Concatenated inverse tone mapping and tone mapping

Abstract

1. A method comprising: obtaining standard dynamic range data; obtaining information representative of an inverse tone mapping process adapted to generate high dynamic range data from the standard dynamic range data (601); inserting the information into metadata; and providing video data representative of the standard dynamic range data (600) together with the metadata (602).

Description

[Technical field]

[0001] At least one of the embodiments relates generally to the field of High Dynamic Range (HDR) video production, and more particularly to methods, devices and equipment for inverse tone mapping and regenerating SDR data as close as possible to the original SDR data after tone mapping. [Background technology]

[0002] Recent advances in display technology are beginning to enable an extended dynamic range of color, brightness and contrast in displayed images. The term image, as used herein, refers to image content, which may be, for example, video or a still picture or image.

[0003] High-Dynamic-Range video (HDR video) refers to video with a greater dynamic range than Standard-Dynamic-Range video (SDR video). HDR video involves capture, production, content / encoding and display. HDR capture and display devices can have brighter whites and deeper blacks. To address this, HDR encoding standards allow for increased maximum brightness and use 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 over this extended range.

[0004] HDR production is a new field, and there is a transition phase where both HDR and SDR content will coexist. During this coexistence phase, the same live content will be produced simultaneously in HDR and SDR versions. Users can then view either the HDR or SDR version of the content depending on their preferences or capabilities.

[0005] The current trends in the content production industry are as follows: ● First, produce the HDR content and then use an automated tool to automatically derive the SDR content from the HDR content. ● Second, apply a controlled and safe approach to HDR production to avoid the delivery of bad HDR content to users, which may be counterproductive to HDR technology.

[0006] In that regard, some recommendations have been introduced by the ITU-R document "Report ITU-R BT.2408-3, Guidance for operational practices in HDR television production, 07 / 2019", hereafter simply referred to as the BT.2408-3 report. One important recommendation introduced in the BT.2408-3 report is the constraint to set HDR diffuse white to a fixed value equal to "203" nits. This constraint makes it possible to use a fixed 3D Look-Up Table (LUT) to perform the conversion from SDR to HDR (i.e., Inverse Tone Mapping, ITM) and from HDR to SDR (Tone Mapping, TM).

[0007] Live HDR content is generally a mix of the main HDR video content with other types of content, such as graphics for logos and scores or advertisements. These added contents may be SDR and therefore need to be converted to HDR before being mixed with the main HDR video content. Since the resulting mixed HDR content is likely to be converted to SDR, a new constraint appears: the SDR content resulting from the so-called SDR-HDR-SDR round-trip conversion of these added contents (i.e., ITM conversion followed by TM conversion (for SDR delivery)) must be identical to the original SDR content. The same SDR-HDR-SDR round-trip constraint exists if a content creator generates HDR content from an original SDR content, but for some reason wants the SDR content generated from this HDR content to be identical to the original SDR content.

[0008] The recommendations of the BT.2408-3 report provide a solution that respects the SDR-HDR-SDR roundtrip constraints. However, the constraints applied to HDR content make these HDR contents dull and unattractive. Furthermore, these constraints prevent HDR cameras from being utilized to their full potential and HDR cameramen / directors of photography are significantly limited in their choices / artistic intent.

[0009] It would be desirable to overcome the above deficiencies.

[0010] It would be particularly desirable to propose a system that allows more flexibility, more artistic freedom in HDR creation, and thus makes it possible to obtain more attractive HDR content. Summary of the Invention

[0011] In a first aspect, one or more of the present embodiments provide a method, the method including obtaining standard dynamic range data, obtaining information representative of an inverse tone mapping process adapted to generate high dynamic range data from the standard dynamic range data, inserting the information into metadata, and providing video data representative of the standard dynamic range data together with the metadata.

[0012] In one embodiment, the video data representing standard dynamic range data includes standard dynamic range data or high dynamic range data obtained from the standard dynamic range data by applying an inverse tone mapping process.

[0013] In one embodiment, the information represents an inverse tone mapping curve or a tone mapping curve.

[0014] In one embodiment, if the information represents a tone mapping curve, the inverse of the inverse tone mapping curve used to define the inverse tone mapping process is calculated.

[0015] In one embodiment, the method includes calculating a first lookup table and a second lookup table from an inverse of an inverse tone mapping curve, where the first lookup table is adapted to tone map a luminance component of the high dynamic range data and the second lookup table is adapted to correct a color component of the high dynamic range data, and estimating from the first and second lookup tables a first variable representing a tone mapping function and a second variable representing a color correction function, where the first and second variables are information representing the inverse tone mapping process inserted in the metadata.

[0016] In a second aspect, one or more of the present embodiments provide a method, the method including: acquiring video data representing standard dynamic range data; determining whether metadata including first information representing an inverse tone mapping process adapted to generate high dynamic range data from the standard dynamic range data has been acquired together with the video data; and in response to acquiring the metadata, applying a first tone mapping process to the high dynamic range data acquired from the video data based on the first information; and if not, calculating second information representing a second tone mapping process from the video data representing the standard dynamic range data, and applying the second tone mapping process to the high dynamic range data acquired from the video data based on the information.

[0017] In one embodiment, the video data includes standard dynamic range data or high dynamic range data obtained from the standard dynamic range data by applying an inverse tone mapping process.

[0018] In one embodiment, the information represents an inverse tone mapping curve or a tone mapping curve.

[0019] In one embodiment, the method includes, if the information represents an inverse tone mapping curve, inverting the inverse tone mapping curve.

[0020] In a third aspect, one or more of the present embodiments provide a device comprising an electronic circuit configured to obtain standard dynamic range data, obtain information representative of an inverse tone mapping process adapted to generate high dynamic range data from the standard dynamic range data, insert the information into metadata, and provide video data representative of the standard dynamic range data together with the metadata.

[0021] In one embodiment, the video data representing standard dynamic range data includes standard dynamic range data or high dynamic range data obtained from the standard dynamic range data by applying an inverse tone mapping process.

[0022] In one embodiment, the information represents an inverse tone mapping curve or a tone mapping curve.

[0023] In one embodiment, if the information represents a tone mapping curve, the electronic circuitry is further configured to calculate an inverse of the inverse tone mapping curve used to define the inverse tone mapping process.

[0024] In one embodiment, the electronic circuit is further configured to calculate (6012) a first lookup table and a second lookup table from the inverse of the inverse tone mapping curve, where the first lookup table is adapted to tone map a luminance component of the high dynamic range data and the second lookup table is adapted to correct a color component of the high dynamic range data, and to estimate (6013) from the first and second lookup tables a first variable representing a tone mapping function and a second variable representing a color correction function, where the first and second variables are information representing the inverse tone mapping process inserted in the metadata.

[0025] In a fourth aspect, one or more of the present embodiments provide a device comprising an electronic circuit, the electronic circuit configured to: acquire video data representing standard dynamic range data; determine whether metadata including first information representing an inverse tone mapping process adapted to generate high dynamic range data from the standard dynamic range data has been acquired together with the video data; and in response to receiving the metadata, apply a first tone mapping process to the high dynamic range data acquired from the video data based on the first information; and if not, calculate second information representing a second tone mapping process from the video data representing the standard dynamic range data; and apply the second tone mapping process to the high dynamic range data acquired from the video data based on the information.

[0026] In one embodiment, the video data includes standard dynamic range data or high dynamic range data obtained from the standard dynamic range data by applying an inverse tone mapping process.

[0027] In one embodiment, the information represents an inverse tone mapping curve or a tone mapping curve.

