Seismic attributes were introduced in the 70's to reveal geologic characteristics, like unconformities, stratigraphy, lithology, gas accumulations… This paper proposes an original approach, based on trigonometric polynomials interpolation of the seismic signal, to compute the most used attributes. The first advantage of this method is to give a simple analytic formula of a wide panel of instantaneous attributes. It also allows to compute easily and quickly accurate geometrical attributes like dip, curvatures and semblance.