Digital Preservation

The primary purpose of digital preservation is to ensure long-term viability of a digital resource. This means that a resource can be accessed and viewed long after it was first created. Digital preservation also aims to verify that a complete version of the digital resource exists. Complete in terms of content, metadata, and bit-size.

Digital preservation considerations can happen at any point in digital asset creation. For example, decisions about which file format to use, when and if to embed technical metadata into your file, and whether or not to run checksums or take a disc image throughout production or use of a digital resource can play a part in how well a digital asset is able to be preserved in the long run.  

General Tips:

File format: When selecting a file format, it is best to avoid proprietary formats. A few common proprietary format types are - .docx (from Microsoft Word), .xls (from Microsoft Excel), or .psd (from Photoshop). It's better to save things in open formats so that you avoid software specifications and items can be open without the use of a specific application. Therefore, .docx would become PDF or ODT, .xls would become CSV, and .psd would become JPEG. In addition to selecting file formats that are nonproprietary, consider also selecting more stable file formats that can help prevent bit rot, which can occur over time and during manipulation of files. Certain file types can protect your work from bit rot better than others, these include: .mp3 (Audio), TIFF (Image), JPEG2000 (Image), and PDF/A (Document). 

File size: It's best to keep and then store uncompressed versions of digital resources as the preservation copy when possible. In many cases an uncompressed version of a file will be stored as preservation, while a more reasonably sized file will become the access copy. This is typical for images, where a TIF will be stored in a preservation layer, and a JPG will become the reference file. It is beneficial to keep an uncompressed copy of your files because those files contain the most data, and once something is compressed you generally won't be able to restore the file to its original depth and size. Similarly, it is also best practice to keep original copies, particularly of images and datasets, and then generate a reference copy before doing any manipulation. 

Have questions or want to confirm you're making wise choices for your digital resources? Please contact digitalscholarship@georgetown.edu.