METHOD OF PROCESSING THE DIGITAL IMAGE OF THE SURFACE OF A PNEUMATIC TIRE FOR DETECTION OF ANOMALY

摘要

To analyze a tire surface, a 3D elevational image is captured, which is formed of pixels representing points on the surface. Each point is assigned a grey-level value proportional to its elevation relative to a surface level. Based on the elevations in the elevational image, an orientational image is formed showing elevation gradients of the surface. In the orientational image, which is formed of pixels representing points on the surface, each point is assigned a grey-level value proportional to an angle formed with a direction given by a projection in an image plane of a non-zero norm vector substantially corresponding, at this point, to a gradient vector tangent to the surface and oriented in a direction of greatest slope. A filtered image is determined by transforming the orientational image using a filter to select areas that include structures similar to those in a reference orientational image of a blow hole.