Abstract: A video decoding apparatus includes matrix reference pixel derivation circuitry that derives reference samples by using top neighboring samples and left neighboring samples of a current block, weight matrix derivation circuitry that derives a weight matrix, matrix prediction image derivation circuitry that derives a prediction image, and matrix prediction image interpolation circuitry that derives a predicted image by using the prediction image. A size index is derived according to a value of a target block width and a value of a target block height. A prediction size is derived using the size index. In a case that a first condition, that both the value of the transform block width and the value of the transform block height are equal to 4, is true, the size index is set equal to 0 and the prediction size is set equal to 4.

Abstract: A video decoding apparatus is a video decoding apparatus for deriving a prediction image by using a reference picture included in a reference picture list.

Abstract: An image decoding apparatus and an image coding apparatus that reduce complexity of high image quality processing are implemented. The image decoding apparatus includes an inter prediction parameter decoding processing unit that includes processing of, regarding two motion vectors, modifying the two motion vectors from an error of two prediction images. In a case that neither of the two prediction images is a case of weighted prediction, the processing of modifying the two motion vectors is performed.

Abstract: In a case that two reference picture lists are selected with one index value, the reference picture lists may not be determinable depending on the number of two reference picture list structures. Provided is a prediction unit that decodes a reference picture list structure including multiple reference picture lists and selects two reference picture lists from the reference picture list structure for each picture or for each slice. The prediction unit selects two reference picture lists with one index value depending on the number of two reference picture list structures.

Abstract: A prediction image generation is provided. First and second luminance values corresponding, respectively, to first and second positions on a luminance image are derived. First and second chrominance values corresponding, respectively, to first and second positions on a chrominance image are derived. First and second difference values indicate, respectively, a first difference between the first and second luminance values and a second difference between the first and second chrominance values. A shift value is derived for a shift operation and a first parameter is derived by using the first and second difference values, and a second parameter is derived by using the second luminance value, the second chrominance value, the first parameter, and the shift value according to a formula. The shift value is set to a first threshold if a value derived by using the first and second difference values is less than the first threshold.

Abstract: A coding device and a decoding device are configured to include an estimated prediction mode deciding section (122a) including: a reference block selecting section (1223a) for selecting a reference block for use in estimating an intra-prediction mode for a subject block; an estimating number deciding section (1222a) for deciding an estimating number of estimated values to be estimated for the intra-prediction mode; and an estimated prediction mode deriving section (1221a) for estimating, based on a reference block, the estimating number of estimated values of the prediction mode.

Abstract: Delay based on WPP processing is reduced. An image decoding apparatus (31) includes: a prediction image generation unit (308) by using decoded data from a first position to a second position, the first position being, in a CTU row immediately above a CTU row including a target CTU, identical to a position of the target CTU, the second position being a position one CTU forward relative to the first position; and an entropy decoding unit (301) that performs decoding of the target CTU by using the decoded data from the first position to the second position, the first position being, in the CTU row immediately above the CTU row including the target CTU, identical to the position of the target CTU, the second position being a position one CTU forward relative to the first position.

Abstract: A non-transitory machine-readable medium of an electronic device that stores one or more computer-executable instructions is provided. The one or more computer-executable instructions, when executed by at least one processing unit of the electronic device, cause the electronic device to: decode a wavefront parallel processing (WPP) enabled flag that indicates whether a rectangular tile or a coding tree unit (CTU) row having a height of one CTU exists in a segment in an object tile group; and decode an end bit of the segment. When the WPP enabled flag is 1, after decoding a CTU at a right end of the CTU row, an end bit of a first segment having a first fixed value is decoded. When the WPP enabled flag is 0, after decoding a CTU at a bottom right of a tile, an end bit of a second segment having a second fixed value is decoded.

Abstract: To achieve a reduction in the amount of coding taken in the use of an asymmetric partition and to implement efficient encoding/decoding processes exploiting the characteristics of the asymmetric partition. An image decoding device includes a motion compensation parameter derivation unit configured to derive a motion compensation parameter indicating either a uni-prediction scheme or a bi-prediction scheme. In a case that a prediction unit has a size less than or equal to a predetermined value, the motion compensation parameter derivation unit is configured to derive the motion compensation parameter by switching between the prediction schemes.

Abstract: An image decoding apparatus and an image coding apparatus that reduce complexity of high image quality processing are implemented. The image decoding apparatus includes an inter prediction parameter decoding processing unit that includes processing of, regarding two motion vectors, modifying the two motion vectors from an error of two prediction images. In a case that neither of the two prediction images is a case of weighted prediction, the processing of modifying the two motion vectors is performed.

