Luminance mapping with chroma scaling for progressive decoding refresh

Abstract

A method, apparatus, and computer program product for managing a luminance mapping with chroma scaling (LMCS) process for progressive decode refresh (GDR) pictures. In the context of the method, the method accesses a picture to be decoded and determines whether the picture is within a GDR period. The method can also prevent the LMCS decoding process from being applied to pictures within the GDR period. Another method can determine whether a virtual boundary is within a current coding tree unit of a picture having a GDR period, and if so, prevent the chroma residual scaling decoding process associated with LMCS from being applied to one or more coding units within a clean area. Another method can fill an adjacent pixel region with one or more reconstructed pixels from a clean area for the chroma residual scaling decoding process associated with LMCS.

Description

Technical Field

[0001] Example embodiments generally relate to video coding techniques, and more particularly to techniques for efficient management of a luminance mapping process with chroma scaling. Background Art

[0002] In video coding designs such as Advanced Video Coding (AVC), High Efficiency Video Coding (HEVC), and / or Versatile Video Coding (VVC), an encoded video sequence may include intra-coded pictures and inter-coded pictures. Intra-coded pictures typically use more bits than inter-coded pictures, so the transmission time of intra-coded pictures increases the encoder-to-decoder delay. For low-latency applications, it may be desirable for all encoded pictures to use a similar number of bits so that the encoder-to-decoder delay can be reduced to approximately one picture interval. Thus, intra-coded pictures are not suitable for (ultra-) low-latency applications. However, intra-coded pictures may be required at random access points.

[0003] Methods such as Gradual Decoding Refresh (GDR), Gradual Random Access (GRA), and Progressive Intra Refresh (PIR) can mitigate the latency issue of intra-coded pictures. Instead of encoding an intra picture at a random access point, GDR gradually refreshes a picture by extending the intra-coded region over several pictures. However, GDR may encounter incompatibilities with certain coding tools and / or other problems, such as Luminance Mapping with Chroma Scaling (LMCS), which is a process applied as part of the decoding process that maps luminance samples to specific values and may apply a scaling operation to the values of chroma samples. Summary of the Invention

[0004] In one embodiment, there is provided an apparatus that includes at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus to access a picture to be decoded. The at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to determine whether the picture is within a gradual decoding refresh period. The at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to: prevent a luminance mapping with chroma scaling decoding process from being applied to the picture in the case where the picture is within the gradual decoding refresh period.

[0005] In some embodiments of the apparatus, the luminance mapping decoding process with chroma scaling includes all decoding processes associated with the luminance mapping with chroma scaling. In some embodiments of the apparatus, the luminance mapping decoding process with chroma scaling only includes the chroma residual scaling decoding process associated with the luminance mapping with chroma scaling. In some embodiments of the apparatus, the prevention of the luminance mapping decoding process with chroma scaling is applied regardless of whether the picture is within a progressive decoding refresh period. In some embodiments of the apparatus, the prevention of the luminance mapping decoding process with chroma scaling is also based on an enable value associated with a virtual boundary within the picture. In some embodiments of the apparatus, the use of the enable value associated with the virtual boundary is based on a second enable value associated with the luminance mapping with chroma scaling (LMCS).

[0006] In another embodiment, an apparatus is provided that includes means for accessing a picture to be decoded. The apparatus further includes means for determining whether the picture is within a progressive decoding refresh period. The apparatus further includes means for preventing the luminance mapping decoding process with chroma scaling from being applied to the picture if the picture is within a progressive decoding refresh period. In some embodiments, the luminance mapping decoding process with chroma scaling includes all decoding processes associated with the luminance mapping with chroma scaling. In some embodiments, the luminance mapping decoding process with chroma scaling only includes the chroma residual scaling decoding process associated with the luminance mapping with chroma scaling. In some embodiments of the apparatus, the prevention of the luminance mapping decoding process with chroma scaling is applied regardless of whether the picture is within a progressive decoding refresh period. In some embodiments of the apparatus, the prevention of the luminance mapping decoding process with chroma scaling is also based on an enable value associated with a virtual boundary within the picture. In some embodiments of the apparatus, the use of the enable value associated with the virtual boundary is based on a second enable value associated with the luminance mapping with chroma scaling (LMCS).

[0007] In another embodiment, a computer program product is provided that includes a non-transitory computer-readable storage medium having program code portions stored thereon, the program code portions being configured to access a picture to be decoded when executed. The program code portions are further configured to determine whether the picture is within a progressive decoding refresh period when executed. The program code portions are further configured to, when executed: prevent the luminance mapping decoding process with chroma scaling from being applied to the picture if the picture is within a progressive decoding refresh period.

[0008] In some embodiments of the computer program product, the luminance mapping decoding process with chroma scaling includes all decoding processes associated with the luminance mapping with chroma scaling. In some embodiments of the computer program product, the luminance mapping decoding process with chroma scaling only includes the chroma residual scaling decoding process associated with the luminance mapping with chroma scaling. In some embodiments of the computer program product, the prevention of the luminance mapping decoding process with chroma scaling is applied regardless of whether the picture is within a progressive decoding refresh period. In some embodiments of the computer program product, the prevention of the luminance mapping decoding process with chroma scaling is also based on an enable value associated with a virtual boundary within the picture. In some embodiments of the computer program product, the use of the enable value associated with the virtual boundary is based on a second enable value associated with the luminance mapping with chroma scaling (LMCS).

[0009] In another embodiment, a method is provided that includes accessing a picture to be decoded. The method further includes determining whether the picture is within a progressive decoding refresh period. The method further includes: in the case where the picture is within a progressive decoding refresh period, preventing the luminance mapping decoding process with chroma scaling from being applied to the picture. In some embodiments of the method, the luminance mapping decoding process with chroma scaling includes all decoding processes associated with the luminance mapping with chroma scaling. In some embodiments of the method, the luminance mapping decoding process with chroma scaling only includes the chroma residual scaling decoding process associated with the luminance mapping with chroma scaling. In some embodiments of the method, the prevention of the luminance mapping decoding process with chroma scaling is applied regardless of whether the picture is within a progressive decoding refresh period. In some embodiments of the method, the prevention of the luminance mapping decoding process with chroma scaling is also based on an enable value associated with a virtual boundary within the picture. In some embodiments of the method, the use of the enable value associated with the virtual boundary is based on a second enable value associated with the luminance mapping with chroma scaling (LMCS).

[0010] In another embodiment, an apparatus is provided that includes at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus to access a picture to be decoded within a progressive decoding refresh period. The at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to determine whether a virtual boundary is within the current coding tree unit of the picture, the virtual boundary defining the separation between the clean area and the dirty area of the picture. The at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to: in the case where the virtual boundary is within the current coding tree unit, prevent the chroma residual scaling decoding process associated with the luminance mapping with chroma scaling from being applied to one or more coding units within the clean area.

