Fourier filtering

filtering process in which spatial or time domain data are subject to a Fourier transformation FT yielding amplitudes for differing spatial or temporal frequencies: a frequency spectrum. Suppression or weighting of any of the frequencies within this spectrum represents the filtering process. Inverse Fourier transformation of the filtered spectral data then yields the filtered spatial or time domain data. Suppressing all frequencies above a certain level will result in a low pass filter, suppressing all frequencies below a certain level results in a high pass filter.

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