Abstract: In a video coding and decoding method, in a case that a transmission rate is low, image quality is deteriorated due to coding distortion, but the image quality can be improved owing to post-filter processing using a neural network. However, a problem is that there may be no method of defining a strength control value to be input in the post-filter processing. A video decoding apparatus according to an aspect of the present invention includes an image decoding apparatus that generates a decoded image, and a post-filter processing apparatus that performs post-filter processing on the decoded image. In accordance with an input format for luminance and chrominance of the decoded image to be input in the post-filter processing, a strength control value obtained in a process of generating the decoded image is transformed, and the post-filter processing is performed.

Abstract: In a case that two reference picture lists are selected with one index value, the reference picture lists may not be determinable depending on the number of two reference picture list structures. Provided is a prediction unit that decodes a reference picture list structure including multiple reference picture lists and selects two reference picture lists from the reference picture list structure for each picture or for each slice. The prediction unit selects two reference picture lists with one index value depending on the number of two reference picture list structures.

Abstract: A coding device and a decoding device are configured to include an estimated prediction mode deciding section (122a) including: a reference block selecting section (1223a) for selecting a reference block for use in estimating an intra-prediction mode for a subject block; an estimating number deciding section (1222a) for deciding an estimating number of estimated values to be estimated for the intra-prediction mode; and an estimated prediction mode deriving section (1221a) for estimating, based on a reference block, the estimating number of estimated values of the prediction mode.

Abstract: A moving image decoding method is provided for decoding encoded data of a tile group generated by splitting a picture into one or more rectangular regions. The tile group includes one or more segments. The moving image decoding method includes decoding a wavefront parallel processing (WPP) enabled flag indicating whether a rectangular tile or a coding tree unit (CTU) row having a height of one CTU exists in a segment in an object tile group; and decoding an end bit of the segment. When the WPP enabled flag is 1, after decoding a CTU at a right end of the CTU row, an end bit of a first segment having a first fixed value is decoded. When the WPP enabled flag is 0, after decoding a CTU at a bottom right of a tile, an end bit of a second segment having a second fixed value is decoded.

Abstract: An image decoding apparatus includes: a first filter unit configured to apply a first filter to an image (a luminance image and a chrominance image); a second filter unit configured to apply a second filter to an output image of the first filter; a filter set derivation unit configured to decode a filter coefficient from coded data; and a third filter unit configured to apply a third filter to an output image of the second filter by using the filter coefficient. In a case that the third filter unit performs filter processing for the luminance image by using a luminance output image of the second filter, the third filter unit performs processing of clipping an amount of change of a pixel value through the filter processing within a prescribed range of value.

Abstract: The amount of memory required for CCLM prediction is reduced. The CCLM prediction parameter derivation unit (310442) derives a scale shift value corresponding to a luma difference value, and derives a CCLM prediction parameter, by shifting, by using the scale shift value, a value obtained by multiplying a value of a table referred to with a value obtained by performing right shift of the luma difference value by the scale shift value as an index and a chroma difference value. In addition, in a case of deriving a prediction image, a bit width is reduced by adaptively deriving a shift amount of a linear prediction parameter from the chroma difference value.

Abstract: In a scheme in which only a part of one picture is intra-predicted and the rest of the region is inter-predicted, generation of a significant code amount and generation of a delay can be avoided in a specific picture. However, because only a part of the picture is coded by means of the intra prediction, coding efficiency is deteriorated as compared to an I picture in which the entire picture is coded by means of the intra prediction. A picture is split into a restricted region and a non-restricted region. Prediction is performed by using an intra prediction in which only a pixel of the restricted region is referred to or an inter prediction in which a restricted reference region of a reference picture is referred to for a block of the restricted region. Prediction is performed by using the intra prediction in which a decoded pixel in the picture is referred to or the inter prediction in which the reference picture is referred to for the block of the non-restricted region.

Abstract: A reference picture information decoding unit (13) omits decoding of a reference list sorting presence or absence flag and/or a reference list sorting order based on the number of current picture referable pictures.

Abstract: The amount of memory required for CCLM prediction is reduced. The CCLM prediction parameter derivation unit (310442) derives a scale shift value corresponding to a luma difference value, and derives a CCLM prediction parameter, by shifting, by using the scale shift value, a value obtained by multiplying a value of a table referred to with a value obtained by performing right shift of the luma difference value by the scale shift value as an index and a chroma difference value. In addition, in a case of deriving a prediction image, a bit width is reduced by adaptively deriving a shift amount of a linear prediction parameter from the chroma difference value.

Abstract: An image decoding device (31) includes a transform coefficient decoding unit (311) configured to decode a transform coefficient for a transform tree included in a coding unit. In the transform tree, the transform coefficient decoding unit splits a transform unit corresponding to luminance and then decodes the transform coefficient related to the luminance, and does not split the transform unit corresponding to chrominance and decodes the transform coefficient related to the chrominance.