[0011] In some embodiments of the apparatus, regardless of whether the picture is within the progressive decoding refresh period, prevention of applying the chrominance residual scaling decoding process associated with the luminance mapping with chrominance scaling to one or more coding units within the clean area is applied. In some embodiments of the apparatus, prevention of applying the chrominance residual scaling decoding process associated with the luminance mapping with chrominance scaling to one or more coding units within the clean area is further based on an enable value associated with a virtual boundary within the picture. In some embodiments of the apparatus, the use of the enable value associated with the virtual boundary is based on a second enable value associated with the luminance mapping with chrominance scaling (LMCS).

[0012] In another embodiment, there is provided an apparatus that includes components for accessing a picture to be decoded within a progressive decoding refresh period. The apparatus further includes components for determining whether a virtual boundary is within the current coding tree unit of the picture, the virtual boundary defining a separation between the clean area and the dirty area of the picture. The apparatus further includes: components for preventing the chrominance residual scaling decoding process associated with the luminance mapping with chrominance scaling from being applied to one or more coding units within the clean area when the virtual boundary is within the current coding tree unit.

[0013] In some embodiments of the apparatus, regardless of whether the picture is within the progressive decoding refresh period, prevention of applying the chrominance residual scaling decoding process associated with the luminance mapping with chrominance scaling to one or more coding units within the clean area is applied. In some embodiments of the apparatus, prevention of applying the chrominance residual scaling decoding process associated with the luminance mapping with chrominance scaling to one or more coding units within the clean area is further based on an enable value associated with a virtual boundary within the picture. In some embodiments of the apparatus, the use of the enable value associated with the virtual boundary is based on a second enable value associated with the luminance mapping with chrominance scaling (LMCS).

[0014] In another embodiment, there is provided a computer program product that includes a non-transitory computer-readable storage medium having program code portions stored thereon, the program code portions being configured to, when executed: access a picture to be decoded within a progressive decoding refresh period. The program code portions are further configured to, when executed: determine whether a virtual boundary is within the current coding tree unit of the picture, the virtual boundary defining a separation between the clean area and the dirty area of the picture. The program code portions are further configured to, when executed: prevent the chrominance residual scaling decoding process associated with the luminance mapping with chrominance scaling from being applied to one or more coding units within the clean area when the virtual boundary is within the current coding tree unit.

[0015] In some embodiments of the computer program product, regardless of whether the picture is within the progressive decoding refresh period, the prevention of applying the chrominance residual scaling decoding process associated with the luminance mapping with chrominance scaling to one or more coding units within the clean area is applied. In some embodiments of the computer program product, the prevention of applying the chrominance residual scaling decoding process associated with the luminance mapping with chrominance scaling to one or more coding units within the clean area is also based on an enable value associated with a virtual boundary within the picture. In some embodiments of the computer program product, the use of the enable value associated with the virtual boundary is based on a second enable value associated with the luminance mapping with chrominance scaling (LMCS).

[0016] In another embodiment, a method is provided that includes accessing a picture to be decoded within a progressive decoding refresh period. The method also includes determining whether a virtual boundary is within the current coding tree unit of the picture, where the virtual boundary defines the separation between the clean area and the dirty area of the picture. The method further includes, in the case where the virtual boundary is within the current coding tree unit, preventing the chrominance residual scaling decoding process associated with the luminance mapping with chrominance scaling from being applied to one or more coding units within the clean area.

[0017] In some embodiments of the method, regardless of whether the picture is within the progressive decoding refresh period, the prevention of applying the chrominance residual scaling decoding process associated with the luminance mapping with chrominance scaling to one or more coding units within the clean area is applied. In some embodiments of the method, the prevention of applying the chrominance residual scaling decoding process associated with the luminance mapping with chrominance scaling to one or more coding units within the clean area is also based on an enable value associated with a virtual boundary within the picture. In some embodiments of the method, the use of the enable value associated with the virtual boundary is based on a second enable value associated with the luminance mapping with chrominance scaling (LMCS).

[0018] In another embodiment, a device is provided that includes at least one processor and at least one memory containing computer program code, where the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to: access the current coding unit of a picture to be decoded within a progressive decoding refresh period, where the current coding unit is within the clean area. The at least one memory and the computer program code are also configured to, together with the at least one processor, cause the device to: determine whether one or more pixels within an adjacent pixel region are within the dirty area. The at least one memory and the computer program code are also configured to, together with the at least one processor, cause the device to: in the case where one or more pixels within the adjacent pixel region are determined to be within the dirty area, prevent all pixels within the adjacent pixel region from being used for the chrominance residual scaling process associated with the luminance mapping with chrominance scaling.

[0019] In some embodiments of the apparatus, regardless of whether the picture is within the progressive decoding refresh period, prevention of all pixels in the adjacent pixel region from being used in the chrominance residual scaling process associated with the luminance mapping with chrominance scaling is applied. In some embodiments of the apparatus, prevention of all pixels in the adjacent pixel region from being used in the chrominance residual scaling process associated with the luminance mapping with chrominance scaling is further based on an enable value associated with a virtual boundary within the picture. In some embodiments of the apparatus, the use of the enable value associated with the virtual boundary is based on a second enable value associated with the luminance mapping with chrominance scaling (LMCS).

[0020] In another embodiment, there is provided an apparatus that includes means for accessing a current coding unit of a picture to be decoded within a progressive decoding refresh period, the current coding unit being located within a clean region. The apparatus further includes means for determining whether one or more pixels within an adjacent pixel region are within a dirty region. The apparatus further includes means for preventing all pixels within the adjacent pixel region from being used in the chrominance residual scaling process associated with the luminance mapping with chrominance scaling in the case where one or more pixels within the adjacent pixel region are determined to be within the dirty region.

[0021] In some embodiments of the apparatus, regardless of whether the picture is within the progressive decoding refresh period, prevention of all pixels in the adjacent pixel region from being used in the chrominance residual scaling process associated with the luminance mapping with chrominance scaling is applied. In some embodiments of the apparatus, prevention of all pixels in the adjacent pixel region from being used in the chrominance residual scaling process associated with the luminance mapping with chrominance scaling is further based on an enable value associated with a virtual boundary within the picture. In some embodiments of the apparatus, the use of the enable value associated with the virtual boundary is based on a second enable value associated with the luminance mapping with chrominance scaling (LMCS).

