Multispectral imaging (MSI) captures light from a range of wavelengths – visible and invisible to the human eye – across the electromagnetic spectrum using special camera technology, light sources, and filters.
The resulting “stacks” of images are used to analyze substances and surfaces to determine readability, authenticity, age, and material-characterization and distribution.
- Analysis of documents – Readability of text on parchment, scrolls, and paper, often in poor condition is one application.
- Analysis of polychrome surfaces such as paintings – on canvas, wood, stone, and other materials. Applications include non-invasive analysis for conservation work and authentication.
- Analysis of Fabrics of all kinds – such as historic research to determine age and material.
- Police, forensic and crime scene investigation. Analysis for residue of human fluids on fabric, fingerprints, marks from use of weapons, and crime scene evidence.
- Materials characterization and sorting. Applications include quality assurance, research and evelopment of new materials, and analysis for machine vision.
- General: MSI is used to differentiate subject matter based upon the differentiated response from materials with different chemical compositions.
MSI Outstanding Benefits for Analysis
- Non-invasive contactless analysis
- Quick first step for further analysis – Do it once, do it right
- Nondestructive thanks to low energy LED lighting
- Modular and mobile capturing solutions
- The growth of multispectral Imaging applications is based upon the use of new developments within LED lighting, wide spectrum and high-resolution digital camera sensors, as well as conservation methodology.
- LED lighting can be specified to deliver select “slices”, or bands, of the spectrum from UV light, through visible light and into IR light.
- In a darkened studio, LED lighting in combination with filters in front of the camera is used to capture two types of images.
- Images of reflected light: The different light bands enter into the surface of the subject matter and are reflected from different layers. Characteristics are then captured of the visible top surface, and of the layers below, to reveal information about, for example, earlier text scraped away on parchment and palimpsests, paints used, re-touching, underdrawings, state of conservation etc.
- Images of photo-induced luminescence: A given wavelength of light induces energy in the subject-matter and can result in luminescence, showing up as illuminations in a longer wavelength. The term “luminescence” also includes fluorescence. The luminescence is captured by filtering away the reflected shorter original wavelength, by using filters in front of the camera.
- Captured image stacks are analyzed visually or by scientific methods used to discover or enhance content in the subject matter. The calibration steps are based on well-defined standards and targets.
- Scientific methods include libraries for statistical analysis of the stack, typically Principal Component Analysis. Matlab and Paleo Toolbox are two examples of such libraries.
- For visual analysis, Rainbow software has presets according to the CHARISMA project manual made by British Museum in collaboration with EU partners.
Multispectral cameras have been available in the market for many years but the calibration process, as well as the techniques for changing material sizes whilst maintaining consistent images that can be stacked and analyzed efficiently, has been a challenge and created significant overhead.
Phase One has worked with specialists on MSI projects over years. Based upon this experience and learning, we have devised a flexible and easy to handle, yet robust MSI solution with a workflow based on best practices.
The Rainbow capture process is fully automated: simply position the subject matter and press ‘Capture’. The full stack of captures are then made with automated focus, automated “flattening”, automated exposure normalization, and automated alignment to deliver the perfect stack, again and again – with perfect repeatability and stability.
The Rainbow MSI software controls all the elements – focusing the camera, moving the filter carousel on the filter wheel, turning the lights on and off in the correct order and timing, aligning the images, and finally creating the perfect stack.
The Rainbow Camera
The iXG 100MP Wide Spectrum camera employs a high-resolution color accurate CMOS sensor and advanced focusing to deliver sharp, reliable and repeatable results through the entire sweep of the light wavelengths involved.
The Wide Spectrum RGB sensor is tailored for multispectral work, with the added benefit of being able to also do normal digitization work “Do it once, do it right”. Just attach the included IR/UV-cut filter to the magnetic holder of the lens, and you are good to go, following Metamorfoze, FADGI and ISO color standards.
The CMOS sensor provides a responsive live-view for quick and safe positioning of subject matter.
To keep out stray light, the camera comes with a custom lens shade tube mounted on the filter wheel.
The iXG 100MP Wide Spectrum camera comes with 72mm and a 120mm lenses and extension tubes, all suited for the wide range of MSI imaging tasks, as well as normal flat copy digitization work.
The RS leaf shutter of the iXG camera guarantees 1 million actuations. Working with the electronic shutter of the iXG camera gives you infinite durability. The precise focusing mechanism of iXG measures distances accurately, and provides for Auto PPI functionality, which makes digitization work at different resolutions quick and easy.
The filter wheel can hold up to five filters. It is configured to support the filtering needs of accurate visible imaging and luminescence imaging, which fits many applications, including the CHARISMA standard manual.
The carousel, which holds the filters is removable and can be configured with any 2” filters for future scientific applications. The factory capture settings can be adjusted to suit different filter configurations. To support different MSI applications, you can simply work with two or more filter carousels.
The Rainbow LED Lights
Rainbow supports two types of LED lights for a wide range of applications:
- Multiband DedoLight, delivering narrowband UV, broadband visible light, broadband and narrowband IR. This light is often used for MSI applications related to Art Conservation and to Police Forensics. Recipes for the capture of images following the CHARISMA standard manual are included.
- Narrowband EurekaLight, delivers 16 narrowbands of light from UV, through visible to IR. This light is often used for MSI applications related to Document Readability.
The Rainbow MSI Solution
iXG 100MP Wide Spectrum
|Sensor size||53.4 x 40.0|
|Resolution||11608 x 8708|
|Pixel size (μm)||4.6|
|File Formats||Raw 14bit, Raw 16bit|
|Lenses||Schneider Kreuznach RS 72mm and/ or 120mm|
|Lenses||Schneider Kreuznach RS 72mm and/ or 120mm|
|Weight (gr) with 72mm lens||2,300 incl. L Bracket|
|Approvals||FCC Class A, CE, RoHS|
|Operating Temperature (°C )||-10º to 40º|
|Operating Humidity (% )||15 – 80 (non-condensing)|
|Accessories||BG39 filter for normal photography, with magnetic adaptors.
Custom lens shade suited for the supplied filter wheel
|Multiband Solution||Narrowband Solution|
|Included LED lights||2 x UV, inc. UG11 filters (365 µm)
2 x VIS, inc. BG39 filters
2 x IR (860µm & 960µm)
|Wavelengths (µm): 365, 385, 410,
420, 450, 480, 510, 530, 550, 600,
630, 640, 660, 740, 850, 940
|Configuration||2 banks with UV-, VIS-, IR- emission each||2 panels with 16 LEDs in each|
|Filter Wheel||Included, controlled via USB|
|Communication with lights and filter wheel||USB via 7 – port powered hub|
|Light stands||Not included|
|Included Capture Computer||DELL Mobile Precision 7740 CTO BASE, 17.3”, i9 processor, 64GB RAM, 1TB SSD, Windows 10 OS|
|Workflow Software||Phase One Rainbow MSI software|
|Output||8-image stack, according to Charisma Guidelines||16-image monochrome stack, ready for statistical analysis|
|Output Luminescence||3 channels||15 channels|
Ready to take the next step?
Please contact us for pricing, in person / virtual demonstrations, or just to learn more about this fantastic new product.