Introduction

In () I presented an efficient algorithm that attenuates coherent noise based on the spatial predictability of noise and signal. I called this algorithm the subtraction method. In this paper I show that the subtraction approach is closely related to another described method, the filtering method (, , , ) if I use a preconditioning strategy (). In a second part I prove that the Spitz estimate for the signal PEF () makes the inversion of the Hessian stable in the subtraction method.