input modules), (iii) a universal serial bus (USB) input module, and / or (iv) a high-definition multimedia interface (HDMI) input module. Figure 7C Other examples not shown include composite video.

[0049] In various embodiments, as is known in the art, the input module of block 72 has associated corresponding input processing elements. For example, the RF module may be associated with elements suitable for: (i) selecting a desired frequency (also referred to as selecting a signal, or band limiting a signal to a frequency band); (ii) down-converting the selected signal; (iii) again band-limiting a narrower frequency band to select, for example, a signal band, which may be referred to as a channel in some embodiments; (iv) demodulating the down-converted and band-limited signal; (v) performing error correction; and (vi) demultiplexing to select a desired data packet stream. The RF module of various embodiments includes one or more elements that perform these functions, such as a frequency selector, a signal selector, a band limiter, a channel selector, a filter, a down-converter, a demodulator, an error corrector, and a demultiplexer. The RF portion may include a tuner that performs various of these functions, including, for example, down-converting a received signal to a lower frequency (e.g., an intermediate frequency or near baseband frequency) or down-converting to baseband. Various embodiments rearrange the order of the above (and other) elements, remove some of these elements, and / or add other elements that perform similar or different functions. Adding elements can include inserting elements between existing elements, such as, for example, inserting an amplifier and an analog-to-digital converter. In various embodiments, the RF module includes an antenna.

[0050] Additionally, the USB and / or HDMI modules may include corresponding interface processors for connecting system A to other electronic devices across the USB and / or HDMI connections. It is to be understood that various aspects of input processing, such as Reed-Solomon error correction, may be implemented, for example, within a separate input processing IC or within the processing module 70 as desired. Similarly, various aspects of USB or HDMI interface processing may be implemented, for example, within a separate interface IC or within the processing module 70 as desired. The demodulated, error corrected, and demultiplexed stream is provided to the processing module 70.

[0051] The various elements of system A can be provided in an integrated housing. In the integrated housing, the various elements can be interconnected and data can be transmitted between them using a suitable connection arrangement, such as an internal bus known in the art, including an inter-IC (I2C) bus, wiring, and a printed circuit board. For example, in system A, processing module 70 is interconnected with other elements of the system A via bus 705.

[0052] The communication interface 704 of the processing module 70 allows the system A to communicate over the communication network 71. The communication network 71 may be implemented, for example, within a wired and / or wireless medium.

[0053] In various embodiments, data is streamed or otherwise provided to system A using a wireless network such as a Wi-Fi network, for example IEEE802.11 (IEEE refers to the Institute of Electrical and Electronics Engineers). The Wi-Fi signals of these embodiments are received by a communication network 71 and a communication interface 704 adapted for Wi-Fi communications. The communication network 71 of these embodiments is typically connected to an access point or router that provides access to an external network (including the Internet) for allowing streaming applications and other over-the-top communications. Still other embodiments use the RF connection of the input box 72 to provide streaming data to system A. As described above, for example, when system A is a smart phone or tablet, various embodiments provide data in a non-streaming manner. Additionally, various embodiments use wireless networks other than Wi-Fi, such as cellular networks or Bluetooth networks.

[0054] System A may provide output signals to various output devices using communication network 71 or bus 705. For example, system A may provide HDR video.

[0055] System A can provide output signals to various output devices, including an HDR display 15, speakers 76, and other peripherals 77. The HDR display 15 of various embodiments includes, for example, one or more of a touch screen display, an organic light emitting diode (OLED) display, a curved display, and / or a foldable display. The HDR display 15 can be used in a television, a tablet computer, a laptop computer, a cellular phone (mobile phone), or other devices. The HDR display 15 can also be integrated with other components (for example, as in a smartphone), or be separate (for example, an external monitor for a laptop computer). In various examples of embodiments, the other peripherals 77 include one or more of the following: a stand-alone digital video disk (or digital versatile disk) (DVR, for both terms), a disk player, a stereo system, and / or a lighting system. Various embodiments use one or more peripherals 77 that provide functionality based on the output of system A. For example, a disk player performs the function of playing the output of system A.

[0056] In various embodiments, control signals are transmitted between system A and the HDR display 15, speaker 76, or other peripheral device 77 using signaling such as AV.Link, consumer electronics control (CEC), or other communication protocols that enable device-to-device control with or without user intervention. The output devices may be communicatively coupled to system A via dedicated connections through respective interfaces 73, 74, and 75. Alternatively, the output devices may be connected to system A via communication interface 704 using a communication network 71. The HDR display 15 and speaker 76 may be integrated with other components of system A in a single unit in an electronic device such as, for example, a television. In various embodiments, the display interface 73 includes a display driver, such as, for example, a timing controller (T Con) chip.

