1. A method of generating signals representing absolute motion vectors of an image of a video sequence, the method comprising: defining horizontal and vertical weighing functions with values over pixels belonging to a first portion of the image being larger than values over pixels outside the first portion of the image; computing horizontal and vertical characteristic curves of the image and of a preceding image in the video sequence; determining a horizontal global displacement between the two images that minimizes a weighted average, calculated using the horizontal weighing function, of an absolute value of a difference between taps of the horizontal characteristic curve of the current image and of a translated replica of the horizontal characteristic curve of the preceding image in the sequence; determining a vertical global displacement between the two images that minimizes a weighted average, calculated using the vertical weighing function, of an absolute value of a difference between taps of the vertical characteristic curve of the current image and of a translated replica of the vertical characteristic curve of the preceding image in the sequence; aligning the image with the preceding image in the sequence and calculating relative motion vectors between the aligned images; and generating the signals representing absolute motion vectors between the images as a vector sum of the relative motion vectors and the horizontal and vertical global displacement.