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24 October 2026 · Updated at 07:47 GMT FR EN ES Member area Log in
Certification

Scientific imaging

Infrared reflectography, ultraviolet fluorescence, X-radiography, macrophotography and 3D survey: seeing below the surface without touching the work.

Updated : October 28, 2026· 3 min read

Seeing what the eye cannot see

Head of Proserpina, Gian Lorenzo Bernini (1650–1700)
Head of Proserpina, Gian Lorenzo Bernini (1650–1700)

Scientific imaging brings together non-invasive techniques that make hidden information visible: preparatory drawing under the painted layer, pentimenti, modern retouching, internal structures of a sculpture, effaced inscriptions.

It is the first family of analyses requested (46% of analyses carried out in 2024): inexpensive, quick, without sampling. It costs from €250 to €700 excl. VAT depending on the technique and the number of shots.

Its results are integrated into the expert's opinion and also feed conservation reports.

  • Infrared
  • Ultraviolet
  • X-rays
  • 3D

Imaging in figures

€250 to €700indicative price excl. VAT
1 to 2weeks timeframe
6techniques
46%of the network's analyses

The techniques

Six complementary techniques
TechnologyWhat it reveals
Infrared reflectographyUnderdrawing, pentimenti, inscriptions under the paint
Ultraviolet fluorescenceOld varnishes, retouching, restorations
X-radiographyInternal structure, nails, cracks, lead-rich layers
MacrophotographyDetails of workmanship, craquelure, wear
Raking lightReliefs, lifting, deformations
3D surveyVolumes, deformations, comparison of sculptures

Course of an imaging session

  1. Preparation

    Setting up the work, calibrating the light.

  2. Shooting

    Series of images per technique, always in the same conditions.

  3. Assembly

    Gathering of the images and normalisation.

  4. Reading

    The expert interprets by comparing the layers.

  5. Image file

    The images are added to the file and the passport.

Leaf from a Psalter and Prayerbook: Ornamental Border with Carnations, a Thistle, and a Cook Ladling Soup (verso) (c. 1524)
Leaf from a Psalter and Prayerbook: Ornamental Border with Carnations, a Thistle, and a Cook Ladling Soup (verso) (c. 1524)
Portrait of a Woman, Corneille de Lyon (c. 1540)
Portrait of a Woman, Corneille de Lyon (c. 1540)
Compass and Sun Dial (1700–1750)
Compass and Sun Dial (1700–1750)

A screening tool

Infrared or X-rays

Medal of Claude Joseph Rouget de L'Isle (1760-1836), Alfred Borrel (1911)

Infrared

Seeing beneath the painted layer
  • Preparatory drawing
  • Pentimenti
  • Effaced inscriptions

For paintings.

Medal: In Commemoration of the Fiftieth Anniversary - The Warner and Swasey Company, Victor D. Brenner (1930)

X-rays

Seeing inside
  • Structure of the support
  • Nails and cracks
  • Lead-rich layers

For paintings and sculptures.

Imaging techniques used in 2024

UV fluorescence34%
Infrared29%
X-radiography18%
Macrophotography13%
3D survey6%

Source: partner laboratories (indicative).

Case study: a revealing pentimento

A signature that betrays

Situation

A painting attributed to a Flemish master is studied by infrared reflectography.

Actions
  1. The underdrawing reveals a hesitant line, hardly compatible with the master's hand.
  2. A retouching is detected in ultraviolet at the location of the signature.
  3. The expert concludes an attribution to the workshop.
Outcome

A “workshop” certificate is issued; the signature is described as later.

Calendar of a session

  1. Agreement

    Techniques chosen.

  2. Shooting

    On site or in the workshop.

  3. Assembly

    Standardised images.

  4. Report

    Expert's reading.

Imaging and conservation

The images produced do not serve only for authentication. They constitute a reference condition of the work at a given date, valuable in the event of a claim, restoration or dispute. They are kept in the file for the same period as the other documents.

For a loan or transport, comparing images before and after makes it possible to spot alterations the eye would not have seen. The conservation report relies on the same techniques.

Portrait of a Man, Louis Lafitte (1793)
Portrait of a Man, Louis Lafitte (1793)
An Indigo Factory, Allahabad, Louis-Théophile Marie Rousselet (1865–68, published 1869–70)
An Indigo Factory, Allahabad, Louis-Théophile Marie Rousselet (1865–68, published 1869–70)
Fragment of a belt (hizam) (1800s)
Fragment of a belt (hizam) (1800s)

A principle of curiosity

Peregrine Falcons (Duck Hawks), John James Audubon (c. 1827)
« A good image proves nothing: it poses the question one would have forgotten to ask. »
Dr. Lucía Ferrer, member of the certification committee

Vocabulary of imaging

Reflectography
Infrared imaging that passes through certain layers of paint.
Pentimento
Change of composition visible beneath the paint.
UV fluorescence
Emission of visible light under ultraviolet illumination.
Radiography
Image obtained by X-rays.

Frequently asked questions

Is imaging safe?

Yes, the doses and powers are controlled and have no effect on the material.

Can it be done at my home?

For portable techniques (UV, macrophotography, infrared), yes; X-rays require a laboratory.

How many images are produced?

From 20 to 200 depending on the work and the techniques.

Do the images belong to me?

They are added to the file; you may request a copy.

Useful documents

Contacts

Architectural Conference (c. 1622)
Architectural Conference (c. 1622)
Certification DepartmentParis — Headquarters+33 1 00 00 00 00certification@oimap.exampleMonday to Friday, 9 a.m. – 5 p.m.

Request imaging

Portrait of a Woman, Anna Claypoole Peale (1820)

The expert will propose the most useful techniques.

Submit a case
Image credits (16)
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