[0057] For example, if the RF module of block 72 is part of a separate set-top box, the HDR display 15 and speaker 76 may alternatively be separate from one or more other components. In various embodiments in which the HDR display 15 and speaker 76 are external components, the output signal may be provided via a dedicated output connection including, for example, an HDMI port, a USB port, or a COMP output.

[0058] Figure 7B A block diagram of an example of a system B adapted to implement the pre-processing module 11 is illustrated, in which various aspects and embodiments are implemented.

[0059] System B may be embodied as a device including the various components and modules described above, and configured to perform one or more aspects and embodiments described in this document.

[0060] Examples of such devices include, but are not limited to, various electronic devices such as personal computers, laptop computers, cameras, smart phones, and servers. The elements or modules of system B may be embodied individually or in combination in a single integrated circuit (IC), multiple ICs, and / or discrete components. For example, in at least one embodiment, system B includes a processing module 70 that implements preprocessing module 11. In various embodiments, system B is communicatively coupled to one or more other systems or other electronic devices via, for example, a communication bus or through dedicated input and / or output ports.

[0061] Inputs to the processing module 70 may be provided by various input modules indicated in block 72, as already described with reference to Figure 7C as described.

[0062] The various elements of system B may be provided in an integrated housing. Within the integrated housing, the various elements may be interconnected and data may be transmitted between them using a suitable connection arrangement, such as an internal bus known in the art, including an inter-IC (I2C) bus, wiring, and a printed circuit board. For example, in system B, processing module 70 is interconnected with other elements of the system B via bus 705.

[0063] The communication interface 704 of the processing module 70 allows the system B to communicate over the communication network 71. The communication network 71 may be implemented, for example, within a wired and / or wireless medium.

[0064] In various embodiments, data is streamed or otherwise provided to system B using a wireless network such as a Wi-Fi network, for example IEEE 802.11 (IEEE refers to the Institute of Electrical and Electronics Engineers). The Wi-Fi signals of these embodiments are received through a communication network 71 and a communication interface 704 adapted for Wi-Fi communications. The communication network 71 of these embodiments is typically connected to an access point or router that provides access to external networks (including the Internet) for allowing streaming applications and other over-the-top communications. Still other embodiments use the RF connection of input box 72 to provide streaming data to system B. As indicated above, various embodiments provide data in a non-streaming manner.

[0065] When a figure is presented as a flow chart, it should be understood that it also provides a block diagram of the corresponding apparatus. Similarly, when a figure is presented as a block diagram, it should be understood that it also provides a flow chart of the corresponding method / process.

[0066] The implementations and aspects described herein can be implemented in, for example, methods or processes, devices, software programs, data streams, or signals. Even if only discussed in the context of a single form of an implementation (e.g., discussed only as a method), the implementation of the features discussed can also be implemented in other forms (e.g., devices or programs). The device can be implemented in, for example, appropriate hardware, software, and firmware. The method can be implemented in, for example, a processor, which generally refers to a processing device, including, for example, a computer, a microprocessor, an integrated circuit, or a programmable logic device. The processor also includes a communication device, such as, for example, a computer, a cellular phone, a portable / personal digital assistant ("PDA"), a smart phone, a tablet computer, and other devices that facilitate information communication between end users.

[0067] Reference to "one embodiment" or "an embodiment" or "one implementation" or "an implementation" and other variations thereof mean 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" or "in an embodiment" or "in an implementation" or "in an implementation" and any other variations appearing in various places throughout this application are not necessarily all referring to the same embodiment.

[0068] Additionally, the present application may involve "determining" various pieces of information. Determining information may include, for example, estimating information, calculating information, predicting information, retrieving information from a memory, or obtaining information, for example, from another device, module, or user.

[0069] Further, the present application may refer to "accessing" various pieces of information. Accessing information may include, for example, one or more of receiving information, retrieving information (e.g., from a memory), storing information, moving information, copying information, calculating information, determining information, predicting information, or estimating information.

[0070] Additionally, the present application may involve "receiving" various pieces of information. Like "accessing," receiving is intended to be a broad term. Receiving information may include, for example, one or more of accessing information or retrieving information (e.g., from a memory). Further, during operations such as, for example, storing information, processing information, sending information, moving information, copying information, erasing information, calculating information, determining information, predicting information, or estimating information, "receiving" is typically involved in one way or another.

