Multilevel Preconditioning Strategies for Convex Optimisation Methods in Image Deblurring

  • Aleotti, Stefano (University of Insubria)
  • Binda, Claudia (University of Insubria)
  • Donatelli, Marco (University of Insubria)
  • Krause, Rolf (KAUST)

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Proximal gradient methods are widely used in imaging, and their convergence can be accelerated by incorporating variable metrics and/or extrapolation steps. Recent works have shown that preconditioning strategies can significantly enhance this acceleration, in particular, for image deblurring problems. In parallel, a multilevel framework has been introduced to speed up inertial and inexact forward–backward schemes for image restoration problems. In this talk, we combine preconditioning and multilevel strategies to design a robust and consistent acceleration framework for both standard and inexact forward–backward schemes applied to regularized convex optimization problems. Numerical experiments in image deblurring confirm that our approach yields a substantial improvement in convergence speed compared to standard methods.