About the project
Paper-based Watermark Extraction project (WatEx) was established in October 2004 as a Ph.D. research study, the aim of this project is to automatically retrieve and store paper watermarks in a digital representation in order to preserve its historical value, and to provide better access and distribution with the current Information and Computing Technology (ICT). The focus will be on the digital acquisition, and automatic processing and analysis of the visible paper-based watermark, probing beyond the paper surface data to extract the watermark design and to create a digital representation for long term preservation.
Overview
Paper watermarks can be defined as the designs or the patterns that are embedded during paper production, it can be line or wire ‘thin’ watermarks, or shade and light ‘thick’ watermarks, these designs can be seen by facing the paper against light, but some watermarks can only be seen over a black surface. Paper watermarks usually hold the name of the manufacturer, geometric designs, images of animals, etc (Paper watermarks, 2004).
Paper watermarks appeared before 700 years ago by the papermakers in Italy, the oldest watermarked paper was in 1292, originated to the Fabriano town (Katzenbeisser and Petitcolas, 2000). After its invention, watermarks quickly spread in Italy and then over Europe. “Paper watermarks may originally have served to identify papers produced by different workmen within a factory (who were paid by the piece)” (Allison, 2001), then it was used to indicate the paper brand; it later served as an indication for paper format, quality, and strength. It was the use of watermarks in bank notes and stamps that first inspired the use of the term “digital watermarking”. Since then, the concept of watermarking has continued to evolve from identification, authentication, and protection of analogue artefacts, including invaluable paper-based documents, books, as well as current digital materials such as digital images, audio, and video recordings (Johnson and Jajodia, 1998).
Challenges
Paper-based watermarks are considered important artefacts for copyright protection, and authentication purposes. The materials of these papers are decaying over time due to natural processes; also, these papers contain foreground interference (i.e. writings in front and the back) and background interference (i.e. paper defects like folding).
There are a wide range of digitisation initiatives to create digital copy of the paper-based materials. However, the current digitisation processes do not normally capture the complete representation. Typical digitisation processes are only concerned with the paper surface. There is hidden ‘visually’ information, particularly the watermark which is embedded in the paper, is not being digitised and may be lost forever.
