Claims:We Claim :
[1] An image decoding device comprising:
an intra prediction unit (34) for, when a coding mode for a coding block is an intra coding mode, carrying out an intra-frame prediction process on each of processing blocks to generate a prediction value for each of pixels of a prediction image, each of the processing blocks being the coding block or a sub-block obtained by dividing the coding block,
wherein, when an intra prediction parameter indicates a horizontal prediction process, the intra prediction unit (34) adds, at each row within a predetermined number of a row or rows locating from an upper end of the processing block, a value to a luminance value of a pixel adjacent to left of the processing block and sets a result of the addition as a predicted value of the prediction image, the value being proportional to an amount of change in a horizontal direction of luminance values of pixels adjacent to top of the processing block and being obtained by scaling the amount of change, and the intra prediction unit (34) sets, at remaining rows of the processing block, a luminance value of a pixel adjacent to left of the processing block as a predicted value of the prediction image.

[2] The image decoding device according to claim 1, wherein the one row in the processing block is an uppermost row in the processing block.

[3] An image decoding method comprising an intra prediction processing step performed by an intra prediction unit (34 ), the intra prediction processing step including processes of, when a coding mode for a coding block is an intra coding mode, carrying out an intra-frame prediction process on each of processing blocks to generate a prediction value for each of pixels of a prediction image, each of the processing blocks being the coding block or a sub-block obtained by dividing the coding block, and
when an intra prediction parameter indicates a horizontal prediction process, adding, at each row within a predetermined number of a row or rows locating from an upper end of the processing block, a value to a luminance value of a pixel adjacent to left of the processing block and sets a result of the addition as a predicted value of the prediction image, the value being proportional to an amount of change in a horizontal direction of luminance values of pixels adjacent to top of the processing block and being obtained by scaling the amount of change, and setting, at remaining rows of the processing block, a luminance value of a pixel adjacent to left of the processing block as a predicted value of the prediction image.

[4] The image decoding method according to claim 3, wherein the one row in the processing block is an uppermost row in the processing block.

[5] An image encoding device comprising:
an intra prediction unit (4) for, when a coding mode for a coding block is an intra coding mode, carrying out an intra-frame prediction process on each of processing blocks to generate a prediction value for each of pixels of a prediction image, each of the processing blocks being the coding block or a sub-block obtained by dividing the coding block,
wherein, when an intra prediction parameter indicates a horizontal prediction process, the intra prediction unit (4) adds, at each row within a predetermined number of a row or rows locating from an upper end of the processing block, a value to a luminance value of a pixel adjacent to left of the processing block and sets a result of the addition as a predicted value of the prediction image, the value being proportional to an amount of change in a horizontal direction of luminance values of pixels adjacent to top of the processing block and being obtained by scaling the amount of change, and the intra prediction unit (4) sets, at remaining rows of the processing block, a luminance value of a pixel adjacent to left of the processing block as a predicted value of the prediction image.

[6] The image encoding device according to claim 5, wherein the one row in the processing block is an uppermost row in the processing block.

[7] An image encoding method comprising an intra prediction processing step performed by an intra prediction unit (4), the intra prediction processing step including processes of,
when a coding mode for a coding block is an intra coding mode, carrying out an intra-frame prediction process on each of processing blocks to generate a prediction value for each of pixels of a prediction image, each of the processing blocks being the coding block or a sub-block obtained by dividing the coding block, and
when an intra prediction parameter indicates a horizontal prediction process, for generating the prediction value for each of pixels in one or more rows in the processing block, adding, at each row within a predetermined number of a row or rows locating from an upper end of the processing block, a value to a luminance value of a pixel adjacent to left of the processing block and sets a result of the addition as a predicted value of the prediction image, the value being proportional to an amount of change in a horizontal direction of luminance values of pixels adjacent to top of the processing block and being obtained by scaling the amount of change, and setting, at remaining rows of the processing block, a luminance value of a pixel adjacent to left of the processing block as a predicted value of the prediction image.

[8] The image encoding method according to claim 7, wherein the one row in the processing block is an uppermost row in the processing block.
, Description:Please see the attached documents