Patent ID: 7236634

Claim:
An encoding method of moving pictures which generates a predictive picture for a current picture based on a reference picture and a motion vector, comprising the steps of: dividing a macroblock into a plurality of subblocks smaller than the macroblock; setting an initial value of the motion vector for the plurality of subblocks; calculating in each of the plurality of subblocks an evaluated value E on a difference between the current picture and the reference picture, E = ∑ i , j ⁢ ( TB i , j - SW i + Vx , j + Vy ) 2 , wherein TB i,j represents pixel value at pixel position (i, j) in a template block of the current picture, SW i,j represents pixel value at pixel position (i, j) in a search window of the predictive picture, and V x and V y represent the motion vector in x and y directions, and differential coefficients thereof in x and y directions, ∂E/∂x and ∂E/∂y; evaluating in each of the plurality of subblocks the value E at a plurality of pixel positions in a direction having the steepest downward gradient derived from the differential coefficients to determine the minimum evaluated value; expanding each of the plurality of subblocks to a macroblock by supplementing defective portions; and selecting the smallest value among the minimum evaluated values obtained on the plurality of subblocks to determine the motion vector based on the pixel position of the smallest value.