Title :
Wiener Filters for the restoration of radiographs
Author :
Mitsiadis, G. ; Venetsanopoulos, Anastasios
Author_Institution :
Dept. of Electr. Eng., Toronto Univ., Ont., Canada
fDate :
4/1/1987 12:00:00 AM
Abstract :
A new model of the radiologic process is developed. The model is based on a block diagram representation involving a nonlinear transformation. The optimal linear filter, in the mean square error sense (Wiener), retrieves information from a certain layer of the exposed object. It is derived by considering the contribution of the other layers as additive noise. Closed-form expressions are given for special cases to illustrate the filter behaviour for low and high frequencies. It is shown that the filter can be determined even if the focal spot is modelled as a point source. The effect of the distortion caused by the focal spot is found to be minimal compared to that of the superposition of the images produced by the other layers of the object. Experimental results show that optimal filtering exhibits improved performance over inverse filtering, which was previously used in a similar application.
Keywords :
filtering and prediction theory; optimisation; picture processing; radiography; Wiener filters; additive noise; images; mean square error sense; nonlinear transformation; optimal linear filter; radiographs; restoration; superposition; Equations; Films; Information filters; Mathematical model; Radiography; Wiener filters;
Journal_Title :
Electrical Engineering Journal, Canadian
DOI :
10.1109/CEEJ.1987.6592802