[0022] In another embodiment, there is provided a computer program product that includes a non-transitory computer-readable storage medium having program code portions stored thereon, the program code portions being configured to, when executed: access a current coding unit of a picture to be decoded within a progressive decoding refresh period, the current coding unit being located within a clean region. The program code portions are further configured to, when executed: determine whether one or more pixels within an adjacent pixel region are within a dirty region. The program code portions are further configured to, when executed: prevent all pixels within the adjacent pixel region from being used in the chrominance residual scaling process associated with the luminance mapping with chrominance scaling in the case where one or more pixels within the adjacent pixel region are determined to be within the dirty region.

[0023] In some embodiments of the computer program product, regardless of whether the picture is within the progressive decoding refresh period, the prevention of all pixels in the adjacent pixel region from being used in the chrominance residual scaling process associated with the luminance mapping with chrominance scaling is applied. In some embodiments of the computer program product, the prevention of all pixels in the adjacent pixel region from being used in the chrominance residual scaling process associated with the luminance mapping with chrominance scaling is further based on an enable value associated with a virtual boundary within the picture. In some embodiments of the computer program product, the use of the enable value associated with the virtual boundary is based on a second enable value associated with the luminance mapping with chrominance scaling (LMCS).

[0024] In another embodiment, a method is provided that includes accessing a current coding unit of a picture to be decoded within a progressive decoding refresh period, the current coding unit being located within a clean region. The method further includes determining whether one or more pixels within an adjacent pixel region are within a dirty region. The method further includes preventing all pixels within the adjacent pixel region from being used in the chrominance residual scaling process associated with the luminance mapping with chrominance scaling in the case where one or more pixels within the adjacent pixel region are determined to be within the dirty region.

[0025] In some embodiments of the method, regardless of whether the picture is within the progressive decoding refresh period, the prevention of all pixels in the adjacent pixel region from being used in the chrominance residual scaling process associated with the luminance mapping with chrominance scaling is applied. In some embodiments of the method, the prevention of all pixels in the adjacent pixel region from being used in the chrominance residual scaling process associated with the luminance mapping with chrominance scaling is further based on an enable value associated with a virtual boundary within the picture. In some embodiments of the method, the use of the enable value associated with the virtual boundary is based on a second enable value associated with the luminance mapping with chrominance scaling (LMCS).

[0026] In another embodiment, an apparatus is provided that includes at least one processor and at least one memory containing computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus to: access a current coding unit of a picture to be decoded within a progressive decoding refresh period, the current coding unit being located within a clean region. The at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to: determine whether one or more pixels within an adjacent pixel region are within a dirty region. The at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus to: in the case where one or more pixels within the adjacent pixel region are determined to be within the dirty region, fill the adjacent pixel region with one or more reconstructed pixels from the clean region for the chrominance scaling decoding process associated with the luminance mapping with chrominance scaling.

[0027] In some embodiments of the apparatus, regardless of whether the picture is within the progressive decoding refresh period, filling of adjacent pixel regions from one or more reconstructed pixels in the clean region is applied for the chrominance scaling decoding process associated with a luminance mapping having chrominance scaling. In some embodiments of the apparatus, filling of adjacent pixel regions from one or more reconstructed pixels in the clean region for the chrominance scaling decoding process associated with a luminance mapping having chrominance scaling is further based on an enable value associated with a virtual boundary within the picture. In some embodiments of the apparatus, the use of the enable value associated with the virtual boundary is based on a second enable value associated with a luminance mapping with chrominance scaling (LMCS).

[0028] In another embodiment, there is provided an apparatus that includes means for accessing a current coding unit of a picture to be decoded within a progressive decoding refresh period, the current coding unit being located within a clean region. The apparatus further includes means for determining whether one or more pixels within an adjacent pixel region are within a dirty region. The apparatus further includes means for filling the adjacent pixel region from one or more reconstructed pixels in the clean region for a chrominance residual scaling decoding process associated with a luminance mapping having chrominance scaling when one or more pixels within the adjacent pixel region are determined to be within the dirty region.

[0029] In some embodiments of the apparatus, regardless of whether the picture is within the progressive decoding refresh period, filling of adjacent pixel regions from one or more reconstructed pixels in the clean region is applied for the chrominance scaling decoding process associated with a luminance mapping having chrominance scaling. In some embodiments of the apparatus, filling of adjacent pixel regions from one or more reconstructed pixels in the clean region for the chrominance scaling decoding process associated with a luminance mapping having chrominance scaling is further based on an enable value associated with a virtual boundary within the picture. In some embodiments of the apparatus, the use of the enable value associated with the virtual boundary is based on a second enable value associated with a luminance mapping with chrominance scaling (LMCS).

[0030] In another embodiment, there is provided a computer program product that includes a non-transitory computer-readable storage medium having program code portions stored thereon, the program code portions being configured to, when executed: access a current coding unit of a picture to be decoded within a progressive decoding refresh period, the current coding unit being located within a clean region. The program code portions are further configured to, when executed: determine whether one or more pixels within an adjacent pixel region are within a dirty region. The program code portions are further configured to, when executed: fill the adjacent pixel region from one or more reconstructed pixels in the clean region for a chrominance residual scaling decoding process associated with a luminance mapping having chrominance scaling when one or more pixels within the adjacent pixel region are determined to be within the dirty region.

[0031] In some embodiments of the computer program product, regardless of whether the picture is within the progressive decoding refresh period, filling of adjacent pixel regions from one or more reconstructed pixels in a clean region is applied for a chrominance scaling decoding process associated with a luminance mapping having chrominance scaling. In some embodiments of the computer program product, filling of adjacent pixel regions from one or more reconstructed pixels in a clean region for a chrominance scaling decoding process associated with a luminance mapping having chrominance scaling is also based on an enable value associated with a virtual boundary within the picture. In some embodiments of the computer program product, use of the enable value associated with the virtual boundary is based on a second enable value associated with a luminance mapping with chrominance scaling (LMCS).

[0032] In another embodiment, a method is provided that includes accessing a current coding unit of a picture to be decoded within a progressive decoding refresh period, the current coding unit being within a clean region. The method further includes determining whether one or more pixels within an adjacent pixel region are within a dirty region. The method further includes: in the case where one or more pixels within the adjacent pixel region are determined to be within the dirty region, filling the adjacent pixel region from one or more reconstructed pixels in the clean region for a chrominance residual scaling decoding process associated with a luminance mapping having chrominance scaling.

