Tag Archives: Multispectral Imaging

Techniques for recovering lost texts

Research Fellow Renate Smithuis and Research Associate Stefania Silvestri, are working on a Catalogue of Codices, Scrolls, and Other Texts in Hebrew Script in The University of Manchester Library.

The Library holds one of the most important smaller collections of Hebrew manuscripts in Europe and this project will create a full, online catalogue compliant with current cataloguing and metadata standards. To support the production of the catalogue, digitisation of a number of manuscripts is being undertaken. All images, included fully digitised volumes, are added to the Hebraica Collection in the John Rylands Library Image Collections, LUNA.

A substantial portion of the Rylands Gaster manuscript collection have already been selected for digitisation, including a number of manuscripts that suffered water damage during the Second World War. The level of water damage varies, some texts are still legible but faint, others have whole sections of pages rendered illegible.

The Heritage Imaging Team have been investigating the best way to recover the text in these volumes, unsurprisingly, we have found that a single solution does not fit all. The aim of this blog post is to demonstrate the different processing options available to researchers. We are researcher-led in the work that we do with Multispectral Imaging of our collections, so if you come across a text you cannot read, please get in touch to discuss your needs in more detail (email: uml.chicc@manchester.ac.uk).

I should note at this point that these examples are not exhaustive and we are always in the process of developing new techniques.

Trials in image processing have been run on pages from Gaster Hebrew MS 1832. The first step of carrying out any specialist techniques is to produce a high resolution ‘standard’ light photographs. These are the images that you can access in high resolution in our online image collections. Often, close inspection at high resolution enables a reader to decipher more than they can read with the ‘naked eye’.

In this example, the first image shows page 1 recto of Gaster Hebrew MS 1832 in ‘standard’ light. You are able to see that there is some faded text on the page but it is extremely faded in some areas:

Gaster Hebrew MS 1832

Gaster Hebrew MS 1832 1 recto standard image

The second image shows a standard high resolution image which has undergone additional image processing in Photoshop. The image has been inverted to help the text show through in certain areas of the page.

Gaster Hebrew MS 1832

Gaster Hebrew MS 1832 1 recto standard image with processing

The third image shows page 1 recto again, a standard high resolution image which has undergone processing in Photoshop to bring out the most faded central areas of the text.

Gaster Hebrew MS 1832

Gaster Hebrew MS 1832 1 recto standard image with additional processing

Here is a detail from each file type for comparison:

The benefit of this approach is that these results can be achieved without any additional imaging of the manuscript and standard photo manipulation software can be used. In addition, once results have been achieved, these can be batch applied to a set of images for an entire manuscript. The results may not be 100% consistent depending upon the range of damage to each page, but if the results are ‘good enough’ it will save many hours of image processing time.

 

Our next example shows firstly, page 2 recto of Gaster Hebrew MS 1832 in ‘standard’ light, plus an example of the same image which has been processed in Photoshop:

However, with this example we took several further steps to recover the lost text. In this instance, the manuscript has also been imaged using Multispectral Imaging. We now use a Phase One Achromatic IQ260 digital back, iXr camera body and standard lens combined with Megavision LED lighting panels and a filter wheel to capture 17 images at different points along the electromagnetic spectrum. I have included 2 images here, take at 370nm (UV) with a long pass violet filter, and at 448nm (Deep blue) as these single images give the best results. In the infrared wavelength, the text on this manuscript disappeared completely, which suggests that it is an iron gall based ink.

 

Using multispectral imaging we are able to take our image processing and textual recovery even further. Using ImageJ software I have combined several of the individual wavelengths to create a ‘pseudocolour’ image. This applies false colours to areas of difference across the page. Note the two images below in colour.

The colour results are not attractive to every eye, especially to the colour blind so can be converted in to greyscale. In the examples here, I have added an additional filter using the Channel Mixer in Photoshop to increase the contrast of the text even further.

Here you can see details of all 8 examples described above, click on the image to flick through each detail.

There are obvious benefits of taking every possible step of image processing to recover as much text as possible. However, there are also drawbacks. The manuscript must be subjected to a second round of digitisation using the Multispectral Imaging system, this is not only time consuming, but for fragile items it also increases the possible risk of damage to the physical item. There is additional time required for the photographer to process the images and store the additional data. Metadata must be produced to accompany the new images and to detail the processing work that has been carried out on the images.

