Abstract: A method and apparatus for image processing on a radiation image which may be a conventional radiographic image on X-ray film or a radiation image which is stored in a stimulable phosphor and read out therefrom. The radiation image is scanned by a light beam or stimulating rays and an image signal is obtained by use of a photodetector. The image signal is subjected to a frequency processing by use of an unsharp masking process. The unsharp mask signal (Sus) is used for conducting an operation ofSorg+.beta.(Sorg-Sus)to obtain an image-processed signal S, wherein Sorg is a digital signal for each picture element of the scanned image and .beta. is a frequency emphasizing coefficient. The median of a group of digital signals in an unsharp mask of a predetermined size is employed.

Abstract: An acousto-optic apparatus utilizing multiplexing techniques, for obtaining he correlation of N pairs of signals. First and second sets of signals are combined in a piezoelectric crystal, and each signal in the first set is correlated only with its pair signal in the second set, that is, with the signal in the second set which has the same R.F. frequency. Each signal is a composite signal comprised of an envelope modulating an R.F. signal, and when a laser beam is directed across the interaction area of the crystal and directed onto a square law detector, the correlation of the envelopes of the N pairs of signals is obtained.