[0071] It is to be appreciated that use of any of the following “ / ”, “and / or”, and “at least one of”, “one or more of” (e.g., in the case of “A / B”, “A and / or B”, and “at least one of A and B”, “one or more of A and B”) is intended to encompass selection of only the first listed option (A), or only the second listed option (B), or both options (A and B). As further examples, in the case of “A, B, and / or C” and “at least one of A, B, and C”, “one or more of A, B, and C”, such wording is intended to encompass selection of only the first listed option (A), or only the second listed option (B), or only the third listed option (C), or only the first listed option and the second listed option (A and B), or only the first listed option and the third listed option (A and C), or only the second listed option and the third listed option (B and C), or all three options (A and B and C). This may be extended to as many items as listed, as will be apparent to one of ordinary skill in the art and related arts.

[0072] It will be apparent to one of ordinary skill in the art that implementations or embodiments may generate a variety of signals that are formatted to carry information that can be stored or transmitted, for example. The information may include, for example, instructions for executing a method, or data generated by one of the described implementations or embodiments. For example, a signal may be formatted to carry an SDR image or video sequence and SL-HDRx metadata of the described embodiment. Such a signal may be formatted as, for example, an electromagnetic wave (e.g., using the radio frequency portion of the spectrum) or a baseband signal. Formatting may include, for example, encoding an SDR image or video sequence with SL-HDR1 metadata in a coded stream and modulating a carrier with the coded stream. The information carried by the signal may be, for example, analog or digital information. As is well known, signals may be transmitted over a variety of different wired or wireless links. The signal may be stored on a processor-readable medium.

[0073] Figure 2 Illustration of the post-processing that allows the generation of an HDR picture from an SDR picture.

[0074] Figure 2 The post-processing process described is an overview of the post-processing process described in Section 7.2.4 of the standard SL-HDR1 (ETSI TS103433-1 V1.4.1, High-performance single-layer high dynamic range (HDR) systems for use in consumer electronic devices; Part 1: Direct standard dynamic range (SDR) compliant HDR systems (SL-HDR1)).

[0075] For example, when the processing module 70 of system A implements the post-processing module 14, the module executes Figure 2 post-processing process.

[0076] In step 140, the processing module 70 obtains the decoded SDR video and SL-HDR1 metadata. In this case, the system A has received an encoded video stream including the SDR video and the SL-HDR1 metadata, and has decoded the video stream using a decoding module such as the decoding module 13.

[0077] In step 142, processing module 70 derives the ITM function to be applied to the brightness (ie, luminance) component of the SDR video from the SL-HDR1 metadata. During step 142, the process described in section 7.2.3.1 of the SL-HDR1 specification is applied.

[0078] In step 143, the processing module 70 derives a color correction function to be applied to the chrominance (ie chromaticity) component of the SDR video from the SL-HDR1 metadata. During step 143, the process described in section 7.2.3.2 of the SL-HDR1 specification is applied.

[0079] In step 144, the processing module 70 reconstructs the HDR video from the SDR video and the SL-HDR1 metadata. During step 144, the process described in section 7.2.4 of the SL-HDR1 specification is applied. Figure 3 An example of implementation of step 144 is detailed.

[0080] Figure 3 Diagram illustrating the SDR to HDR reconstruction process.

[0081] In general, the decoded SDR video is represented in the YUV 420 format with limited range, while the internal calculations in the post-processor are performed in the YUV 444 format with full range. Limited range means that the range of possible values ​​defined by the bit depth (8 bits, 10 bits, 12 bits, etc.) is not fully occupied. An example of a typical limited range for a bit depth of 10 bits for the Y (respectively for U or V) component is [64; 940] (respectively [64; 960]), while the full range allowed by 10 bits is [0; 1023].

[0082] For each picture of the SDR video (hereinafter referred to as SDR picture), execute Figure 3 process.