[0028] In one embodiment, if the information represents an inverse tone mapping curve, the electronic circuitry is further configured to invert the inverse tone mapping curve.

[0029] In a fifth aspect, one or more of the present embodiments provide a signal generated using the method of the first aspect or using the device of the third aspect.

[0030] 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.

[0031] In a seventh 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. [Brief description of the drawings]

[0032] [Figure 1A] Specifies the scale of luminance values ​​on which diffuse white appears. [Figure 1B] This shows the separation of the scale of luminance values ​​when the diffuse white is fixed at '203' nits. [Figure 1C] 1 illustrates a schematic of the context of various embodiments; [Diagram 2] Shown is the current single stream HDR / SDR workflow. [Diagram 3] 1 illustrates a single stream HDR / SDR workflow according to one embodiment. [Figure 4] 1 shows the known SL-HDR pre-processor. [Diagram 5] 1 illustrates a known inverse tone mapping process. [Figure 6A] 1 illustrates a schematic diagram of an example of an ITM process according to one embodiment. [Figure 6B] 1 illustrates a schematic diagram of an example of a TM process according to one embodiment. [Figure 6C] 14 details example steps of a TM process according to one embodiment in the context of SL-HDR1. [Figure 7A] 1 shows a first example of an ITM curve. [Figure 7B] A second example of an ITM curve is shown. [Figure 8] 1 illustrates an example process for determining a luminance mapping parameter. [Figure 9] 1 illustrates an example process for determining color correction adjustment variables. [Figure 10A] 13 illustrates a schematic diagram of an example process according to an alternative embodiment. [Figure 10B] 13 shows details of example steps of a process according to a variant embodiment in the context of SL-HDR1. [Figure 11A] 1 illustrates generally an example of a hardware architecture of a processing module capable of implementing various aspects and embodiments. [Figure 11B] 1 illustrates a block diagram of an example of a first system in which various aspects and embodiments may be implemented. [Figure 11C] FIG. 2 illustrates a block diagram of an example of a second system in which various aspects and embodiments may be implemented. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] As mentioned earlier, the BT.2408-3 report proposed some recommendations, especially constraints on diffuse white. Diffuse white is defined in the BT.2408-3 report as "the white color provided by a card that approximates a perfect reflecting diffuser by minimizing specular highlights and minimizing spectral power absorptance, being not only colorimetrically gray but also spectrally gray." A "perfect reflecting diffuser" is defined as "an ideal isotropic non-fluorescent diffuser with a spectral radiance coefficient equal to 1 at each wavelength of interest."

[0034] In other words, diffuse white is the luminance level of a video signal that separates: ● A scene with all details corresponding to luminance levels below diffuse white. Specular, i.e. very bright pixels, typically close to white, with very little detail and corresponding to luminance levels above the diffuse white level.

[0035] Figure 1A shows the scale of luminance values ​​on which diffuse white appears. As can be seen, diffuse white separates the set of all possible luminance values ​​into two parts.

[0036] The concept of diffuse white is valid for HDR and SDR signals.

[0037] The BT.2408-3 report specifies that HDR diffuse white is equal to 203 nits.

[0038] However, the "203" nit limit is only a recommendation, and many content creators disagree with it.

[0039] In practice, this specification introduces a major drawback in that HDR content is constrained, i.e. for a typical 1000 nit HDR content, only a small amount of the HDR luminance range [0 - 203 nit] is dedicated to scene details, while most of the HDR luminance range [203 - 1000 nit] is reserved for specular reflections that do not introduce detail.

[0040] FIG. 1B shows the separation of the luminance value scales when the diffuse white is fixed at 203 nits.

[0041] One of the reasons for this restriction is the need for controlled, "very safe" live HDR content production. In addition, this restriction has the following advantages: ● Implementing HDR to SDR conversion (i.e., tone mapping (TM)) is simpler since HDR diffuse white, defined at '203' nits, needs to be mapped to SDR diffuse white, typically defined at 90% - 100% SDR (i.e., 90nit - 100nits). Therefore, tone mapping can be implemented using a very basic static 3D-LUT. ● Implementing SDR to HDR conversion (i.e. inverse tone mapping (ITM)) is also simpler for the same reason; inverse tone mapping can also be implemented using a very basic static 3D-LUT.

[0042] However, such a ratio between the luminance values ​​assigned to scene details and the luminance values ​​assigned to the specular reflections caused by a diffuse white of 203 nits makes the resulting HDR image very dull and unattractive.

[0043] The following embodiment makes it possible to eliminate these drawbacks by proposing the following system: ● Allows for more flexibility and more artistic freedom in HDR generation and therefore makes it possible to obtain more compelling HDR content by using dynamic conversion both for dynamic conversion from HDR to SDR (tone mapping) and for dynamic conversion from SDR to HDR (inverse tone mapping). ● It allows concatenating ITM and TM processing (TM processing applies the inverse of ITM processing) for a full SDR-HDR-SDR round trip.

[0044] Indeed, one feature of current HDR authoring environments is that the ITM and TM tools operate independently, with the result that there is no correlation between the algorithms applied in the ITM tool and those applied in the TM tool, and no communication between these tools to specify the properties of the ITM (or TM) transform that is applied prior to the TM (or ITM) transform.

[0045] FIG. 1C illustrates an example of a context in which various embodiments may be implemented.

[0046] In FIG. 1C, the live production system 20 is in communication with the master central control system 21. The live production system 20 provides HDR and SDR versions of the same live content simultaneously. The master central control system 21 then encodes the same or enhanced versions of these SDR and HDR versions and provides these encoded versions to the devices 22A and 22B. In one embodiment, the master control system 21 encodes the HDR and SDR versions using an AVC ((ISO / CEI 14496-10 / ITU-T H.264) encoder, a HEVC (ISO / IEC 23008-2-MPEG-H Part 2, High Efficiency Video Coding / ITU-T H.265) encoder, a VVC (ISO / IEC 23090-3-MPEG-I, Versatile Video Coding / ITU-T H.266) encoder, or any other encoder.

[0047] Devices 22A and 22B are display devices such as PCs, televisions, smartphones, tablets, head-mounted displays, and devices connected to the display devices such as set-top boxes. Device 22A, which has HDR capabilities, receives the encoded HDR version. Device 22B, which has only SDR capabilities, receives the encoded SDR version.

[0048] A current single stream HDR / SDR workflow is shown in Figure 2. Figure 2 provides details about a live production system 20 and a master central control system 21.

[0049] The live production system 20 includes two sources: an HDR source 200 and an SDR source 201. Each source comprises at least one of a camera, a playback system, or a system that generates graphics. The SDR source 201 is connected to multiple ITM tools. ● One ITM Tool 202A (ITM1) for upconverting SDR camera output to HDR. ● One ITM Tool 202B (ITM2) for upconverting SDR playback content to HDR. ● One ITM tool 202C (ITM3) for upconverting SDR graphics (e.g. score insertion) content to HDR.

[0050] The HDR content routing and switching system takes multiple HDR inputs coming from either HDR sources 200 or SDR sources 201, and then produces multiple HDR outputs.

[0051] From these HDR outputs, multiple TM tools are used. • A TM tool 204B (TM1) for generating predicted SDR output used by shader operators to evaluate the quality of the generated SDR content sent to the master central control system 21. A TM tool 204A (TM2) for generating SDRs that are provided to the master central control system 21.

