Abstract: The invention relates to a method of focusing, by an imaging device, of images of a substantially planar surface of an object including the step of determining the attitude of the surface of the object with respect to a reference plane by scanning this surface by means of at least one triangulation sensor along exactly two parallel lines in the reference plane. The invention further includes the steps of splitting the surface of the object into areas of a size corresponding to the size of a taken image, inferring from the attitude respective elevations of the image areas, and adjusting, for each area, the focus with respect to the elevation thereof.