[0033] In some embodiments of the method, regardless of whether the picture is within the progressive decoding refresh period, filling of adjacent pixel regions from one or more reconstructed pixels in a clean region is applied for a chrominance scaling decoding process associated with a luminance mapping having chrominance scaling. In some embodiments of the method, filling of adjacent pixel regions from one or more reconstructed pixels in a clean region for a chrominance scaling decoding process associated with a luminance mapping having chrominance scaling is also based on an enable value associated with a virtual boundary within the picture. In some embodiments of the method, use of the enable value associated with the virtual boundary is based on a second enable value associated with a luminance mapping with chrominance scaling (LMCS). BRIEF DESCRIPTION OF THE DRAWINGS

[0034] After generally describing certain example embodiments of the present disclosure, reference will be made hereinafter to the accompanying drawings, which are not necessarily to scale, in which:

[0035] Figure 1 is a representation of an example picture within a GDR period according to an example embodiment of the present disclosure, where the clean region and the dirty region are separated by a virtual boundary;

[0036] Figure 2 is a representation of an example coding tree unit according to an example embodiment of the present disclosure;

[0037] Figure 3 is a block diagram of an apparatus that can be specifically configured according to example embodiments of the present disclosure;

[0038] Figure 4A is a flowchart showing operations performed according to example embodiments;

[0039] Figure 4B is a representation of an example usage of top and left neighboring blocks during combined inter-intra prediction weight derivation;

[0040] Figure 4C is a representation of an example usage of top and left neighboring blocks during combined inter-intra prediction weight derivation;

[0041] Figure 5A is a flowchart showing operations performed according to example embodiments;

[0042] Figure 5B is a representation of specific changes in the decoding process of the VVC specification according to example embodiments;

[0043] Figure 6A is a flowchart showing operations performed according to example embodiments;

[0044] Figure 6B is a representation of specific changes in the decoding process of the VVC specification according to example embodiments;

[0045] Figure 7A is a flowchart showing operations performed according to example embodiments; and

[0046] Figure 7B is a representation of specific changes in the decoding process of the VVC specification according to example embodiments. Detailed Description

[0047] Some embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the present disclosure are shown. In fact, the embodiments may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals always refer to like elements. As used herein, the terms "data", "content", "information" and similar terms may be used interchangeably to refer to data that can be transmitted, received and / or stored according to embodiments of the present disclosure. Thus, the use of any such term should not be taken to limit the spirit and scope of the embodiments of the present disclosure.

[0048] In addition, as used herein, the term "circuitry" refers to (a) an implementation using only hardware circuits (e.g., an implementation in analog circuitry and / or digital circuitry); (b) a combination of circuitry and (one or more) computer program products, including software and / or firmware instructions stored on one or more computer-readable memories that work together to cause an apparatus to perform one or more functions described herein; and (c) circuitry that requires software or firmware to operate even if the software or firmware is not physically present, such as (one or more) microprocessors or a portion of (one or more) microprocessors. This definition of "circuitry" applies to all uses of this term herein, including in any claim. As another example, as used herein, the term "circuitry" also includes an implementation that includes one or more processors and / or portions thereof and attendant software and / or firmware. As another example, the term "circuitry" as used herein also includes, for example, a baseband integrated circuit or an application processor integrated circuit for a mobile phone, or a similar integrated circuit in a server, a cellular network device, other network devices (such as a core network device), a field programmable gate array, and / or other computing devices.

[0049] Overview

[0050] As described above, the GDR method can mitigate the latency problem of intra-coded pictures. Instead of coding an intra-picture at a random access point, GDR gradually refreshes the picture by extending the intra-coded region over several pictures in a GDR period. Typical pictures in a GDR period include a clean region (e.g., a region that has undergone intra-refresh) and a dirty region (e.g., a region that has not yet undergone intra-refresh), where the clean region may include a forced intra-region next to the dirty region, and the forced intra-region is used for progressive intra-refresh (PIR).

[0051] The picture header of the Versatile Video Coding (VVC) specification includes virtual boundary syntax. Using the virtual boundary syntax included in the picture header, a picture can have its own virtual boundary. For example, the virtual boundary can be a horizontal or vertical line that defines the boundary between the clean region and the dirty region.

[0052] Figure 1An example of a vertical GDR with a vertical virtual boundary is shown, where the GDR period starts with picture POC(n) and ends with picture POC(n+N-1), including a total of N pictures. The first picture POC(n) within the GDR period is called the GDR picture. The forced intra-coded region 105 gradually expands from left to right over N pictures within the GDR period, and the clean region 110 gradually expands from picture POC(n) to picture POC(N+n-1). Picture POC(n+N) is called the recovery point picture. The virtual boundary 120 separates the clean regions (110 and 105) and the dirty region 115 of picture POC(n+1) in the GDR period. The current picture within the GDR period includes a clean region and a dirty region, where the clean region may include a forced intra region next to the dirty region, and this forced intra region is used for progressive intra refresh (PIR), as Figure 1 shown in picture POC(n+1) in

[0053] The VVC includes an encoding tool called luminance mapping with chroma scaling (LMCS). LMCS is a process applied as part of the decoding process that maps luminance samples to specific values and can apply a scaling operation to the values of chroma samples. According to the current VVC specification ("Versatile Video Coding" by B. Bross, J. Chen, S. Lin, and Y-K. Wang, JVET-Q2001-v13, January 2020, which is incorporated herein by reference and hereinafter referred to as the "VVC specification"), the LMCS of the coding units in the clean region can use the pixels in the dirty region. Therefore, it may not be possible to achieve exact_match in GDR using LMCS.

[0054] Figure 2 An example of how the LMCS of the CU in the clean region utilizes the reconstructed pixels in the dirty region is shown, where the coding tree unit (CTU) size is set to 128×128 pixels, and the virtual boundary passes through the current CTU, and the current coding unit 205 of 32×32 within the current CTU is located in the clean region.

[0055] In the VVC specification, the syntax element sps_log2_ctu_size_minus5 is signaled, and the associated variable is calculated as follows:

[0056] CtbSizeY = 1 << (sps_log2_ctu_size_minus5 + 5), sizeY = Min(CtbSizeY, 64)

[0057] For the current CU in the current CTU, the array recLuma[i] (where i = 0, 1, …, 2*sizeY - 1) is defined as the set of reconstructed neighboring pixels to the left of sizeY and above sizeY, as Figure 2 shown, where sizeY = 64.

[0058] The average value of the array recLuma[i] (where i = 0, 1, …, 2*sizeY - 1) is calculated as follows:

[0059]

[0060] Then, the scaling factor varScale for the chrominance residuals is determined using the variable invAvgLuma calculated above:

[0061] invAvgLuma → vatScale.