[0052] The master control system 21 comprises an HDR master control system 212 and an SDR master control system 213. The HDR and SDR master control systems are responsible for the distribution of SDR / HDR content. In the example of FIG. 2, the master control system 21 comprises a source 210 that generates SDR advertisements and an ITM tool that converts advertisements from SDR to HDR. The HDR master control system 212 receives these advertisements converted to HDR and mixes these advertisements with the received HDR content. The HDR (or SDR) master control system 212 (or 213) encodes the HDR (or SDR) data it receives or the HDR (or SDR) data resulting from the mixing of the HDR (or SDR) data it receives with other data. For example, the SDR and HDR data may be encoded by an AVC ((ISO / CEI 14496-10 / ITU-T H.264) encoder, a HEVC (ISO / IEC 23008-2-MPEG-H Part 2, High Efficiency Video Coding / ITU-T H.265) encoder, a VVC (ISO / IEC 23090-3-MPEG-I, Versatile Video Coding / ITU-T H.266) encoder, or any other encoder.

[0053] As can be seen, in the HDR production environment of FIG. 2, the ITM tool and the TM tool run independently without any communication between these tools.

[0054] In known implementations, each TM tool of the HDR authoring environment of FIG. 2 (e.g., TM tool 204A (TM2) and TM tool 204B (TM1)) is implemented in, for example, a pre-processor conforming to the standard SL-HDR1 (ETSI TS 103 433 v1.4.1), hereinafter referred to as the SL-HDR pre-processor.

[0055] FIG. 4 illustrates the process applied by the known SL-HDR pre-processor.

[0056] The process of FIG. 4 may be implemented, for example, by a processing module that is described in further detail below in conjunction with FIG. 11A.

[0057] In step 401, the processing module obtains HDR input data. Generally, the HDR input data is in YUV format.

[0058] In step 402, the processing module performs an input content formatting process, which consists of formatting the HDR input data into an internal representation.

[0059] In step 403, the processing module analyzes the formatted HDR input data to calculate SL-HDR metadata. The analysis typically includes calculating a histogram of the formatted HDR input data. The SL-HDR metadata includes (or represents) the following: ● Luminance mapping variables defined in section 6.2.5 of the SL-HDR1 specification (ETSI TS 103 433 v1.4.1). ● Color correction adjustment variables defined in section 6.2.6 of the SL-HDR1 specification (ETSI TS 103 433 v1.4.1).

[0060] In step 404, the processing module inserts the SL-HDR metadata into the vertical auxiliary channel of the Serial Digital Interface (SDI) interface according to the standard SMPTE ST 2108-1, the SL-HDR metadata being dynamic metadata type 5 defined in section 5.3.5 of the same document. This is typically the usual way to transport SL-HDR metadata between a device integrating a SL-HDR pre-processor and a video encoder such as an AVC ((ISO / CEI 14496-10 / ITU-T H.264) encoder, a HEVC (ISO / IEC 23008-2-MPEG-H Part 2, High Efficiency Video Coding / ITU-T H.265)) encoder, a VVC (ISO / IEC 23090-3-MPEG-I, Versatile Video Coding / ITU-T H.266) encoder or any other encoder.

[0061] In step 405, the processing module calculates a lookup table (LUT, hereafter referred to as "L-LUT") representing a tone mapping (TM) function described by the luminance mapping variables calculated in step 403, and a LUT (hereafter referred to as "B-LUT") representing a color correction function described by the color correction adjustment variables calculated in step 403. The L-LUT is a first lookup table that tone maps the luminance component of the high dynamic range data, and the B-LUT is a second lookup table that corrects the color components of the high dynamic range data.

[0062] In step 406, the processing module generates SDR output data from the formatted HDR input data by applying a TM process based on the L-LUT and the B-LUT.

[0063] Figure 5 illustrates a known inverse tone mapping (ITM) process. The ITM process of Figure 5 is typically applied by each ITM tool (ITM1 202A, ITM2 202B, and ITM3 202C) in the HDR production environment of Figure 2. The process of Figure 5 is implemented, for example, by a processing module described in more detail below in connection with Figure 11A.

[0064] In step 501, the processing module obtains SDR input data. Generally, the SDR input data is in YUV format.

[0065] In step 502, the processing module analyzes the SDR input data, uses the results of the analysis to calculate a most appropriate inverse tone mapping (ITM) curve, and outputs HDR data using this ITM curve. The ITM curve is used to define the ITM process that is applied to the SDR data to obtain the output HDR data.

[0066] As can be seen, there is no link between the ITM process applied in step 502 and the TM process applied in step 406. There is nothing to guarantee that the SDR-HDR-SDR roundtrip constraints are respected by the processes of Figures 4 and 5.

[0067] In one embodiment, it is proposed to link ITM and TM tools in an HDR production system by: • Creating a communication channel between the ITM tool and the TM tool that allows them to communicate in order to: o Define an HDR to SDR transform that allows the TM tool to generate an SDR output that matches the SDR input of the ITM tool to get a complete SDR-HDR-SDR round trip; o Or define an SDR to HDR transformation to be applied by the ITM tool, so that the TM tool can compute the inverse HDR to SDR transformation that allows to obtain a full SDR-HDR-SDR round trip again.

[0068] FIG. 3 illustrates a single stream HDR / SDR workflow according to this embodiment.

[0069] The systems, devices and modules of Figures 1C and 2 appear similarly in Figure 3. In the HDR production environment of Figure 3, ITM tools ITM1 202A, ITM2 202B and ITM3 202C generate HDR content along with metadata that describes either: ● HDR to SDR conversion, allowing a TM tool (that understands these metadata) to generate an SDR output that matches the ITM tool's SDR input. ● The SDR to HDR transformation applied by the ITM tool, so that the TM tool (which understands these metadata) can calculate the inverse transformation.

[0070] In addition, two TM tools (TM1 204B and TM2 204A) receive either: ● HDR content with metadata, when the routing and switching tool 203 outputs the content from one of the SDR sources 201. The TM tool then interprets the metadata and either directly applies the HDR to SDR transformation described in the metadata, or uses the metadata describing the SDR to HDR transformation applied by the ITM tool to compute a TM that corresponds to the inverse of the ITM. In both cases, a full SDR-HDR-SDR round trip is obtained. • HDR content without metadata when the routing and switching tool 203 outputs content from one of the HDR sources 200.

[0071] The embodiment of Figure 3 is described in further detail below, and in particular an example of coupling between ITM and TM processes is described in detail in relation to Figures 6A, 6B and 6C.

[0072] FIG. 6A illustrates an example of an ITM process according to one embodiment. The ITM process of FIG. 6A is typically performed by a module responsible for generating HDR data from SDR data. The ITM process of FIG. 6A is typically performed by a processing module, which will be described in more detail later in connection with FIG. 11A.

[0073] The ITM process of FIG. 6A begins with steps 501 and 502 already described in connection with FIG.

[0074] In step 600, the processing module provides (i.e. outputs or transmits) the calculated HDR data to a module responsible for generating SDR data from HDR data by respecting the SDR-HDR-SDR roundtrip constraints.

[0075] In step 601, the processing module calculates information representative of an ITM process adapted to generate HDR data from the SDR data applied in step 502. In one embodiment of step 601, the information representative of the ITM process includes information representative of an ITM curve calculated in step 502. In a variation of step 601, the information representative of the ITM process includes information representative of a TM curve estimated from the ITM curve calculated in step 502. In step 601, the processing module inserts information into metadata.

[0076] In step 602, the processing module provides (i.e., outputs or transmits) the metadata to a module responsible for generating SDR data from HDR data.

