
removal using median filtering. This type of noise otherwise cannot be removed
by conventional convolution filtering.
6.3 Fourier Transform Methods
In many cases, frequency domain filtering is more effective than its spatial
domain counterpart because noise can be more easily separated from the objects
in the frequency domain. When an image is transformed into the frequency
domain, low-frequency components correspond to smooth regions or large
structures in the image; medium-frequency components correspond to image
features; and high-frequency components are dominated by noise. Hence one
can design filters, using the knowledge of the frequency components, ...