[0083] In step 1441, the processing module 70 converts the current SDR picture into a converted picture in the YUV 444 format with a full range. To this end, the processing module 70 starts by upsampling the chrominance components of the input SDR picture to obtain an SDR picture in the YUV 444 format. Then, each component of each sample of the picture in the YUV 444 format is converted from a limited range to a full range, for example by applying the following process:

[0084] Y in =(Y in_lr -64) / 876×1023

[0085] U in =(U in_lr -512) / 896×1023+512

[0086] V in =(V in_lr -512) / 896×10233+512

[0087] Among them, Y in_lr , U in_lr and V in_lr are the three components of a sample of an SDR picture in YUV 444 format, and Y in , U in and V in are the three components of the corresponding samples of the converted picture. In other words, the processing module 70 converts the values ​​of the samples (i.e., Y, U and V components) representing the SDR picture in the YUV 444 format from a first range (i.e., a limited range) to a second range (i.e., a full range), the second range being larger than the first range. During step 1441, the processing module 70 converts the obtained chrominance component U using equation (25) of section 7.2.4 of the SL-HDR1 specification. in and V in Center to obtain the centered component U post1 and V post1 :

[0088]

[0089] Here, the value midSampleVal is defined in the SL-HDR1 specification (512 for 10-bit components).

[0090] It may be noted that the current SDR picture may be in another format, such as the format YUV 444. In the latter case, no upsampling of the chroma components is required.

[0091] In step 1442, the processing module 70 determines whether all samples of the converted picture have been processed. If at least one sample of the converted picture is still to be processed, step 1442 is followed by steps 1443 to 1447. Steps 1443 to 1447 are applied to one sample of the converted picture, hereinafter referred to as the current sample.

[0092] In step 1443, the processing module 70 calculates the brightness component Y post2 To this end, the processing module first applies resaturation to the luminance component Yin of the current sample using equation (26) specified in section 7.2.4 of the SL-HDR1 specification to obtain the resaturated luminance component Y post1 :

[0093] Y post1 =Y in +Max(0;mu0×U post1 +mu1×V post1 )

[0094] Then, the resaturation value Y is converted to post1 Clamp in the range [0; 1023] to obtain the luminance component value Y post2 :

[0095] Y post2 =Clip3(0;maxSampleVal-1;Y post1 )

[0096] In step 1444, the processing module 70 uses the SL-HDR1 metadata to calculate the color correction function. The calculation of the color correction function is equivalent to constructing a color correction lookup table lutCC[]. The construction of the lookup table lutCC[] uses equations (21) and (22) of section 7.2.3.2 of the SL-HDR1 specification, as shown below:

[0097] lutCC[0]=0,125

[0098]

[0099] in and g(), L(), and R sgf Defined in the SL-HDR1 specification.

[0100] In step 1445, the processing module 70 uses the lookup table lutCC[] to calculate the chrominance component value U post1 and V post1 Apply inverse color correction. To this end, processing module 70 applies equation (28) of Section 7.2.4:

[0101]

[0102] In step 1446, the processing module 70 calculates the components S0, U post3 、V post3 Components S0, U post3 and V post3 This is calculated using equations (29) and (30) as specified in section 7.2.4 of the SL-HDR1 specification as follows:

[0103] S0 is initialized to zero.

[0104] T=k0×U post2 ×V post2 +k1×U post2 ×U post2 +k2×V post2 ×V post2

[0105] If (T≤1), then U post3 =U post2 And V post3 =V post2 ,

[0106] Otherwise (T>1), from U post2 and V post2 Export U post3 and V post3 , as shown below:

[0107]

[0108] The most common implementation of SL-HDR1, known as non-constant luminance (NCL) mode, specifies k0=k1=k2=0. Therefore, in NCL mode, S0, U post3 、V post3 According to is defined as follows:

[0109] S0=1

[0110] U post3 =U post2

[0111] V post3 =V post2

[0112] In most cases, these equations are sufficient to accurately render HDR video in NCL mode. However, in some specific cases some errors may occur.

[0113] As an example, an integer implementation of the post-processor module 14 in NCL mode may use a precision of 14 bits + 1 sign bit for the chrominance values ​​U post2 and V post2 , and uses 9 bits + 1 bit of sign precision for the chrominance value U post3 and V post3 Representation.

[0114] In this integer implementation, and for some very saturated reds and blues in the SDR video (e.g., provided by the preprocessor 11), U post2 and / or V post2 can have an absolute value higher than 9 bits. In this case, when U post2 / V post2 With an absolute value higher than 9 bits, from U about 14 bits + 1 bit symbol post2 / V post2 To U about 9-bit + 1-bit symbol post3 / V post2 The conversion of implies clipping. This clipping is the source of errors in the reconstructed HDR picture.

[0115] In step 1447, processing module 70 uses equations (31), (32) and (33) of section 7.2.4 of the SL-HDR1 specification to calculate the value S0, U post3 and V post3 Exports the RGB values ​​of the sample of the HDR image corresponding to the current sample.

