always be preserved, even if they have been digitized. Born-digital photographs also require preservation, using digital preservation techniques. Safeguarding European Photographic Images for Access (SEPIA) lists ten principles for digitization of historical photograph. Summarized, they are: Photographs are an essential part of our cultural heritage, which contain our past, documentary and artistic value and the history of photographic processes; Digitizing photographs that deteriorate quickly is urgent matter to facilitate access for a large audience; Since digitization is not an end itself but a tool, selection of photographs to digitize should be based on an understanding of the nature and potential use of the collection; It's essential to define the aims, priorities, technical requirements, procedures and future use for investments; The creation of a digital image is a sophisticated activity which requires photographic expertise with ethical judgment; Digital images need regular maintenance in order to keep pace with changing technologies; A good digitization project requires teamwork, combining expertise on imaging, collection management, IT, conservation, descriptive methods and preservation strategies; The input of specialists in every project is essential to integrate preservation measures in the work-flow, handle fragile materials and avoid damage to the originals; Preservation specialists need to manage of digital assets in line with the overall preservation policy of the organization; and Museums, archives and libraries actively involve to develop international standards for the preservation of digital collections in the long-term view. Examples An example of digitization as part of a photograph preservation strategy is the photographic collection of the Tay Bridge disaster of 1879. These photographs have been digitized and disseminated more widely. Only the positive prints survive, owing to the widespread practice of recycling the original glass negatives to reclaim the silver content. Even when carefully preserved and kept in the dark, damage can occur through intermittent exposure to light, as shown by damage to the image of the intact bridge (at left). An example of a larger digitization project is the Cased Photographs Project, which provides access to digital images and detailed descriptions of daguerreotypes, ambrotypes, tintypes, and related photographs in the collections of the Bancroft Library and the California State Library. Conservation treatments Photograph conservation involves the physical treatment of individual photographs. As defined by the American Institute for Conservation, treatment is “the deliberate alteration of the chemical and/or physical aspects of cultural property, aimed primarily at prolonging its existence. Treatment may consist of stabilization and/or