Abstract: Restoration of bi-level images is generally performed in two steps, i.e., restoration and thresholding segmentation, which generally does not produce ideal results. This paper proposes a nonlinear regularization method for bi-level image restoration by explicitly using the knowledge of the bi-level image. Unlike the Tikhonov regularization method which eventually results in a linear system of equations, the proposed method leads to a nonlinear optimization problem, solved with the global Barzilai and Borwein gradient method. Simulation results show feasibility and effectiveness of the method.

Key words: image restoration, regularization, degradation, noise