[0116] When all samples of the converted image have been processed, the processing module stops the calculation of the HDR image.

[0117] Figure 4 An example of a post-processing procedure allowing the generation of an HDR picture from an SDR picture, wherein the risk of clipping is limited, is illustrated.

[0118] like Figure 4 As shown in the figure, Figure 2 During the post-processing process, an additional step 141 is introduced between steps 140 and 142.

[0119] In step 141 , the processing module 70 applies a correction process to the SDR video obtained in step 140 . Figure 5 and Figure 6 The correction process is detailed in . Steps 142 to 144 are then applied to the corrected version of the SDR video, rather than to the original SDR video decoded from the video stream.

[0120] Figure 5 Illustration of the correction process applied to SDR pictures.

[0121] Figure 5 The purpose of this process is to prevent the chrominance component value U post2 and V post2 any clipping. Figure 5 The process is applied to each SDR picture of the decoded SDR video.

[0122] In step 1411 , the processing module 70 converts the current SDR picture into a converted picture in the YUV 444 format with a full range by applying the same process as in step 1441 .

[0123] In step 1412, the processing module 70 determines whether all samples of the converted picture have been processed. If at least one sample of the converted picture is still to be processed, step 1412 is followed by step 1413. Step 1413 is applied to a sample of the converted picture, hereinafter referred to as the current sample.

[0124] During a step 1413, the processing module 70 corrects the current sample if necessary, ie if the current sample risks inducing clipping during post-processing. Figure 6 Step 1413 is described in detail.

[0125] If all samples of the converted picture have been processed, the processing module converts the corrected converted picture (in YUV 444 format with full range) back to an SDR picture in YUV 420 format and limited range. The conversion is typically performed as follows:

[0126] Y in_corr_lr =(INT)(Y in_corr / 1023*876+64.5)

[0127] U in_corr_lr =(INT)(U in_corr / 1023*896+512.5)

[0128] V in_corr_lr =(INT)(V in_corr / 1023*896+512.5)

[0129] Among them, Y in_corr , U in_corr and V in_corr is the component of the sample of the corrected transformed image, and Y in_corr_lr , U in_corr_lr and V in_corr_lr are the components of samples of the rectified converted picture in YUV 420 format and limited range.

[0130] Figure 6The details of the correction process of step 1413 are shown.

[0131] Figure 6 The correction process is illustrated being applied to the current sample of the converted picture, the same process being applied to each sample of the converted picture.

[0132] In step 14131, processing module 70 uses a color correction function to calculate the chrominance components of the sample based on the chrominance components of the current sample. In one embodiment, during step 14131, processing module 70 performs Figure 3 In other words, the processing module 70 uses the color correction function represented by the lookup table lutCC[] to calculate the chrominance component U according to the components of the current sample. post3 and V post3 .

[0133] In step 14132, the processing module 70 calculates the chrominance component U post3 and V post3 And based on the component U calculated in step 1446 post3 and V post3 The purpose of step 14132 depends on the implementation of the post-processor module 14 to estimate when the value U post3 and U post3 There is a risk of clipping.

[0134] Again, let's take the integer implementation of the post-processor module 14 in NCL mode as an example - using 14 bits + 1 bit of sign precision for the chrominance value U post2 and U post2 The internal representation of the chrominance value U is represented using 9 bits + 1 bit of sign precision. post3 and V post3 The representation of U post3 (Correspondingly, U post3 ) can take a maximum absolute value equal to "2 9 =511" Umax (correspondingly, Vmax). When converted to 9-bit + 1-bit symbols to calculate U post3 and V post3 When all U greater than "511" post3 (Correspondingly, Y post3 ) are clipped to “511”.

[0135] The following process is applied during step 14132 to determine the clipping factor div_UV (all calculations are performed in floating point):

[0136] If (U post2 >U max),but

[0137] div_U=U post2 / U max ;

[0138] If (U post2 <-U max ),but

[0139] div_U=-U post2 / U max ;

[0140] If (U post2 )>V max ),but

[0141] div_V=V post2 ) / V max ;

[0142] If (V post2 )<-V max ),but

[0143] div_V=-V post2 ) / V max ;

[0144] div_UV=MAX(div_U,div_V);

[0145] In step 14133, the processing module 70 converts each calculated chrominance component U post3 and V post3 Expressed as a product of a first sub-portion depending on a luma component of a current sample and a second sub-portion depending on a corresponding chroma component of the current sample, and obtaining a first ratio partY of a correction factor to be applied to the first sub-portion and a second ratio (1-partY) of a correction factor to be applied to the second sub-portion, the correction factor being based on a clipping factor.

