Abstract: A sleeve (2) of elastomeric material is operationally mounted on support rollers (5, 6) which can be operated to rotate the sleeve. At least one or more television camera (15) shoots the surface (2a) of the sleeve (2) which is illuminated with light at a low angle. The superficial appearance of the sleeve (2) is recorded in the form of images, each divided into a plurality of pixels (P) distributed in an orderly fashion. The values of luminosity of the individual pixels (P) are recorded and processed to highlight those pixels wherein due to superficial irregularities (C) on the sleeve (2), a variation is detected of the light reflected by the surface (2a) of the sleeve itself. On the basis of the position occupied by the highlighted pixels (P) it is possible to go back to the position of the superficial defects (C) along the extension of the sleeve (2).