Die “Virtual Library Eduard Imhof” – Digitalisierung und Präsentation von kartographischen Bilddokumenten

Summary

This article documents the conception, implementation, and scholarly significance of the Virtual Library Eduard Imhof, an online collection developed by the ETH Zurich Library to preserve and disseminate the legacy of Eduard Imhof (1895–1986), a leading twentieth-century cartographer, artist, ETH professor, and founding president of the International Cartographic Association. Initiated in conjunction with a 1997 exhibition, the project sought to create security and access copies of valuable originals, provide a bilingual thematic web resource, and establish a basis for future educational CD-ROM products. More than 200 maps, panoramas, bird’s-eye views, atlas drafts, drawings, watercolors, and relief-related documents were organized into twelve biographical and thematic chapters. These cover Imhof’s education, Alpine panoramas, school maps and atlases, the 1930 Minya Konka expedition, three-dimensional mountain models, the Atlas of Switzerland, artistic works, and comprehensive biographical and bibliographical records. The workflow combined professional photography, archival microfilming, digitization, image processing, cataloging, and HTML-based presentation. The originals were recorded twice on Ilfochrome Micrographic film, expected to remain stable for 200–300 years, and digitized at approximately 700 dpi for high-quality reproduction and 75 dpi for web delivery. Adobe Photoshop was used for rotation, cropping, separation of captions, and global corrections to color balance, brightness, and contrast. Web pages were assembled in HotMetal, with small thematic images linked to larger versions to reduce loading time. The project demonstrates that digitization from microfilm is economical, protects fragile and oversized originals, and circumvents large-format scanning difficulties. However, color correction emerged as the principal challenge because aged paper, film intermediaries, image reduction, and users’ display equipment alter visual perception; direct scanning generally provides greater color fidelity when the format and condition of an item permit it. The authors therefore recommend archival film for long-term security, differentiated resolutions for preservation and online access, JPEG derivatives for web use, and two-tier image presentation. Scholarly value was strengthened through contextual introductions, searchable bibliographies, repository shelf marks, and links to holding institutions. The Virtual Library combines a digital exhibition with preservation, research, and teaching resources. It also offers a transferable workflow for libraries digitizing historically significant cartographic image collections, while emphasizing that technical decisions must balance conservation, cost, fidelity, accessibility, and intellectual organization.