Patent ID: 8135064

Claim:
An intra prediction apparatus comprising: an acquiring unit configured to acquire information identifying a display form of a plurality of pixels that makes up input video data, the display form being used for displaying the plurality of pixels as a picture; a candidate narrowing-down unit configured to narrow down, from a plurality of intra prediction directions, intra prediction direction candidates based on the information acquired by the acquiring unit, the intra prediction direction candidates being applied to a block composed of the plurality of pixels; and an intra prediction execution unit configured to execute intra prediction on the block using the intra prediction direction candidates narrowed down by said candidate narrowing-down unit, wherein a combination of the intra prediction direction candidates narrowed down by said candidate narrowing-down unit changes depending on horizontal and vertical distribution of the plurality of pixels as indicated by the information acquired by the acquiring unit, (a) a majority of the intra prediction directions included in the narrowed-down intra prediction direction candidates each have more vertically oriented components than horizontally oriented components when a comparison between the vertical distribution and the horizontal distribution of the plurality of pixels shows that density of the vertical distribution is higher than density of the horizontal distribution, and (b) a majority of the intra prediction directions included in the narrowed-down intra prediction direction candidates each have more horizontally oriented components than vertically oriented components when a comparison between the vertical distribution and the horizontal distribution of the plurality of pixels shows that density of the horizontal distribution is higher than density of the vertical distribution.