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EP-4742659-A1 - DIMD WITH ALTERNATIVE FILTER KERNELS

EP4742659A1EP 4742659 A1EP4742659 A1EP 4742659A1EP-4742659-A1

Abstract

A decoding method is disclosed. Gradients for a current block are first obtained by filtering samples in a neighboring template of the current block, wherein obtaining gradients for a current block comprises substituting at least one of a Sobel filter or an edge detection filter by a generic filter. A histogram of oriented gradients (HoG) is then obtained for the current block based on the gradients. An intra mode is selected for the current block based on the HoG. The current block is then decoded using the selected intra mode.

Inventors

  • UTIDA BARBOSA FERREIRA, Renan
  • BONNINEAU, Charles
  • MARZUKI, Ismail
  • PURI, Saurabh

Assignees

  • InterDigital CE Patent Holdings, SAS

Dates

Publication Date
20260513
Application Date
20241108

Claims (15)

  1. A decoding method comprising: obtaining gradients for a current block by filtering samples in a neighboring template of the current block, wherein obtaining gradients for a current block comprises substituting at least one of a Sobel filter or an edge detection filter by a generic filter; obtaining a histogram of oriented gradients (HoG) for the current block based on the gradients ; selecting an intra mode for the current block based on the HoG; and decoding the current block using the selected intra mode.
  2. A decoding apparatus comprising one or more processors and at least one memory coupled to said one or more processors, wherein said one or more processors are configured to perform : obtaining gradients for a current block by filtering samples in a neighboring template of the current block, wherein obtaining gradients for a current block comprises substituting at least one of a Sobel filter or an edge detection filter by a generic filter; obtaining a histogram of oriented gradients (HoG) for the current block based on the gradients ; selecting an intra mode for the current block based on the HoG; and decoding the current block using the selected intra mode.
  3. The method of claim 1 or apparatus of claim 2, wherein parameters of the generic filter are decoded from a picture parameter set (PPS) or from a sequence parameter set (SPS).
  4. The method of claim 1 or 3 or the apparatus of claim 2 or 3, wherein parameters of the generic filter are dependent on a size of the current block.
  5. The method of claim 1 or 3 or the apparatus of claim 2 or 3, wherein parameters of the generic filter are different for each intra prediction mode in case of a virtual intra prediction mode (VIPM).
  6. The method of any one of claims 1, 3 to 5 or the apparatus of any one of claims 2 to 5, wherein substituting at least one of a Sobel filter or an edge detection filter by a generic filter only applies to obtain a virtual intra prediction mode (VIPM).
  7. The method of any one of claims 1, 3 to 5 or the apparatus of any one of claims 2 to 5, wherein substituting at least one of a Sobel filter or an edge detection filter by a generic filter only applies to obtain a decoder-side intra mode derivation (DIMD).
  8. The method of any one of claims 1, 4 to 7 or the apparatus of any one of claims 2, 4 to 5, wherein parameters of the generic filter are obtained from a look-up-table (LUT) using an index identifying an entry in the LUT, said LUT comprising a fixed number of filter kernels.
  9. The method of any one of claims 1 or 3 to 8 or the apparatus of any one of claims 2 to 8, further comprising decoding a flag indicating whether the Sobel filter is to be substituted by the generic filter and responsive to a determination that the Sobel filter is to be substituted by the generic filter, decoding at least another flag indicating whether parameters of the generic filter are signaled in a bitstream or whether an entry of a LUT is signaled in the bitstream that identifies a particular filter kernel.
  10. An encoding method comprising: obtaining gradients for a current block by filtering samples in a neighboring template of the current block, wherein obtaining gradients for a current block comprises substituting at least one of a Sobel filter or an edge detection filter by a generic filter; obtaining a histogram of oriented gradients (HoG) for the current block based on the gradients ; selecting an intra mode for the current block based on the HoG; and encoding the current block using the selected intra mode.
  11. An encoding apparatus comprising one or more processors and at least one memory coupled to said one or more processors, wherein said one or more processors are configured to perform : obtaining gradients for a current block by filtering samples in a neighboring template of the current block, wherein obtaining gradients for a current block comprises substituting at least one of a Sobel filter or an edge detection filter by a generic filter; obtaining a histogram of oriented gradients (HoG) for the current block based on the gradients ; selecting an intra mode for the current block based on the HoG; and encoding the current block using the selected intra mode.
  12. The method of claim 10 or the apparatus of claim 11, wherein parameters of the generic filter are encoded in a picture parameter set (PPS) or in a sequence parameter set (SPS).
  13. The method of claim 10 or the apparatus of claim 11, wherein parameters of the generic filter are obtained from a look-up-table (LUT) using an index identifying an entry in the LUT, said LUT comprising a fixed number of filter kernels.
  14. The method of any one of claims 10, 12 to 13 or the apparatus of any one of claims 11 to 13, further comprising encoding a flag indicating whether the Sobel filter is to be substituted by the generic filter and responsive to a determination that the Sobel filter is to be substituted by the generic filter, encoding at least another flag indicating whether parameters of the generic filter are signaled in a bitstream or whether an entry of a LUT is signaled in the bitstream that identifies a particular filter kernel.
  15. A signal comprising a bitstream, formed by performing the method of any one of claims 10 and 12 to 14.