[0146] As detailed in equation (29) of the SL-HDR1 specification:

[0147] U post3 =lutCC[ post2 ].U post1

[0148] V post3 = lutCC[Y post2 ].V post1

[0149] When the clipping factor div_UV of the current sample is greater than "1", it means that the chrominance component U post3 and V post3 Need to be modified as follows:

[0150]

[0151]

[0152] lutCC[Y post2 ] corresponds to the first sub-part and U post1 It can be seen that a part of the correction is applied to the luminance component Y post2 The first sub-part lutCC[Y post2 ], brightness component Y post2 Directly depends on the brightness component Y of the converted image in The second part of the correction is applied to the chrominance component U post1 and V post1 , chrominance component U post1 and V post1 Directly depends on the chrominance component U of the converted image in and V in .

[0153] The first ratio partY defines what correction needs to be applied to the luminance component of the converted picture, and via the second ratio (1-partY) what correction needs to be applied to the chrominance components of the converted picture to avoid any clipping on the post-processor module 14 side.

[0154] The ratio partY has a direct impact on the displayed SDR video. If the correction is only applied to the luma component Y of the current sample in , i.e. partY=1, then the corrected sample appears much brighter when compared to the corresponding sample in the decoded SDR picture. If the correction is applied only to the chrominance component U of the current sample in and V in , i.e. partY=0, then the corrected samples appear much darker when compared with the corresponding samples of the decoded SDR picture.

[0155] In one embodiment, the first ratio partY is a predetermined fixed value defined for all samples. The fixed value can be selected by finding the best compromise for a set of selected SDR pictures that initially cause the post-processor module to clip, the best compromise being the ratio partY that minimizes the visual difference between the decoded SDR picture and the corrected SDR picture.

[0156] In one embodiment, the first ratio partY is predetermined, but dynamic between pictures, i.e., it can be adapted to the characteristics of each picture. In this case, the ratio partY is the same for the entire picture. For example, the ratio partY depends on the brightness of the current picture, or on its relative saturation. As an example, if the picture is a relatively bright picture, partY may need to have a higher value than for a dark picture. Then, the average brightness value of the entire picture can be used to adjust the partY value of the entire picture. Similarly, if the picture is a relatively saturated picture, (1-partY) may need to have a higher value than for a dark picture. Then, the average saturation value of the entire picture can be used to adjust the partY value of the entire picture.

[0157] In one embodiment, the ratio partY is predetermined, but dynamic within the picture, i.e., it can be adapted to the characteristics of each sample. In this case, the ratio partY is not the same for the entire picture. For example, the ratio partY may depend on the brightness of the current sample, or on its relative saturation. As an example, if the current sample is a relatively bright sample, partY may need to have a higher value than for a dark sample. The brightness value of the current sample can then be used to adjust the partY value of the current sample. Similarly, if the current sample is a relatively saturated sample, (1-partY) may need to have a higher value than for a dark sample. The saturation value of the current sample can then be used to adjust the partY value of the current sample.

[0158] In one embodiment, the ratio partY value is fixed to "0.75" for all samples, so (1-partY)=0.25. It has limited perceptual impact on the corrected picture, and it has the advantage of being efficiently implemented on CPU-based platforms. In fact, in CPU-based platforms, the square root function is very efficient and very fast, while the power function is much slower and less efficient. Using partY=0.75 results in the following calculation:

[0159] divUV (1-partY) =div_UV 0.25 =div_UV 0.5x0.5 =sqrt(div_UV).sqrt(div_UV)

[0160]

[0161] In step 14134, the processing module 70 calculates a corrected luminance value Y of a sample of the corrected SDR picture corresponding to the current sample by dividing the first sub-portion by the correction factor raised to the power of the first ratio. in_corr , as shown below:

[0162]

[0163] In the first embodiment of step 14134, since the color correction function represented by the lookup table lutCC[] is always a monotonically decreasing function, this can be achieved by increasing the value y by a small increment value Δ (eg, Δ=1). in_corr Gradually increase until you find a of y in_corr The value of . of y in_corr The final value of corresponds to the searched value Y in_corr .

[0164] In the second embodiment of step 14134, the corrected brightness value Y is calculated by binary division. in_corr .

