Designing reliable and fast segmentation algorithms of ancient documents has been a topic of major interest for many libraries and the prime issue of research in the document analysis community. Thus, we propose in this article a fast ancient document enhancement and segmentation algorithm based on using Simple Linear Iterative Clustering (SLIC) superpixels and Gabor descriptors in a multi-scale approach. Firstly, in order to obtain enhanced backgrounds of noisy ancient documents, a novel foreground/background segmentation algorithm based on SLIC superpixels, is introduced. Once, the SLIC technique is carried out, the background and foreground superpixels are classified. Then, an enhanced and non-noisy background is achieved after processing the background superpixels. Subsequently, Gabor descriptors are only extracted from the selected foreground superpixels of the enhanced gray-level ancient book document images by adopting a multi-scale approach. Finally, for ancient document image segmentation, a foreground superpixel clustering task is performed by partitioning Gabor-based feature sets into compact and well-separated clusters in the feature space. The proposed algorithm does not assume any <i>a priori</i> information regarding document image content and structure and provides interesting results on a large corpus of ancient documents. Qualitative and numerical experiments are given to demonstrate the enhancement and segmentation quality.
The ancient documents present an important part of our individual and collective memory. In addition
to their preservation, the digitization of these documents may offer users a great number of services
like remote look-up and browsing rare documents. However, the documents, digitally formed, are likely
to be modified or pirated. Therefore, we need to develop techniques of protecting images stemming
from ancient documents. Watermarking figures to be one of the promising solutions. Nevertheless, the
performance of watermarking procedure depends on being neither too robust nor too invisible. Thus,
choosing the insertion field or mode as well as the carrier points of the signature is decisive.
We propose in this work a method of watermarking images stemming from ancient documents based
on wavelet packet decomposition. The insertion is carried out into the maximum amplitude ratio being
in the best base of decomposition, which is determined beforehand according to a criterion on entropy.
This work is part of a project of digitizing ancient documents in cooperation with the National Library
of Tunis (BNT).