Method of chekcing the appearance of the surface of a tyre

A method of detecting an anomaly on an internal surface of a tyre through digital processing of an image of the internal surface of the tyre, the method comprising steps of:

• capturing a grey-level original image (f) of the internal surface of the tyre and transforming the original grey-level image into an orthonormal space, in which an x-axis (OX) represents a circumferential direction, and in which a y-axis (OY) represents a radial direction;
• transforming the original grey-level image using a predetermined series of filters (F1f, F2f, FLf), to obtain a multivariate original image;
• splitting the multivariate original image into multivariate sub-images (WF), to obtain predefined tiling in the axial direction and the circumferential direction;
• transforming each of the multivariate sub-images is transformed into one-dimensional vectors using a given descriptor (H,G, . . . N), to obtain a simplified multivariate image (KWF, GWF, HWF) formed from a collation of the vectors;
• reducing a number of dimensions of the simplified multivariate image data using a data analysis tool, to obtain a reduced factorial space;
• and,
• in the reduced factorial space, evaluating a distribution of sub-images containing an anomaly in relation to a distribution of sub-images containing no anomaly, in order to assess a separating power of the given descriptor.