[0062] Using the scaling factor varScale, the chrominance components (Cb and Cr) of the current CU are thus reconstructed as follows, where the subscript rec represents reconstruction, pre represents prediction, and res represents the residual:

[0063] Cb rec [i][j] = Cb pre [i][j] + Cb res [i][i] × varScale

[0064] Cr rec [i][j] = Cr pre u][j] + Cr res [i][j] × varScale

[0065] However, some elements of the array recLuma[i] (where i = 0, 1, …, 2*sizeY - 1) may be within the dirty region, and thus the final reconstruction of the chrominance components of the current CU in the clean region may use the reconstructed neighboring luma pixels in the dirty region, which may lead to leakage and result in the inability to achieve exact_match. For example, as Figure 2 shown, for the current CU 205, the above-reconstructed neighboring luma pixel 210 is within the dirty region.

[0066] Example device

[0067] Figure 3An example of an apparatus 300 that can be configured to perform operations in accordance with the embodiments described herein is depicted. As Figure 3 shown, the apparatus includes processing circuitry 32, a memory 34, and a communication interface 36, which are associated with or communicate with each other. The processing circuitry 32 can communicate with the memory via a bus to transfer information between the components of the apparatus. The memory can be non-transitory and can include, for example, one or more volatile and / or non-volatile memories. In other words, for example, the memory can be an electronic storage device (e.g., a computer-readable storage medium) that includes gates configured to store data (e.g., bits) that can be retrieved by a machine (e.g., a computing device such as the processing circuitry). The memory can be configured to store information, data, content, applications, instructions, etc., such that the apparatus can perform various functions in accordance with example embodiments of the present disclosure. For example, the memory can be configured to buffer input data for processing by the processing circuitry. Additionally or alternatively, the memory can be configured to store instructions for execution by the processing circuitry.

[0068] In some embodiments, apparatus 100 can be embodied in various computing devices. However, in some embodiments, the apparatus can be embodied as a chip or a chipset. In other words, the apparatus can include one or more physical packages (e.g., chips) that include materials, components, and / or wires on a structural component (e.g., a substrate). The structural component can provide physical strength, dimensional conservation, and / or electrical interaction limitations for the component circuitry included thereon. Thus, in certain cases, the apparatus can be configured to implement embodiments of the present disclosure on a single chip or as a single “system-on-a-chip”. Accordingly, in some cases, the chip or chipset can constitute a component for performing one or more operations to provide the functions described herein.

[0069] The processing circuitry 32 can be embodied in a number of different ways. For example, the processing circuitry can be embodied as one or more hardware processing components, such as a coprocessor, a microprocessor, a controller, a digital signal processor (DSP), a processing element with or without an accompanying DSP, or various other circuitry including integrated circuits, such as an ASIC (application-specific integrated circuit), an FPGA (field-programmable gate array), a microcontroller unit (MCU), a hardware accelerator, a dedicated computer chip, etc. Thus, in some embodiments, the processing circuitry can include one or more processing cores configured to execute independently. A multi-core processing circuitry can implement multi-processing within a single physical package. Additionally or alternatively, the processing circuitry can include one or more processors configured in series via a bus to enable independent execution of instructions, pipelining, and / or multi-threading.

[0070] In an example embodiment, the processing circuitry 32 may be configured to execute instructions stored in the memory device 34 or instructions accessible to the processing circuitry. Alternatively or additionally, the processing circuitry may be configured to execute hard-coded functions. Thus, whether configured by hardware or software methods, or by a combination thereof, the processing circuitry can represent an entity (e.g., physically embodied in circuitry) that, when configured accordingly, is capable of performing operations in accordance with an embodiment of the present disclosure. Thus, for example, when the processing circuitry is embodied as an ASIC, FPGA, etc., the processing circuitry can be specially configured hardware for performing the operations described herein. Alternatively, as another example, when the processing circuitry is embodied as an executor of instructions, the instructions can specifically configure the processor to perform the algorithms and / or operations described herein when the instructions are executed. However, in some cases, the processing circuitry can be a processor of a particular device (e.g., an image or video processing system) that is configured to further configure the processing circuitry by instructions for performing the algorithms and / or operations described herein to adopt an embodiment. The processing circuitry may include a clock, an arithmetic logic unit (ALU), and logic gates configured to support the operation of the processing circuitry.

[0071] The communication interface 36 can be any component, such as a device or circuitry embodied in hardware or a combination of hardware and software, that is configured to receive and / or transmit data, including media content in the form of video or image files, one or more audio tracks, etc. In this regard, the communication interface may include, for example, an antenna (or antennas) and supporting hardware and / or software to enable communication with a wireless communication network. Additionally or alternatively, the communication interface may include circuitry for interacting with the (multiple) antennas to cause signals to be transmitted through the (multiple) antennas or to process signals received through the (multiple) antennas. In some environments, alternatively or additionally, the communication interface may also support wired communication. For example, the communication interface may include a communication modem and / or other hardware / software to support communication over a cable, digital subscriber line (DSL), universal serial bus (USB), or other mechanism.

[0072] According to some embodiments, the apparatus 300 may be configured in accordance with an architecture for providing video encoding, decoding, and / or compression. In this regard, the apparatus 300 may be configured as a video encoding device. For example, the apparatus 300 may be configured to encode video according to one or more video compression standards, such as the VVC specification. Although some embodiments herein relate to operations associated with the VVC standard, it is noted that the processes discussed herein can be used for any video encoding standard.

[0073] Example process for LMCS for GDR

[0074] In the embodiments described herein, a new variable WithinGdrPeriodFlag can be introduced in the picture header semantics as shown in Table A1 below.

[0075]

[0076]

[0077] Table A1

[0078] Alternatively, WithinGdrPeriodFlag can be derived as follows:

[0079] When the current picture is a GDR picture, the variables GdrPicOrderCntVal and RpPicOrderCntVal are derived as follows:

[0080] GdrPicOrderCntVal = PicOrderCntVal

[0081] RpPicOrderCntVal = GdrPicOrderCntVal + recovery_poc_cnt

[0082] For the current picture, if the GdrPicOrderCntVal of any GDR picture is less than or equal to PicOrderCntVal and RpPicOrderCntVal is greater than PicOrderCntVal, the variable WithinGdrPeriodFlag is derived to be equal to 1, otherwise it is derived to be equal to 0.

[0083] The above derivations for ending the GDR period and WithinGdrPeriodFlag are merely exemplary embodiments, and other embodiments can be implemented similarly. For example, some of the above derivations assume that recovery_poc_cnt is allowed to be equal to 0 (e.g., the GDR picture is also a recovery point). In one example, the derivation process is adjusted according to different semantics of recovery_poc_cnt, where it specifies the last picture within the GDR period rather than the recovery point picture, and thus the GDR picture is not allowed to be a recovery point picture either. In this case, for the current picture, if the GdrPicOrderCntVal of any GDR picture is less than or equal to PicOrderCntVal and RpPicOrderCntVal is greater than or equal to PicOrderCntVal, the variable WithinGdrPeriodFlag is derived to be equal to 1, otherwise it is derived to be equal to 0.

