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Multispectral Imaging Through Collaboration

I am sure you have all been following the Library’s exploration into Multispectral Imaging (MSI) here on Bitstreams, Preservation Underground and the News & Observer.  Previous posts have detailed our collaboration with R.B. Toth Associates and the Duke Eye Center, the basic process and equipment, and the wide range of departments that could benefit from MSI.  In early December of last year (that sounds like it was so long ago!), we finished readying the room for MSI capture, installed the equipment, and went to MSI boot camp.

Obligatory before and after shot. In the bottom image, the new MSI system is in the background on the left with the full spectrum system that we have been using for years on the right. Other additions to the room are blackout curtains, neutral gray walls and black ceiling tiles all to control light spill between the two camera systems. Full spectrum overhead lighting and a new tile floor were installed which is standard for an imaging lab in the Library.

Well, boot camp came to us. Meghan Wilson, an independent contractor who has worked with R.B. Toth Associates for many years, started our training with an overview of the equipment and the basic science behind it. She covered the different lighting schemes and when they should be used.  She explained MSI applications for identifying resins, adhesives and pigments and how to use UV lighting and filters to expose obscured text.   We quickly went from talking to doing.  As with any training session worth its salt, things went awry right off the bat (not Meghan’s fault).  We had powered up the equipment but the camera would not communicate with the software and the lights would not fire when the shutter was triggered.  This was actually a good experience because we had to troubleshoot on the spot and figure out what was going on together as a team.  It turns out that there are six different pieces of equipment that have to be powered-up in a specific sequence in order for the system to communicate properly (tee up Apollo 13 soundtrack). Once we got the system up and running we took turns driving the software and hardware to capture a number of items that we had pre-selected.  This is an involved process that produces a bunch of files that eventually produce an image stack that can be manipulated using specialized software.  When it’s all said and done, files have been converted, cleaned, flattened, manipulated and variations produced that are somewhere in the neighborhood of 300 files. Whoa!

This is not your parents’ point and shoot—not the room, the lights, the curtains, the hardware, the software, the pricetag, none of it. But it is different in another more important way too. This process is team-driven and interdisciplinary. Our R&D working group is diverse and includes representatives from the following library departments.

  • The Digital Production Center (DPC) has expertise in high-end, full spectrum imaging for cultural heritage institutions along with a deep knowledge of the camera and lighting systems involved in MSI, file storage, naming and management of large sets of files with complex relationships.
  • The Duke Collaboratory for Classics Computing (DC3) offers a scholarly and research perspective on papyri, manuscripts, etc., as well as  experience with MSI and other imaging modalities
  • The Conservation Lab brings expertise in the Libraries’ collections and a deep understanding of the materiality and history of the objects we are imaging.
  • Duke Libraries’ Data Visualization Services (DVS) has expertise in the processing and display of complex data.
  • The Rubenstein Library’s Collection Development brings a deep understanding of the collections, provenance and history of materials, and valuable contacts with researchers near and far.

To get the most out of MSI we need all of those skills and perspectives. What MSI really offers is the ability to ask—and we hope answer—strings of good questions. Is there ink beneath that paste-down or paint? Is this a palimpsest? What text is obscured by that stain or fire-damage or water damage? Can we recover it without having to intervene physically? What does the ‘invisible’ text say and what if anything does this tell us about the object’s history? Is the reflectance signature of the ink compatible with the proposed date or provenance of the object? That’s just for starters. But you can see how even framing the right question requires a range of perspectives; we have to understand what kinds of properties MSI is likely to illuminate, what kinds of questions the material objects themselves suggest or demand, what the historical and scholarly stakes are, what the wider implications for our and others’ collections are, and how best to facilitate human interface with the data that we collect. No single person on the team commands all of this.

Working in any large group can be a challenge. But when it all comes together, it is worth it. Below is a page from Jantz 723, one processed as a black and white image and the other a Principal Component Analysis produced by the MSI capture and processed using ImageJ and a set of tools created by Bill Christens-Barry of R.B. Toth Associates with false color applied using Photoshop. Using MSI we were able to better reveal this watermark which had previously been obscured.

Jantz 723

I think we feel like 16-year-old kids with newly minted drivers’ licenses who have never driven a car on the highway or out of town. A whole new world has just opened up to us, and we are really excited and a little apprehensive!

What now?

Practice, experiment, document, refine. Over the next 12 (16? 18) months we will work together to hone our collective skills, driving the system, deepening our understanding of the scholarly, conservation, and curatorial use-cases for the technology, optimizing workflow, documenting best practices, getting a firm grip on scale, pace, and cost of what we can do. The team will assemble monthly, practice what we have learned, and lean on each other’s expertise to develop a solid workflow that includes the right expertise at the right time.  We will select a wide variety of materials so that we can develop a feel for how far we can push the system and what we can expect day to day. During all of this practice, workflows, guidelines, policies and expectations will come into sharper focus.

As you can tell from the above, we are going to learn a lot over the coming months.  We plan to share what we learn via regular posts here and elsewhere.  Although we are not prepared yet to offer MSI as a standard library service, we are interested to hear your suggestions for Duke Library collection items that may benefit from MSI imaging.  We have a long queue of items that we would like to shoot, and are excited to add more research questions, use cases, and new opportunities to push our skills forward.   To suggest materials, contact Molly Bragg, Digital Collections Program Manager (molly.bragg at Duke.edu), Joshua Sosin, Associate Professor in Classical Studies & History (jds15 at Duke.edu) or Curator of Collections (andrew.armacost at Duke.edu).