Abstract: A mechanism is provided that implements video coding and decoding such that only a specific partial image region on a screen can be independently decoded. A video decoding apparatus (31) according to an aspect of the present invention configures, in intra prediction, inter prediction, loop filter processing, or the like, a partial image region in a picture, handles a region outside the partial image region in a similar manner to a region outside the picture, and does not apply such restriction to a non-partial image region other than the partial image region in the picture.

Abstract: An adaptive motion vector prediction unit configured to adaptively perform spatial prediction that performs prediction using a motion vector around a target block and temporal prediction that performs prediction using a motion vector of a collocated picture is included, and in the temporal prediction performed by the adaptive motion vector prediction unit, the collocated picture to be referred to is designated on a per picture basis, and a reference list is designated on a per slice basis.

Abstract: According to an embodiment, an encoding device includes an index setting unit and an encoding unit. The index setting unit generates a common index in which reference indices of one or more reference images included in a first index and a second index are sorted in a combination so as not to include a same reference image in accordance with a predetermined scanning order. The first index representing a combination of the one or more reference images referred to by a first reference image. The second index representing a combination of the one or more reference images referred to by a second reference image. The encoding unit encodes the common index.

Abstract: A mechanism is provided that implements video coding and decoding such that only a specific partial image region on a screen can be independently decoded. A video decoding apparatus (31) according to an aspect of the present invention configures, in intra prediction, inter prediction, loop filter processing, or the like, a partial image region in a picture, handles a region outside the partial image region in a similar manner to a region outside the picture, and does not apply such restriction to a non-partial image region other than the partial image region in the picture.

Abstract: According to an embodiment, an image coding method is for coding an image including a luminance component and color difference components. The method includes acquiring a reference image; and generating a predicted image by interpolating the luminance component and the color difference components in the reference image according to a motion vector. If a size of a block, which is designated as a unit of the interpolation, is equal to or smaller than a predetermined first threshold value, the generating includes inhibiting a bi-directional prediction, and performing only a uni-directional prediction to generate the predicted image according to the motion vector.

Abstract: An image decoding apparatus is implemented that can suppress a decrease in coding efficiency in a case that a high compression rate is achieved. The image decoding apparatus includes a parameter decoder, and the parameter decoder decodes a skip flag indicating whether a skip mode is applied, and in a case that the skip flag does not indicate the skip mode, decodes a merge flag indicating whether a merge mode is applied, and in a case that the merge flag does not indicate the merge mode, decodes an MMVD flag indicating whether an MMVD mode is applied.

Abstract: According to an embodiment, an encoding device includes an index setting unit and an encoding unit. The index setting unit generates a common index in which reference indices of one or more reference images included in a first index and a second index are sorted in a combination so as not to include a same reference image in accordance with a predetermined scanning order. The first index representing a combination of the one or more reference images referred to by a first reference image. The second index representing a combination of the one or more reference images referred to by a second reference image. The encoding unit encodes the common index.

Abstract: A prediction image generation method is provided. The method derives a down-sampled luminance image and a down-sampled neighboring luminance image by down-sampling the luminance image of a target block and a neighboring luminance image based on information related to a down-sampling and indicating one of a plurality of position relationships between at least one luma pixel and a chroma pixel. The method derives a neighboring chrominance image, parameters derived from the down-sampled neighboring luminance image and the neighboring chrominance image, and the prediction image by using the down-sampled luminance image and the parameters. The position relationships include that a position of the chroma pixel is identical to a position of one of the at least one luma pixel and that the position of the chroma pixel is located in an intermediate of two of the at least one luma pixel on a left side of a 2×2 luma pixel block.

Abstract: According to an embodiment, an image coding method is for coding an image including a luminance component and color difference components. The method includes acquiring a reference image; and generating a predicted image by interpolating the luminance component and the color difference components in the reference image according to a motion vector. If a size of a block, which is designated as a unit of the interpolation, is equal to or smaller than a predetermined first threshold value, the generating includes inhibiting a bi-directional prediction, and performing only a uni-directional prediction to generate the predicted image according to the motion vector.

Abstract: In the related art, in some cases the weighted prediction processing is performed even in a case that normal prediction processing is to be performed. A video decoding apparatus includes a weighted prediction processing unit configured to decode a weight coefficient and an offset value from coded data and to generate a prediction image by multiplying an interpolation image by the weight coefficient and adding the offset value to the interpolation image, and a normal prediction processing unit configured to generate a prediction image from the interpolation image. In a case that in the weighted prediction processing unit, a bi-prediction is performed and information of the weight coefficient and the offset value is absent for both a reference list 0 and a reference list 1, the normal prediction processing unit generates a bi-prediction image.