[0084] In one embodiment, the encoder determines whether a picture is within a GDR period, for example, by deriving the WithinGdrPeriodFlag as described above. When the picture is determined to be within the GDR period, the encoder turns off the LMCS. For example, by setting the ph_lmcs_enabled_flag in the picture header to be equal to zero (0), or by setting the slice_lmcs_enabled_flag in all slice headers of the picture to be equal to zero (0).

[0085] In one embodiment, the encoder determines whether a picture is within a GDR period, for example, by deriving the WithinGdrPeriodFlag as described above. When the picture is determined to be within the GDR period, the encoder turns off the chroma residual scaling of the LMCS, for example, by setting the ph_chroma_residual_scale_flag in the picture header to be equal to 0.

[0086] Figure 4A A flowchart is shown that includes operations of one embodiment where control is for the LMCS. At operation 401, apparatus 300 includes components such as processing circuitry 32, memory 34, etc., that are configured to access a picture to be decoded. For example, as described above, the picture may be included as part of an encoded video sequence, and apparatus 300 may be configured to access the picture during the encoding process of the encoded video sequence (such as during the decoding process).

[0087] At operation 402, apparatus 300 includes components such as processing circuitry 32, memory 34, etc., that are configured to determine whether the picture is within a progressive decoding refresh (GDR) period. In some embodiments, determining whether the picture is within the GDR period may include analyzing a flag variable associated with the picture. As Figure 4B shown, an example picture header structure syntax includes a boolean flag variable WithinGdrPeriodFlag. In this regard, if the picture is within the GDR period (WithinGdrPeriodFlag!= 0), then no LMCS-related syntax elements are signaled, and the LMCS-related decoding process will be skipped, which can save bits as well as the processing cycles that would otherwise be implemented. As Figure 4B shown, for a picture within the GDR period where the WithinGdrPeriodFlag variable is not equal to zero, the syntax flag ph_lmcs_enabled_flag is not signaled and is inferred to be equal to zero.

[0088] Since the flag ph_lmcs_enabled_flag is equal to 0, for pictures with a GDR period, the decoding process associated with LMCS will not be implemented. In this regard, at operation 403, in the case where the picture is a picture within the GDR period, the apparatus 300 includes components such as processing circuitry 32, memory 34, etc., which are configured to prevent the luminance mapping decoding process with chroma scaling from being applied to pictures within the GDR period.

[0089] In another embodiment, the LMCS decoding process may be limited to the chrominance component. In this embodiment, if the current picture is within the GDR period, the syntax flag ph_chroma_residual_scale_flag will not be signaled, and the decoding process of chroma residual scaling associated with LMCS will be prevented from occurring. For example, Figure 4C Another example picture header structure syntax is shown. As shown, for pictures within the GDR period (e.g., when the WithinGdrPeriodFlag is not equal to 0), the syntax flag ph_chroma_residual_scale_flag is not signaled and is inferred to be equal to 0. Since the flag ph_chroma_residual_scale_flag is equal to 0, for pictures within the GDR period, the decoding process associated with the chroma scaling of LMCS will not be implemented. In this regard, in some embodiments, the apparatus 300, such as components like processing circuitry 32, memory 34, etc., is configured to only prevent the chroma residual scaling decoding process associated with LMCS from being applied to pictures within the GDR period.

[0090] In another embodiment, for the current CU in the clean region of the current CTU where the virtual boundary passes through, if any of the reconstructed adjacent pixels above sizeY (or to the left of sizeY) of it are in the dirty region, the chroma residual scaling of LMCS for the current CU within the clean region of the current CTU can be prevented. For Figure 2 example, since the virtual boundary 220 passes through the current CTU and the current CU 205 within the current CTU is in the clean region of the current CTU, the chroma residual scaling of LMCS for the current CU 205 can be prevented.

[0091] As Figure 5AAs shown, at operation 501, apparatus 300 includes components such as processing circuitry 32, memory 34, etc., which are configured to access pictures to be decoded within the GDR period. As described above, pictures within the GDR period may be included as part of an encoded video sequence, and apparatus 300 may be configured to access pictures within the GDR period during the encoding process of the encoded video sequence (such as during the decoding process). At operation 502, apparatus 300 includes components such as processing circuitry 32, memory 34, etc., which are configured to determine whether a virtual boundary is within the current coded tree unit of a picture within the GDR period. In some embodiments, the virtual boundary may define the separation between the clean area and the dirty area of a picture within the GDR period. At operation 503, apparatus 300 includes components such as processing circuitry 32, memory 34, etc., which are configured to, in the case where the virtual boundary is within the current coded tree unit, prevent the chrominance residual scaling decoding process associated with the luminance mapping with chrominance scaling from being applied to one or more coded units within the clean area.

[0092] These operations may be performed by changing the decoding process. Shown in Table A below are the changes to the section "Image Reconstruction Using Luminance-Dependent Chrominance Residual Scaling Process for Chrominance Samples" of the VVC specification according to certain embodiments described herein. Figure 5B The specific changes to the sections proposed herein are further emphasized.

[0093]

[0094]

[0095]

[0096]

[0097] Table A

[0098] In another embodiment, for a current CU within the clean area of the current CTU through which the virtual boundary passes, if any of the reconstructed adjacent pixels above it (or to the left of it) with sizeY are located in the dirty area, then the entire sizeY rows above (or sizeY columns to the left of) the reconstructed adjacent pixels may be considered unavailable for the chrominance residual scaling of the LMCS of the current CU. For example, in Figure 2 , since the above-mentioned reconstructed adjacent pixel 210 of the current CU 205 is located in the dirty area, the entire row of 64 above the reconstructed adjacent pixel is considered unavailable for the chrominance residual scaling of the LMCS. In this regard, as Figure 6AAs shown, at operation 601, apparatus 300 includes components such as processing circuitry 32, memory 34, etc., which are configured to access a current coding unit of a picture to be decoded during a GDR period, where the current coding unit is located within a clean region. As described above, pictures during the GDR period can be included as part of an encoded video sequence. At operation 602, apparatus 300 includes components such as processing circuitry 32, memory 34, etc., which are configured to determine whether one or more pixels within an adjacent pixel region are within a dirty region. At operation 603, apparatus 300 includes components such as processing circuitry 32, memory 34, etc., which are configured to prevent all pixels within the top (or left) adjacent pixel region from being used for a chrominance residual scaling decoding process associated with a luminance mapping having chrominance scaling in the case where one or more pixels within the top (or left) adjacent pixel region are determined to be within the dirty region.

