The image processing apparatus includes an image obtaining part configured to obtain a first image and a second image. A method for controlling the access to data by such a circuit. In accordance with one aspect of the invention, several observation units and associated lighting sources are integrated in each measuring head. The shift mode generally operates with multiple scan clocks that are clocked simultaneously. 1 to 4 ms, which is established so that the disperse phase of the aerosol is deposited on the internals in the reactor.