Finally depending upon the nature of the damage to the page, a reader may need to consult a combination of 2 or 3 final processed images in order to read the entire page. Additionally, there must be a flow of communication between the reader/researcher and the person processing the images in order to process the ‘best’ results.

Specialists are currently working on software solutions to allow us to present the data to readers which will allow the reader themselves to combine and ‘play’ with images to suit their needs. We will report on developments in this area when they are available. Until then, we will continue to take a ‘triage’ approach to image recovery, assessing each item against the needs of the researcher to take the right steps to uncover lost texts.

 

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Revealing Galen’s Simples at UPenn… and a whole lot more

Processed image of the Syriac Galen Palimpsest at Revealing Galens Simples Workshop, Kislak Centre for Special Collections, UPenn

Processed image of the Syriac Galen Palimpsest at Revealing Galens Simples Workshop, Kislak Centre for Special Collections, UPenn

 

An article published in the New York Times on June 1, 2015, described the discovery of a Syriac manuscript that contained the oldest known translation of Galen’s On the Mixtures and Powers of Simple Drugs. Nearly a year later, scholars, scientists and imaging specialists came together for ‘Revealing Galen’s Simples‘ a workshop and symposium hosted by the Kislak Centre for Special Collections, Rare Books and Manuscripts at the University of Pennsylvania. On Wednesday 27th April CHICC’s Carol (Heritage Imaging Manager) Tony and Gwen (Heritage Photographers) travelled to Philadelphia to take part in the event. Here is a brief overview of our time at the conference, and associated meetings, which were truly inspiring and have changed the way we think about the way we work.

Philadelphia on the horizon

Philadelphia on the horizon

We arrived at UPenn on Thursday morning and began our day of meetings with a tour of the SCETI (Schoenberg Center for Electronic Text and Images) digitisation suite. We met with Mick Overgard and his colleagues and discussed all things digitisation, including some skills swap sessions, they demonstrated the new Capture One Cultural Heritage software capabilities – (a vast improvement on the trial we had tested last year – thanks for the demo Andrea!) and we shared our multi-spectral imaging developments and techniques for imaging gold. A really fruitful discussion around advanced imaging techniques followed and we hope that SCETI might join AHFAP so that we can keep the conversation going. In fact we had so much to say that we had to come back after our next meeting to carry on our conversations!

The team at SCETI are very impressive, highly skilled and very friendly – we couldn’t believe that we came all the way to Philadelphia and bumped into a Liverpudlian though (hi Craig!). We were very jealous of the space the team have to work in, each photographer has their own ‘pod’ and they have given us lots of ideas about how to maximise space in our modest studio. I was also particularly impressed with the presence of a record player and a huge stack of vinyl, great idea!

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Following our meeting with SCETI we met with Dot Porter, Curator of Digital Research Services, and Mitch Fraas, Curator of Special Collections, to discuss digital collections, access, discoverability and engagement. Dot told us about different aspects of her engagement work including a workshop she recently delivered to students at Yale on how to access and download digital content and told us more about her video orientations for manuscripts (watch this space!).

We then met with data geniuses Doug Emery and Jessie Dummer to learn about OPENN, a revolutionary way of delivering Open Access image data. The data is presented in a simple structure that enables you to download an entire manuscript in high resolution, very easily using wget. All of the data on the site is in the public domain or released under Creative Commons licences as Free Cultural Works. This repository is now the home of the Archimedes Palimpsest and the Syriac Galen Palimpsest. The data is presented with long term storage and accessibility in mind, and all data is in a digital preservation format. The interface is not inspiring, but is designed so that anyone can use the data to build their own front-end. As more institutions begin to deliver their data in this way, the opportunities for digital curation are endless.

This meeting was followed by a sit down with Mike Toth, Project Manager for both the Archimedes and Syriac Galen Palimpsest Projects and Will Noel, Director, Kislak Center for Special Collections, Rare Books and Manuscripts and Schoenberg Institute for Manuscript Studies. Following a very quick ‘get to know each other’ we began to discuss potential collaborative projects and very quickly came up with some very viable ideas. We are now, already, in the process of putting pilots for these projects in place. We will announce developments here.

These very inspiring meetings were rounded off with some refreshments at Monk’s Cafe – the home of so many beers, they have their own bible! (From left to right, Doug Emery, Meghan Hill, Bill Christen-Barry, Mike Toth, Gwen Riley Jones, Carol Burrows. Photo by Tony Richards)

After a very fruitful day of meetings, some refreshment was required!

