The Kupferstichkabinett Digitisation Project

The Kupferstichkabinett – the Hamburger Kunsthalle’s Department of Prints and Drawings – has one of most important collections of works on paper in Europe, with vast holdings comprising more than 130,000 drawings, prints and photographs. The collection is notable above all for the outstanding quality of its holdings, but also for the depth and variety of these works, which make it possible to trace the history of drawing and printmaking in Europe from the 15th century through to the present day. Among the strengths of the collection are old master drawings of the Italian, Dutch and German schools. The group of drawings by Spanish old masters is particularly strong, making it one of the top three collections of its kind outside Spain, along with those of the Louvre and the Uffizi. Among the other first-rate holdings in the Kupferstichkabinett is a rich collection of Italian, German and Dutch prints and exceptional graphic works by artists such as Albrecht Dürer, Rembrandt, Giovanni Battista Piranesi and Francisco de Goya. The department also has a sizeable collection of German Romantic drawings, with fine examples by artists such as Caspar David Friedrich and Philipp Otto Runge. Along with French 19th-century prints, the Kupferstichkabinett (Department of Prints & Drawings) has strong holdings of Edvard Munch, Käthe Kollwitz and German Expressionism. The Kunsthalle also houses a number of special collections, including 19th-century art from Hamburg and a selection of important works by Horst Janssen, as well as numerous print portfolios and graphic series.

Up to now, anyone who wanted to find out more about individual artworks in our extensive collection – such as the exceptional drawings by Dürer, Rembrandt or Leonardo da Vinci – could consult existing inventory catalogues and publications from past exhibitions. Unfortunately, however, only a limited number of works have been included in the catalogues published to date, so that the information available was not very extensive.

This situation is about to change. In July 2012 we began the lengthy process of digitising all the prints and drawings that are held in the Kupferstichkabinett and the adjoining library. Our ambitious undertaking is supported by the Hamburg Senate, which has made the digital capture of the entire holdings of Hamburg’s state museums a key element of its cultural policy and has provided substantial funding to this end. The digitisation project has also received considerable support from other institutions such as the Hermann Reemtsma Stiftung and the sponsoring association »Die Meisterzeichnung. Freunde des Hamburger Kupferstichkabinetts e.V.«

From now on, the results of the project will be presented on this website and will be continually updated. The first works to be made available are the museum’s entire holdings of German, Dutch and Italian drawings. The scholarly evaluation and digital capture of these works was carried out between 2001 and 2011 and would not have been possible without the generous support of the ZEIT-Stiftung Ebelin und Gerd Bucerius. A large portion of the Italian prints held in the Kupferstichkabinett and the library will now be digitised with considerable support from the Hermann Reemtsma Stiftung, which has approved two funding measures for the indexing and digitisation of prints in bound volumes. For the latter procedure, a specially adapted book cradle has been developed and acquired with funds from the association »Die Meisterzeichnung«.

As of December 2018, more than 30,000 artworks are accessible in our online database. An important first step has therefore been made towards digitising the entire holdings of the Kupferstichkabinett and the Kunsthalle library, which we aim to have completed by 2021.

Scholarly Framework of the Digitisation Project

From the very beginning of the project we were aware that priorities had to be set, taking into account the limited time and financial resources available. This aspect is key to an understanding of the potential scope as well as the limitations of our online database. The main objective of the digitisation project is to provide accurate records and high-quality digital images of the objects in our collections. On principle, the digital copies of these drawings and prints are made from the original artwork. We also aim to provide full-text transcription. A more detailed technical analysis of the materials and papers used can only be conducted in individual cases, for example in the context of preparing an exhibition. This also applies to the recording of watermarks, which will be more extensively researched at a later date.

Given the vast resources that are now available on the internet, we have chosen to provide only brief biographical information on the artists/makers. The same applies to any persons depicted. More detailed information has, however, been provided in cases where the artist/maker of the artwork is less well known or where resources are scarce. Bibliographic references are currently limited to the relevant catalogues raisonnés. Secondary literature is only included if it contains a specific reference to the work in the collection of the Hamburger Kunsthalle.

The digitisation project places particular emphasis on provenance research. To this end we not only use the extensive source materials in the archive of the Hamburger Kunsthalle but also consult external archives, including those of the art trade. Provenance research is a lengthy and complex process, and it is to be expected that further archival studies will produce useful new findings.

The close cooperation between the Kupferstichkabinett (Department of Prints & Drawings) and the adjoining library is a unique feature in a German museum of this size and enables us to process very extensive groups of artworks by many artists.

Despite our best intentions, time constraints and the limitations of our own scholarly research and knowledge mean there is always a possibility that the information we provide contains mistakes and omissions. We are therefore very grateful for any corrections, comments or suggestions you may have – please send these by e-mail to kk-digital@hamburger-kunsthalle.de.

In order to offer both professionals and non-professionals the best possible user experience, we provide digital copies up to a maximum image size of 1,250 x 1,250 pixels. These are highly suitable for non-commercial use (also for PowerPoint presentations). For any form of commercial use we ask you to contact the Bildarchiv Preußischer Kulturbesitz (bpk Berlin –click on the link next to the object), where you can also order higher resolution image files. The original drawings and prints held in the Kupferstichkabinett or Hamburger Kunsthalle collections can of course also be viewed by appointment. For further information please visit http://www.hamburger-kunsthalle.de/kupferstichkabinett.

