1. A process for determining the displacement of an entity equipped with a sensor for capturing a sequence of images, the process comprising: determining dimensions of a first block of pixels in a current image in the sequence of images as a function of a motion vector associated with an image preceding the current image in the sequence of images; and determining a motion vector associated with the current image in the sequences of images as a function of at least one correlation calculated between the first block of pixels in the current image and a second block of pixels from which the vector points towards said first block of pixels, with the second block being in a previous image in the sequence of images.