FADGI stands for Federal Agencies Digital Guidelines Initiative. It is a collaborative initiative of US federal agencies created to define common guidelines, standards, and practices for the digitization of historical and cultural heritage materials. The FADGI score is a quantitative metric (often expressed as a "star" rating, for example from 1 to 4) used to evaluate the technical quality and accuracy of digitized still images, audio, and video files against rigorous benchmarks.
The primary purpose of the FADGI rating is to provide an objective and measurable standard to ensure that digital files are of sufficient quality for long-term preservation, access, and future reuse . It answers the question: "How good is this digital copy, technically speaking?" It measures key metrics including:
Spatial resolution (e.g., PPI – pixels per inch)
Tonal/color accuracy (evaluated with standard charts such as IT8.7/2)
Dynamic range (ability to capture detail in shadows and highlights)
Color channel registration (alignment of red, green, and blue channels)
Noise and uniformity
Star system (for still images):
★ 1 star (Minimum/Discovery): Suitable for basic online viewing and discovery. Has obvious technical flaws, but is acceptable for quick reference.
★★ 2 stars (Good): Good quality image, suitable for most access and playback uses.
★★★ 3 stars (Excellent): high-quality image, suitable for most preservation and publication needs; often the goal of cultural heritage projects.
★★★★ 4 stars (Archival): highest standard achievable, designed for the most critical preservation and academic use; requires exceptional equipment and calibration.
The FADGI classification is used by:
Cultural heritage institutions: libraries, archives, and museums (e.g., Library of Congress, National Archives) to benchmark laboratories and suppliers.
Digitization providers and service bureaus: communicate their ability to produce files that comply with specific FADGI levels.
Grant-funded projects: some funding bodies require deliverables to comply with a certain FADGI level to ensure quality and consistency.