[0077] FIG. 6B shows an example of a decoding process of an embodiment. The TM process of FIG. 6B is typically applied by a module responsible for generating SDR data from HDR data by adhering to the SDR-HDR-SDR round-trip constraint. The process of FIG. 6B is implemented, for example, by a processing module that will be described in detail later in connection with FIG. 11A.

[0078] Steps 401 and 402 of Fig. 4 are retained in the process of Fig. 6B. Steps 403 and 404 are removed. Step 405 is followed by step 610. Step 406 is replaced by steps 611 and 612. It should be noted that in step 401, the processing module receives the HDR data generated in step 502.

[0079] In step 610, the processing module determines whether metadata has been received with the HDR data.

[0080] If no metadata was received with the HDR data, the processing module applies step 611. In step 611, the processing module analyzes the formatted HDR data and uses the results of the analysis to calculate the most appropriate Tone Mapping (TM) curve. Step 611 is followed by step 612.

[0081] If metadata was received along with the HDR data, step 610 is immediately followed by step 612.

[0082] In step 612, the processing module generates SDR output data from the formatted HDR input data by applying a TM process based on either the metadata representing the information representing the ITM process applied in step 502 or the TM process defined by the TM curve calculated in step 611. When the information representing the ITM process represents an ITM curve, the processing module calculates a TM curve from the ITM curve by inverting the ITM curve, and applies tone mapping to the HDR data using the calculated TM curve. In fact, the information representing the ITM curve also represents a TM curve that can be estimated from the ITM curve. When the information representing the ITM process represents a TM curve, the processing module directly uses the TM curve to calculate the SDR data.

[0083] In the following, the processes of Figures 6A and 6B are detailed in the context of SL-HDR1 in relation to Figure 6C. In this context, the ITM process of Figure 6A is typically performed by a processing module of each ITM tool (ITM1 202A, ITM2 202B, and ITM3 202C) of the HDR production environment of Figure 3. The TM process of Figure 6B is typically performed by a processing module of each TM tool (TM1 204B and TM2 204A) of the HDR production environment of Figure 3, or by a processing module of a SL-HDR pre-processor such as Figure 4.

[0084] 6C details step 601. Step 601 is divided into three steps: step 6011, step 6012, and step 6013.

[0085] In step 6011, the processing module calculates the inverse of the inverse tone mapping curve calculated in step 502. An example of a process for calculating the inverse of the inverse tone mapping curve is described below.

[0086] In step 6012, the processing module calculates the L-LUT and the B-LUT from the inverse tone mapping curve. The L-LUT and the B-LUT are calculated in a format adapted to the format used by the SL-HDR pre-processor.

[0087] In step 6013, the processing module estimates the luminance mapping parameters defined in section 6.2.5 of the SL-HDR1 specification from the L-LUT and the color correction adjustment parameters defined in section 6.2.6 of the SL-HDR1 specification from the B-LUT.

[0088] In step 602, when applied in the context of SL-HDR1, the processing module inserts SL-HDR metadata including or representing luminance mapping variables and color correction adjustment variables, as in step 404, into the vertical auxiliary channel of the SDI interface and provides these metadata to a module in charge of generating SDR data from HDR data by respecting the SDR-HDR-SDR roundtrip constraints. In one embodiment, the SL-HDR metadata is provided in an ST2108 container.

[0089] As can be seen, in steps 600 and 602, the processing module provides a stream representative of the calculated HDR data together with SL-HDR metadata, which specifies the tone mapping process to be applied to the HDR data. Note that since the HDR data is obtained (in step 502) from the SDR data, the HDR data with metadata represents the SDR data.

[0090] When applying step 612 in the context of SL-HDR, a processing module of the module responsible for generating SDR data (e.g., a SL-HDR pre-processor) calculates the L-LUT and B-LUT from the luminance mapping variables and color correction adjustment variables represented in the SL-HDR metadata received in the ST2108 container.

[0091] The processing module then generates SDR output data from the formatted HDR input data by applying a TM process based on the L-LUT and the B-LUT, in other words, the processing module applies a tone mapping process specified by the SL-HDR metadata to the HDR data.

[0092] It should be noted that in the concatenated ITM / TM process of Figures 6A and 6B, when applied in the context of SL-HDR1, the SL-HDR metadata is no longer generated by the module responsible for the TM process (e.g., the SL-HDR pre-processor), but by the module responsible for the ITM process (e.g., the ITM tool).

[0093] In an embodiment, referred to as the first dynamic embodiment, the concatenated ITM / TM process of Figures 6A and 6B is applied to each image contained in the SDR data acquired in step 501. Thus, the module in charge of the TM process (e.g. the SL-HDR pre-processor or the TM tool of Figure 3) receives new metadata for each image contained in the HDR data.

[0094] In another embodiment, referred to as the second dynamic embodiment, the concatenated ITM / TM process of Figures 6A and 6B is applied to a group of images contained in the SDR data acquired in step 501. Thus, the module in charge of the TM process (e.g. the SL-HDR pre-processor or the TM tool of Figure 3) receives new metadata for each group of images contained in the HDR data.

[0095] In another embodiment, called fixed embodiment, in step 502, instead of dynamically calculating the ITM curve, the ITM curve is fixed for the SDR data. Thus, the module in charge of the TM process (e.g., the SL-HDR pre-processor or the TM tool in FIG. 3) receives fixed metadata of the HDR data once, e.g., at the beginning of the HDR / SDR content production. Nevertheless, even with this fixed ITM curve, the SDR-HDR-SDR round trip constraint is respected.

[0096] Below, further details are provided regarding step 601, which is the inverse calculation of the inverse tone mapping curve.

[0097] Document ITU-R BT.2446-1 describes in section 4.2 a method for converting SDR content into HDR content by using the following extension functions: Y' exp (P)=Y''(P) E(Y’’(P)) During the ceremony, ● Y' is in the range [0...1]. ● Y''=255.0×Y' ● When Y''≦T, E=a1Y'' 2 +b1Y''+c1 ● When Y''>T, E=a2Y'' 2 +b2Y''+c2 ● T=70 ● a1=1.8712e-5, b1=-2.7334e-3, c1=1.3141 ● a2=2.8305e-6, b2=-7.4622e-4, c2=1.2528

[0098] As can be seen, the expansion function is based on a power function where the exponent depends on the luminance value of the current pixel. This is called global expansion, which means that all input pixels with the same luminance at the input (SDR input) will have the same luminance at the output (HDR output).

[0099] There is another method called local expansion, which can be expressed as follows:

[0100]

number

[0101] In both cases (global or local augmentation), the augmented output is monotonic to match the input SDR image, and when Y at the input is 0, Y at the output is 0. exp is also 0.

[0102] It should be understood that if the augmentation method used for ITM is local, the method is not bijective, i.e., the SL-HDR preprocessor cannot retrieve SDR data. Retrieving SDR data is only possible if the augmentation method is global (monotone as described above) and therefore bijective. Nevertheless, using local augmentation for ITM can improve the visual quality of the retrieved SDR data by adding details locally.

[0103] The same document ITU-R BT.2446-1 also specifies that the chroma portion of the input SDR data (i.e. UV) should be scaled by using a chroma scaling factor Sc. SDR ) is described.

[0104]

number

[0105]

number

[0106] Considering a peak nit of "1000" nits for HDR data, it must be understood that the ITM curve must stay below the peak nit value to be reversible. An example of an ITM curve is shown in Figure 7A that follows this recommendation. In effect, each input value is associated with a unique output value.

