Method for identifying and defining basic patterns forming the tread pattern of a tyre

An inspection method for inspecting a tread of a tyre having a tread pattern formed of elements that are juxtaposed circumferentially and separated from one another by identically shaped boundaries, and having basic patterns in a number sequenced in a known manner, the basic patterns including a basic pattern on which tread wear indicators are placed that are associated a characteristic point of the basic pattern, the method comprising steps of:

• obtaining an image of a tyre tread to be inspected;
• identifying tread wear indicators present on the image;
• grouping together sub-sets of the tread wear indicators corresponding to a basic pattern that includes the tread wear indicators;
• determining characteristic points of elements of the sub-sets of the tread wear indicators;
• determining a sequence of distances by computing distances between the characteristic points of the elements of the sub-sets of the tread wear indicators;
• comparing the sequence of distances with a known sequence of distances between characteristic points of at least one basic pattern, and confirming a coincidence between the sequences;
• and
• projecting a shape of a boundary between elements of the at least one basic pattern onto a surface to be inspected according to the known sequence of distances between the characteristic points of the at least one basic pattern.