AbstractWe study minimization of a structured objective function, being the sum of a smooth function and a composition of a weakly convex function with a linear operator. Applications include image reconstruction problems with regularizers that introduce less bias than the standard convex regularizers. We develop a variable smoothing algorithm, based on the Moreau envelope with a decreasing sequence of smoothing parameters, and prove a complexity of $${\mathcal {O}}(\epsilon ^{-3})$$
O
(
ϵ
-
3
)
to achieve an $$\epsilon $$
ϵ
-approximate solution. This bound interpolates between the $${\mathcal {O}}(\epsilon ^{-2})$$
O
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ϵ
-
2
)
bound for the smooth case and the $${\mathcal {O}}(\epsilon ^{-4})$$
O
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ϵ
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4
)
bound for the subgradient method. Our complexity bound is in line with other works that deal with structured nonsmoothness of weakly convex functions.