[0107] FIG. 7B shows another example of an ITM curve that is not fully reversible, i.e., Y SDR All values ​​above 235 are extended to 1000, which means that when converted back to SDR they will be clipped to 235.

[0108] It is very easy to invert an ITM curve if the ITM curve itself is obvious. An example of an obvious ITM curve is given by the following equation: Y exp (Y)=Y 1.25* 1023 / 255 1.25 Here, the extended values ​​of Y in the range [0...255] are mapped into the range [0...1023]. The inverse curve can be expressed as: Y=(10 (logYexp-A) ) 1 / 1.25 Here, A=log(1023 / 255 1.25 )=1.7 10 -3

[0109] For example, if Y=157, Y exp =557.92. Using the inverse formula, we get: Y=(10 (logYexp-A) ) 1 / 1.25 =(10 (2.7466-0.0017) ) 1 / 1.25 =(555.78) 1 / 1.25 =157

[0110] This allows a LUT with '1024' entries to fill every value of Yexp between '0' and '1023' using this formula.

[0111] However, the ITM curve is less clear (e.g., when the expansion is done using a gain function that varies with Y: exp =Y G(Y) ,The ,difficulty ,increases ,if ,the ,ITM ,is ,dynamic, ,i.e., ,the ,gain ,function ,depends ,on ,a ,criterion ,extracted ,from ,the ,current ,image., ,Then, ,using ,a ,lookup ,table, ,the ,ITM ,curve ,is ,evaluated ,on ,the ,run ,(one ,curve ,per ,image) ,and ,the ,inverse ,ITM ,curve ,follows ,the ,same ,behavior.

[0112] As an example, consider the following: ● The ITM lookup table ITMlut has "1025" input and floating point output, where Y is in the range [0...255]. The inverse or reverse ITM lookup table RITMlut has "1025" input and floating point output, where Yexp is in the range [0...1000].

[0113] next, ● ITMlut[0] contains the extended value of Y=0, and ITMlut

[1024] contains the extended value of Y=255. Then, each entry i of ITMlut is * Stores an extended value of 255 / 1024. This extended value is rescaled from the range [0...1000] to the range [0...1024]. ● RITMlut[0] contains the value Y that produces an extended value equal to “0”, so RITMlut[0] = 0, and RITMlut

[1024] contains the value of Y that produces an extended value equal to “1024”, so RITMlut

[1024] = 255.

[0114] Next, constructing the inverse ITM lookup table RITMlut consists of finding, for each entry j of RITMlut (for each value of j between "0" and "1024"), a pseudo-entry in the ITM lookup table ITMlut, i.e. an entry located between two successive real entries of the ITM lookup table ITMlut that produces the exact integer value j. This is done using interpolation: given j, the first integer value i whose value ITMlut[i] is immediately above j is searched for. Then, the value delta is calculated. delta = ITMlut[i] - ITMlut[i-1] next, RITMlut[j]=(i-1)+(j-ITMlut[i-1]) / delta

[0115] As a numerical example, the following can be considered. If ITMlut

[0500] = 200.3 and ITMlut

[0501] = 202.4, then delta = 202.4 - 200.3 = 2.1.

[0116] The values ​​of the inverse ITM lookup table RITMlut for j=201 and j=202 are as follows: RITMlut

[0201] =(500+(201-200.3) / 2.1) * 255 / 1024=124.59 RITMlut

[0202] =(500+(202-200.3) / 2.1) * 255 / 1024=124.71 On the other hand, "500" and "501", when rescaled to 255, become "124.51" and "124.76".

[0117] It should be noted that if the expansion function does not rise to the peak nit, it will not be possible to find the highest entry value of the inverse ITM lookup table RITMlut. Then, these highest values ​​can be set to "255".

[0118] When the inverse ITM lookup table RITMlut is used in an integer context, for example if the output has to be loaded into an L-LUT which is a 16-bit integer, the floating-point numbers in the inverse ITM lookup table RITMlut are scaled to 65535 and rounded to integer values, which means that 65535 matches the maximum SDR input value, i.e. 255.

[0119] It has been found that in terms of chroma components, a general HDR transformation can be expressed as follows: UV HDR =sat(Y) * (Y HDR / Y) * UV

[0120] On the SL-HDR side, the B-LUT is addressed by the output of the L-LUT (and then by Y) (i.e. the input / entry of the B-LUT is the output of the L-LUT), and the output of the B-LUT is addressed by UV to extract the UV values. HDR The above equation can be written as: UV HDR =sat(Y) * (Y G(Y) / Y) * UV=sat(Y) * (Y G(Y)-1 ) * UV

[0121] next UV=UV HDR * (Y 1-G(Y) / sat(Y)

[0122] Finally, the B-LUT is a function of Y. B-LUT[Y]=Y 1-G(Y) / sat(Y) G(Y) is the gain function used in the expansion, Y HDR =Y G(Y) It is.

[0123] In the following, further details are provided regarding step 601, the estimation of metadata from the L-LUT and B-LUT.

[0124] Estimation of luminance mapping variables As described in §6.2.5 of the SL-HDR1 specification, the luminance mapping variables are defined by two sets of parameters: ● The first set of parameters includes six parameters used to define the luminance mapping curve: tmInputSignalBlackLevelOffset, tmInputSignalWhiteLevelOffset, shadowGain, highlightGain, midToneWidthAdjFactor, and tmOutputFineTuningNumVal. ● A second set of parameters, including a limited number of pairs (tmOutputFineTuningX[i], tmOutputFineTuningY[i]) used in the tone mapping output fine tuning function. These pairs define the coordinates of the pivot point, where the first coordinate tmOutputFineTuningX[i] corresponds to the position of the pivot point and the second coordinate tmOutputFineTuningY[i] corresponds to the value of the pivot point.

[0125] Figure 8 illustrates an example of a process for determining luminance mapping variables. The process of Figure 8 is typically applied by each ITM tool (ITM1 202A, ITM2 202B, and ITM3 202C) in the HDR production environment of Figure 3. The process of Figure 8 is implemented, for example, by a processing module described in more detail below in connection with Figure 11A.

[0126] The two sets of parameters are estimated in two successive steps.

[0127] In step 801, the processing module determines a first set of parameters by default as a function of the HDR peak luminance value, whatever the L-LUT and B-LUT values ​​are, in other words, the parameters of the first set of parameters are given default values ​​that depend on the HDR peak luminance value.

[0128] In a variation of step 801, if the lookup of the L-LUT is very far from the luminance mapping curve derived from the default set of parameters after being transformed into the perceptually uniform domain, additional processes are performed. For example, if the slope of the LUT curve at the origin and the slope of the luminance mapping curve derived from the default set of parameters are very different, the parameter shadowGain defined in the SL-HDR1 specification is modified to better match at low luminance levels.

[0129] In steps 802 and 803, the processing module recursively determines a second set of parameters by optimizing the positions (tmOutputFineTuningX) and values ​​(tmOutputFineTuningY) of the pivot points. In the embodiment of step 802, the number of pivot points (given by the value tmOutputFineTuningNumVal) is fixed to "10", the maximum value possible in the SL-HDR1 specification. However, tmOutputFineTuningNumVal may be less than "10".

