Automatic setting of optimal search window dimensions for motion estimation

The method according to the preceding claim wherein the dimension of said search window established for the current picture is established according to the following operations:

• calculating the product between the maximum motion vector calculated with said preliminary estimation, applied to the last picture of B kind if the current picture is of P kind or to the current picture in the other cases, and the time separation (gap) expressed in number of frames between the picture on which said preliminary estimation is applied and the relative reference picture,
• calculating the length of the shortest bit-string necessary for encoding a motion vector whose amplitude is equal to said product,
• setting said dimension of said search window established for the current picture equal to the minimum amplitude of a search window suitable to detect the maximum motion vector that can be encoded with a bit-string of said length or having a bit more, depending on the fact that said product does not exceed or exceeds a certain threshold value, determined in function of said length and of a certain non negative coefficient.

The method according to the preceding claim wherein said threshold value is equal to one half of the average weighed with a certain coefficient of

• the maximum amplitude of a motion vector that can be encoded with a bit-string of said length, and
• the maximum amplitude of a motion vector that can be encoded with a bit-string of said length reduced by one.