Automatic equipment, in which each of a plurality of identical devices is positioned automatically to co-operate with processing means and/or test probes, has a TV camera considered as being arranged to move in a raster scan over each device, and to provide signals in response to detecting boundaries of an orthogonal pattern of device features. Initially, with a unique pattern of feature boundaries having been determined, and possibly by reference to the representation, provided by a display unit driven by the camera, of a manually, accurately, located device, there is caused to be generated, in each frame scan period, pairs of signals, individually corresponding to, and representative of a defined location for, a determined feature boundary, each signal representing a marker boundary as if detected by the camera. For each subsequent device, automatically, at least, coarsely positioned, if each determined feature boundary is detected by discriminating means, operating upon the corresponding pair of signals and the signal from the camera in response to detecting the determined feature boundary, not to be within a threshold distance of its defined location, the device is caused to be displaced automatically along the appropriate orthogonal axis, or axes, to become capable of co-operating with the processing means and/or test probes. The latter condition is obtained when the discriminating means detects that each of the determined feature boundaries are within the threshold distances of their defined locations.

An object to be inspected is illuminated and its image is picked up by an optical image sensor which provides a video signal thereof. The optical image is divided into at least two portions which are mutually symmetrical to each other, and the specific video signals of corresponding parts of the mutually symmetrical portions are compared sequentially to thereby determine whether the object has a defect or not.

An improved method and device for detecting a position of a mark formed on an object, by providing plural peaks in an image density distribution, wherein the image of the object having the mark is picked up to provide an image signal which in turn is processed to provide an integrated image-density distribution of the image in a predetermined direction and wherein the position of the mark is detected on the basis of the plural peaks in the integrated image-density distribution.

A pattern checking apparatus carries out the detection of candidate defects through a primary selection with a sensitivity high enough to detect any existing defect, and then carries out a detailed analysis by a controlling processor for a pattern including the periphery of the detected candidate defect through a secondary selection in which a candidate defect which is not a defect in a practical sense is removed from candidates, so that only real defects are detected.

A paper machine wet line monitor is provided by photographing the surface of the wire of a paper machine in the area of the wet line (sometimes known as the dry line) with a video camera to generate video signals. The video signals are digitized and define a line corresponding to the wet line of the machine and this line is displayed preferably while also indicating the average location of the wet line across the machine. The processed digitized signal may be imposed on an automatic headbox control to influence this control and maintain the position of the wet line.