(1) | ||

- is a data-fitting operator, mainly composed of a scattering and a downward continuation operator, but which also incorporates the background wavefield Biondi and Sava (1999),
- is a model-styling operator, either an isotropic Laplacian or an anisotropic steering-filter Clapp and Biondi (1998), which imposes smoothing on the model,
- and are respectively the slowness perturbation (the model) and the image perturbation (the data),
- is a scalar parameter controlling the weight of each of the individual goals.

To speed-up the inversion procedure, we can precondition the model in Equation 1 and solve the system

(2) | ||

4/27/2000