Digitizing the collections held by community museums and local archives involves decisions that affect both the immediate usability of the resulting files and their long-term preservation value. For small institutions in Canada, the relevant guidance comes from federal frameworks published by Library and Archives Canada and from provincial heritage programmes that coordinate digitization projects across their jurisdictions.
Resolution Requirements
Resolution for digitized materials is expressed in pixels per inch (ppi) or dots per inch (dpi), two terms that are often used interchangeably for scanned output. The appropriate resolution depends on the type of material being digitized and its intended use.
Recommended Scanning Resolutions by Material Type
- Text documents (standard size): 300 ppi minimum; 400 ppi preferred for smaller type.
- Photographic prints (standard): 400–600 ppi to retain tonal detail.
- Photographic negatives and slides: 1200–2400 ppi depending on format size (35mm vs. medium format).
- Maps and large-format items: 300–400 ppi measured at the original dimensions.
- Deteriorating or fragile items: Err toward higher resolution to reduce future handling.
These figures represent practical minimums for access-quality files. Preservation masters intended for long-term archival storage are typically produced at higher resolutions than access copies. The access copy (intended for public online viewing or printing) is derived from the preservation master through a defined workflow.
File Formats for Preservation and Access
The choice of file format affects both the long-term accessibility of a digitized item and the storage space required. The archival digitization community distinguishes between preservation master formats and access formats.
Preservation Master Formats
TIFF (Tagged Image File Format) is the standard for uncompressed or losslessly compressed preservation masters of raster images. It is format-stable, widely supported across archival software, and does not degrade with saving. The master TIFF file should not use lossy compression (JPEG compression within a TIFF is discouraged for preservation copies).
For text documents and compound documents combining text with images, PDF/A (ISO 19005) is the standard archival format. PDF/A embeds all fonts, prohibits external content dependencies, and defines specific colour space requirements that support long-term rendering consistency.
Access Copy Formats
JPEG remains the practical standard for access-copy photographic images due to its compact file size and universal browser and software support. For access JPEGs derived from TIFF masters, a quality setting of 80–90% (on a 0–100 scale) typically produces files suitable for online display without visible compression artefacts on screen.
PNG is preferred over JPEG for access copies of documents with predominantly text, line art, or flat colour areas, since PNG compression is lossless and preserves sharp edges without the blurring artefacts that JPEG introduces at text boundaries.
Metadata Schema
Metadata is the structured information attached to each digitized item that describes its provenance, content, and technical characteristics. Without adequate metadata, a digitized collection becomes difficult to search, manage, or share with other institutions.
Dublin Core
Dublin Core is a minimal, widely supported metadata schema consisting of 15 elements (title, creator, subject, description, publisher, contributor, date, type, format, identifier, source, language, relation, coverage, rights). It is sufficient for basic catalogue records and is supported by most collection management systems used by small Canadian museums. Its simplicity makes it accessible for institutions without a specialist cataloguer on staff.
VRA Core and MODS
For institutions with photographic collections or more complex object types, VRA Core (Visual Resources Association) provides a more detailed schema suited to describing visual materials. MODS (Metadata Object Description Schema) from the Library of Congress is used in contexts where interoperability with academic libraries and national aggregators is required.
Minimum Metadata Fields for Community Archive Digitization
- Title: Descriptive name for the item or "Untitled" with additional description.
- Date: Creation date of the original item (estimated range where exact date is unknown).
- Creator / Contributor: Person or organisation responsible for the original.
- Description: Free-text note on content, context, and condition.
- Rights: Copyright status and any access restrictions.
- Identifier: Unique identifier linking the digital file to the physical item.
- Format: Technical format of the digital file (TIFF, JPEG, PDF).
Colour Profiles and Colour Management
Digitized images intended for faithful reproduction of original materials should be captured and stored with an embedded ICC colour profile. For most archival digitization, the sRGB profile is appropriate for access copies, while the larger-gamut Adobe RGB (1998) profile may be used for preservation masters of materials with significant colour content.
Scanners should be calibrated regularly using a reference target (such as an IT8 target for photographic scanners) to maintain consistency across sessions and over time. Colour calibration records should be kept as part of the digitization project documentation.
Canadian Heritage Digitization Context
Several Canadian provincial programmes support community museums in undertaking digitization projects. Ontario's community museum programme, British Columbia's Royal BC Museum network, and various provincial archives offices provide technical guidance and, in some cases, equipment loan programmes for smaller institutions.
The Canadiana network aggregates digitized Canadian heritage content from participating institutions and accepts contributions that meet its technical specifications. Participation provides an additional distribution channel for community museum collections.
Further Reference
Library and Archives Canada publishes guidance on digitization and digital preservation. The Federal Council's digitization guidelines for heritage institutions are coordinated through a network of federal cultural agencies.