Description

BACKGROUND The present application is related to a method and an apparatus for intra prediction in video encoding and decoding. BRIEF SUMMARY Briefly stated, in one embodiment a decoding method is presented. Gradients for a current block are obtained by filtering samples in a neighboring template of the current block, wherein obtaining gradients for a current block comprises substituting at least one of a Sobel filter or an edge detection filter by a generic filter. A histogram of oriented gradients (HoG) is then obtained for the current block based on the gradients. An intra mode is selected for the current block based on the HoG. The current block is then decoded using the selected intra mode. In another embodiment, a decoding apparatus comprising one or more processors and at least one memory coupled to said one or more processors is presented. The one or more processors are configured to perform obtaining gradients for a current block by filtering samples in a neighboring template of the current block, wherein obtaining gradients for a current block comprises substituting at least one of a Sobel filter or an edge detection filter by a generic filter; obtaining a histogram of oriented gradients (HoG) for the current block based on the gradients ; selecting an intra mode for the current block based on the HoG; and decoding the current block using the selected intra mode. In one embodiment an encoding method is presented. Gradients for a current block are obtained by filtering samples in a neighboring template of the current block, wherein obtaining gradients for a current block comprises substituting at least one of a Sobel filter or an edge detection filter by a generic filter. A histogram of oriented gradients (HoG) is then obtained for the current block based on the gradients. An intra mode is selected for the current block based on the HoG. The current block is then encoded using the selected intra mode. In another embodiment, an encoding apparatus comprising one or more processors and at least one memory coupled to said one or more processors is presented. The one or more processors are configured to perform obtaining gradients for a current block by filtering samples in a neighboring template of the current block, wherein obtaining gradients for a current block comprises substituting at least one of a Sobel filter or an edge detection filter by a generic filter; obtaining a histogram of oriented gradients (HoG) for the current block based on the gradients ; selecting an intra mode for the current block based on the HoG; and encoding the current block using the selected intra mode. BRIEF DESCRIPTION OF THE DRAWINGS The following detailed description will be better understood when read in conjunction with the appended drawings, in which there are shown examples of one or more of the multiple embodiments of the present disclosure. It should be understood, however, that the embodiments described herein are not limited to the precise arrangements and instrumentalities shown in the drawings. In the drawings: FIG. 1 is a block diagram illustrating an example system according to one or more embodiments of the present disclosure;FIG. 2 is a block diagram illustrating an example video encoder according to one or more embodiments of the present disclosure;FIG. 3 is a block diagram illustrating an example video decoder according to one or more embodiments of the present disclosure;FIG. 4 depicts a template (set of chosen pixels) on which a gradient analysis is performed;FIG. 5 illustrates convolution of the 3x3 Sobel gradient filter with a template;FIG. 6 illustrates the current set of filters used by DIMD in ECM-13.0 ;FIG. 7 illustrates DIMD design for small blocks ;FIG. 8 is a block diagram illustrating an example decoding method according to one or more embodiments of the present disclosure; andFIG. 9 is a block diagram illustrating an example encoding method according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION In describing the various embodiments of the present disclosure, certain terminology is used herein for convenience only and should not be considered as limiting such embodiments. In the drawings, the same reference numerals are employed for designating the same elements throughout the several figures and the present description. Referring to the drawings, there is shown in FIG. 1 a block diagram illustrating an example system 100 in which embodiments of the present disclosure can be implemented. The system 100 may be an electronic device including, for example, a personal computer, laptop computer, mobile phone, tablet computer, multimedia set-top box, digital television receiver, personal video recording system, connected home appliance, vehicle control and/or entertainment system, and server. One or more elements of the system 100, singly or in combination, may be implemented as an integrated circuit (IC), multiple ICs, and/or discrete components. For example, in one