Exploring

Digitization

Digitization Procedures

Despite the possible variations in technical requirements, there are several standard steps in digital imaging. As with other reformatting methods, most institutions will find digitization too complex and expensive to undertake in-house; contracting with a vendor experienced in working with historical paper-based collections is recommended.

The Digitization Process

The basic steps in digital imaging are as follows:

• Image capture—The document(s) or other materials are captured in digital form using a scanner or digital camera. Decisions made about the desired image quality during benchmarking (e.g., the type of scan, the resolution of the scan, the bit depth) are implemented.


• Image processing—This includes image editing if necessary (e.g., compression of files, sharpening of images) and the creation of metadata (sometimes defined as "data about data"). Metadata indexes and describes the scanned materials. A table explaining the types of metadata can be found within Moving Theory into Practice: Digital Imaging Tutorial.


• Image delivery—This is the process of getting the scanned images to the user through computer networks, monitors, and printers. Delivery methods, file formats, file compression, and acceptable image quality will differ depending on various user characteristics. It is crucial to consider image delivery needs during project planning, not after the images have already been created.


• Quality control—This involves both initial and ongoing evaluation of whether the technical requirements for image capture, processing, and delivery are being met. At the beginning of the project, it is a good idea to digitize a representative sample of documents to be sure that all quality requirements are being met.

Storage and Maintenance

After digital objects are created and appropriately indexed and described, they must be stored on-line, near-line, and/or off-line. Over time, however, obsolescence of hardware and software (the technology chain used to access digital objects) becomes a far greater concern. If a CD-ROM survives intact for 50 or even 100 years, but no device survives that can retrieve the data, then the data have effectively been lost.

At present, there are significant obstacles to maintaining the integrity and functionality of the technology chain. Upgrading to new hardware and software platforms may prove prohibitively expensive over time. To further complicate matters, a practical and universally reliable way of migrating existing digital data to newer hardware and software platforms has yet to be developed. Even if migration procedures were more standardized, they would necessarily involve a significant commitment of time and resources, making them challenging to implement.

See the RLG-OCLC (Online Computer Library Center) report Trusted Digital Repositories: Attributes and Responsibilities (PDF) for a summary of the requirements for an effective digital repository.