After a very fruitful day of meetings, some refreshment was required!

Day two began with an exclusive look at the Syriac Galen Manuscript itself, with an introduction from Abigail Quandt, Head of Book and Paper Conservation at the Walters Art Museum and lead conservator on the Archimedes and the Syriac Galen Palimpsest Projects. Abigail explained both the processes for dis-binding (so flat pages of the manuscript could be imaged using multispectral imaging) and rebinding the palimpsest for this project, but also how the palimpsest was made in the first place. The pages of Galen’s text were soaked in some kind of acid, milk or lemon juice maybe, to remove the text – rather than the alternative process of scraping off the old text. After being soaked in acid, the pages were coated with a white chalky substance, which is still visible in some places, before the over-text was written. These techniques have a significant effect of the chemical make up of the manuscript, and therefore how it performs under light during multi-spectral imaging.

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Revealing Galen Simples Workshop Group Photo

Revealing Galen Simples Workshop Group Photo

This fascinating introduction was followed by a series of informal presentations and discussions amongst the scientists and the scholars, before the groups split off to do more detailed work in the afternoon. The scholars had the opportunity to work collaboratively, deciphering the text, whilst the imaging scientists compared techniques for image processing. It was very interesting to compare the benefits of different techniques (there is not one techniques which is ‘best’) and also think about what is ‘good enough’ – a question you can only really answer when imaging scientists and scholars are able to work closely together. Open Access data and spaces for cross-discipline scholarship, such as the John Rylands Research Institute, are the key to enable these types of research partnerships.

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During the afternoon workshop sessions, the CHICC team took the opportunity to take a ‘break-out’ session with Meghan [Hill] Wilson, Multi-spectral Imaging Preservation Specialist, Library of Congress. Meghan has trained in advanced camera and spectral imaging system operation, imaging processing software, database management, metadata creation, digital data storage, and object cataloging. As we are finalising our multi-spectral imaging strategy and workflows, Meghan’s advice and expertise was invaluable. We were very interested in the wide-range of applications of multi-spectral imaging, beyond only palimpsests. We invited Meghan to come to Manchester to deliver advance workflow and data management training for our multi-spectral imaging work, to deliver a seminar to share with curators, conservators and researchers the varied uses of multi-spectral imaging, and to collaborate on some of her own research work in to identifying pigments. I am very pleased to say that we have now secured funding for Meghan’s visit and we look forward to welcoming her to Manchester this summer.

On Saturday was the symposium itself, you can view the list of speakers here. The talks included 3 cross-discipline speakers from the University of Manchester, Peter Pormann, Director of the John Rylands Research Institute and Professor of Classics and Graeco-Arabic Studies on The Final Frontier: Galen’s Syriac Versions and Graeco-Arabic Translation Technique, Dr. Bill Sellers, Faculty of Life Sciences on Working with the Data and Dr Corneliu Arsene, Faculty of Humanities on his new techniques for Revealing the Palimpsest. In addition to the Manchester speakers, we heard from a range of historians, scholars, scientists, conservators and data managers in a truly cross-discipline discussion on the subject. There was also another chance to view the manuscript, in the somewhat more historic setting of the Henry Charles Lea Library.

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In amongst all this work we did get a little time to see some sights, starting with the Liberty Bell (see photographers at work), but somehow the work always seemed to carry on in the bar…! We also came across a statue of ‘Barry’ – who it turns out is a distant relative of our colleague Bill Christens-Barry, picked up some fashion tips for Jamie – who was back at the ranch. Met Millie Emery, Doug Emery’s very gorgeous bulldog! And finally ran up the Rocky steps (well one of us did) in a not so sunny Philadelphia! We had an absolutely fantastic trip, it was so valuable to be able to attend this conference first hand and be involved in conversations with the full team of people that have pioneered these important techniques. We have returned to the UK fired up and ready to develop our work on to the next stage. So a big thanks to the John Rylands Research Institute and Professor Peter Pormann’s AHRC funded project ‘The Syriac Galen Palimpsest: Galen’s On Simple Drugs and the Recovery of Lost Texts through Sophisticated Imaging Techniques’, to all at UPenn, and everyone involved in the symposium. And a special thanks to Mike Toth for his continued excellent work in bringing all of these people together.

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