Boundary detection in scintigraphic images.

Automatic boundary detection in image signals obtained from an Anger scintillation camera requires special methods. On the one hand the mapped object is defocussed by the limited resolution of the camera and the radioactive process; on the other hand the true boundaries of the mapped organs for the comparison of different algorithms are not very easily obtainable. Therefore different filtering and boundary detection algorithms have been applied to phantom scintigrams from different objects, i.e., hollow spheres

The expansion of an optical signal into a discrete set of Gaussian beams

It is shown how an optical signal can be expanded in Gaussian beams. The expansion is essentially the one suggested by Gabor in 1946, when he proposed to expand a signal into a discrete set of properly shifted and modulated Gaussian elementary signals; determining the expansion coefficients, however, seemed difficult, since the set of Gaussian elementary signals is not orthogonal. A set of functions is described, wnich is bi-orthonormal to the set of Gaussian elementary signals; this bi-orthonormality property allows an easy determination of the expansion coefficients