[0130] During step 802, the processing module applies an initialization process to the pivot points. In this initialization process, an initial set of pivot points is defined. The number of pivot points in the initial set can be set to different values ​​from "10" to the number of points in the L-LUT. As an example, the number of pivot points is set to "65". During the initialization process, each pivot point is given an initial value (tmOutputFineTuningX[i], tmOutputFineTuningY[i]), for i in [0..tmOutputFineTuningNumVal-1]. ● tmOutputFineTuningX[i]: The value of the given x[i] in nits between '0' and HDR peak luminance. HDR_nits [i] HDR input luminance is within the HDR perceptual uniformity region x PU _ HDR The luminance mapping curve derived from the first set of parameters determined in step 801 is transformed into the input x PU _ HDR For [i], output tmOutputFineTuningX[i]. ● tmOutputFineTuningY[i]: previous x HDR_nits [i] corresponds to the index k[i] at the input of the L-LUT. HDR_nits [i] is chosen such that k[i] is an integer. tmOutputFineTuningY[i] is the transformation of the output L-LUT[k[i]] to the SDR perceptually uniform domain.

[0131] In step 803, the processing module recursively removes pivot points to maintain a number of pivot points in the set, tmOutputFineTuningNumVal, at the end of step 803. To determine which pivot points can be removed, a criterion based on a cost function is applied. Several cost functions can be used. A cost function corresponding to the error function between the L-LUT and the reconstructed L-LUT based on the estimated parameters; ● A cost function corresponding to the error function between an upsampled version of the tone mapping output tweak function with an initial pivot point of '65' and an upsampled version of the tone mapping output tweak function with the remaining pivot points.

[0132] Estimation of color correction adjustment variables As described in §6.2.6 of the SLHDR1 specification, the color correction adjustment variables consist of a limited number of pairs (saturationGainX[i], saturationGainY[i]) used in the saturation gain function. These pairs define the coordinates of a pivot point, where the first coordinate saturationGainX[i] corresponds to the position of the pivot point and the second coordinate saturationGainY[i] corresponds to the value of the pivot point.

[0133] Figure 9 illustrates an example of a process for determining color correction adjustment variables. The process of Figure 9 is typically applied by each ITM tool (ITM1 202A, ITM2 202B, and ITM3 202C) in the HDR production environment of Figure 3. The process of Figure 9 is implemented, for example, by a processing module described in more detail below in connection with Figure 11A.

[0134] In step 901, the processing module calculates an initial LUT SqrtL_over_BetaP as a function of: ● HDR peak brightness value, • The brightness mapping variables estimated above in the process of Figure 8 .

[0135] In steps 902 and 903, the position (saturationGainX[i]) and value (saturationGainY[i]) of the pivot point are recursively calculated.

[0136] In step 902, the processing module applies an initialization process. The recursive process starts again with the initialization process, in which an initial set of pivot points is calculated. The number of pivot points in the initial set can be set to different values ​​from "10" to the number of points in the L-LUT. As an example, the number of pivot points is set to "65". During the initialization process, each pivot point is given an initial value saturationGainY, which is defined as the ratio between the initial LUT SqrtL_over_BetaP and the B-LUT.

[0137] In step 903, the processing module recursively removes pivot points in order to keep the number of pivot points in the set, tmOutputFineTuningNumVal, at the end of step 903. To determine which pivot points can be removed, a criterion based on a cost function is applied. For example, a cost function corresponding to the error function between the B-LUT and a reconstructed B-LUT based on the estimated parameters (i.e., both the luminance mapping variables and the color correction adjustment variables) is used.

[0138] In some cases, content producers may wish to deliver SDR content that guarantees a full SDR-HDR-SDR roundtrip and allows for HDR reconstruction by adding metadata alongside the delivered SDR content, without the need for HDR content reuse on the production side.

[0139] In this case, the linked processes described in connection with Figures 6A and 6B may be simplified and replaced by the integrated SDR roundtrip variant for the distribution solution described in Figure 10A.

[0140] Fig. 10A shows a schematic example of a process according to a variant embodiment. The process of Fig. 10A is typically applied by a module in charge of providing original SDR data, which can then be manipulated by other modules to generate HDR from the original SDR data and then SDR again. The process of Fig. 10A is implemented, for example, by a processing module that will be described in detail later in relation to Fig. 11A.

[0141] The process of FIG. 10A begins with step 501, already described in connection with FIG. 6A.

[0142] In step 1000 , the processing module directly outputs (ie, transmits or provides) the SDR data obtained in step 501 .

[0143] In step 1001, the processing module generates metadata representative of an ITM process applied to SDR data in order to generate HDR data from these SDR data. More precisely, in step 1001, the processing module calculates information representative of the ITM process adapted to generate HDR data from the SDR data (e.g., an ITM curve or a TM curve) and inserts this information into the metadata.

[0144] In step 1002, the processing module provides (i.e., outputs or transmits) metadata together with the output SDR data to a module responsible for generating HDR data from the SDR data.

[0145] Figure 10B details step 1001 of the process of Figure 10A in the context of SL-HDR1, in which the processes of Figures 10A and 10B are applied, for example, by a module located after the SDR source 201 of Figure 3.

[0146] In step 10011, the processing module analyzes the SDR input data and uses the results of the analysis to calculate the most appropriate inverse tone mapping curve for generating HDR data from the SDR data.

[0147] Step 10011 is followed by steps 6011, 6012 and 6013 already described in relation to FIG. 6B.

[0148] Step 603 is followed by step 1002. In the context of SL-HDR1, during step 1002 the estimated SL-HDR metadata is inserted into the vertical auxiliary channel of the SDI interface and delivered directly together with the output SDR data.

[0149] As can be seen, in steps 1000 and 1002, the processing module provides a stream representing SDR data together with SL-HDR metadata that specifies the tone mapping process to be applied to the HDR data, but also indirectly specifies the inverse tone mapping process that allows these HDR data to be obtained.

[0150] FIG. 11A illustrates an example of a hardware architecture of a processing module 110 included in a live production system 20, a system or module included in the live production system 20, such as ITM tools 202A, 202B and 202C or TM tools 204B and 204A, the master central control system 21, or a system or module of the master central control system 21, such as ITM tool 211, or devices 22A and 22B. The processing module 110 includes a processor or central processing unit (CPU) 1100, including, by way of non-limiting example, one or more microprocessors, general purpose computers, special purpose computers, and processors based on multi-core architectures, connected by a communication bus 1105; a random access memory (RAM) 1101; a read only memory (ROM) 1102; and a memory controller 1104, which may be an electrically erasable programmable read-only memory (EEPROM), a read only memory (ROM), a programmable read-only memory (PROM), a random access memory (RAM), a dynamic random access memory (DRAM), a static random access memory (SRAM), a flash, a magnetic disk drive, and / or an optical disk drive, or a secure digital (SD) card reader and / or a hard disk drive. a storage unit 1103 that may include non-volatile memory and / or volatile memory including, but not limited to, a storage media reader such as a storage drive (HDD) and / or a network-accessible storage device, and at least one communication interface 1104 for exchanging data with other modules, devices, systems, or equipment.The communication interface 1104 may include, but is not limited to, a transceiver configured to transmit and receive data over the communication network 111. The communication interface 1104 may include, but is not limited to, a modem or a network card.

[0151] For example, the communication interface 1004 may enable the processing module 100 to receive HDR or SDR data and output HDR or SDR data along with SL-HDR metadata, for example.

[0152] The processor 1100 can execute instructions loaded into the RAM 1101 from the ROM 1102, an external memory (not shown), a storage medium, or a communication network. When the processing module 110 is powered on, the processor 1100 can read instructions from the RAM 1101 and execute them. These instructions form a computer program that causes the processor 1100 to perform an ITM or TM process, including, for example, the processes described in connection with Figures 4, 5, 6A, 6B, 8, 9, and 10.

