Analysis of document snippets as a basis for reconstruction

Abstract

In Archaeography, Philology, Forensics, and related research areas fragments of documents are very common. These fragments are the basis for the subsequent reconstruction process, where the goal is to make the original information spread over several fragments visible again. The fragments can originate from paper shredders, hand torn pages or in the case of ancient manuscripts this is due to bad storage conditions, or other destroying facts. So we can distinguish between an "on-purpose" destruction because the information contained on the pages should not be readable anymore or a "time-induced" destruction for ancient documents which is unintentional. Nevertheless the reconstruction of document fragments is an interesting research question. This paper shows a preliminary step for the page reconstruction namely the automatic orientation of snippets in order to eliminate the rotation in the later reconstruction (puzzling) process. Furthermore features like paper color and the color of the inks used are analyzed as a pre-classification step to find matching snippets. In the case of "on-purpose" destruction there is no a-priori information on which fragment belongs to which page which makes a reconstruction based on thousands of fragments from unknown sources difficult since the combinatorial effort explodes (NP-hardness). Preliminary results on orientation and color segmentation are presented and show that these pre-processing steps can be performed reliably and can be used for reconstruction and snippet classification.