FADGI Star Ratings Explained: What to Ask Before Buying a Book Scanner

A book scanner's brochure resolution tells you very little about whether it will meet an archival digitisation specification. Institutions that follow FADGI, the US Federal Agencies Digital Guidelines Initiative, judge scanners by measured image quality at a defined star level, from 1-star to 4-star, not by a single dpi figure.

That distinction matters at procurement stage. Libraries, archives, universities and heritage institutions worldwide now write FADGI star levels, or the international technical specification ISO/TS 19264-1, into digitisation tenders and grant conditions. A scanner that cannot produce measurable results at the required level can turn into an expensive mismatch. This guide explains what FADGI's third edition changed, what the star levels actually grade, how ISO/TS 19264-1 fits in, and the questions to put to any supplier before you buy an overhead book scanner.

What FADGI Is and What the 2023 Edition Changed

FADGI is a collaboration of US federal agencies that publishes technical guidelines for digitising cultural heritage materials. According to the Library of Congress, the third edition of the Technical Guidelines for Digitizing Cultural Heritage Materials was published in final form on 10 May 2023. A draft was released in June 2022 for public comment, which closed in August 2022. Earlier editions were published in 2010 and 2016.

Although FADGI was written for US federal agencies, its star levels are widely used as a shared vocabulary for image quality in cultural heritage digitisation well beyond the United States. When a tender says "FADGI 3-star", it is pointing to a specific, published set of measured criteria rather than a general promise of "high quality".

The Library of Congress also notes that FADGI has developed its own software tools to support implementation of the Guidelines. That is a practical point for buyers: measuring scanner output against FADGI does not depend on one manufacturer's software.

What the Star Levels Actually Grade

FADGI star levels grade the images a digitisation system produces, not the scanner on its own. The Guidelines define four levels: 4-star (highest), 3-star, 2-star and 1-star (lowest). For each evaluation category, they "specify the minimum or range of values an image must meet" at each level.

Three consequences follow for anyone buying a book scanner:

• Several criteria are measured, not one. A high stated resolution does not ensure a star level if other measured criteria fall short.
• Files matter as well as images. The Library of Congress notes that the Guidelines specify the master file format, colour space and other file requirements for each material category and star level.
• Some parameters are informational. The Library of Congress notes that certain evaluation parameters are informational and not essential to validate star-level conformance, so the full Guidelines should be read rather than a summary.

Because a result depends on the scanner, lighting, calibration, settings and operator together, the honest question is never "is this scanner FADGI 4-star?" but "what star level does this system produce, measured on our kind of material, in our working conditions?"

Where ISO/TS 19264-1 Fits

ISO/TS 19264-1 is the international technical specification for image quality analysis of imaging systems that digitise reflective originals. Reflective originals include bound books, loose documents, maps and photographic prints: in other words, most of what goes under an overhead book scanner.

Where FADGI is a set of US federal guidelines, ISO/TS 19264-1 is an international specification. Many cultural heritage institutions outside the United States reference it directly, and some projects cite both. For buyers, the practical point is the same: both approaches measure output with targets and analysis software, and both expect results to be repeatable rather than achieved once at installation.

If your tender or funder names one of these frameworks, ask the supplier which one their demonstration results are measured against, and make sure your own acceptance testing uses the same one.

Questions to Ask Before You Buy a Book Scanner

A reliable way to avoid a mismatched purchase is to ask for measured evidence on your own material. A practical checklist:

Question	Why it matters
Which star level, or ISO/TS 19264-1 criteria, does our project actually require?	A 4-star requirement for rare volumes is a different purchase from a 2-star access copy programme.
Can you demonstrate results with a target and analysis software, on material like ours?	Star levels are measured outputs, so a demonstration should produce a measured report.
Which master file formats and colour spaces can the system produce?	FADGI sets file requirements per material category and star level.
How is the system calibrated, and how often should it be re-checked?	Lighting and camera settings drift; repeatability is part of quality.
How does the cradle protect fragile bindings at the opening angle we need?	Meeting an image specification should never mean forcing a spine flat.
What operator training and after-sales support are included?	The operator is part of the system that earns the star level.

For the difference between overhead book scanners and sheet-fed or flatbed document scanners, see our book scanner vs document scanner guide.

Frequently Asked Questions

What is FADGI?

FADGI is the Federal Agencies Digital Guidelines Initiative, a collaboration of US federal agencies that publishes the Technical Guidelines for Digitizing Cultural Heritage Materials. The current third edition was published on 10 May 2023, following earlier editions in 2010 and 2016.

What do FADGI star ratings mean?

FADGI grades digitisation quality at four levels, from 1-star (lowest) to 4-star (highest). For each evaluation category, the Guidelines specify the minimum or range of values an image must meet at each level, and they also set the master file format, colour space and other file requirements for each material category and star level.

Is a book scanner FADGI certified?

FADGI star levels describe the images a digitisation system produces, measured with targets and analysis software under real working conditions. A rating therefore depends on the scanner, lighting, calibration, settings and operator together. Ask any supplier to demonstrate measured results on your own material type rather than relying on a label.

What is ISO/TS 19264-1?

ISO/TS 19264-1 is the international technical specification for analysing the image quality of imaging systems used to digitise reflective originals such as books, documents and prints. Many cultural heritage projects use it alongside or instead of FADGI as the basis for measuring scanner output.

Is resolution enough to judge a book scanner?

No. Resolution is one of several measured criteria. FADGI evaluates images across multiple categories at each star level, so a scanner with a high stated resolution can still fall short if, for example, colour, tone or lighting uniformity do not meet the level your project requires.

Request a Quote for Book Scanners or Book Scanning Services

Tell us what you are digitising, the star level or specification your project requires, and the volumes involved, and we will recommend an overhead book scanner configuration or scope the work through our book scanning services. Browse document and book scanning equipment, then Request a Quote. Supplied from Singapore; availability and delivery dates confirmed on each quotation.

Contact: sales@micrographicsdata.com | +65 6472 7255

Sources: Library of Congress, The Signal, "FADGI Third Edition Still Image Guidelines" (blogs.loc.gov, May 2023); Federal Agencies Digital Guidelines Initiative (digitizationguidelines.gov); ISO/TS 19264-1, Photography — Archiving systems — Imaging systems quality analysis — Part 1: Reflective originals.