Abstract: An image decoding method includes: restoring a selected prediction mode used in prediction at a time of coding; and decoding a current block included in coded image data to generate a decoded block, according to the prediction based on the selected prediction mode. The restoring includes: determining a first estimated prediction mode; determining a second estimated prediction mode different from the first estimated prediction mode; and restoring the selected prediction mode based on the mode information, the first estimated prediction mode, and the second estimated prediction mode.

Abstract: An encoder includes circuitry, and memory coupled to the circuitry. The circuitry, in operation, for each of a plurality of sub-bitstreams having mutually different frame rates, encodes identification information into a header of a bitstream including the plurality of sub-bitstreams, the identification information indicating a temporal ID that is an identifier of a temporal layer related to a temporal scalability and corresponds to the sub-bitstream, and encodes level information indicating a conformance level of the sub-bitstream.

Abstract: An encoder includes circuitry and memory. Using the memory, the circuitry performs: deriving a plurality of reference samples positioned on a first line, for intra prediction; and generating a prediction image using the plurality of reference samples. The deriving includes interpolating a value on a second line perpendicular to the first line using values of encoded pixels on the second line to generate an interpolated value, and deriving one of the plurality of reference samples by projecting the interpolated value onto the first line.

Abstract: An encoder includes circuitry and memory coupled to the circuitry. In operation, the circuitry: writes, into a sequence parameter set which is header information of a sequence, video usability information syntax which is information for realizing an additional function in display of an image, and syntax different from the video usability information syntax. The syntax includes at least one parameter related to display timing of the image.

Abstract: A data generation method is for generating video data that covers a second luminance dynamic range wider than a first luminance dynamic range and has reproduction compatibility with a first device that does not support reproduction of video having the second luminance dynamic range and supports reproduction of video having the first luminance dynamic range, and includes: generating a video signal to be included in the video data using a second OETF; storing, into VUI in the video data, first transfer function information for identifying a first OETF to be referred to by the first device when the first device decodes the video data; and storing, into SEI in the video data, second transfer function information for identifying a second OETF to be referred to by a second device supporting reproduction of video having the second luminance dynamic range when the second device decodes the video data.

Abstract: An image decoding method includes: restoring a selected prediction mode used in prediction at a time of coding; and decoding a current block included in coded image data to generate a decoded block, according to the prediction based on the selected prediction mode. The restoring includes: determining a first estimated prediction mode; determining a second estimated prediction mode different from the first estimated prediction mode; and restoring the selected prediction mode based on the mode information, the first estimated prediction mode, and the second estimated prediction mode.

Abstract: A data generation method is for generating video data that covers a second luminance dynamic range wider than a first luminance dynamic range and has reproduction compatibility with a first device that does not support reproduction of video having the second luminance dynamic range and supports reproduction of video having the first luminance dynamic range, and includes: generating a video signal to be included in the video data using a second OETF; storing, into VUI in the video data, first transfer function information for identifying a first OETF to be referred to by the first device when the first device decodes the video data; and storing, into SEI in the video data, second transfer function information for identifying a second OETF to be referred to by a second device supporting reproduction of video having the second luminance dynamic range when the second device decodes the video data.

Abstract: A data generation method is for generating video data that covers a second luminance dynamic range wider than a first luminance dynamic range and has reproduction compatibility with a first device that does not support reproduction of video having the second luminance dynamic range and supports reproduction of video having the first luminance dynamic range, and includes: generating a video signal to be included in the video data using a second OETF; storing, into VUI in the video data, first transfer function information for identifying a first OETF to be referred to by the first device when the first device decodes the video data; and storing, into SEI in the video data, second transfer function information for identifying a second OETF to be referred to by a second device supporting reproduction of video having the second luminance dynamic range when the second device decodes the video data.

Abstract: A data generation method is for generating video data that covers a second luminance dynamic range wider than a first luminance dynamic range and has reproduction compatibility with a first device that does not support reproduction of video having the second luminance dynamic range and supports reproduction of video having the first luminance dynamic range, and includes: generating a video signal to be included in the video data using a second OETF; storing, into VUI in the video data, first transfer function information for identifying a first OETF to be referred to by the first device when the first device decodes the video data; and storing, into SEI in the video data, second transfer function information for identifying a second OETF to be referred to by a second device supporting reproduction of video having the second luminance dynamic range when the second device decodes the video data.

Abstract: A data generation method is for generating video data that covers a second luminance dynamic range wider than a first luminance dynamic range and has reproduction compatibility with a first device that does not support reproduction of video having the second luminance dynamic range and supports reproduction of video having the first luminance dynamic range, and includes: generating a video signal to be included in the video data using a second OETF; storing, into VUI in the video data, first transfer function information for identifying a first OETF to be referred to by the first device when the first device decodes the video data; and storing, into SEI in the video data, second transfer function information for identifying a second OETF to be referred to by a second device supporting reproduction of video having the second luminance dynamic range when the second device decodes the video data.

Abstract: An image decoding method includes: restoring a selected prediction mode used in prediction at a time of coding; and decoding a current block included in coded image data to generate a decoded block, according to the prediction based on the selected prediction mode. The restoring includes: determining a first estimated prediction mode; determining a second estimated prediction mode different from the first estimated prediction mode; and restoring the selected prediction mode based on the mode information, the first estimated prediction mode, and the second estimated prediction mode.

