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DNA and Social Responsibility: Not another conference: A letter from Sir Nevill M...: While trawling through the papers relating to political activism it is difficult it is difficult to keep track of the myriad political gro...

Digitising X-rays: the digitisation of the Biophysics collection

In this week’s post, I discuss some of the digitisation aspects of the project with special reference to the work of one of our digitisation contractors, MAX (previously MAX COMMUNCATIONS,) who digitised 4,000 of the glass and acetate material.

In October 2011, two of the digitisers from Max Ltd visited the archives in order to familiarise themselves with the collection and carry out some test scanning. The material was quite diverse: photographic prints, x-ray acetates, various sizes of glass plate negatives, folded negative rolls and 35mm mounted slides. The majority of this material required external specialists with the required expertise and equipment to undertake the scanning. A small test file was created composed of quarter plate glass negatives and x-ray acetates and sent to the Wellcome for approval. Both Iain Stringer, who would go on to digitise the collection, and David Cordery, head of Max Ltd, have prior professional experience of working with glass plate and acetate x-ray collections at various institutions  around the UK and we were fully confident of their ability to handle the fragile items and successfully scan them. The test images that were sent to the Wellcome were approved and scanning commenced in December 2011.

 The images were scanned at 300 dpi (dots per inch) at 8-bit (bit rate) RGB (Red Green Blue) using an Epsom V750 Pro scanner. This type of flatbed scanner is reliable and fast and from a preservation perspective, the scanner was suitable for digitising the x-ray acetates as the two- inch gap between the bed of the scanner and the top scanner head meant that it did not press onto the x-rays and so would not cause any further damage to the x-rays afflicted with vinegar syndrome (vinegar syndrome occurs when an acetate degrades and begins to oxidise creating a vinegar smell. The surface often begins to warp and crack and this eventually affects the emulsion. Unfortunately the process is irreversible and it is why digitisation is one of the most effective ways of preserving an accessible copy of the item.)

An example of an X-ray acetate diffraction image from the collection.  The  sleeve caption information has been added to the image. This diffraction image was taken by Wilkins around 1953-1955 and the likely source of the DNA originated from human subjects supplied by Leonard Hamilton and Ralph Barclay of the Sloan Kettering Cancer Center in New York.

I asked Iain to tell me about his experience scanning our material compared to his previous experience with similar collections. He said that the plates, in terms of general condition, were some of the best that he has worked with as hardly any were chipped or broken. The only slight issue that he encountered was that some of the slides were mounted with red strips, the adhesive of which had begun to seep and caused them to attach themselves to their transparent sleeves. In such cases, he therefore had to carefully remove the slide from its sleeve. This required a degree of perseverance, depending on the age and location of the adhesive strips on the slide.  

Regarding the x-ray acetates, I had assumed that this material would be trickier to scan considering the conditions that some of them were in. Iain surprised me by saying that for the purposes of scanning they were quicker to scan than the glass plates. Whilst care had to be taken in handling small, fragile and brittle objects like deteriorating x-ray acetates, the most time consuming element of scanning an x-ray was the post-production.

MAX Ltd provided us with images in three formats:  the raw TIFF original file, the enhanced TIFF amended file and a JPEG file. While enhancing an image can be difficult with regard to obtaining an authentic copy of the original, in a situation where the original is difficult to discern, post-production ‘clean up’ is necessary. The majority of the x-ray acetates retained a degree of visible content and by using Adobe Photoshop post production, it made it easier to enhance the original pattern of the x-ray and compensate for some of the surface damage caused by any deterioration.

Finally, I asked Iain what he thought of the acetate and glass material as a whole. He said:

“ I found the material quite interesting…I’ve learnt more about DNA than I have since school,, good thing about my job that I don’t have to concentrate on one specific thing. X-rays of DNA, diffraction, very interesting. They would definitely make a good print, stretched over a canvas, especially one of the really clear ones like ‘Photo 51’”

I agreed, diffraction patterns such as ‘Photo 51’ are visually striking though I personally am more in awe about the crystalline A-form DNA pictures as there is something rather mesmerising about the symmetry of these patterns. You can judge for yourself however, as these two x-ray patterns are shown below.

A-form DNA

B-form DNA