[0099] These operations can be performed by changing the decoding process. Table B below describes changes to the "Image Reconstruction Using Luminance-Related Chrominance Residual Scaling Process for Chrominance Samples" section of the VVC specification according to certain embodiments described herein. Figure 6B Specific changes to the sections presented herein are further emphasized.

[0100]

[0101]

[0102]

[0103] Table B

[0104] In another embodiment, for a CU within the clean region of a current CTU through which a virtual boundary passes, if one or more of the reconstructed adjacent pixels above it (or to its left) of sizeY are within the dirty region, for the chrominance residual scaling of the LMCS of the current CU, the reconstructed adjacent pixels within the dirty region can be filled from the reconstructed pixels within the clean region. For example, in Figure 2 , since the above-mentioned reconstructed adjacent pixels 210 of the current CU 205 are within the dirty region, they are filled from the reconstructed pixel 95. In this regard, as Figure 7AAs shown, at operation 701, apparatus 300 includes components such as processing circuitry 32, memory 34, etc., which are configured to access a current coding unit of a picture to be decoded within a GDR period, where the current coding unit is located within a clean region. As described above, pictures within a GDR period may be included as part of an encoded video sequence. At operation 702, apparatus 300 includes components such as processing circuitry 32, memory 34, etc., which are configured to determine whether one or more pixels within an adjacent pixel region are within a dirty region. At operation 703, apparatus 300 includes components such as processing circuitry 32, memory 34, etc., which are configured to, in the case where one or more pixels within an adjacent pixel region are determined to be within a dirty region, fill adjacent pixels within the dirty region with one or more reconstructed pixels from the clean region for a chrominance residual scaling decoding process associated with a luminance mapping having chrominance scaling.

[0105] These operations may be performed by changing the decoding process. Table C describes changes to the section "Image Reconstruction Using Luminance-Dependent Chrominance Residual Scaling Process of Chrominance Samples" of the VVC specification according to certain embodiments described herein. Figure 7B The specific changes to the sections proposed herein are further emphasized.

[0106]

[0107]

[0108]

[0109]

[0110] Table C

[0111] In another embodiment, for a current CU within the clean region of a current CTU through which a virtual boundary passes, if one or more of its reconstructed adjacent pixels above sizeY (or to the left of sizeY) are located within a dirty region, they are considered unavailable for the LMCS chrominance residual scaling of the current CU. For example, referring again to Figure 2 , since the above-mentioned reconstructed adjacent pixels 210 of current CU 205 are located within a dirty region, they are not used for the chrominance residual scaling of LMCS of current CU 205.

[0112] In another embodiment, regardless of whether the picture is within a GDR period, any of the above-described embodiments involving changes to the decoding process may be applied to all virtual boundaries. Thus, by setting the WithinGdrPeriodFlag to 1, the above-described embodiments involving changes to the decoding process are unconditionally applicable to the decoding process.

[0113] In another embodiment, any of the above-described embodiments involving changes in the decoding process can be applied to the indicated virtual boundaries. The encoder can indicate that any of the above embodiments is applicable to the case where the WithinGdrPeriodFlag for pictures within the GDR period is equal to 1 (e.g., in pictures where the WithinGdrPeriodFlag is equal to or will be equal to 1), and is applicable to the case where the WithinGdrPeriodFlag for any picture outside the GDR period is equal to 0 (e.g., in pictures where the WithinGdrPeriodFlag is equal to or will be equal to 0). However, the encoder can alternatively or additionally use the indication for purposes other than GDR; for example, for projection 360° video with discontinuous projection surfaces, such as the cube faces of a cube map, which are defined by virtual boundaries. The encoder indicates in the syntax structure (such as in the picture parameter set) and the decoder decodes from the syntax structure (such as from the picture parameter set decoding) one or more syntax elements, such as flags, to control how any of the above embodiments involving changes in the decoding process is applied. The (multiple) syntax elements (such as flags) can jointly control all virtual boundaries within the scope of the syntax structure, or there can be (multiple) separate syntax elements to control one or more virtual boundaries respectively. For example, any of the above embodiments can be applied by setting the WithinGdrPeriodFlag equal to the value of a flag in the syntax structure. For example, ph_lmcs_over_virtual_boundaries_flag can be included in the picture parameter set syntax structure together with other syntax elements of the virtual boundary as follows:

[0114]

[0115] Table D

[0116] In another embodiment, any of the above-described embodiments involving changes in the decoding process can be applied to the indicated virtual boundaries. The encoder can indicate that any of the above embodiments applies to the case where the WithinGdrPeriodFlag for pictures within the GDR period is equal to 1 (e.g., in pictures where the WithinGdrPeriodFlag is equal to or will be equal to 1), and applies to the case where the WithinGdrPeriodFlag for any picture outside the GDR period is equal to 0 (e.g., in pictures where the WithinGdrPeriodFlag is equal to or will be equal to 0). However, the encoder can alternatively or additionally use the indication for purposes other than GDR; for example, for a projected 360° video with discontinuous projection planes, such as the cube faces of a cube map, which are defined by virtual boundaries. The encoder indicates in a syntax structure (such as in the picture parameter set) and the decoder decodes from the syntax structure (such as from the picture parameter set) one or more syntax elements, such as flags, to control how any of the above embodiments involving changes in the decoding process is applied. The (multiple) syntax elements (such as flags) can jointly control all virtual boundaries within the scope of the syntax structure, or there can be (multiple) separate syntax elements to control one or more virtual boundaries respectively. For example, any of the above embodiments can be applied by setting the WithinGdrPeriodFlag equal to the value of a flag in the syntax structure. For example, ph_lmcs_over_virtual_boundaries_flag can be included in the picture parameter set syntax structure together with other syntax elements of the virtual boundary. For example, ph_lmcs_over_virtual_boundaries_flag can be regulated by a flag enabled by LMCS (e.g., ph_lmcs_enabled_flag), as shown in Table E below.

