
146 ◾ Moises Padilla and Manuel Servin
From this equation, the rst term on the right
is a
quadratic delity metric between the smoothed ltered-estimated eld
f(x, y) and the observed data I(x, y) in a least-squares sense; this is called
the interaction term. e remaining quadratic terms tend to keep the
ltered-estimated image f(x, y) within the space of continuous functions
up to the rst derivative, the C
1
functional space. is rst-order regu-
larizer is known as a rubber membrane regularizer because this func-
tional corresponds to the mechanical energy of a 2-D rubber membrane.
is membrane model is attached by li