Abstract: The invention relates to a novel method for automatically inspecting, e.g., aluminium cast parts using a monocular sequence of X-ray images taken of the test piece in different positions. Known methods for the automatic detection of casting defects use modified median filters which estimate X-ray images that are free of defects using recorded X-ray images. These images are compared with each other and casting defects are detected when a particularly great difference exists between them. However, the configuration of each filter depends to a considerable extent on the size, shape and position of the constructional structure of the test piece. These characteristics of the test piece therefore have to be considered a priori. The invention provides a method enabling casting defects to be automatically detected in two steps. The method uses a single filter and no a priori knowledge of the structure of the test piece.

Abstract: A process obtains a compression quantity to compensate the nonuniformity of a surface wave convolver. A surface wave convolver includes an elongate piezoelectric crystal, to the ends of which interdigital transducers are fitted to convert electrical input signals applied to signal inputs into acoustic surface waves. At its integration electrode it is possible to pick off an output signal which corresponds to the convolution product of the electrical input signals. In order to compensate errors caused by the nonuniformity of the surface wave convolver in consequence of inhomogeneities of its integration electrode and of the piezoelectric crystal, a constant input signal is applied to one of the signal inputs and a predeterminable signal which determines a desired pulse response of the surface wave convolver, it is applied to the other signal input of the surface wave convolver.