Patent ID: 6040853
Filing Date: 2000-03-21
Classification: G01C,G01N

Abstract:
Process for detecting surface defects in a substantially plane textured surface,wherein it comprises the following steps of:a) making, with the aid of an optical sensor presenting an inclination of sight with respect to the substantially plane textured surface and being in relative movement with respect to this surface, a succession of images of parts of this surface at successive instants, each image corresponding to a surface part of length L in the direction of displacement, each image being offset from the preceding one by a length 1, 1 being equal to L/K with K, a whole, greater than 2;b) defining sub-images corresponding to elementary portions of the surface whose length is equal to 1 in the direction of displacement, whereby for the length of portion of surface 1, K sub-images of this portion are available;c) extracting from these K consecutive sub-images N sub-images (Ii) corresponding to the same portion of the surface of length 1 at N successive instants with N included between 2 and K;d) applying to each of the N sub-images (Ii) the same spatial mathematical processing in order possibly to demonstrate a configuration of presumed defect, which gives a processed intermediate sub-image (Yi);e) applying to the first processed elementary sub-image (Yo) a combinatorial algorithm for detection of presumed defect in the elementary sub-image, whereby a spatial and temporal sub-image ST.sub.0 is obtained;f) iteratively repeating the application of said combinatorial algorithm to the spatial and temporal sub-image ST.sub.i-1 obtained at instant ti-1 and to the processed elementary sub-image Yi in order to obtain a spatial and temporal sub-image ST.sub.i up to i=N-1; andg) obtaining with the spatial and temporal sub-image ST.sub.N-1 the image of the elementary portion of the textured surface with its possible defects.