Method and apparatus for detecting defects on the surface of tyres

An apparatus for detecting one or more possible elongated defects on an inner or outer surface of a tyre comprising:

• a support for a tyre;
• a command and control unit to rotate the tyre around its axis of symmetry on the support;
• at least one source to emit at least one light radiation for illuminating a surface portion of the tyre, when set on the support;
• a detection system comprising a camera with an objective line lying on an optical plane passing through the camera, wherein the detection system acquires one or more digital images of the inner or outer surface of the tyre, the one or more digital images comprise a structure comprising one or more structure sections corresponding to a pattern of linear elements and to the one or more possible elongated defects, and the one or more structure sections comprise one or more pixels of the structure;
• and
• a processor that has a digital model of the pattern, wherein the digital model of the pattern comprises one or more pixels and one or more pattern sections, wherein each pixel of the digital model of the pattern is associated with a first index indicating whether the pixel belongs to the one or more pattern sections and wherein when the respective pixel belongs to the one or more pattern sections, the pixel is associated with a second index of an orientation of the one or more pattern sections;
• wherein the processor further calculates for each pixel of the structure, a third index of an orientation of the structure sections to which the respective pixel belongs;
• compares the third index with the second index, for each pixel of the structure having a corresponding pixel in the digital model of the pattern belonging to the one or more pattern sections of the digital model;
• and establishes if the pixel of the structure belongs to the one or more sections corresponding to the one or more possible elongated defects based on the comparison.