Images

Collections of Turner’s prints are scattered across the world, in institutions, with private collectors, and in the commercial stocks of dealers. This project would not have been possible without extensive contributions from all these. Digital technology can bring these collections together virtually, so enabling their study across the world. The quality of digital imaging and rendering those images online enables their comparison, line by line, dot by dot. Previous catalogues have rarely recorded the specific impressions being used for comparisons – often just the current owners. Given that Turner insisted on a succession of developing stages of a plate, and the actual order of those stages is usually unknown, and many of the stages have disappeared, it can be difficult to be sure what evidence and thought process previous scholars used.

Over the period of Turner’s work with prints, roughly 1790 to 1851, the techniques of engraving and etching developed enormously, in part due to his pushing the methods and expectations of the engravers. In the C18th, the line engraving techniques were stylised for the high quality prints and crude for the cheaper ones. The engraved lines on a copper plate wear quickly so both types of engraving aimed to extend a plate’s useful life before it needed repair. In general, a resolution of ca 600-900 ppi on a digital image of these earlier impressions can capture the details of an engraver’s line. Mezzotint plates are made by raising fragile points on the copper surface and require a higher resolution imaging, ca 1200 ppi. However through the first half of the C19th, the resolutions achieved by the engravers quickly rose, especially when the harder steel plates were introduced from 1820. Some of the most delicate engraving and mezzotint impressions require imaging around 3000 ppi to capture the detail of the work and its deterioration over time. This is of the same order as the paper fibers on which they are printed, which limited further improvement of resolution of the impressions. Turner seems to have rejected the use of lower resolution printing techniques, such as wood engraving and photographic methods, for his prints.

In order to see the detail in high resolution images, one has to zoom into the image. We have chosen to use iiif technology. During the building of a website image database, this tool imports the captured image file, cuts it into segments that can be retrieved and transmitted separately. The import tool repeats the process after reducing the resolution of the image step by step, at each step constructing a set of segments of the image at lower resolution. The last step aims to fill the user’s screen with a complete, downsized, unsegmented image. When a user requests an image from the website, the browser calls for the segments to be viewed, receives them, reconstructs that area of the image, then renders the required part of the image on the screen. Zooming an image actually tells the browser to call for appropriate segments of a higher resolution. This means that only a screen-full of pixels from the image is downloaded, instead of downloading the complete image file. Some of the largest image files are ca 20GB which would take ages to download and would then be unmanageable on many computers.

Increasingly, institutions are creating images of their prints then making these available online. This site draws heavily upon the excellent coverage of Turner’s prints in Yale Center for British Art and in the Print Room of British Museum, both of whom have made considerable efforts to digitise their collections then make available online at reasonably high resolutions. Comparable images from other institutions with smaller Turner holdings have also been incorporated into this site. The sources of these images (including the accession numbers) are provided with the other metadata for each image. In the majority of cases, the user is directed to the institution’s web page showing the image with its metadata. Although images described by iiif and associated JSON metadata have the potential to enable easy image sharing, the diversity of cataloguing systems and their implementation makes integrating data from different data creators difficult, so has not been attempted (yet).

A significant contribution to this site has been from private collections. Collectors of impressions now in institutions focused on the pre-published and first published states. Impressions now in private collections tend to follow the reuse of Turner’s prints over decades. In general, these impressions have been scanned at higher resolutions than those in institutions. To aid traceability in the future, each impression has been given a unique number, akin to accession numbers in institutions. These impressions were scanned at higher resolution, >1200 up to 2400 ppi depending on the resolution of the original printing. The images were captured on an Epson 12000XL scanner, A3 size. For impressions larger than this, portions of the image were captured as tiles, then stitched together with PTGui, a panoramic image stitching software. Although designed to create panoramas from photographs of landscapes, by adjusting its settings adequate mosaics of the fairly flat paper impressions can be generated. However compromises in the stitching process mean that these mosaics may not be accurate in dimensions, overlaps etc.

Data

Each of the prints has a link to digitised copies of the standard printed catalogues, which is the starting point for further scholarship. A few of Turner's prints had not been identified by those authors and have not acquired as much context.

For an impression viewed on institutional website, its metadata is provided on the institution’s webpage. The declared state of the impression has usually been drawn from the printed catalogues. Where the state appears to need modifying in the light of the other impressions gathered for this site, the proposed state is given on this site’s webpage.

For an impression in a private collection, metadata is provided on this site’s webpage. Physical data is measured from the impression. Many impressions have markings indicating previous owners, state etc. These are interpreted then the state reassessed as appropriate.

Contemporary references to Turner’s prints and publications have been searched for in the burgeoning online databases of C19th journals. These resources have been only cursorily scratched, with citations given to relevant articles, adverts etc. Some of these journals are on open access through the HathiTrust, Google etc services. The majority of the digitised images are subject to licensing restrictions. For instance, Google Books has created a wealth of images of journals and books. However, it is not allowed to copy and show these images on a web page. Similarly, many historic UK newspapers online are behind paywalls – and from photographs of poor quality. These typically require access through a university or similar library account and are subject to considerable restrictions. These restricted images have been transcribed with some assistance of (improving) Optical Character Recognition packages. Links to these images are given where relevant.