Rare and Special in the Digital Environment: Damaged Texts and Digitisation Technologies Professor Melissa Terras Professor of Digital Humanities, UCL Dept of Information Studies Co-Director, UCL Centre for Digital

Image Quality 1: Resolution The higher the resolution, the higher the quality of image. 20 dpi 72 dpi300 dpi

Image Quality 2: Bit Depth Use bi-tonal: when shading is not an issue –modern printed books –Line art –But high res to capture detail Use Grey-scale: tones of Grey – black and white photographs, half-tone illustrations, typescript, archival materials in black and white –Where colour isnt important Use colour whenever colour is present in the original and it conveys meaning –Trade off in file sizes

Compression and File Formats

Biblia Latina, Petrus Angleus de Monte Ulmi, 1492 The first printed edition of Euclid, translated by Adelardus of Bath and with the commentary of Novarese,

Close up - Tablet 1563  Complex incisions  Woodgrain  Surface discolouration  Warping  Cracking  Noisy image  Palimpsest  Long process

Image processing: illumination correction Original image After illumination correction

After woodgrain removal Image processing: woodgrain removal -1 Original image With thanks to Dr Segolene Tarte, eSAD project, OeRC

Transmittance factors of 21 optical bandpass filters in the visible spectrum – with thanks to Lindsay Macdonald

Syriac Galen Palimpsest (see ) – with thanks to Alejandro Giacometti, and Adam Gibsonhttp://digitalgalen.net/

1632, burnt in Guildhall Fire in 1786

- with thanks to Tim Weyrich and Kazim Pal

With thanks to eSAD Project –Prof Alan Bowman, Prof Mike Brady, Dr Ségolène Tarte, Dr Henriette Roued-Cunliffe Cultural Heritage Destruction Project –Alejandro Giacometti, Dr Adam Gibson, Lindsay MacDonald, Alberto Campagnolo, Simon Mahony Great Parchment Book Project –Dr Tim Weyrich, Kazim Pal, Alberto Campagnolo, Philippa Smith, Caroline De Stefani, Rachael Smither, Patricia Stewart, Nicola Avery. Science Museum Shipping Gallery –A Prugnon, J Hindmarch, Matthew Shaw, William Trossell, Anita Soni, Prof Stuart Robson