1. A method to process an image acquired through an optical-fiber guide, the method comprising: acquiring a recalibration image through the optical-fiber guide; determining a geometrical transformation to make the recalibration image coincide with a first reference image derived from a first image acquired through the optical-fiber guide in a preliminary stage; deriving from the geometrical transformation and from a stored first detection map spatially identifying each fiber of the optical-fiber guide on a second calibration image acquired in the preliminary stage, a new detection map spatially identifying each fiber of the optical-fiber guide on the recalibration image; and processing individually zones of the acquired image corresponding to each fiber of the optical-fiber guide using the new detection map.