Fourier Transformation of Image Data

Many of the geometric enhancement techniques used with remote sensing image data can be carried out using the simple template-based techniques of Chap. 5. More flexibility is offered however if procedures are implemented in the so-called spatial frequency domain by means of the Fourier transformation. As a simple illustration, filters can be designed to extract periodic noise from an image that is unable to be removed by practical templates. As demonstrated in Sect. 5.4 the computational cost of using Fourier transformation for geometric operations is high by comparison to the template methods usually employed. However with the computational capacity of modem workstations, and the flexibility available in Fourier transform processing, this approach is one that should not be ignored.