On Image Processing and Pattern Recognition for Thermograms of Watermarks in Manuscripts - A First Proof-of-Concept

Dominik Hauser, Matthias Beckmann, Günther Koliander, H. Siegfried Stiehl

Abstract: Watermarks in historical manuscripts are figural shapes serving as tokens for provenance research (e.g. scribe identification, dating, papermill attribution, scribe-papermaker relation, trading, etc.) in Humanities such as Musicology. As of today, they come in a variety of formats: digitized handtracings and rubbings, X-ray based imagery and, more recently, thermograms acquired with infrared (IR) cameras – all of which have been made accessible via image data bases in libraries or archives like the watermark information system (WZIS). A key use case from a scholar’s perspective is the search for similar or even equal watermarks in whatever digitized data collections. Non-surprisingly, the prerequisite is the availability of a versatile, reliable, and user-friendly tool comprising methods from digital image processing (IP) and pattern recognition (PR). In our paper, we focus on bridging the gap between digitized thermograms of music manuscripts and watermark classification for similarity-based search through (i) a state-of-the-art (SOTA) analysis, (ii) a resulting conceptual design based on well-understood SOTA as well as novel methods, (iii) an easy-to-use implementation, and (iv) an experimental validation as Proof-of-Concept (PoC). The current system performance is characterized using thermograms recently made openly available within the DRACMarkS project as well as WZIS. The experimental results clearly demonstrate success in bridging the existing gap hence also setting a baseline for an as yet lacking benchmark.