Image Transforms
9. Linear Shift-Invariant Systems and Convolution:
Most imaging systems may be modeled as linear, shift-invariant or position-invariant systems, which are completely characterized by their responses to point inputs, called the point spread function (PSF), denoted usually by h(x, y).
The FT of the PSF H(n, v) is known as the modulation transfer function (MTF).
The output of such a system is given as the convolution of the input image with the PSF:
Upon Fourier transformation, the convolution changes over
tomultiplication of the two spectra: G (u, v ) = F (u, v ) .H (u, v )