What is the difference between a preservation master copy and an access copy when you scan records?

When you scan records, a single page often becomes more than one digital file. Mature digitization programs commonly produce two distinct outputs from one capture: a preservation master copy and an access copy. They serve different goals, so they are made and managed differently.

The preservation master copy

The preservation master is the highest-fidelity capture you make. It is meant to be the durable, authoritative digital version of the original record — the file you keep for the long term and the one all other copies are derived from.

Master copies typically favor:

• High resolution and full color/bit depth, capturing as much detail as practical so the file can substitute for the original.
• Uncompressed or losslessly compressed formats (for example, TIFF for images), avoiding quality loss over time.
• Rich metadata, including technical capture details and information that supports authenticity and provenance.

Because masters are large and information-dense, they are stored in managed, secured storage and are generally not handed out for everyday use.

The access copy

The access copy (sometimes called a derivative or service copy) is generated from the master and optimized for everyday use, sharing, and delivery — on the web, in a recordkeeping system, or in response to a request.

Access copies usually favor:

• Smaller, widely supported formats (such as PDF or JPEG) that open easily and transfer quickly.
• Lower resolution or lossy compression, balancing readability against file size.
• Searchability, often adding OCR text so documents can be found and read.

If an access copy is damaged or becomes obsolete, you can simply regenerate a fresh one from the master.

Why keep both

The two-tier approach lets one program meet competing needs at once: long-term integrity from the master, and convenient day-to-day access from the derivative. It also supports format migration — as standards change, you re-derive access copies from preserved masters rather than rescanning originals.

For more on capturing and managing scanned records, see the digitization and imaging topic hub. Recognized guidance such as FADGI’s technical guidelines and the Library of Congress’s digital preservation resources can help you set appropriate targets for resolution, formats, and metadata.