Inverse halftonning using sparse coding methods

We propose a new inverse halftonning algorithm based on sparse coding approach, which is able to simultaneously reconstruct the continuous-tone image from the halftonned one and increase spatial image resolution. To achieve this goal, we introduce the halftonning operator that maps the continuous-tone signal into the same representation as the halftonned one. Resolution enhancement is obtained with a pair of the linked dictionaries which consist of low resolution and high resolution patches. Comparison with some famous algorithms has demonstrated that our algorithm outperformed them by both image quality and applicability to different halftone types.