Intelligent hybrid watermarking ancient-document wavelet packet decomposition-singular value decomposition-based schema

The ancient documents represent one of the author´s history pillars that preserve the historical events for the next generation. Many digitisation projects have been launched to preserve and to diffuse them to the public. However, ensuring security is a challenge since digital documents are susceptible to be hacked. Thus, watermarking the images of the documents seems to be a promising solution mainly for protect the copyright. Many watermarking algorithms have been proposed particularly in the medical field. However, no solution has been recommended for the images of ancient documents. In this study, the authors present a watermarking approach devoted to store images. Their algorithm is based on a wavelet packet decomposition, an intelligent choice of the best base carrier points by way of the singular value decomposition. In their approach, the insertion base and the carrier points of the signature are dynamic, varying from one image to another. For a better preservation of the watermark, they exploited a convolutional encoder to encode data. The results recorded in a set of images of ancient documents taken from the National Library of Tunisia and from the National Archives of Tunis have shown promising results.