DETECTION OF IRREGULARITIES IN A CONVEX SURFACE, SUCH AS A TIRE SIDEWALL, USING BAND-PASS FILTERING

摘要

The invention relates to the detection of an edge-free irregularity (50b) in a convex surface which comprises a structuring (50a) that is delimited by edges. According to the invention, a three-dimensional representation of the surface is generated. The convexity is extracted from the three-dimensional representation of the surface, and the edges of the structuring are smoothed in order to obtain a convex-free representation of the convex surface which exhibits the irregularity and the structuring whose edges are now smoothed. The convex-free representation is compared with a threshold value in order to detect the flat areas of the convex-free representation. The surfaces of the detected areas (50a, 50b) are analyzed, whereby an area (50b) is detected as being irregular when the surface thereof is larger than its predetermined surface. Bulges or constrictions can be identified with certainty during real-time operation by using this device for carrying out quality control of tires, and can be differentiated from a marking which is intentionally provided on the tire. Band-pass filtering is carried out by means of two low-pass filters. The smoothing is non-linear. Pixel artifacts and singular artifacts are removed. A media filter is used.