Digitization of the parchments

In the course of the digitization process, while the documents were being transported and digitized, it was often not possible to ensure the required preservation conditions. Digitization involves a rise in air temperature, reduction of humidity, and strong light pollution around the camera. Thus, it is important to know about and take into consideration the necessary preservation requirements in order to great as optimal a workflow as possible and minimize the harm done to the condition of the parchment.

The camera, software and calibration system with high technical specifications used to digitize the collection ensured stable and high-quality files (also called master copies), which were checked by a 100% visual examination throughout the course of the project. No less important in the assessment of the quality of the parchment documents’ files was the critical analysis regarding the extent to which it is even technically possible to digitally reproduce the information in the documents.

The digitization tool used in this project is the same one that has proven to be reliable at the Kanut 2008 (Linhof Master Digi Repro System, Anagramm production 2 Scanback). The lens used throughout the project was the Schneider-Kretuznach APO-Digitar 5,6/120 mm.

In the test table, the resolution required for the digitization was at least 2.8 lines/mm throughout the entire surface. The high quality of the equipment being used enabled a resolution of 6.3 lines/mm according to the Resolution Pattern (ISO 3334, ISO #2, Optical Test Chart, NBS 1010a, NBS 1963, T-10) without an interfering moiré effect

Since parchment is a delicate and easily damaged material, then the optimal aperture opening was between F11 and F16, and this ensured a quality result in a scan time that did not damage the parchment (it took about 2 minutes to scan one side of a parchment). Throughout the project, the even focus and scan time was resolved so that the depth of field settings covered 2.5-3 cm. In 99% of the cases, the variations in the surface of the documents were within these parameters.

Digitization of a volume at the Estonian Open Air Museum Conservation and Digitization Center Kanut. Equipment: Linhof Master Digi Repro System and Anagramm production 2 Scanback solution. Photo: J. Heinla

Since the parchments were in various conditions, i.e. with break points, deformations, various reflective surfaces, then depending on the need, the digitization system was adjusted to provide the maximum level of detail, which ensured the high-quality reproduction of the document. The jobs have also been continued following this principle.

Concessions in quality (i.e. when it was difficult to achieve the authentic tonality) had to be made in cases when a deformed document in poor condition needed was being digitized , or if the surface, or individual areas, of the document being digitized had different reflective properties (the shiny metal surrounds of seals, velvet and silk textiles, textiles with metal threads and plaited ribbons).

Quality control is always an important, but time-consuming, part of a comprehensive solution. In this work process, the control of the files was resolved by a two-step solution: first, the name, color and framing of the file was checked after digitization; and thereafter, the files were reviewed by specialists from the National Archives. 99.1% of the digitized document conformed to the quality requirements. If the file did not conform to the requirements, if possible, it was re-digitized. The non-conformity with quality requirements was usually caused by the poor condition of the document; or by the fact that the document had attachments of different heights that extended outside of the focus area and if their scan time were extended, the parchment might be damaged.

The logistical organization of the project worked well thanks to the reliability of digitizing equipment, the flexible work organization (schedule) and qualifications of the working group members. Of the five possible risks in the list of project risks and countermeasures, the ones that slowed the pace most, were the larger than planned volume of preparatory and conservation work, which significantly exceeded the parameters of the initial schedule.   In order to avoid stoppages, the number of documents in the stages were changed as needed and, if necessary, the documents of one client were replaced by those of another.

The damages and attributes were photographed with a Nikon D3x (24,5 M/pixels) and Nikon D800E cameras under direct, ranked and penetrating light.

The images of the parchment documents are available on the National Archives website.