Because details and sharp edges introduce significant gray-level variations over short distances, they are associated with moderate to high spatial frequencies in an image. Gradually varying patterns are associated with low spatial frequencies.

An image can have extraneous noise introduced during the digitization process, such as periodic stripes. In the frequency domain, the periodic pattern is reduced to a limited set of high spatial frequencies. Truncating these particular frequencies and converting the filtered FFT image back to the spatial domain produces a new image in which the grid pattern has disappeared, while the overall features remain.