Prototype manuscript viewer by Colin Dunn, Scriptura Ltd. Images © Stonyhurst College, Lancashire and Scriptura Ltd
The Virtual Vellum project provides distributed access to research-quality digitisations of folios from the Chronicles of Jean Froissart, the principal historical source for the first phase of the 100 Years War between England and France. Images are digitally photographed and stored as TIFFs. Quick access to the images is achieved by storing them in tile-based data structures, either in JPEG or JPEG 2000 format. The files are therefore enabled in a form of Virtual Research Environment. It is not necessary for a user to access the whole image when seeking to view an area at very high resolution; he or she can simply retrieve the relevant tiles, at a level of magnification they have specified, from the tile structure. There is also a ‘hotspotting’ facility, whereby information about the MS (translations, transcriptions, notes on the art and calligraphy) is accessible by clicking on an icon for an image. These can be accessed from the internet via an SRB-enabled portal.
Manuscripts such as those containing Froissart’s Chronicles are immensely valuable, both financially and scholastically. Libraries and other publicly funded institutions charged with their curation and care are therefore extremely reluctant to allow scholars – still less the general public – even limited access to them, especially since regular or even periodic exposure to light results in (incremental) damage. The public Library at Toulouse, for example, operates a policy whereby vellum manuscripts are only exhibited in show cases for a maximum of three months at a time, in darkened conditions. At other libraries, researchers are allowed access to the manuscripts for necessarily short intervals. Typically therefore, these researchers are forced to rely for intensive, long-term research, on surrogate media, typically monochrome microfiche copies or b&w microfilms of the folios (colour microfiches are available in some libraries). Otherwise, in-house digitisations are occasionally made available, but these attract very high direct and overhead costs. Furthermore, there are complex practical and political problems for researchers wishing to employ their own photographers.
The aim of the EPSRC demonstrator project is to overcome these very severe limitations by providing free access (subject to the usual safeguards) to high resolution digital photographs of the manuscripts, using open source and grid-supported delivery software. This will enable their usage in a variety of environments, including individual users’ desktops, Access Grid venues and live displays at conferences/seminars. From October 2007-March 2007, the virtual manuscript material will be displayed alongside an exhibition of contemporary arms and armour at the Royal Armouries, Leeds, and as a complement to the presence and display of at least one real manuscript.
The manuscripts are photographed at 500 dpi resolution. The large image files are split into sections (‘tiles’). At high levels of magnification, a small number of tiles are viewed in one screen although at lower levels, using just this technique, more tiles would be needed. Therefore to increase efficiency, at lower magnifications, the image is rescaled to half its original size, and tiled again. The rescaling is done several times to produce a collection of tiled images at different resolutions thus allowing the viewing software to select the most efficient set of images to display based on the overall magnification level.
Two data storage arrangements are employed. The first uses a collection of JPEG images to tile and resize the larger image into fragments. The second approach encodes the tiled and rescaling technique in a single JPEG 2000 file, thus reducing the redundancy of the tiled JPEG method. A detailed technical paper will shortly be available on the project website.
The project will provide a demonstrator indicating the functionality of the viewer. A licensed version is under consideration for commercial deployment. Academic researchers will have access to a copy free of charge.
User-friendly user and technical guides have been prepared and are about to go online. The software will be obtainable by download from a URL hosted by the Humanities Research Institute, University of Sheffield. A draft technical reference is now available.
The project is scoping the use of the JPEG2000 standard, which permits multi-resolution tiling within a single file. This will largely automate the tiling process. For the data structures, XML is used.
The software is written in Java using only the APIs available to Java version 1.2 or above. The decision to use an older version of Java than is currently available was taken to ensure maximum compatibility with machines wanting to run the software without having to update their installation of Java. The software is completely contained within Java code, which includes a JPEG 2000 decoder.
Flash 8 was also considering, however there was not enough flexibility to facility the inclusion of a JPEG 2000 decoder.
Gridsphere and INCIPIT portal for hosting a VLE\VRE that hosts a copy of Virtual Vellum for viewing the Froissart manuscripts.