Authored by Jack Reese from Ancestry
In 2005 we finished scanning the UK Census collection from the microfilm reels that were available at the time and discovered that the writing on many of the images was very faint and unreadable in many cases. Certified genealogist and then-head of Ancestry’s Indexing department, noted that as many as 730,000 names from 1841 and 1851 had been categorized as missing, damaged, or of poor quality. While some of the original pages were known to be unavailable, it was believed that hundreds of thousands of these missing names could be recovered by imaging directly from original content rather than from microfilm. Knowing that these damaged records would only continue to deteriorate, we were determined to rescue and preserve images of these documents before the pages deteriorated completely.
In September 2005, we went to The National Archives in Kew to inspect the damaged 1841 and 1851 census pages first hand and found that using high-res, powerful digital cameras with low-light photography techniques combined with a range of specifications, we were able to reveal hints of the faded writing on the pages (Figure 1).
However, it quickly became apparent that the project was going to be more difficult than we had anticipated. The image processing technique we were using to make the script readable once again, required a certain amount of time per image and the “enhanced” writing was still so faint that reading or transcribing would have been too difficult and inaccurate.
Fortunately, we had already set in motion plans to deal with more difficult content that may require analysis of the effects of imaging with different wavelengths – also known as ‘spectral analysis’. After a couple of days of limited success using the traditional image processing techniques, we proceeded with our spectral analysis. For those of you who may be unfamiliar with the term, HDR is the process of taking overexposed and underexposed images and combining them to get a resulting image that reveals more detail throughout the image – especially in dark and bright regions of the image.
Using the best forensic document analysis equipment available, we analyzed foreground (ink) and background (paper) regions of numerous sample pages. Within the first few minutes of analysis the writing began to emerge (Figures 2-3).
Encouraged by the initial results, we proceeded to complete the spectral analysis testing hundreds of combinations of light sources and light source filtering combined with filtering of the wavelengths reflected and sometimes fluorescing from the document. The term ‘fluorescing’ refers to the emission of electromagnetic radiation.
With data captured from dozens of sample documents from the collection we identified the most effective configurations for revealing the information on the pages within the collection. Given that many census enumerators were using different writing instruments, a variety of ultra-violet (UV) and infrared (IR) imaging techniques proved effective (Figure 4).
After completing our analysis it was clear that no commercially available system was going to meet the resolution, spectral sensitivity, lighting, filtering, size, and speed requirements necessary to enable us to digitize these damaged documents. Determined to capture and preserve what information remained on these documents, we set out to build a bespoke camera – our very own DaRC (Document Restoration Camera) system (Figure 5) specially designed to safely and efficiently capture images revealing previously hidden information on these damaged documents.
To read more about the restoration work carried out on these records and to start searching them, go to www.ancestry.co.uk/Manchester.
Jack Reese is a Digital Imaging expert in Preservation and spearheaded the restoration of the damaged 1851 Census records.
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