Panasonic Intellectual Property Corporation of America

Ryuichi Kanoh

Takahiro Nishi

Tadamasa Toma

Kiyofumi Abe

Chong Soon Lim

Hai Wei Sun

Han Boon Teo

Ru Ling Liao

Sughosh Pavan Shashidhar

Jing Ya Li

Takashi Hashimoto

Masato Ohkawa

Hideo Saitou

Virginie Drugeon

Luca Rigazio

Alec Hodgkinson

A decoder includes circuitry and memory. Using the memory, the circuitry, in a first operating mode, derives first motion vectors for a first block obtained by splitting a picture, using a first inter prediction scheme, and generates a prediction image corresponding to the first block, by referring to spatial gradients of luminance generated based on the first motion vectors. Using the memory, the circuitry, in a second operating mode, derives second motion vectors for a sub-block obtained by splitting a second block, using a second inter prediction scheme different from the first inter prediction scheme, the second block being obtained by splitting the picture, and generates a prediction image corresponding to the sub-block without referring to spatial gradients of luminance.

Encoder, decoder, encoding method, and decoding method

An encoder partitions into blocks using a set of block partition modes. The set of block partition modes includes a first partition mode for partitioning a first block, and a second block partition mode for partitioning a second block which is one of blocks obtained after the first block is partitioned. When the number of partitions of the first block partition mode is three, the second block is a center block among the blocks obtained after partitioning the first block, and the partition direction of the second block partition mode is same as the partition direction of the first block partition mode, the second block partition mode indicates that the number of partitions is only three. A parameter for identifying the second block partition mode includes a first flag indicating a horizontal or vertical partition direction, and does not include a second flag indicating the number of partitions.

Encoder, decoder, encoding method, decoding method, and recording medium

Various embodiments provide an encoder that generates a plurality of quantization matrix elements for a current block; generates a quantization matrix using the plurality of quantization matrix elements; and quantizes, using the quantization matrix, transform coefficients of the current block. The quantization matrix includes only a subset of quantization matrix elements of the plurality of quantization matrix elements. Each of the subset of quantization matrix elements has an x-coordinate value less than a threshold x-coordinate value, a y-coordinate value less than a threshold y-coordinate value, or an x-coordinate value less than the threshold x-coordinate value and a y-coordinate value less than the threshold y-coordinate value.

Encoder, decoder, and related non-transitory computer readable medium

An encoder, includes: circuitry; and memory. Using the memory, the circuitry: in inter prediction for a current block, determines a base motion vector, and writes, in an encoded signal, a delta motion vector representing (i) one direction among a plurality of directions including a diagonal direction and (ii) a distance from the base motion vector; and encodes the current block using the delta motion vector and the base motion vector as a motion vector of the current block.

An encoder includes: circuitry; and memory, in which using the memory, the circuitry, in affine motion compensation prediction in inter prediction for a current block, places a limit on a range within which motion estimation or motion compensation is performed, and performs the motion compensation for the current block.

An image encoder performs a first partitioning including using a first partition mode, without writing first splitting information indicative of the first partition mode into a bitstream, to split a first block into a plurality of second blocks in response to that the first block is located adjacent to an edge of a picture and that the dimensions of the first block satisfy a first condition; and performs a second partitioning on the second block by writing second splitting information indicative of a second partition mode into the bitstream, and using the second partition mode to split the second block into a plurality of coding units (CUs), wherein the second partition mode prohibits the quad tree splitting of the second block in certain conditions.

Encoder, decoder, encoding method, and decoding method using a first partition mode to split a first block into a plurality of second blocks and a second partition mode to split the second block into a plurality of coding units

An encoder that encodes a current block in a picture includes circuitry and memory. Using the memory, the circuitry: splits the current block into a first sub block, a second sub block, and a third sub block in a first direction, the second sub block being located between the first sub block and the third sub block; prohibits splitting the second sub block into two partitions in the first direction; and encodes the first sub block, the second sub block, and the third sub block.

