ABSTRACT
The wavenumber transform is a Fourier transform, where time is replaced by space. Wavenumber processing allows spatial and even directional information to be extracted from waves sampled with an array of sensors at precisely known spatial positions. Wavenumber processing can be used to enhance imagery from telescopes, digitized photographs, and video where focus or camera steadiness is poor. Small wavenumbers near zero correspond to light with slowly varying brightness across the pinhole side of the camera while the large wavenumbers correspond to sharply varying brightness such as edges from shadows. The physics to be noted is that “focus” for a camera system is definable as a wavenumber filter and those out-of-focus objects can be digitally recovered if the lens system wavenumber filtering response is known. A very common coherent wavenumber system is the parabolic reflector used widely in radar, solar heating, and for acoustic sensors.
