The Tissandier Collection was purchased by the Library of Congress in 1930 and contains approximately eight thousand items that were collected by the French brothers Albert and Gaston Tissandier, who were famous balloonists and writers. The collection documents the early history of aeronautics with an emphasis on balloon flight in France and other European countries.

The aim of the research project is to provide a comprehensive and complete database of watermarks in the collection, using a simple, cost effective and reproducible method of recording the designs legibly. Ultimately, these enhanced images will enable identification of provenance or dating.

At the Library of Congress, I experimented and developed a method that uses transmitted light photography followed by manipulations in Photoshop to record the watermarks because the method is simple, quick and cheap. It is also directly generating digital data and allows future additional manipulations.

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The challenge to producing a readable image is the high contrast between the dark areas from the writing and the transparency of the watermark that appears weak in comparison. Reducing the contrast makes the watermark appear more legible. 
By converting a transmitted light image into digital form and using Photoshop, the media that frequently obscures a watermark can be diminished and the watermark image can significantly improve. The contrast can also be increased, enhancing the watermark’s contours.

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