The elimination of foreign bodies from tobacco during processing has always been an important consideration as much for the threshing as for the general preparation lines. SEITA has perfected a system that allows any foreign body to be located and ejected in a continuous flow of tobacco. Fault detection is carried out with a linear camera, which, associated with a transputer card via a real time card, analyses in shades of grey the flow of tobacco being transported on a roller conveyor at 160 m/min and illuminated by a halogen lamp device. The ejection system for the foreign body detected consists of an articulated paddle assembly located on a centre line parallel to the rollers of the conveyor. It consists of a temporary diversion of the part of the main tobacco flow containing the object to be ejected less than 60 milliseconds after its detection. The tests carried out on an experimental line have allowed : _ to estimate the probability of detection of objects to be eliminated as a function of their size and shades of grey. _ to observe the proper synchronization of the detection and ejection operations. _ to evaluate statistically, based on different variants of"puros", the overall performance on"typical"objects which may be detected on the processing lines. The satisfactory results of these tests have led to the installation of the system in a factory for industrial use.