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Digitization and metadata

From its beginnings in the early 1990s, BnF has always considered digitization as a reproduction and preservation technique in its own right. This principle is reflected in choices relating to formats, resolutions, and image acquisition. Digitization in image format continues to be a priority, since it makes it possible to provide users with a faithful reproduction of an original document. Accordingly, digital documents are structured and organized using specific methods to ensure that they can be both properly viewed and protected.
The full range of digitization rules is brought together in BnF’s Technical Digitization Charter (Charte technique de numérisation).

Digitization techniques

The techniques used to digitize documents depend on their physical condition: size, volume, fragility, etc.

BnF’s documents are digitized using a wide variety of devices, either in the library’s own studios or by external service providers.

Digitizing original documents

Original documents are digitized using equipment appropriate to image acquisition conditions and the physical constraints of each document.
There are two main image acquisition techniques, each of which uses hardware that varies in line with the constraints of the document: digitization by taking photographs and digitization by scanning.

Digitization by taking photographs

A digital camera photographs the document one page at a time.
The distance between the camera and the page must be accurately analyzed so as to optimize image definition.
This technique is used when digitizing small or medium-sized documents.

Two types of machine are used for digitization by taking photographs:

Kirtas device

Kirtas device

@BnF

A machine with a V-shaped cradle for fragile documents, consisting of a camera facing each side of the cradle and a page-turning robot to minimize human intervention.
Copybook device

Copybook device

© BnF

A machine consisting of an equalizer tray for documents that can be digitized flat (some paperbacks and books with flexible bindings).

Digitization by scanning

Digibook 2000LC, Suprascan A0 device

Digibook 2000LC, Suprascan A0 device

@BnF

Sensors scan the document and reconstruct the image a pixel at a time.

This technique is used to digitize large or bulky documents (maps and atlases, brochures, registers, press publications, some manuscripts, etc.).

The sensor is fitted to a moving arm. The distance between the sensor and the document being digitized is adjustable. The entire document is scanned.

Pages are manually turned by an operator.

A V-shaped cradle may be used for documents with fragile bindings.

Manuscripts and posters

The majority of manuscripts and posters are digitized using machines consisting of a digital camera mounted on a bracket above a work surface that can be adjusted to suit various document types (e.g. a table for flat documents, a V-shaped cradle for documents with a reduced angle of opening, an equalizer tray for thick bindings, etc.). These machines can handle documents of a wide variety of sizes (up to A0) but which require specific adjustments (on a per document or even per capture basis).

Digitizing microforms

Wilks & Wilson machine (for microfiches)

Wilks & Wilson machine (for microfiches)

@BnF

Microfiche, microfilm, xerographies, slides, etc. are digitized using specific machines suited to each of these media and enabling automated or semi-automated image capture. 

Tuesday, March 22, 2011