[0153] All or part of the algorithms and steps of the process may be implemented in software form by execution of a set of instructions by a programmable machine such as a Digital Signal Processor (DSP) or a microcontroller, or in hardware form by a machine or dedicated component such as a Field-Programmable Gate Array (FPGA) or an Application-Specific Integrated Circuit (ASIC).

[0154] FIG. 11C illustrates a block diagram of an example of a system A corresponding to a device 22A or 22B in which various aspects and embodiments are implemented.

[0155] System A may be embodied as a device including various components or modules and configured to generate SDR or HDR content adapted to be displayed on an adapted display device. 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, alone or in combination, may be embodied in a single Integrated Circuit (IC), multiple ICs, and / or separate components. For example, in at least one embodiment, System A comprises one processing module 110 that implements the decoding of SDR or HDR content. 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 through dedicated input and / or output ports.

[0156] Input to the processing module 110 may be provided via various input modules, as shown in block 60. Such input modules may include, but are not limited to, (i) a Radio Frequency (RF) module that receives, for example, a radio frequency (RF) signal transmitted over the air from a broadcast station, (ii) a component (COMP) input module (or a 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 include composite video, not shown in FIG. 11C.

[0157] In various embodiments, the input modules of block 60 have associated respective input processing elements as known in the art. 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) band-limiting again to a narrower frequency band to select a signal frequency band, which in certain embodiments may be referred to (for example) as a channel, (iv) demodulating the down-converted and band-limited 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 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 section may include, for example, a tuner that performs various of these functions, including down-converting a received signal to a lower frequency (e.g., an intermediate frequency or a frequency close to baseband) or to baseband. In various embodiments, the order of the above-described (and other) elements is rearranged, some of these elements are removed, and / or other elements that perform similar or different functions are added. Adding elements may include inserting elements between existing elements, such as inserting amplifiers and analog-to-digital converters. In various embodiments, the RF module includes an antenna.

[0158] Additionally, the USB module and / or HDMI module may include respective interface processors for connecting system A to other electronic devices via a USB connection and / or an HDMI connection. It should be understood that various aspects of the input processing, e.g., Reed-Solomon error correction, may be implemented, for example, in a separate input processing IC or within processing module 110, as appropriate. Similarly, aspects of the USB or HDMI interface processing may be implemented in a separate interface IC or within processing module 110, as appropriate. The demodulated, error corrected, and demultiplexed stream is provided to processing module 110.

[0159] The various elements of system A may be provided in a unitary housing, where the various elements may be interconnected and transmit data between them using any suitable connection arrangement, e.g., an internal bus, including an Inter-IC (I2C) bus, wires, and printed circuit boards, as known in the art. For example, in system A, processing module 110 is interconnected to the other elements of system A by bus 1105.

[0160] A communication interface 1104 of the processing module 110 enables System A to communicate over a communication network 111. The communication network 111 may be implemented, for example, in a wired and / or wireless medium.

[0161] Data is streamed or otherwise provided to system A in various embodiments using a wireless network such as a Wi-Fi network, e.g., IEEE 802.11 (IEEE refers to the Institute of Electrical and Electronics Engineers). The Wi-Fi signal in these embodiments is received by a communication network 111 and a communication interface 1104 adapted for Wi-Fi communication. The communication network 111 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. In still other embodiments, the RF connection of the input block 60 is used to provide streaming data to system A. As noted above, various embodiments provide data in a non-streaming format, for example, when system A is a smartphone or tablet. Additionally, various embodiments use wireless networks other than Wi-Fi, e.g., cellular networks or Bluetooth networks.

[0162] System A can provide output signals to various output devices using communication network 111 or bus 1105. For example, system A can provide a decoded SDR or HDR signal.

[0163] System A can provide output signals to various output devices, including a display 64 (e.g., if system A is a set-top box providing the decoded SDR or HDR signal to a display device), speakers 65, and other peripheral devices 66. The display 64 in 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 display 64 can be for a television, a tablet, a laptop, a mobile phone, or other device. The display 64 can also be integrated with other components (e.g., as in a smartphone) or can be separate (e.g., an external monitor for a laptop). The display device 64 is compatible with SDR or HDR content. The other peripheral devices 66 in various example embodiments include one or more of a standalone digital video disc (or digital versatile disc) (DVR in both terms), a disc player, a stereo system, and / or a lighting system. Various embodiments use one or more peripheral devices 66 that provide functionality based on the output of system A. For example, a disc player performs the function of playing the output of system A.

[0164] In various embodiments, control signals are communicated between system A and display 64, speaker 65, or other peripheral devices 66 using signal transmission such as AV.Link, Consumer Electronics Control (CEC), or other communication protocols that allow control between devices with or without user intervention. The output devices can be communicatively coupled to system B via dedicated connections through respective interfaces 61, 62, and 63. Alternatively, the output devices can be connected to system A via communication interface 1104 and using communication network 111. Display 64 and speaker 65 can be integrated into a single unit with other components of system A in an electronic device such as, for example, a television. In various embodiments, display interface 61 includes a display driver such as, for example, a Timing Controller (T Con) chip.

[0165] Display 64 and speakers 65 may alternatively be separate from one or more of the other components, for example, if the RF module of input 60 is part of a separate set-top box. In various embodiments in which display 64 and speakers 65 are external components, the output signals may be provided via dedicated output connections including, for example, an HDMI port, a USB port, or a COMP output.

[0166] FIG. 11B shows a block diagram of an example of a system B adapted to implement a live production system 20, or a module or device of the live production system 20, or a master central control system 21, or a module or device of the live control system 21, in which various aspects and embodiments are implemented.

[0167] System B may be embodied as a device including various components and modules as previously described and configured to perform one or more of the aspects and embodiments described in this document.

[0168] Examples of such devices include various electronic devices, such as, but not limited to, personal computers, laptop computers, cameras, smartphones, and servers. The elements or modules of System B, alone or in combination, can be embodied in a single Integrated Circuit (IC), multiple ICs, and / or separate components. For example, in at least one embodiment, System B comprises one processing module 110 that implements either an ITM tool (202A, 202B, 202C, 211) or a TM tool (204A, 204B). 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 through dedicated input and / or output ports.

[0169] Input to the processing module 110 may be provided via various input modules as indicated at block 60 already described with respect to FIG. 11C.

[0170] The various elements of system B may be provided in a unitary housing, where the various elements may be interconnected and transmit data between them using any suitable connection arrangement, e.g., an internal bus, including an Inter-IC (I2C) bus, wires, and printed circuit boards, as known in the art. For example, in system B, processing module 110 is interconnected to other elements of system B by bus 1105.

[0171] A communication interface 1104 of the processing module 110 enables System B to communicate over a communication network 111. The communication network 111 may be implemented, for example, in a wired and / or wireless medium.

[0172] Data is streamed or otherwise provided to system B in various embodiments using a wireless network such as a Wi-Fi network, e.g., IEEE 802.11 (IEEE refers to the Institute of Electrical and Electronics Engineers). The Wi-Fi signal in these embodiments is received by a communication network 2 and a communication interface 1104 adapted for Wi-Fi communication. The communication network 111 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. In yet other embodiments, the RF connection of input block 60 is used to provide streaming data to system B. As indicated above, various embodiments provide data in a non-streaming manner.

[0173] Where a figure is presented as a flow diagram, it should be understood that the figure also provides a block diagram of the corresponding apparatus. Similarly, where a figure is presented as a block diagram, it should be understood that the figure also provides a flow diagram of the corresponding method / process.

