ABSTRACT
Filtering is a method which can be used to enhance certain aspects of actual radiological images. It is the modification of the amplitudes of the frequency components of a signal. Filtering and windowing are dual operations — filtering is a modification of the amplitudes of the frequency domain components of a signal; windowing is the modification of the time domain components of a signal. The examples of filtering deal with sound, since humans have a natural understanding of sounds in terms of frequencies. A common type of spatial filtering operation is edge enhancement. The chapter examines the effect of an edge enhancement operation in the space domain for a pixel in a constant region, and for pixels on either side of an edge. The most frequent radiological application of the windowing operation is the selection of a region of interest.