An encoding method includes: determining a merge mode to be applied to a current block, the merge mode including a sub-block merge mode and a first merge mode, wherein in the merge mode, inter-prediction parameters are inferred from a neighboring block neighboring the current block, and wherein in the sub-block merge mode, the current block includes a plurality of sub-blocks, and inter-prediction parameters are provided for each of the plurality of sub-blocks; in response to the merge mode being determined to be the first merge mode, generating a prediction image for the current block by performing a bi-directional optical flow prediction process, wherein the bi-directional optical flow prediction process uses a spatial gradient for the current block; and in response to the merge mode being determined to be the sub-block merge mode, generating a prediction image for the current block by not performing the bi-directional optical flow prediction process.

Encoding method, decoding method, and processing method

An encoder which encodes a current block to be encoded in an image includes: a transformer which performs a primary transform from residuals of the current block to primary coefficients, determines whether to apply a secondary transform to the current block, and performs the secondary transform from the primary coefficients to secondary coefficients when the secondary transform is applied; a quantizer which calculates quantized primary coefficients by performing a first quantization on the primary coefficients when a secondary transform is not applied, and calculates quantized secondary coefficients by performing a second quantization different from the first quantization on the secondary coefficients when the secondary transform is applied; and an entropy encoder which generates an encoded bitstream by encoding either quantized primary coefficients or quantized secondary coefficients.

An encoder that; obtains two prediction images by performing motion compensation using two motion vectors; obtains a gradient value of each of pixels included in the two prediction images; derives a local motion estimation value for each of sub-blocks based on the pixel value and the gradient value of each of the pixels, the sub-blocks being obtained by partitioning the current block; and generates a final prediction image for the current block using the pixel value and the gradient value of each of the pixels, and the local motion estimation value derived for each of the sub-blocks. Each of the pixels in the two prediction images is interpolated with sub-pixel accuracy, and a reference range for the interpolation is included in a normal reference range that is referred to for motion compensation for the current block in normal inter prediction performed without using the local motion estimation value.

An encoder that encodes a current block in a picture includes circuitry and memory. Using the memory, the circuitry: performs a first transform on a residual signal of the current block using a first transform basis to generate first transform coefficients; and performs a second transform on the first transform coefficients using a second transform basis to generate second transform coefficients and quantizes the second transform coefficients, when the first transform basis is the same as a predetermined transform basis; and quantizes the first transform coefficients without performing the second transform, when the first transform basis is different from the predetermined transform basis.

Encoder, encoding method, decoder, and decoding method

Provided is an encoder which includes circuitry and memory. Using the memory, the circuitry splits an image block into a plurality of partitions, obtains a prediction image for a partition, and encodes the image block using the prediction image. When the partition is not a non-rectangular partition, the circuitry obtains (i) a first prediction image for the partition, (ii) a gradient image for the first prediction image, and (iii) a second prediction image as the prediction image using the first prediction image and the gradient image. When the partition is a non-rectangular partition, the circuitry obtains the first prediction image as the prediction image without using the gradient image.

An encoder includes circuitry and memory. Using the memory, the circuitry, in inter prediction processing: derives a first motion vector of a current block to be processed, using a motion vector of a previous block which has been previously processed; derives a second motion vector of the current block by performing motion estimation in the vicinity of the first motion vector; and generates a prediction image of the current block by performing motion compensation using the second motion vector.

A decoder includes a memory and processing circuitry. The processing circuitry, in operation, changes values of pixels in a first block and a second block to filter a boundary therebetween, using clipping such that change amounts of the respective values are within respective clip widths. The clip widths for the pixels in the first block and the second block are selected based on block sizes of the first block and the second block. The pixels in the first block include a first pixel located at a first position, and the pixels in the second block include a second pixel located at a second position corresponding to the first position with respect to the boundary. The clip widths include a first clip width and a second clip width corresponding to the first pixel and the second pixel, respectively, and the first clip width is different from the second width.

An encoder includes circuitry and memory. Using the memory, the circuitry performs a primary transform on a derived prediction error, performs a secondary transform on a result of the primary transform, quantizes a result of the secondary transform, and encodes a result of the quantization as data of an image. When a current block to be processed has a predetermined shape, the encoder performs the secondary transform using, among secondary transform basis candidates that are secondary bases usable in the secondary transform, only a secondary transform basis candidate having a size that is not largest size containable in the current block.

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Osaka, Japan

Ryuichi Kanoh