The scanning process and following reconstruction of the scan data produces a 3-d dataset. Essentially, for every point in space in the object we scan, we get a number that can represent a colour. Using some excellent free software â€“ Drishti - we can turn this data into an explorable computer model. This lets us do fun things like fly though a scroll.
Aside from being a fun video, it is a great way to present the possibilities of our work to archivists, conservators and the general public. You canâ€™t read the ink that is between layers in the video, but you can see hints of its existence â€“ this may provide enough clues to identify the item, or to determine how to further process or conserve the object.
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(Wouldn’t have happened if this was recorded on parchment…)
When the BBC heard about our efforts to Reveal the Unreadable they got in contact. They wanted to know if we had anything they could film and use for television.Â At the time we were working on the Bressingham Roll (see past posts) and were about to reveal the hidden text inside the roll.
A film crew came along for the day and the video below is the result.
To get some idea of the internal structure of the Bressingham Roll, it was instructive to generate a fly-though animation. This peels away the scroll, layer by layer showing what is underneath various layers of parchment and how they are stuck together (if they are).
The two videos below show two different “cuts” though the roll. The first is parallel to the long axis of the roll. The second is across the long axis of the roll – equivalent to making slices of a Swiss roll.
In this video, you can make out some writing – in places the ink was clear enough to give a good X-Ray contrast with minimal post-processing needed to make it visible.
You can see some dark marks on the parchment in this video, some of these are ink, others are some other material in the roll that is also showing up strongly in X-Rays. It’s much harder to recognise the writing in this view, because it isn’t presented to you in the usual format you see it.
Soon after the Bressingham Scroll arrived, we performed a quick test CT scan to determine the settings needed so we could image both the parchment and any ink on it.
A single slice of the scan is shown here, the ink shows up as brighter patches on the whirls of the parchment.
The end-on single slice view of Bressingham roll shows both the parchment and evidence of ink very clearly.
This was imaged at 30kV with a 200um Al filter and post-processing with in-house developed beam hardening correction software.
As part of our continuing collaboration with the Norfolk Record Office, weâ€™ve recently taken temporary possession of a parchment roll from a bundle in their archives (Call number PHI468,577X9)
The Bressingham Roll as unrolled as possible. The section to the right of the image is stuck together.
End view of the parchment roll in rolled up-state
The roll is unfit for production in the archives, with the inner portion becoming stuck together.
The ink used in the writing contains both iron and copper, so should have good contrast in X-Ray imaging.
This pleasing endorsement of the project arrived from Dr John Alban at the Norfolk Record Office.
Through my colleagues in the Norfolk Record Officeâ€™s conservation section, I have been following your project with great interest, and we were pleased to provide you with a â€˜non-archival, non contextual off-cutâ€™ on which to experiment. It has been intriguing to see the results of your processes for reading unrolled manuscripts and the way in which they have been improving. The latest example which I have seen has amazing legibility, and I am sure that this process is going to provide archivists and historians with an invaluable means of gaining access to the contents of rolled-up documents which, because of their condition, have hitherto been unreadable.
Dr John Alban
[Posted with kind permission of Dr Alban]
Thanks to the efforts of Meagen Smith at Camberwell, The small scroll of parchment from the Norfolk Archives has been successfully unrolled. We can now compare the X-Ray digital unrolling with the until now hidden text.
Unrolled Norfolk Archives parchment
Digitally extracted text from the XMT scanned parchment scroll
It is clear that the extracted text is from the middle portion of the scroll â€“ the text matches perfectly.