ABSTRACT
Filtering is the modification of the amplitude of the frequency components of a signal. Filtering is the same operation as convolution, but it is viewed from the perspective of the frequency domain. The Wiener filter combines the statistical model of signals with the linear, time invariant model of systems using convolution. Convolution and filtering are the same operation. Convolution is the time domain description and filtering is the frequency domain description. The purpose of sampling is to transform a continuous signal into a discrete signal. Sampling is very important in radiology since all of the computerized imaging modalities use sampling to transform continuous data to discrete signals. Sampling is modeled in the time domain as a multiplication of the comb signal with the original signal. The power spectral density function is defined for wide sense stationary stochastic processes. It is the Fourier transform of the autocorrelation function.
