The Lotus Sutra Manuscripts Digitisation Project: the collaborative work between the Heritage Made Digital team and the International Dunhuang Project team

Digitisation has become one of the key tasks for the curatorial roles within the British Library. This is supported by two main pillars: the accessibility of the collection items to everybody around the world and the preservation of unique and sometimes, very fragile, items. Digitisation involves many different teams and workflow stages including retrieval, conservation, curatorial management, copyright assessment, imaging, workflow management, quality control, and the final publication to online platforms.

The Heritage Made Digital (HMD) team works across the Library to assist with digitisation projects. An excellent example of the collaborative nature of the relationship between the HMD and International Dunhuang Project (IDP) teams is the quality control (QC) of the Lotus Sutra Project’s digital files. It is crucial that images meet the quality standards of the digital process. As a Digitisation Officer in HMD, I am in charge of QC for the Lotus Sutra Manuscripts Digitisation Project, which is currently conserving and digitising nearly 800 Chinese Lotus Sutra manuscripts to make them freely available on the IDP website. The manuscripts were acquired by Sir Aurel Stein after they were discovered in a hidden cave in Dunhuang, China in 1900. They are thought to have been sealed there at the beginning of the 11th century. They are now part of the Stein Collection at the British Library and, together with the international partners of the IDP, we are working to make them available digitally.

The majority of the Lotus Sutra manuscripts are scrolls and, after they have been treated by our dedicated Digitisation Conservators, our expert Senior Imaging Technician Isabelle does an outstanding job of imaging the fragile manuscripts. My job is then to prepare the images for publication online. This includes checking that they have the correct technical metadata such as image resolution and colour profile, are an accurate visual representation of the physical object and that the text can be clearly read and interpreted by researchers. After nearly 1000 years in a cave, it would be a shame to make the manuscripts accessible to the public for the first time only to be obscured by a blurry image or a wayward piece of fluff!

With the scrolls measuring up to 13 metres long, most are too long to be imaged in one go. They are instead shot in individual panels, which our Senior Imaging Technicians digitally “stitch” together to form one big image. This gives online viewers a sense of the physical scroll as a whole, in a way that would not be possible in real life for those scrolls that are more than two panels in length unless you have a really big table and a lot of specially trained people to help you roll it out. 

Or.8210/S.1530: individual panels

Or.8210/S.1530: stitched image

This post-processing can create issues, however. Sometimes an error in the stitching process can cause a scroll to appear warped or wonky. In the stitched image for Or.8210/S.6711, the ruled lines across the top of the scroll appeared wavey and misaligned. But when I compared this with the images of the individual panels, I could see that the lines on the scroll itself were straight and unbroken. It is important that the digital images faithfully represent the physical object as far as possible; we don’t want anyone thinking these flaws are in the physical item and writing a research paper about ‘Wonky lines on Buddhist Lotus Sutra scrolls in the British Library’. Therefore, I asked the Senior Imaging Technician to restitch the images together: no more wonky lines. However, we accept that the stitched images cannot be completely accurate digital surrogates, as they are created by the Imaging Technician to represent the item as it would be seen if it were to be unrolled fully.

Or.8210/S.6711: distortion from stitching. The ruled line across the top of the scroll is bowed and misaligned

Similarly, our Senior Imaging Technician applies ‘digital black’ to make the image background a uniform colour. This is to hide any dust or uneven background and ensure the object is clear. If this is accidentally overused, it can make it appear that a chunk has been cut out of the scroll. Luckily this is easy to spot and correct, since we retain the unedited TIFFs and RAW files to work from.

Or.8210/S.3661, panel 8: overuse of digital black when filling in tear in scroll

Sometimes the scrolls are wonky, or dirty or incomplete. They are hundreds of years old, and this is where it can become tricky to work out whether there is an issue with the images or the scroll itself. The stains, tears and dirt shown in the images below are part of the scrolls and their material history. They give clues to how the manuscripts were made, stored, and used. This is all of interest to researchers and we want to make sure to preserve and display these features in the digital versions. The best part of my job is finding interesting things like this. The fourth image below shows a fossilised insect covering the text of the scroll!

Black stains: Or.8210/S.2814, panel 9

Torn and fragmentary panel: Or.8210/S.1669, panel 1

Insect droppings obscuring the text: Or.8210/S.2043, panel 1

Fossilised insect covering text: Or.8210/S.6457, panel 5

Reshoot: Or.8210/S.6501: debris over text / No reshoot: Or.8210/S.4599: debris not covering text.

We want to minimise the handling of the scrolls as much as possible, so we will only reshoot an image if it is absolutely necessary. For example, I would ask a Senior Imaging Technician to reshoot an image if debris is covering the text and makes it unreadable - but only after inspecting the scroll to ensure it can be safely removed and is not stuck to the surface. However, if some debris such as a small piece of fluff, paper or hair, appears on the scroll’s surface but is not obscuring any text, then I would not ask for a reshoot. If it does not affect the readability of the text, or any potential future OCR (Optical Character Recognition) or handwriting analysis, it is not worth the risk of damage that could be caused by extra handling.

These are a few examples of the things to which the HMD Digitisation Officers pay close attention during QC. Only through this careful process, can we ensure that the digital images accurately reflect the physicality of the scrolls and represent their original features. By developing a QC process that applies the best techniques and procedures, working to defined standards and guidelines, we succeed in making these incredible items accessible to the world.

By Francisco Perez-Garcia, Digitisation Officer, Heritage Made Digital: Asian and African Collections. This article was originally posted on Digital Scholarship Blog on 14 March 2022