An inpainting technique based on regularization to remove bleed-through from ancient documents

In the techniques proposed so far to remove bleed-through from digital images of ancient documents, two critical aspects are the identification of the occlusion areas, i.e. those pixels where the bleed-through pattern overlaps with the main fore-ground text, and the in painting of the areas to be removed with a pattern that is in continuity with the surrounding background, often inhomogeneous due to paper texture or noise. In this paper we propose a new method for bleed-through removal that aims at solving both the aforementioned issues. The method first exploits information from the accurately registered images of the manuscript recto and verso to locate, in each side, the pixels corresponding to the interfering text, no matter if they are pure bleed-through or occlusion pixels. Then, processing separately the two sides, the identified areas are filled in by interpolating, through a suitable regularization model, the surrounding regions. We show the promising results obtained with this method on manuscripts affected by a very strong bleed-through.