[0174] The implementations and aspects described herein may be implemented, for example, in a method or process, an apparatus, a software program, a data stream, or a signal. Even if discussed in the context of only a single implementation (e.g., discussed only as a method), the implementation of the discussed features may also be implemented in other forms (e.g., an apparatus or a program). For example, an apparatus may be implemented in suitable hardware, software, and firmware. A method may be implemented, for example, in a processor, where a processor refers to a general processing device including, for example, a computer, a microprocessor, an integrated circuit, or a programmable logic device. A processor also includes, for example, a communication device such as a computer, a mobile phone, a Portable / Personal Digital Assistant ("PDA"), a smart phone, a tablet, and other devices that facilitate communication of information between end users.

[0175] Reference to "one embodiment" or "an embodiment" or "one implementation" or "an implementation," as well as other variations thereof, means that a particular feature, structure, characteristic, etc. described in connection with that embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "an embodiment" or "in one implementation" or "in an implementation," as well as other variations thereof, appearing in various places throughout this application are not necessarily all referring to the same embodiment.

[0176] Additionally, the application may refer to "determining" various information. Determining information may include, for example, one or more of estimating information, calculating information, predicting information, retrieving information from a memory, or retrieving information from, for example, another device, module, or user.

[0177] Additionally, the application may refer to "accessing" various 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.

[0178] Additionally, the application may refer to "receiving" various information. Receiving, like "accessing," 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). Furthermore, "receiving" generally involves in some manner, for example, an operation such as storing information, processing information, transmitting information, moving information, copying information, erasing information, calculating information, determining information, predicting information, or estimating information.

[0179] Use of any of the terms " / ", "and / or", "at least one of", "one or more", e.g., "A / B", "A and / or B", "at least one of A and B", "one or more of A and B" is intended to encompass the selection of only the first listed alternative (A), or the selection of only the second listed alternative (B), or the selection of both alternatives (A and B). As a further example, "A, B, and / or C" and "at least one of A, B, and C", "one or more of A, B, and C" are intended to encompass the selection of only the first listed alternative (A), or the selection of only the second listed alternative (B), or the selection of only the third listed alternative (C), or the selection of only the first and second listed alternatives (A and B), or the selection of only the first and third listed alternatives (A and C), or the selection of only the second and third listed alternatives (B and C), or the selection of all three alternatives (A, B, and C). This may be expanded to include as many of the items listed as would be apparent to one of ordinary skill in this and related arts.

[0180] As will be apparent to one skilled in the art, implementations or embodiments can produce various signals formatted to carry information that can be, for example, stored or transmitted. Information can include, for example, instructions for performing a method or data produced by one of the described implementations or embodiments. For example, a signal can be formatted to convey the HDR or SDR image or video sequence and SL-HDR metadata of the described embodiments. For example, such a signal can be formatted as an electromagnetic wave (e.g., using a radio frequency portion of the spectrum) or as a baseband signal. Formatting can include, for example, encoding the HDR or SDR image or video sequence with the SL-HDR metadata into an encoded stream and modulating a carrier with the encoded stream. The information that the signal carries can be, for example, analog or digital information. As is known, the signal can be transmitted over a variety of different wired or wireless links. The signal can be stored in a processor-readable medium.

[0181] Several embodiments have been described above. The features of these embodiments may be provided alone or in any combination. In addition, the embodiments may include one or more of the following features, devices, or aspects, across various claim categories and types, alone or in any combination. ● A bitstream or signal containing one or more of the described SDR or HDR data and / or SL-HDR metadata, or variations thereof. ● Creating and / or transmitting and / or receiving and / or decoding bitstreams or signals containing one or more of the described SDR or HDR data and / or SL-HDR metadata, or variations thereof. A server, camera, television, set-top box, mobile phone, tablet, personal computer, or other electronic device that executes at least one of the described embodiments. ● A television, set-top box, mobile phone, tablet, personal computer, or other electronic device that performs at least one of the described embodiments and displays the resulting images (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 a channel (e.g., using a tuner) to receive a signal including encoded SDR or HDR data and / or SL-HDR metadata and performs at least one of the described embodiments. ● A television, set-top box, mobile phone, tablet, personal computer, or other electronic device that receives a signal containing SDR or HDR data and / or SL-HDR metadata wirelessly (e.g., using an antenna) and performs at least one of the described embodiments. ● A server, camera, mobile phone, tablet, personal computer, or other electronic device that tunes a channel (e.g., using a tuner) to transmit a signal including SDR or HDR data and / or SL-HDR metadata and performs at least one of the described embodiments. ● A server, camera, mobile phone, tablet, personal computer, or other electronic device that wirelessly transmits (e.g., using an antenna) a signal containing SDR or HDR data and / or SL-HDR metadata and performs at least one of the described embodiments.

Claims

1. Obtaining first standard dynamic range data; obtaining information representative of an inverse tone mapping process adapted to generate high dynamic range data from the first standard dynamic range data, and inserting the information into metadata; and applying an inverse tone mapping process, including generating high dynamic range data from the first standard dynamic range data, using the information representing the inverse tone mapping process inserted in the metadata; obtaining the high dynamic range data and the metadata; and applying a pre-processing process, the pre-processing process comprising applying a tone mapping process derived from the information representing an inverse tone mapping process inserted in the metadata to generate second standard dynamic range data from the high dynamic range data; A method for providing

2. The method of claim 1 , wherein the information represents an inverse tone mapping curve or a tone mapping curve.

3. 3. The method of claim 2, comprising, in response to the information representing a tone mapping curve, calculating an inverse of the inverse tone mapping curve used to define the inverse tone mapping process.

4. calculating a first lookup table and a second lookup table from an inverse of the inverse tone mapping curve, the first lookup table being adapted to tone map a luminance component of high dynamic range data, and the second lookup table being adapted to correct a color component of the high dynamic range data; estimating a first variable representing a tone mapping function and a second variable representing a color correction function from the first and second lookup tables, the first and second variables being the information representing the inverse tone mapping process inserted into the metadata; The method of claim 3 comprising:

5. The method of claim 1 , wherein the method is applied to each picture of the first standard dynamic range data or to a group of pictures of the first standard dynamic range data.

6. A device, acquiring first standard dynamic range data; obtaining information representative of an inverse tone mapping process adapted to generate high dynamic range data from the first standard dynamic range data, and inserting the information into metadata; and applying an inverse tone mapping process, including generating high dynamic range data from the first standard dynamic range data using the information representing the inverse tone mapping process inserted in the metadata; obtaining the high dynamic range data and the metadata; and applying a pre-processing process that includes applying a tone mapping process derived from the information representing an inverse tone mapping process inserted into the metadata to generate second standard dynamic range data from the high dynamic range data. An electronic circuit configured as follows: A device comprising:

7. The device of claim 6 , wherein the information represents an inverse tone mapping curve or a tone mapping curve.

8. 8. The device of claim 7, wherein, in response to the information representing a tone mapping curve, the electronic circuitry is further configured to calculate an inverse of an inverse tone mapping curve used to define the inverse tone mapping process.

9. The electronic circuit calculating a first lookup table and a second lookup table from an inverse of the inverse tone mapping curve, the first lookup table being adapted to tone map a luminance component of high dynamic range data, and the second lookup table being adapted to correct a color component of the high dynamic range data; and estimating a first variable representing a tone mapping function and a second variable representing a color correction function from the first and second lookup tables, the first and second variables being the information representing the inverse tone mapping process inserted into the metadata. The device of claim 8 further configured to:

10. A non-transitory information storage medium having stored thereon program code instructions for carrying out the method of any one of claims 1 to 5.

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