The chemical nature of silver analog prints and negatives implies a certain inevitable level of degradation and raises the need for copying and more recently digital conservation and restoration. Copying and microfilming can be an enormous challenge with negatives more so than with prints. Chris Woods describes a process that lifts the image layer of deteriorating cellulose diacetate negative from its shrinking (and so image distorting) base, to avoid the risk of the “complete loss of information within the next fifty to one hundred years” (1992: 46).
As long as the negatives are in good shape, it is possible to photo-reduce or digitize them. Ruth Kerns describes a preservation project for deteriorating photographic negatives at the Special Collections and Archives of George Mason University that used photo-reduction mechanism capable of producing microfilm directly from the negatives (Kerns 1988: 111). It is interesting to note that image enhancement through “contrast compensation” (Kerns 1988: 112) in the duplicate microfiche was considered to be one of the strengths of this approach. Even though digitization was noted as an option by the author in 1986, the National Archives and National Research Council - Committee on Preservation of Historical Records still recommended the use of micrographic processes for film at this time (Kerns 1988, 112).
The situation changes dramatically over the next ten years of technological innovation, turning digitization of photographic materials into a practical option for many institutions. Lynn Ewbank outlines some of the main advantages of choosing to undertake this option: reducing handling while at the same time increasing access to higher quality images than the photocopies of originals that the archive provided in the past, increased access in-house, across the country and around the world (Ewbank 2000:15-16). The Arkansas History Commission archive[‡‡] project described by Lynn Ewbank was successful in increasing access “because digital data represents a symbolic description of the originals and can be copied without loss, shared easily and viewed without pre-selection” while at the same time enhancing preservation (Ewbank 2002: 57). It is interesting that this particular project decided to use MARC as its metadata format (one record per image) out of the plethora of options[§§]. Cataloging and access are complex challenges requiring human resources and money, but “without a rigorous effort to develop an understandable, expandable, and reliable catalog system, a collection can lose its meaning and value” (Ross 1996: 10). Other decision include policies on file names and formats (e.g.: archival TIFF for preservation and low and high resolutions JPGs for display) as well as rules for cropping and tonal distribution (Ewbank 2002:53).
Roy McCrutchen outlines three types of questions that need to be answered before digitization: the intended purpose of the digital images (distribute prints, view online, distribute for publication), the type of originals (black & white, color, glass, tin, etc.), and miscellaneous (safety of originals, copyright, longevity of media, outsourcing vs. in-house, budget) (2000: 18). McCutchen recommends making photographic copy prints (to preserve original’s safety) and remarks that sometimes it is better to scan from prints rather than low density negatives (2000: 19). Among McCutchen’s other recommendations are Kodak Gold CDs for storage, Fuji Crystal Archive papers for printing and the use of printers that use gaseous RGB lasers such as LightJet 5900 (2000: 19).
Digital cameras capture images on a light-sensitive silicon CCD (Charged Coupled Device). Ross’ report on a yearly seminar on digital preservation [***] identifies resolution in addition to cost and format as “the most important considerations in matching the camera’s features to your project’s needs.” (Ross 1996: 9) Digital resolution implies a division into concrete blocks whereas some claim that analog images “have infinitely smooth variations between light and dark” (Ross 1996: 9). Scanning should be done at highest resolution available requiring large amounts of space. Mortensen states that “the resolution or information within, for example, a 300 dpi, 24.5 MB file of an 8" x 10" print is approximately one-tenth of the information that is in the original image” but admits that his definition of ‘information capture’ may become invalid (1998: 5). It is difficult to measure the quantity of information captured in digitizing since measures such as resolution tell only a part of the story, there are also qualitative changes that are a result of the dimensional reduction involved in moving from a physical object to a two-dimensional digital image: “visual cues embedded in original photographs are homogenized by digitizing into a unity of pre-determined size, quality and tonal range of the digital photograph” (Sassoon 1998: 10).
The digitization project of photographic material from a collection at the Royal Photographic Society (RPS)[†††] recommends a ground-up approach that takes image quality into account during the digitization process, an emphasis on retrieve-ability of the digital information in the future and storage media with long archival life (Birdsey 2000: 2-4). RPS digitized 35mm slides using a Nikon Coolscan that was grey balanced with the Kodak colour test target Q-60 on the same Ektachrome 35mm slide as the source and gamma adjusted for optimal tonal response to the thin images, producing 24bit files measuring 2482 x 3764 pixels 26.7 Mb in size (Birdsey 2000: 4). The files were processed using Matlab image processing, and stored as sRGB[‡‡‡] TIFF on ISO 9660 CD-ROMs (Birdsey 2000: 5).
Joanna Sassoon examines the relationship between photographs as unique physical objects and their digital reproductions and argues for a change towards a more provenance based approach towards documenting their collection: “photographs can be understood from the perspective of the technology which created them, the processes by which the images are revealed, the object itself, the trail of ownership through which it has been preserved, and how the institutions have acquired it” (Sassoon 1998: 5). The fact that multiple photographic prints are made from a negative only implies that the prints are multiple original documents. These documents carry information on the image, but they also carry evidential value through functional context and “a history of the truth of the image – the relationship between the structures which have served to create, authenticate and preserve an image” (Sassoon 1998: 8). The question that Sassoon poses should remain in the forefront of theoretical considerations of digitization of photographic materials: what are “the implications for research of devaluing the materiality of the photograph?” (Sassoon 1998: 13) and we should use the answers to improve the metadata schemas used to catalogue the digital surrogates.
[§§] the choice must be made based on the budget and circumstances, for a review of metadata schemas for images see Neugebauer, Tomasz. “Metadata for Image Resources” PhotographyMedia. 2005. 14. Nov. 2005. <http://www.photomedia.ca/article.php?page=1&article=AImageMetadata>
[***] “Preserving Photographs in a Digital World” was a 1996 seminar sponsored by Rochester Institute of Technology’s Image Permanence Institute <http://www.imagepermanenceinstitute.org/>, Technical and Education Center of the Graphic Arts and Imaging and George Eastman House <http://www.eastmanhouse.org/>. The seminar is available this year (2005) under the title: Preserving Photographs in a Digital World: Balancing Traditional Preservation with Digital Access <http://www.imagepermanenceinstitute.org/sub_pages/8page10.htm> (visited 19 Nov 2005)
[†††] Royal Photographic Society <http://www.rps.org/> (visited 19 Nov 2005) collection includes photographs by Nicéphore Niépce, William Henry Fox Talbot, Julia Margaret Cameron, David Octavius Hill and Robert Adamson, Edward Steichen, Roger Fenton, and Alvin Langdon Coburn (Birdsey 2000: 3).