# Dictionary:Residualize

{{#category_index:R|residualize}}
(r∂ zij’ ∂ w∂l īz,) **1**. To separate a curve or a surface into its long wavelength (or low-frequency) parts, called the **regional**, and its short-wavelength (or high-frequency) parts, called the **residual**. Residualizing attempts to predict regional effects and find local anomalies by subtracting the regional effects. This separation is not unique. Residualizing methods (Figure R-10) include (a) graphical methods, in which a smooth regional is drawn on a profile or contours are smoothed and spaced more uniformly; (b) polynomial method, in which the regional is represented by a polynomial fit to the observed data; (c) spectral-domain filtering, in which certain wavenumbers are attenuated by filtering; (d) stripping method, in which the field of a model that represents certain parts of the geology is calculated and subtracted from the observed field; (e) upward continuation, which attenuates the effects of shallow sources. These methods can be thought of as 2D convolution operations (**map convolution**) and some of them produce halo effects about local anomalies. See Cowan and Cowan (1993).