[0165] In the third embodiment of step 14134, the corrected brightness value Y is directly calculated by calculating the inverse of the color correction function in_corr The inverse color correction function is represented by the lookup table inv_lutCC[]. The corrected brightness value Y in_corr The calculation is as follows:

[0166]

[0167] In step 14135, for each chrominance component (U in and V in ), processing module 70 calculates the chrominance value (U) of the sample of the corrected SDR picture corresponding to the current sample by dividing the second sub-portion of the chrominance component by the correction factor raised to the power of the second ratio in_corr and V in_corr ), as follows:

[0168]

[0169]

[0170] exist Figure 6 At the end of the process, the processing module 70 obtains a component Y in_corr , U in_corr and V in_corr of the calibrated sample.

[0171] In the embodiments described until now, the SDR correction step 141 is performed by the post-processing module 14 during the post-processing process.

[0172] In another embodiment, the SDR correction step 141 is performed by the pre-processing module 11 during the pre-processing process. In this case, the SDR video encoded by the encoding module 12 together with the SL-HDR1 metadata includes corrected SDR pictures resulting from applying the SDR correction step 141 to the SDR video provided by the source module 10 (or resulting from the ITM applied to the HDR video provided by the source 10). In this embodiment, the post-processing module 14 does not have to correct the SDR pictures to avoid clipping, because this has been done by the pre-processing module 11.

[0173] A number of embodiments are described above. Features of these embodiments may be provided individually or in any combination. Further, embodiments may include one or more of the following features, devices, or aspects, individually or in any combination across various claim categories and types:

[0174] A bitstream or signal comprising the corrected SDR video or a variant thereof.

[0175] Creating and / or transmitting and / or receiving and / or decoding a bitstream or signal comprising the corrected SDR video or a variant thereof.

[0176] A server, camera, TV, set-top box, cell phone, tablet computer, personal computer, or other electronic device that performs at least one of the described embodiments. A TV, set-top box, cell phone, tablet computer, personal computer, or other electronic device that performs at least one of the described embodiments and displays (e.g., using a monitor, screen, or other type of display) the resulting picture.

[0177] A TV, set-top box, cellular phone, tablet, personal computer, or other electronic device that tunes (e.g., using a tuner) a channel to receive a signal including encoded SDR video and SL-HDR1 metadata, and performs at least one of the described embodiments.

[0178] A TV, set-top box, cellular phone, tablet, or other electronic device that receives (e.g., using an antenna) a signal including encoded SDR video and SL-HDR1 metadata over the air, and performs at least one of the described embodiments.

[0179] A server, camera, cellular telephone, tablet, personal computer, or other electronic device that tunes (e.g., using a tuner) a channel to transmit a signal including corrected SDR video and SL-HDR1 metadata, and performs at least one of the described embodiments.

[0180] A server, camera, cellular telephone, tablet, personal computer, or other electronic device that transmits over the air (e.g., using an antenna) a signal including the corrected SDR video and SL-HDR1 metadata, and performs at least one of the described embodiments.

Claims

1. A method comprising: Obtain (14131) chroma components from the current sample of the input SDR picture using a color correction function; estimating (14132) a clipping factor based on the obtained chroma component and based on the first range; representing (14133) each obtained chroma component as a product of a first sub-portion of a luma component of the sample depending on an input SDR picture and a second sub-portion of a corresponding chroma component of the sample depending on the input SDR picture, and obtaining a first ratio of a correction factor to be applied to the first sub-portion and a second ratio of the correction factor to be applied to the second sub-portion, the correction factor being based on the clipping factor; Obtaining (14134) luma values ​​of samples of a corrected SDR picture corresponding to the samples of the input SDR picture by dividing the first subportion by the correction factor raised to a power equal to the first ratio; as well as For each chroma component, obtain (14135) chroma values ​​of samples of the corrected SDR picture corresponding to the samples of the input SDR picture by dividing a second sub-portion of the chroma component by the correction factor raised to a power equal to the second ratio. 2 . The method according to claim 1 , wherein the first ratio and the second ratio depend on characteristics of the current sample, the characteristics comprising a value representing brightness of the current sample and / or a value representing saturation of the current sample.

3. A method, wherein the method of claim 1 is applied to all samples of an input SDR picture, and wherein the first ratio and the second ratio are fixed for all samples of the input SDR picture and depend on characteristics of the input SDR picture, the characteristics comprising a value representing the brightness of the input SDR picture and / or a value representing the saturation of the input SDR picture.