Abstract: An encoding device which further improves coding technique includes processing circuitry and memory. By using the memory, the processing circuitry: performs filtering on a pixel value of a current reference sample to be processed included in reference samples located on a left of or above a current block to be predicted, using pixel values of the reference samples; generates a prediction image by performing intra prediction using the filtered pixel value of the current reference sample. When performing the filtering, the processing circuitry: determines a weight for each reference sample, based on a distance between the reference sample and the current reference sample and a difference in pixel value between the same; and performs filtering on the pixel value of the current reference sample by weighted addition using each of the pixel values of the reference samples and the weight determined for each reference sample.

Abstract: An encoder includes circuitry and memory. The circuitry, using the memory: derives a one-dimensional array of a plurality of reference samples for intra prediction; performs smoothing on the one-dimensional array of the plurality of reference samples which has been derived; and generates a prediction image using the plurality of reference samples. In deriving the one-dimensional array, the circuitry projects a value of at least one decoded pixel located on a first line onto a second line perpendicular to the first line, to derive at least one of the plurality of reference samples, and the smoothing is performed on the at least one decoded pixel projected onto the second line.

Abstract: A data generation method is for generating video data that covers a second luminance dynamic range wider than a first luminance dynamic range and has reproduction compatibility with a first device that does not support reproduction of video having the second luminance dynamic range and supports reproduction of video having the first luminance dynamic range, and includes: generating a video signal to be included in the video data using a second OETF; storing, into VUI in the video data, first transfer function information for identifying a first OETF to be referred to by the first device when the first device decodes the video data; and storing, into SEI in the video data, second transfer function information for identifying a second OETF to be referred to by a second device supporting reproduction of video having the second luminance dynamic range when the second device decodes the video data.

Abstract: A data generation method is for generating video data that covers a second luminance dynamic range wider than a first luminance dynamic range and has reproduction compatibility with a first device that does not support reproduction of video having the second luminance dynamic range and supports reproduction of video having the first luminance dynamic range, and includes: generating a video signal to be included in the video data using a second OETF; storing, into VUI in the video data, first transfer function information for identifying a first OETF to be referred to by the first device when the first device decodes the video data; and storing, into SEI in the video data, second transfer function information for identifying a second OETF to be referred to by a second device supporting reproduction of video having the second luminance dynamic range when the second device decodes the video data.

Abstract: An encoder is an encoder that encodes a block in a picture using a prediction image of the block, and includes circuitry and memory. Using the memory, the circuitry: calculates a first average pixel value which is an average pixel value of first reference samples out of the first reference samples and second reference samples, The first reference samples are referable and located outside the block and adjacent to a first side of the block. The second reference samples are referable and located outside the block and adjacent to a second side of the block. When generating the prediction image, the circuitry applies the same prediction pixel value to inner samples among current samples to be processed that are included in the block. The inner samples constitute a quadrilateral region including at least two current samples in each of a horizontal direction and a vertical direction.

Abstract: A data generation method is for generating video data that covers a second luminance dynamic range wider than a first luminance dynamic range and has reproduction compatibility with a first device that does not support reproduction of video having the second luminance dynamic range and supports reproduction of video having the first luminance dynamic range, and includes: generating a video signal to be included in the video data using a second OETF; storing, into VUI in the video data, first transfer function information for identifying a first OETF to be referred to by the first device when the first device decodes the video data; and storing, into SEI in the video data, second transfer function information for identifying a second OETF to be referred to by a second device supporting reproduction of video having the second luminance dynamic range when the second device decodes the video data.

Abstract: A data generation method is for generating video data that covers a second luminance dynamic range wider than a first luminance dynamic range and has reproduction compatibility with a first device that does not support reproduction of video having the second luminance dynamic range and supports reproduction of video having the first luminance dynamic range, and includes: generating a video signal to be included in the video data using a second OETF; storing, into VUI in the video data, first transfer function information for identifying a first OETF to be referred to by the first device when the first device decodes the video data; and storing, into SEI in the video data, second transfer function information for identifying a second OETF to be referred to by a second device supporting reproduction of video having the second luminance dynamic range when the second device decodes the video data.

Abstract: A data generation method is for generating video data that covers a second luminance dynamic range wider than a first luminance dynamic range and has reproduction compatibility with a first device that does not support reproduction of video having the second luminance dynamic range and supports reproduction of video having the first luminance dynamic range, and includes: generating a video signal to be included in the video data using a second OETF; storing, into VUI in the video data, first transfer function information for identifying a first OETF to be referred to by the first device when the first device decodes the video data; and storing, into SEI in the video data, second transfer function information for identifying a second OETF to be referred to by a second device supporting reproduction of video having the second luminance dynamic range when the second device decodes the video data.

Abstract: A data generation method is for generating video data that covers a second luminance dynamic range wider than a first luminance dynamic range and has reproduction compatibility with a first device that does not support reproduction of video having the second luminance dynamic range and supports reproduction of video having the first luminance dynamic range, and includes: generating a video signal to be included in the video data using a second OETF; storing, into VUI in the video data, first transfer function information for identifying a first OETF to be referred to by the first device when the first device decodes the video data; and storing, into SEI in the video data, second transfer function information for identifying a second OETF to be referred to by a second device supporting reproduction of video having the second luminance dynamic range when the second device decodes the video data.