Metamorfoze
Metamorfoze is the Dutch national programme for preserving paper heritage — launched in 1997 by the Ministry of Education, Culture and Science and hosted by the KB, the National Library of the Netherlands. Its Preservation Imaging Guidelines, written by Hans van Dormolen, set the image quality for every digitisation project the programme funds. Version 1.0 appeared in 2012; the current version 2.0 was published in April 2025, free to read under a Creative Commons licence.
PHOTARCH does not assess objects by Metamorfoze. It assesses them by its own three levels — record shot, study and reproduction, set out under PHOTARCH's levels — and offers Metamorfoze, with FADGI and ISO 19264-1, for paintings, documents, prints and other flat originals, which is what it was written for: a setting in the PHOTARCH app turns them on, clearly labelled. This page explains the standard itself.
What it is for
The guidelines have one main aim: everything visible in the original must also be visible in the preservation master. That is a stricter promise than it sounds. Metamorfoze funds the digitisation of originals that are deteriorating, and once they are digitised they are withdrawn from use. The master has to be good enough to stand in for the original.
That is why Metamorfoze is precise about what a master is: an unprocessed, first-generation camera or scanner file with its colour space embedded. Stitching and focus stacking are not allowed in the master — they belong in the copies made from it — and sharpening is limited to a modulation of 1.05, without halos.
The master and the user files
Version 2.0 divides a project's files in two, and the line between them is the whole point of the guidelines.
The file that is kept in place of the original, and the only one the guidelines measure. It is the first-generation camera or scanner file, unprocessed, with its colour space embedded — eciRGB v2 at Full, Adobe RGB allowed from Light, sRGB at Extra Light — and in principle an uncompressed TIFF 6.0; another format needs the client's approval. What may be done to it is short: a little sharpening (modulation at most 1.05, no halos), rotation by 90° or 180°, and straightening only with the client's permission. A sheet-fed scanner's own editing software has to be switched off.
Everything made from the master to be used: read, published, printed. This is where processing belongs — the stitching of a large original photographed in overlapping parts (at least 15 % overlap), focus stacking, the edits a sheet-fed scanner makes to bring out text, and sharpening, which the guidelines would rather see here than in the master. The guidelines' tolerances are written for the master.
The reason is the programme's purpose: the master must be able to replace a deteriorating original, so it has to be a reliable, unaltered copy of it, measured against it. Anything that combines several captures into one — however good the result — is a new picture, not that copy. Version 1.0 (2012) said less: the master was simply "the first file", and sharpening was not allowed at all. The rule on stitching and stacking is new in 2.0.
Three levels
| Level | Intended for |
|---|---|
| Full | Originals regarded as works of art — letters, illuminated manuscripts, maps, photographs, paintings, drawings. Tightest colour; tone assessed down to deep blacks, L* 5 |
| Light | Books, newspapers, magazines, manuscripts and technical drawings, where colour matters somewhat less. Tone assessed to about L* 20 |
| Extra Light | Text documents up to A3 on sheet-fed scanners, kept only as carriers of text. No colour-accuracy tolerance |
At every level the highlights are held to the same gain modulation, 80–110 %, so that faint information in light areas is never lost.
What it measures
Every tolerance is measured on technical targets with reference values in CIELAB — since version 2.0 that is mandatory — and every master is also inspected by eye for artefacts. Measurements are repeated at set intervals through a project, with daily and weekly targets.
Some of the specifications from §1.6:
| Full | Light | Extra Light | |
|---|---|---|---|
| Colour space | eciRGB v2 | eciRGB v2, Adobe RGB | eciRGB v2, Adobe RGB, sRGB |
| Bit depth | 16 or 8 | 8 | 8 |
| White balance, ΔE | ≤ 3 | ≤ 3 | ≤ 5 |
| Exposure, ΔL* | ≤ 2 | ≤ 2 | ≤ 4 |
| Colour accuracy, ΔE2000 | mean ≤ 3, max ≤ 7 | mean ≤ 4, max ≤ 14 | — |
| Noise, L* | ≤ 1.6 | ≤ 1.6 | ≤ 2 |
| Sampling rate | 300 ppi | 300 ppi | 300 ppi |
| Sharpening, max modulation | ≤ 1.05 | ≤ 1.05 | ≤ 1.05 |
Alongside these: illumination evenness by original size, sharpness (MTF10 and MTF50), colour misregistration, geometric distortion, and the difference between the claimed and the real sampling rate. Colour accuracy is measured on a ColorChecker Digital SG.
Metamorfoze and ISO 19264-1
Version 2.0 measures in accordance with ISO 19264-1 unless it says otherwise. Metamorfoze Full is largely aligned with ISO's Level A, and the guidelines list where they differ: Full is stricter on colour (mean ΔE ≤ 3 against ISO's ≤ 4) and misregistration, and slightly more lenient on distortion, MTF50 and gain modulation in the darker tones.
How to relate to it
- It is a standard for paper. The guidelines say so themselves, and note that originals denser in information than paper may need a higher sampling rate than 300 ppi. Small objects are such originals.
- Its idea of a master carries over in part. Colour-managed, nothing visible lost, and never altered once it is kept — that holds for objects too. Where PHOTARCH differs is what the master may be: for a three-dimensional object it is the finished picture brought in, which may be a focus stack exported as a TIFF from raw frames. Metamorfoze would call that a user file; for an object whose depth no single frame can hold, it is the picture worth keeping — see Focus stacking.
- eciRGB v2 at Full. If you work towards Metamorfoze Full, the master has to be in eciRGB v2; Adobe RGB reaches Light at most.
What PHOTARCH measures, and what it does not
With the setting for flat originals on, the PHOTARCH app grades a photograph against the three Metamorfoze levels on what it can measure: file format, colour space, the bit depth of the file, resolution at the object (300 ppi), and white balance, exposure and colour accuracy from the ColorChecker in the same sitting. The bits the camera recorded are shown beside the file's.
Two limits are stated with the grade. The colour figures are indicative: PHOTARCH reads a ColorChecker Classic, where Metamorfoze specifies the Digital SG. And PHOTARCH does not measure gain modulation, noise, illumination evenness, sharpness (MTF), sharpening, colour misregistration or geometric distortion. Flat originals are lit evenly from two sides, as Metamorfoze asks, but the app does not measure how evenly. A green light means nothing that was measured stands in the way of this level — not that the photograph is a Metamorfoze preservation master.
Sources
- guidelinevan Dormolen, H. (2025). Metamorfoze Preservation Imaging Guidelines, Image Quality, version 2.0, April 2025. KB National Library. CC BY-ND 3.0.§1.1 main aim · §1.3–1.5 the three levels · §1.6 specifications · §2.27 Metamorfoze and ISO 19264-1.
- programmeMetamorfoze, the Dutch national programme for the preservation of paper heritage.