4. A method, wherein the method of claim 1 is applied to all samples of an input SDR picture of an SDR video, and wherein the first ratio and the second ratio are fixed for all samples of all SDR pictures of the SDR video.

5. A method according to any preceding claim, wherein the first ratio and the second ratio are dependent on a single value.

6. A method, wherein the method of any preceding claim is performed in a process for generating SDR pictures or in a process for capturing SDR pictures.

7. A device comprising an electronic circuit, the electronic circuit being configured to: Obtain (14131) chroma components from the current sample of the input SDR picture using a color correction function; estimating (14132) a clipping factor based on the obtained chroma component and based on the first range; representing (14133) each obtained chroma component as a product of a first sub-portion of a luma component of the sample depending on an input SDR picture and a second sub-portion of a corresponding chroma component of the sample depending on the input SDR picture, and obtaining a first ratio of a correction factor to be applied to the first sub-portion and a second ratio of the correction factor to be applied to the second sub-portion, the correction factor being based on the clipping factor; Obtaining (14134) luma values ​​of samples of a corrected SDR picture corresponding to the samples of the input SDR picture by dividing the first subportion by the correction factor raised to a power equal to the first ratio; as well as For each chroma component, chroma values ​​of samples of the corrected SDR picture corresponding to the samples of the input SDR picture are obtained by dividing a second sub-portion of the chroma component by the correction factor raised to a power equal to the second ratio.

8. The device according to claim 7, wherein: The first ratio and the second ratio depend on characteristics of the current sample, the characteristics comprising a value representing brightness of the current sample and / or a value representing saturation of the current sample.

9. A device comprising electronic circuitry adapted to process each sample of an input SDR picture by: Obtain (14131) chroma components from the current sample of the input SDR picture using a color correction function; estimating (14132) a clipping factor based on the obtained chroma component and based on the first range; representing (14133) each obtained chroma component as a product of a first sub-portion of a luma component of the sample depending on an input SDR picture and a second sub-portion of a corresponding chroma component of the sample depending on the input SDR picture, and obtaining a first ratio of a correction factor to be applied to the first sub-portion and a second ratio of the correction factor to be applied to the second sub-portion, the correction factor being based on the clipping factor; Obtaining (14134) luma values ​​of samples of a corrected SDR picture corresponding to the samples of the input SDR picture by dividing the first subportion by the correction factor raised to a power equal to the first ratio; as well as obtaining, for each chroma component, chroma values ​​of samples of the corrected SDR picture corresponding to the samples of the input SDR picture by dividing a second sub-portion of the chroma component by the correction factor raised to a power equal to the second ratio; And wherein the first ratio and the second ratio are fixed for all samples of the input SDR picture and depend on characteristics of the input SDR picture, the characteristics comprising a value representing the brightness of the input SDR picture and / or a value representing the saturation of the input SDR picture.

10. A device comprising electronic circuitry adapted to process each sample of an input SDR picture of an SDR video by: Obtain (14131) chroma components from the current sample of the input SDR picture using a color correction function; estimating (14132) a clipping factor based on the obtained chroma component and based on the first range; representing (14133) each obtained chroma component as a product of a first sub-portion of a luma component of the sample depending on an input SDR picture and a second sub-portion of a corresponding chroma component of the sample depending on the input SDR picture, and obtaining a first ratio of a correction factor to be applied to the first sub-portion and a second ratio of the correction factor to be applied to the second sub-portion, the correction factor being based on the clipping factor; Obtaining (14134) luma values ​​of samples of a corrected SDR picture corresponding to the samples of the input SDR picture by dividing the first subportion by the correction factor raised to a power equal to the first ratio; as well as obtaining, for each chroma component, chroma values ​​of samples of the corrected SDR picture corresponding to the samples of the input SDR picture by dividing a second sub-portion of the chroma component by the correction factor raised to a power equal to the second ratio; And wherein the first ratio and the second ratio are fixed for all samples of all SDR pictures of the SDR video.

11. Apparatus as claimed in any preceding claim 7 to 10, wherein the first ratio and the second ratio are dependent on a single value.

12. The device according to any of the preceding claims 7 to 11, wherein the device is used to generate SDR pictures or to capture SDR pictures.

13. A computer program comprising program code instructions for implementing the method according to any of the preceding claims 1 to 6.

14. A non-transitory information storage medium storing program code instructions for implementing the method according to any of the preceding claims 1 to 6.

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