Abstract: An image coding method includes: selecting a first picture from plural pictures; setting a first temporal motion vector prediction flag which is associated with the first picture and is a temporal motion vector prediction flag indicating whether or not temporal motion vector prediction is to be used, to indicate that the temporal motion vector prediction is not to be used, and coding the first temporal motion vector prediction flag; coding the first picture without using the temporal motion vector prediction; and coding a second picture which follows the first picture in coding order, with referring to a motion vector of a picture preceding the first picture in coding order being prohibited.

Abstract: An image coding method includes coding a motion vector difference indicating a difference between the motion vector and a predicted motion vector, wherein the coding includes: coding a first portion that is a part of a first component which is one of a horizontal component and a vertical component of the motion vector difference; coding a second portion that is a part of a second component which is different from the first component and is the other one of the horizontal component and the vertical component; coding a third portion that is a part of the first component and is different from the first portion; coding a fourth portion that is a part of the second component and is different from the second portion; and generating a code string which includes the first portion, the second portion, the third portion, and the fourth portion in the stated order.

Abstract: A processor obtains pieces of coded data, which are included in a bitstream and generated by coding tiles, and tile boundary independence information, which indicates whether each boundary between the tiles is a first or second boundary. Image data of a first tile is generated by decoding a first code string included in first coded data with reference to decoding information of a decoded tile when the tile boundary independence information indicates the first boundary, and by decoding the first code string without referring to the decoding information when the tile boundary independence information indicates the second boundary. A bit string is added after the first code string to make a bit length of first coded data a multiple of a predetermined N bits, with N being an integer greater than or equal to 2.

Abstract: An image decoding method which can improve both image quality and coding efficiency is an image decoding method for decoding a coded stream which includes a plurality of processing units and a header for the processing units, the coded stream being generated by coding a moving picture, the processing units including at least one processing unit layered to be split into a plurality of smaller processing units, the image decoding method including specifying a hierarchical layer having a processing unit in which a parameter necessary for decoding is stored, by parsing hierarchy depth information stored in the header, and decoding the processing unit using the parameter stored in the processing unit located at the specified hierarchical layer.

Abstract: The image coding method includes: determining a context in a current block in the image, from among a plurality of contexts; and performing arithmetic coding on the control parameter for the current block to generate a bitstream corresponding to the current block, wherein in the determining: the context is determined under a condition that control parameters of neighboring blocks of the current block are used, when the signal type is a first type, the neighboring blocks being a left block and an upper block of the current block; and the context is determined under a condition that the control parameter of the upper block is not used, when the signal type is a second type, and the second type is (i) “merge_flag”, (ii) “ref_idx_l0” or “ref_idx_l1”, (iii) “inter_pred_flag”, (iv) “mvd_l0” or “mvd_l1”, (v) “no_residual_data_flag”, (vi) “intra_chroma_pred_mode”, (vii) “cbf_luma”, and (viii) “cbf_cb” or “cbf_cr”.

Abstract: A moving picture coding apparatus includes an intra-inter prediction unit which calculates a second motion vector by performing a scaling process on a first motion vector of a temporally neighboring corresponding block, when selectively adding, to a list, a motion vector of each of one or more corresponding blocks each of which is either a block included in a current picture to be coded and spatially neighboring a current block to be coded or a block included in a picture other than the current picture and temporally neighboring the current block, determines whether the second motion vector has a magnitude that is within a predetermined magnitude or not within the predetermined magnitude, and adds the second motion vector to the list when the intra-inter prediction unit determines that the second motion vector has a magnitude that is within the predetermined magnitude range.

Abstract: An image coding method comprising: obtaining current signals to be coded of each of the processing units of the image; generating a binary signal by performing binarization on each of the current signals to be coded; selecting a context for each of the current signals to be coded from among a plurality of contexts; performing arithmetic coding of the binary signal by using coded probability information associated with the context selected in the selecting; and updating the coded probability information based on the binary signal, wherein, in the selecting, the context for the current signal to be coded is selected, as a shared context, for a signal which is included in one of a plurality of processing units and has a size different from a size of the processing unit including the current signal to be coded.

Abstract: The image decoding method includes determining a context for use in a current block to be processed, from among a plurality of contexts, wherein in the determining: the context is determined under a condition that control parameters of a left block and an upper block are used, when the signal type is a first type; and the context is determined under a third condition that the control parameter of the upper block is not used and a hierarchical depth of a data unit to which the control parameter of the current block belongs is used, when the signal type is a third type, and the third type is one or more of (i) “merge_flag”, (ii) “ref_idx_I0” or “ref_idx_I1”, (iii) “inter_pred_flag”, (iv) “mvd_I0” or “mvd_I1”, (v) “intra_chroma_pred_mode”, (vi) “cbf_luma”, and (vii) “cbf_cb” or “cbf_cr”.

Abstract: An image encoding method including: a constraint information generating step of generating tile constraint information indicating whether or not there is a constraint in filtering on boundaries between adjacent tiles among a plurality of tiles obtained by dividing a picture, and storing the tile constraint information into a sequence parameter set; and a filter information generating step of generating, for each of the boundaries, one of a plurality of filter information items respectively indicating whether or not filtering is executed on the boundaries, and storing the plurality of filter information items into a plurality of picture parameter sets, wherein, in the filter information generating step, the plurality of filter information items which indicate identical content are generated when the tile constraint information indicates that there is the constraint in the filtering.

