Patent ID: 7139314

Claim:
A decoder of performing a motion compensation between a current image and a reference image for synthesizing an inter-frame predicted image comprising: means for dividing said current image into N patches, N being a positive integer; means for 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); means for obtaining motion vectors of the three representative points; and means for computing a motion vector of each pixel in the patch Pb 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, 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 0 is an integer other than a negative integer, wherein the horizontal and vertical components of the motion vector of each pixel take only values an integral multiple of I/m, where wherein m is a positive integer, and wherein (u(x,y),v(x,y)), where 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 Pb by m, is shown using (u 0 , v 0 ), (u 1 , v 1 ), and (u 2 , v 2 ), where 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 ), and 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), wherein symbol “//” denotes a division that rounds to a nearby 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.