Patent ID: 7519117

Claim:
A method of synthesizing an inter-frame predicted image in a video decoder, comprising the step of: performing a motion compensation process between a current image and a reference image, wherein said motion compensation process includes the steps of: dividing said current image into N patches, N being a positive integer, arranging an assumed patch Pa corresponding to a patch Pb which is one of the N patches, Pa having three assumed grid points as representative points having coordinates (I, J), (I+p, J), and (I, J+q), obtaining motion vectors of the three representative points, and computing a motion vector of each pixel in the patch Pa by affine transformation using the motion vectors of the three representative points, wherein either of p and −p is equal to 2 α , α being a positive integer, wherein either of q and −q is equal to 2 β , β being a positive integer, wherein I and J are integers, and wherein the horizontal and vertical components of motion vectors at representative points (I, J), (I+p, J), and (I, J+q) take only values integral multiples of 1/k, wherein k is equal to 2 h0 and h 0 is an integer other than a negative integer, the horizontal and vertical components of the motion vector of each pixel take only values integral multiples of 1/m, wherein m is a positive integer, and (u(x, y), v(x, y)), wherein x, y, u(x, y), and v(x, y) are integers, obtained by multiplying the horizontal and vertical components of the motion vector of a pixel (x,y) in the patch Pa by m, is shown using (u 0 , v 0 ), (u 1 , v 1 ), and (u 2 , v 2 ), wherein u 0 , v 0 , u 1 , v 1 , u 2 , v 2 are integers, obtained by multiplying the horizontal and vertical components of the motion vectors at the representative points (I, J), (I+p, J), and (I, J+q) by k, as per u(x, y)=((u 0 ·p·q+(u 1 −u 0 ) (x−I′)·q+(u 2 −u 0 ) (y−J′)·p)m)//(p·q·k), wherein v(x,y)=((v 0 ·p·q+(v 1 −v 0 ) (x−I′)·q+(v 2 −v 0 ) (y−J′)·p)m)//(p·q·k), and wherein symbol “//” denotes a division that rounds to a nearest integer an operation result obtained from a division of real numbers when the result is not an integer and its priority as an operator is equal to that of a multiplication or division.