Abstract: The image decoding method includes: determining a context for use in a current block to be processed, from among a plurality of contexts; and performing arithmetic decoding on a bit sequence corresponding to the current block, using the determined context, wherein in the determining: the context is determined under a condition that control parameters of neighboring blocks of the current block are used, when the signal type is a first type, the neighboring blocks being a left block and an upper block of the current block; and the context is determined under a condition that the control parameter of the upper block is not used, when the signal type is a second type, and the second type is one of “ref_idx_l0” and “ref_idx_l1”.

Abstract: An image coding method includes: writing, into a sequence parameter set, buffer description defining information for defining a plurality of buffer descriptions; selecting one of the buffer descriptions for each processing unit that is a picture or a slice, and writing buffer description selecting information for specifying the selected buffer description, into a first header of the processing unit which is included in the coded bitstream; and coding the processing unit using the selected buffer description, and the buffer description defining information includes long-term information for identifying, among a plurality of reference pictures indicated in the buffer descriptions, a reference picture to be assigned as a long-term reference picture.

Abstract: A moving picture coding method includes (i) transforming, for each of one or more second processing units included in the first processing unit, a moving picture signal in a spatial domain into a frequency domain coefficient and quantizing the frequency domain coefficient, and (ii) performing arithmetic coding on a luminance CBF flag indicating whether or not a quantized coefficient is included in the second processing unit in which transform and quantization are performed, wherein, in the arithmetic coding, a probability table for use in arithmetic coding is determined according to whether or not the size of the first processing unit is identical to the size of the second processing unit and whether or not the second processing unit has a predetermined maximum size.

Abstract: An image decoding method of decoding, on a block-by-block basis, image data included in a coded stream includes: deriving candidates for an intra prediction mode to be used for intra prediction for a decoding target block, the number of the candidates constantly being a plural number; obtaining, from the coded stream, an index for identifying one of the derived candidates for the intra prediction mode; and determining, based on the obtained index, one of the derived candidates for the intra prediction mode as the intra prediction mode to be used for intra prediction for the decoding target block.

Abstract: An image coding method includes coding a motion vector difference indicating a difference between the motion vector and a predicted motion vector, wherein the coding includes: coding a first portion that is a part of a first component which is one of a horizontal component and a vertical component of the motion vector difference; coding a second portion that is a part of a second component which is different from the first component and is the other one of the horizontal component and the vertical component; coding a third portion that is a part of the first component and is different from the first portion; coding a fourth portion that is a part of the second component and is different from the second portion; and generating a code string which includes the first portion, the second portion, the third portion, and the fourth portion in the stated order.

Abstract: An image decoding method which can improve both image quality and coding efficiency is an image decoding method for decoding a coded stream which includes a plurality of processing units and a header for the processing units, the coded stream being generated by coding a moving picture, the processing units including at least one processing unit layered to be split into a plurality of smaller processing units, the image decoding method including specifying a hierarchical layer having a processing unit in which a parameter necessary for decoding is stored, by parsing hierarchy depth information stored in the header, and decoding the processing unit using the parameter stored in the processing unit located at the specified hierarchical layer.

Abstract: An image decoding method includes: dividing a current block into sub-blocks; deriving, for each sub-block, one or more prediction information candidates; obtaining an index; and decoding the current block using the prediction information candidate selected by the index.

Abstract: A moving picture coding method includes: making a determination as to whether or not to code all blocks in a current picture in the skip mode; setting, based on a result of the determination, a first flag indicating whether or not a temporally neighboring block is to be referenced, a value of a parameter for determining a total number of merging candidates, and a second flag for each block included in the current picture, the second flag indicating whether or not the block is to be coded in the skip mode; calculating, as a merging candidate, a neighboring block usable for merging; and coding an index which indicates a merging candidate to be used for coding of the current block and attaching the coded index to a bitstream.

Abstract: A moving picture coding apparatus includes an intra-inter prediction unit which calculates a second motion vector by performing a scaling process on a first motion vector of a temporally neighboring corresponding block, when selectively adding, to a list, a motion vector of each of one or more corresponding blocks each of which is either a block included in a current picture to be coded and spatially neighboring a current block to be coded or a block included in a picture other than the current picture and temporally neighboring the current block, determines whether the second motion vector has a magnitude that is within a predetermined magnitude or not within the predetermined magnitude, and adds the second motion vector to the list when the intra-inter prediction unit determines that the second motion vector has a magnitude that is within the predetermined magnitude range.

Abstract: An image decoding apparatus obtain pieces of coded data that is included in a bitstream and generated by coding tiles. Tile boundary independence information is further obtained from the bitstream, with the tile boundary independence information indicating whether each of boundaries between the tiles is one of a first boundary or a second boundary. The pieces of coded data are decoded to generate image data of the tiles. Image data of a first tile is generated by decoding a first code string included in first coded data with reference to decoding information of a decoded tile when the tile boundary independence information indicates the first boundary, and by decoding the first code string without referring to the decoding information of the decoded tile when the tile boundary independence information indicates the second boundary.

Abstract: An image coding method includes: deriving a candidate for a motion vector of a current block from a co-located motion vector; adding the candidate to a list; selecting the motion vector of the current block from the list; and coding the current block, wherein the deriving includes: deriving the candidate by a first derivation scheme in the case of determining that each of a current reference picture and a co-located reference picture is a long-term reference picture; and deriving the candidate by a second derivation scheme in the case of determining that each of the current reference picture and the co-located reference picture is a short-term reference picture.