Multispectral imaging (MSI) is not a term you hear every day, but it’s a technology that is quietly transforming the way we study the past. By capturing information across ultraviolet, visible and infrared wavelengths, MSI can reveal details invisible to the human eye, faded inks, erased markings or underlying layers of paint – all without touching or damaging the object.
It’s an approach that combines high-resolution photography with advanced analysis, and Phase One’s Rainbow MSI Solution is currently setting the standard in this field.
One of the most striking examples of this technology in action comes from China’s Western Zhou Dynasty. Researchers were tasked with studying wooden slips inscribed with vermilion ink, texts that form part of an important record of early Chinese civilization.
Over 2,000 years old, the inscriptions had almost completely faded, rendered illegible by centuries of environmental wear. To the naked eye, they were nothing more than faint, scattered marks.
Using Phase One’s Rainbow MSI system, researchers were able to capture a complete spectral dataset; essentially photographing the wooden slips across 16 distinct wavelengths, from ultraviolet to near-infrared. Each wavelength revealed subtle differences in how the cinnabar pigment (the basis of the vermilion ink) reflected light.
By processing these images, the team could isolate the spectral 'signature' of the ink from the background wood, reconstructing the handwriting in clear detail. Texts once considered lost could finally be read again.
ABOVE: Watch Phase One's Rainbow MSI technology in action
What is Multispectral Imaging?
Photography, as we know it, records only the visible spectrum; the narrow band of colours that our eyes can detect. MSI extends this concept by capturing information across a far wider range of light wavelengths. Materials and pigments reflect light differently across these wavelengths, so multispectral data can reveal contrasts and patterns that are otherwise invisible.
For cultural heritage work, this is revolutionary. MSI can uncover faded text on ancient manuscripts, detect hidden sketches beneath layers of paint or map the material composition of fragile artifacts. Most importantly, it’s a non-invasive method: everything is revealed through light alone, with no need to physically alter the object.
Phase One’s Rainbow MSI Solution is designed to make this complex process accessible and reliable. Traditional MSI involved painstaking manual adjustments for each wavelength and filter; a time-consuming workflow that often led to alignment errors.
The Rainbow MSI automates the entire sequence. Place the object, press 'capture' and the system cycles through the necessary wavelengths, producing a perfectly aligned image stack in minutes.
At the heart of the system are Phase One’s iXH 150MP and iXG 100MP cameras, both built around high-resolution, colour-accurate CMOS sensors and advanced focusing systems that ensure sharp, repeatable results across ultraviolet and infrared light as well as standard visible light.
The same setup can be switched back to conventional high-resolution digitization simply by adding an IR/UV cut filter. These cameras are paired with Schneider Kreuznach 72mm and 120mm lenses, and a custom lens shroud mounted on a filter wheel.
The software is equally powerful. As images are captured, they’re processed into a spectral stack ready for analysis. Built-in tools like PCA and Independent Component Analysis (ICA) separate the spectral data, permitting researchers to highlight specific materials or pigments.
Automation and precision mean the workflow can be up to 50 times faster than older methods, which is crucial when dealing with large archives or fragile collections.
The wooden slips from the Western Zhou Dynasty are a perfect example of the challenges that MSI can solve. Vermilion ink is notoriously difficult to isolate under single UV or infrared lighting because its spectral characteristics are subtle.
By capturing the full spectrum, however, the Rainbow MSI system provided enough data for researchers to distinguish the faint ink traces from the darker wood beneath.
Through spectral analysis, the blurred characters came back into focus, offering historians a wealth of new information about this formative period in China’s history. The success of this project demonstrates not just the power of MSI but its potential to unlock other historical puzzles, from unreadable scrolls to faded paintings.
For those unfamiliar with this technology, it might seem like a niche tool for museums and archives. But the implications are far broader. MSI is redefining what we can learn from our cultural heritage. Every time it recovers lost writing or reveals hidden details, it gives us a more complete understanding of history.
With the Rainbow MSI Solution, this process has become faster, more consistent and more accessible. Its non-contact approach means fragile artifacts remain unharmed, while its high-resolution captures can be used for everything from scholarly research to public exhibitions.
As someone with a background in archaeology, I can see how transformative this is. Traditionally, studying the past has meant carefully excavating or handling physical objects, always with the risk of damage. MSI represents a new kind of excavation done with light rather than tools, uncovering details that were always there but hidden from view.
The Western Zhou project is just one example of what’s possible. From ancient manuscripts to Renaissance paintings, multispectral imaging has the potential to rewrite our understanding of cultural history – and Phase One has showcased many of these examples on its website.
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