Tag Archives: spectral

Spectral Imaging testing at The National Library of Scotland

Combe MS 7382 page 6 in visible light (left) and in UV light (right)

Combe MS 7382 page 6 in visible light (left) and at 365nm UV light with image inverted (right)

On 2nd July the CHICC photographers travelled to Edinburgh for some Multispectral Imaging testing on some George Combe letterbooks at the National Library of Scotland. Francine Millard of the NLS writes:

George Combe (1788-1858) was an Edinburgh lawyer who was among the first converts to phrenology. This was a science which believed that people’s characters could be read from the bumps in their skulls.

The National Library of Scotland holds a remarkable collection of George Combe’s papers from 1804 to 1872. The collection begins with his apprenticeship as a clerk to Writers to the Signet and charts his promotion of phrenology which included co-founding the Edinburgh Phrenological Society in 1820 and the works Elements of Phrenology (1824) and The Constitution of Man (1828). Combe’s outgoing and incoming correspondence document his efforts to spread the causes of phrenology, secular education, and criminal and prison reform.

 

Combe’s letterbooks contain a large proportion of his replies to his brother, Andrew Combe, who was also a fervent supporter of phrenology, and to those seeking his help and advice both in Britain and America. Combe’s replies were copied by wet letter press copying (or wet-transfer) and some pages in these books have now faded to the point of invisibility.

 

The National Library of Scotland teamed up with CHICC in July to see if multi-spectral imaging would be able to render Combe’s words visible. These tests would inform the Library on what approach to take to preserve the Combe papers through digitisation.

To find out more, watch this short film of the work in action:

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Spectral Imaging @CHICC

CLICK for animated gif showing the sequence of the light panels across the spectrum. from UV, through visible to infrared.

Recently at CHICC we have finally begun our tests with our new MegaVision spectral lighting panels. Micheal Toth who has worked on the spectral imaging of the Archimedes palimpsest and other cultural imaging projects joined us for a 2 day workshop. Michael also gave a great presentation to staff about his recent work on the Galen Palimpsest digitisation project, and the importance of creating an online repository for the data. Michael has also been working on an incredible spectral project within St Catherine’s Monastery in the Sinai desert, a wonderful in depth article can be found here.

The light panels work through the electromagnetic spectrum, emitting light from 12 different wavelengths, starting off in UV and working through visible into infrared. We removed the IR filter from our Phase One P45+ back to be able to pick up the invisible light. By photographing objects under this lighting system, we are able to see what is essentially hidden, either text under text, water marks, text on pasted down pages and text obscured by damage.

The 12 wavelengths captured; 365nm UV, 455nm Royal Blue, 470nm, Long Blue, 505nm Cyan,535nm Green, 570nm Amber, 625nm Red700nm IR,735nm IR, 780nm IR, 870nm IR, 940nm IR. This is a Coptic palimpsest fragment, which also has burn damage. Even without processing with ImageJ, we are getting visible results.

The 12 images captured  are then processed through open source software ImageJ. This is the more difficult part of the process. The software is incredibly powerful, but it takes time to process the images and create results. We are currently working with image scientist Bill Christens-Barry in the US who will guide us through imageJ, and work on the images we have collected so far.

We tested the system on a variety of different objects from our collections, to test how the lights can help us with different problems. The famous St. Christopher woodcut, to try and bring out the watermark on the pasted down page. The above Coptic Palimpsest fragment, inscriptions in the Gutenberg Bible that have faded, and most effective without processing, carbonised Greek papyrus fragments, that are barely legible, completely when photographed under normal conditions. The below image shows the difference between normal and infrared. Even without processing the images through ImageJ, you can see the text is now clear.

Carbonised Greek Fragment 222 folio 2.

We will be sending our captured images over to Bill who will guide us through the processing. We will have some more conclusive results soon.

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