Defect detection on rail surfaces by a vision based system

A new vision based inspection technique for rail surface defects is presented. It replaces visual checks with an automatic inspection system. Colour line-scan cameras and a special image acquisition method- the so called spectral image differencing procedure (SIDP- allow the automatic detection of defects on rail surfaces, like flakes, cracks, grooves or break-offs by means of image processing. The system is already used by a rail manufacturer as inline system, but may also be used on testing vehicles. Practice shows that it produces reliable results even for heavily scaled surfaces, which usually pose serious problems to optical inspection systems due to their irregular texture.