Abstract: An image coding apparatus includes a coded data generating unit configured to generate coded data including image data for a subpicture acquired by dividing a picture, where the coded data generating unit generates, on a per subpicture basis, a subpicture header including subpicture identification information used for identifying the subpicture, and causes the generated subpicture header to be included in the coded data.

Abstract: According to an embodiment, an encoding device includes an index setting unit and an encoding unit. The index setting unit generates a common index in which reference indices of one or more reference images included in a first index and a second index are sorted in a combination so as not to include a same reference image in accordance with a predetermined scanning order. The first index representing a combination of the one or more reference images referred to by a first reference image. The second index representing a combination of the one or more reference images referred to by a second reference image. The encoding unit encodes the common index.

Abstract: According to an embodiment, an encoding device includes a deriving unit and an encoding unit. The deriving unit is configured to derive a first reference value based on fixed point precision representing roughness of a weighting factor that is used for multiplying a reference image. The encoding unit is configured to encode a first difference value that is a difference value between the weighting factor and the first reference value and the fixed point precision. The weighting factor is included in a first range of predetermined bit precision having the first reference value at approximate center. The first difference value is in the predetermined range.

Abstract: An image decoding apparatus is implemented that can suppress a decrease in coding efficiency in a case that a high compression rate is achieved. The image decoding apparatus includes a parameter decoder, and the parameter decoder decodes a skip flag indicating whether a skip mode is applied, and in a case that the skip flag does not indicate the skip mode, decodes a merge flag indicating whether a merge mode is applied, and in a case that the merge flag does not indicate the merge mode, decodes an MMVD flag indicating whether an MMVD mode is applied.

Abstract: According to an embodiment, a decoding device includes an acquiring unit configured to acquire first format information, encoded data, and first filter information, the first format information indicating a resolution of a color-difference component of the encoded data; a decoding unit configured to decode the encoded data to obtain a decoded image; and a converting unit configured to convert a color-difference format of the decoded image represented by a first color-difference format by using a filter identified by the filter information.

Abstract: According to an embodiment, a decoding device includes an acquiring unit configured to acquire first format information, encoded data, and first filter information, the first format information indicating a resolution of a color-difference component of the encoded data; a decoding unit configured to decode the encoded data to obtain a decoded image; and a converting unit configured to convert a color-difference formal of the decoded image represented by a first color-difference format by using a filter identified by the filter information.

Abstract: According to an embodiment, an encoding device includes an index setting unit and an encoding unit. The index setting unit generates a common index in which reference indices of one or more reference images included in a first index and a second index are sorted in a combination so as not to include a same reference image in accordance with a predetermined scanning order. The first index representing a combination of the one or more reference images referred to by a first reference image. The second index representing a combination of the one or more reference images referred to by a second reference image. The encoding unit encodes the common index.

Abstract: According to an embodiment, an image coding method is for coding an image including a luminance component and color difference components. The method includes acquiring a reference image; and generating a predicted image by interpolating the luminance component and the color difference components in the reference image according to a motion vector. If a size of a block, which is designated as a unit of the interpolation, is equal to or smaller than a predetermined first threshold value, the generating includes inhibiting a bi-directional prediction, and performing only a uni-directional prediction to generate the predicted image according to the motion vector.

Abstract: An encoding device includes a deriving unit and an encoding unit. The deriving unit is configured to derive a first reference value based on fixed point precision representing roughness of a weighting factor that is used for multiplying a reference image. The encoding unit is configured to encode a first difference value that is a difference value between the weighting factor and the first reference value and the fixed point precision. The weighting factor is included in a first range of predetermined bit precision having the first reference value at approximate center. The first difference value is in the predetermined range.

Abstract: Provided is a video decoding apparatus for decoding coded data of a tile group in which a picture is split into rectangular regions, the tile group being composed of segments, the video decoding apparatus including: a header decoder configured to decode the number of tiles, a WPP enabled flag, and a slice enabled flag indicating whether segments in a target tile group are rectangular tiles, CTU rows, or slices from a tile group header, wherein the header decoder is configured to decode only one of the number of tiles being two or more, the WPP enabled flag being 1, and the slice enabled flag being 1 in one tile group.