[0117] Picture header structure syntax

[0118]

[0119]

[0120] Table E

[0121] In another embodiment, any of the above-described embodiments related to the decoding process variations can be applied to the indicated virtual boundaries. The encoder can indicate that any of the above embodiments is applicable to the case where the WithinGdrPeriodFlag for pictures within the GDR period is equal to 1 (e.g., in pictures where the WithinGdrPeriodFlag is equal to or will be equal to 1), and is applicable to the case where the WithinGdrPeriodFlag for any pictures outside the GDR period is equal to 0 (e.g., in pictures where the WithinGdrPeriodFlag is equal to or will be equal to 0). However, the encoder can alternatively or additionally use the indication for purposes other than GDR; for example, for 360° projection video with discontinuous projection surfaces, such as the cube faces of a cube map, which are defined by virtual boundaries. The encoder indicates in the syntax structure (such as in the picture parameter set) and the decoder decodes from the syntax structure (such as from the picture parameter set) one or more syntax elements, such as flags, to control how any of the above embodiments related to the decoding process variations is applied. The (multiple) syntax elements (such as flags) can jointly control all virtual boundaries within the scope of the syntax structure, or there can be (multiple) separate syntax elements to control one or more virtual boundaries respectively. For example, any of the above embodiments can be applied by setting the WithinGdrPeriodFlag equal to the value of a flag in the syntax structure. For example, ph_lmcs_over_virtual_boundaries_flag can be included in the picture parameter set syntax structure together with other syntax elements of the virtual boundary. For example, the syntax elements of the virtual boundary may appear before the syntax elements of LMCS, and ph_LMCS_over_virtual_boundaries_flag can be regulated by a virtual boundary presentation flag, such as ph_virtuall_boundarys_present_flags, as shown in Table F below.

[0122] Picture header structure syntax

[0123]

[0124]

[0125] Table F

[0126] In another example, ph_lmcs_over_virtual_boundaries_flag can be included in the picture parameter set syntax structure together with other syntax elements of the virtual boundary, and the virtual boundary is regulated by ph_chroma_residual_scale_flag to be equal to 1, as shown in Table G below.

[0127] Picture header structure syntax

[0128]

[0129]

[0130] Table G

[0131] As described above, a method, an apparatus, and a computer program product are disclosed that are used to facilitate the LMCS process based on pictures in a GDR period and provide a solution to the compatibility problem between LMCS and GDR. Advantages of this design include reducing the transmission time of pictures and reducing the encoder-to-decoder delay.

[0132] Figure 4A 、 Figure 5A 、 Figure 6A and Figure 7A show a flowchart depicting the method according to a specific example embodiment. It will be appreciated that each block of the flowchart and combinations of blocks in the flowchart can be implemented in various ways, such as hardware, firmware, processors, circuitry, and / or other communication devices associated with software execution, including one or more computer program instructions. For example, one or more of the above processes can be implemented by computer program instructions. In this regard, the computer program instructions embodying the above processes can be stored by a memory device 34 of a device employing an embodiment of the present disclosure and executed by a processor 32. It will be appreciated that any such computer program instructions can be loaded onto a computer or other programmable device (e.g., hardware) to produce a machine such that the resulting computer or other programmable device implements the functions specified in the flowchart blocks. These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable device to operate in a particular manner such that the instructions stored in the computer-readable memory produce an article of manufacture, the execution of which implements the functions specified in the flowchart blocks. The computer program instructions can also be loaded onto a computer or other programmable device to cause a series of operations to be performed on the computer or other programmable device to produce a computer-implemented process such that the instructions executed in the computer or other programmable device provide operations for implementing the functions specified in the flowchart blocks.

[0133] Accordingly, the flowchart blocks support combinations of methods for performing the specified functions and combinations of operations required for performing the specified functions. It should also be understood that one or more blocks in the flowchart and combinations of blocks in the flowchart can be implemented by a computer system based on dedicated hardware that can perform the specified functions, or by a combination of dedicated hardware and computer instructions.

[0134] Those skilled in the art to which these inventions pertain, having the benefit of the teachings in the above description and the related drawings, will think of many modifications and other embodiments of the inventions described herein. Accordingly, it is to be understood that the disclosure is not limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims.

[0135] In addition, although the above description and the related drawings describe example embodiments in the context of certain example combinations of elements and / or functions, it should be recognized that alternative embodiments may provide different combinations of elements and / or functions without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and / or functions other than those explicitly described above are also contemplated, as set forth in some of the appended claims. Although specific terms are used herein, they are used in a general and descriptive sense only and not for purposes of limitation.

Claims

1. An apparatus for processing pictures, comprising: a component for accessing a picture to be decoded; a component for determining whether the picture is within a progressive decoding refresh period; and in the case where the picture is within the progressive decoding refresh period: a component for preventing a chrominance residual scaling process of a luminance mapping (LMCS) process with chrominance scaling from being applied to the picture.

2. The device according to claim 1, wherein The prevention of the chrominance residual scaling process of the luminance mapping process with chrominance scaling is further based on a control flag associated with the picture, wherein when the control flag does not exist or indicates that chrominance residual scaling is disabled for the picture, the chrominance residual scaling process of the luminance mapping with chrominance scaling is not applied to the picture.

3. The apparatus according to claim 1, wherein, The prevention of the chrominance residual scaling process of the luminance mapping process with chrominance scaling is further based on a second control flag associated with the picture, wherein when the second control flag does not exist or indicates that LMCS is disabled for the picture, the luminance mapping process with chrominance scaling is not applied to the picture.

4. A method for processing pictures, comprising: accessing a picture to be decoded; determining whether the picture is within a progressive decoding refresh period; and in the case where the picture is within the progressive decoding refresh period: preventing a chrominance residual scaling process of a luminance mapping (LMCS) process with chrominance scaling from being applied to the picture.

5. The method according to claim 4, wherein, The prevention of the chrominance residual scaling decoding process of the luminance mapping process with chrominance scaling is further based on a control flag associated with the picture, wherein when the control flag does not exist or indicates that chrominance residual scaling is disabled for the picture, the chrominance residual scaling process of the luminance mapping with chrominance scaling is not applied to the picture.

6. The method according to claim 4, wherein The prevention of the chrominance residual scaling process of the luminance mapping process with chrominance scaling is further based on a second control flag associated with the picture, wherein when the second control flag does not exist or indicates that LMCS is disabled for the picture, the luminance mapping decoding process with chrominance scaling is not applied to the picture.

7. A computer program product, comprising a computer program which, when executed by a processor, causes the processor: to access a picture to be decoded; to determine whether the picture is within a progressive decoding refresh period; and in the case where the picture is within the progressive decoding refresh period: to prevent a chrominance residual scaling process of a luminance mapping (LMCS) process with chrominance scaling from being applied to the picture.

8. The computer program product according to claim 7, wherein, The prevention of the chrominance residual scaling decoding process of the luminance mapping process with chrominance scaling is further based on a control flag associated with the picture, wherein when the control flag does not exist or indicates that chrominance residual scaling is disabled for the picture, the chrominance residual scaling process of the luminance mapping with chrominance scaling is not applied to the picture.

9. The computer program product according to claim 7, wherein, The prevention of the chrominance residual scaling process of the luminance mapping process with chrominance scaling is also based on a second control flag associated with the picture, wherein when the second control flag is absent or indicates that LMCS is disabled for the picture, the luminance mapping decoding process with chrominance scaling is not applied to the picture.

Images