Technique

Digitizing old prints

Books and other (paper) materials from the Special Collections cannot be borrowed, but can only be viewed under supervision in the library's reading rooms. Digitizing these works makes them more accessible for researchers and other users.

Prior to digitization the books are each individually assessed as regards their physical condition. In the preparatory stage, the material preparers closely examine every book and decide whether it qualifies for inclusion in the digitization process. Whether the physical condition is sufficient and whether the book is suitable for scanning with optical character recognition (OCR) are determined for each book. OCR transforms the scanned images to machine-encoded text. This requires the characters on the page being properly recognized by the scanning equipment.

Highly damaged books, ones that are extremely fragile and books of which scanning with OCR will not provide satisfactory results are not included in the selection. In addition, during the material processing it is determined whether the books contain illustrations or folding maps. These books are digitized separately. The results of the material for processing are recorded in a database.

Scanning equipment

When scanning books from the Special Collections it is often not possible to open books flat. Scanning is therefore done by using a special book cradle. This device prevents the binding - especially the spine - from being damaged. The sizes of the digitized works range from small almanacs to large picture books. Based on their size the books are submitted to the digitization company. As a result, the settings of the scanning equipment only have to be changed once in a while and the workflow can continue.

Development of the web Service

The digitized books are made accessible by:

  • the addition of the STCN descriptions
  • the addition of structural metadata so that the digital books can be browsed through
  • Optical Character Recognition (OCR) so that key words can be used to search the text
  • the addition of word coordinates so that search terms can be highlighted in the images of the pages found