Technical Aspects of the Digital Image Production

Camera and book cradle

Since 2003, all photographs of objects in the Kupferstichkabinett collections have been taken with a digital camera. A high-resolution Sinar P3 view camera with a Sinarback 54 FO is used for this purpose. This camera back generates moiré-free images with a maximum size of 5,440 x 4,080 pixels, which corresponds to a file size of approx. 64 MB at 8-bit depth. In general, all images are captured at 16-bit depth, but are only processed and archived as 16-bit files if this is specifically required. The camera is connected by fibreglass cable to a Mac G5 computer. If necessary, microscanning can be used to increase the resolution of the camera to 256/512 MB at 8 or 16 bits. The images are stored as TIFF files.

The camera is mounted on a Homrich reproduction stand, which was built in 1983, and can be moved electronically. Other settings such as focussing, optical correction and aperture are adjusted manually. High-frequency, flicker-free fluorescent tubes are used as reproduction lighting; these emit low levels of UV-A and UV-B radiation and generate relatively little heat. The colour rendering index (CRI) of the lamps is 90+. Colour management is based on a 240-colour Gretag chart in the L-star colour space. The white balance is individually adjusted for each new situation/image size.

To enhance the system described above, which has been in use since 2003, the engineer and book conservator Manfred Mayer from Graz constructed a specially adapted book cradle in 2013. Mayer also developed the Conservation Copy Stand that is used in many libraries. The book cradle was designed for large book formats up to 70 x 100 cm. The aim was to create high-quality reproductions of whole pages of books – not just of the printed image or text – but also to protect the books or bound volumes from damage. To avoid the time-consuming process of focussing the camera and the associated minor but continual changes in scale, a laser unit was installed. This means that the camera only needs to be moved and adjusted once for each book. The laser unit is connected to the computer and also triggers the shutter release, with the result that books can now be digitised at a much faster speed.

Scanner

In summer 2012 a Cruse scanner was purchased for the digitisation project. The selected model features a platform that moves beneath the scanner; the maximum sheet size is 80 x 100 cm. The lighting unit uses bulbs that are technically identical to those in the book cradle. The scanner offers excellent colour management based on the Cruse 800-colour chart in the ECI colour spectrum. Each scan line has 10,000 pixels. In the corresponding format and aspect ratio, the theoretical maximum file size is 700 MB at 8-bit depth. Most images are filed and archived as uncompressed TIFF files between 100 and 350 MB. The scanner is very easy to operate in standard mode, which makes it suitable for team use. The scanning process takes between three and five minutes per object, depending on the size of the original and the required resolution. The maximum scan resolution is 600 dpi in relation to the size of the scanned object. The scanner is installed in a separate, darkened room with two computer workstations and additional work tables.

Data storage and image processing

The unprocessed scanned files are stored directly on a server. Only digital copies are used and processed for display in the database or for publishing purposes. These data are also filed and stored in separate directories. Two identical workstations with calibrated monitors are available for image processing; one of these is mainly used with the scanner. Scanning, photographic capture and image processing are carried out by trained members of the digitisation project team.

How to Use the Online Database

Entering a search term in the Search Box on the home page allows you to conduct a free text search of all the fields used in the categorisation of the objects, including inscriptions, texts, media, materials, dates, bibliographies and provenance records. To conduct a more targeted search, click on Advanced Search and use the search form to optimise the search results. After entering or selecting terms in the individual fields, click on the Search button to the right below the search form. The Artist field contains an index of names as a drop-down list. Entering the first letter of the surname brings up the corresponding section of the index. In this field you will find the names of the artists/makers and any other people who were actively involved in the production of artworks, including engravers, draughtsmen and women, painters, sculptors, architects, printers and publishers. In the Title field you can search for an object by entering its title or name. The Date field refers to the date when the artwork was created. This can be a specific year (e.g. 1582) or a date range (e.g. 1570–1615, 18th century, probably second half 18th century). In the Genre field, select the relevant term from the drop-down menu. The Medium field covers various aspects of artistic technique, e.g. engraving, etching, drawing, lithograph, red chalk, charcoal, pen and ink, brown, black, grey, coloured. Use the Provenance field to search for previous owners of a work or find information on where it was acquired, e.g. the name of a gallery or art dealer. In the description of an artwork, its provenance is shown in a clickable index card below the basic outline. Provenance research is a complex process; for this reason, the information provided here will be modified and updated as required. You can also search for specific terms in the biographical references to an artwork (Bibliography). For the most targeted search of our online database, enter the accession number of the work in the field Acc. No. The accession numbers of works in the library always start with »kb-«. In the description of these works, the shelf mark – indicating the location of the particular publication in the library – is added in brackets. The drop-down menu in the Collections field lists all the current subsections in the database of the Kupferstichkabinett at the Hamburger Kunsthalle. Use the Keywords field to search for particular themes or subject matter. Clicking on this field opens up a menu with a variety of themes and allows you to perform a free text search of the entire database.