Fringe pattern normalization consists in the background suppression and modulation normalization of a given fringe pattern, this process gives as a result a pure sinusoidal phase modulated signal. Normalization is an important operation in the demodulation of the phase from a single fringe pattern where spatially varying background and/or modulation act as error sources. The solution proposed is a direct and isotropic operator, based on the application of an n-dimensional quadrature transform. We have applied the method to simulated as well as experimental data with good results.