“…the non-regularized case obtained by setting = 0, cf. [2,3,4,5,6,7], and subsequently apply the above formal replacement rules for f , g, φ i , and Φ ij , so as to obtain the -regularized reconstruction of interest. Since the Gram matrix Φ ij is known in closed form for the case of standard reconstruction and Gaussian derivative filters φ i of scale s i , say, the -regularized reconstruction scheme is likewise in closed form, and boils down to scale replacements s i → s i + in the unregularized Gram matrix, Φ 0 , and s i + 2 in the free expansion filters, φ i , recall Eq.…”