Africana Poster Credits

Digital Images Processed by:

Luna Imaging, Inc. [1] (archival images on Photo CD)
Preservation Department, Northwestern University Library [2] (derivative images for the Web)

Production Dates:

1996, 1997-98

Intermediate Copies:

Posters photographed on Kodak R2 135-36 (ISO 25 color negative) film using Kemlite MW9
lamps with Speedotron D800 power packs

Archival Images:

Color negative film scanned and captured on Kodak five base (five resolution) Photo CD disks,
with the highest resolution at 2048 x 3072 pixels.

Derivative Images:

Medium resolution images (512 x 768 pixels) were cropped to remove technical reference targets
and resaved in two formats and three sizes:
*JPEG 24 bit color low compression at high quality, 72 dpi, un-resized
*GIF 8 bit color thumbnails in two sizes -- mid-sized (c. 115 x 147 pixels) and small (c. 58 x 74
pixels)

Technical Information Project Narrative

This selection of 366 posters from the library's extensive collection were identified in 1995 as ideal material for a digitization project because of their pictorial interest and the enriched access potential which an online database could provide. Their large, full-color format led to the decision to photograph them first on professional color-negative film and then scan from the film. Before photographing, the first batch of posters scanned in 1996 were removed from mylar encapsulation used for conservation in order to avoid glare and image distortion. However, subsequent experience has shown that the use of polarizing filters on fresh, uncreased mylar can yield acceptable results and avoid the extra task of re-encapsulating. A second batch of 200 posters, digitized in 1997, were left in the mylar during photography and scanning.

The archival digital images were saved in photo CD [3] format which offers cross-platform compatibility and multiple levels of resolution. The original scans were cropped by library staff to remove reference targets (including grayscale and color cards as well as inventory numbers). They were re-saved as low-compression, high quality JPEG images using batch processing, and through further processing they were also saved in GIF format to create smaller-scale "thumbnail" images. Original proportions were retained rather than forcing uniform dimensions or restricting the JPEG images to screen size.

An important aspect of the workflow was to develop a numbering scheme which tracked the migration of images through the several processes. Object numbers were assigned to the posters based on their filing order within a broad organizational scheme, and these were correlated with film and photo CD disc frame numbers; ultimately the digital file numbering created for the web server was based on the photo CD's, not the original object numbers. Batch processing was used for file re-naming.

As with the library's collection of digitized World War II posters [4], it was decided to create individual records for each poster in both the library's online catalog (NUcatWeb [5]) and an online web database to allow complete and flexible access. Full-level MARC records were created and then converted to SGML for use in the web database where they are searched by OpenText's Livelink software [6]. Livelink was chosen for its customizable results page, flexible SGML indexing, and robust search features. The data structure for the web database incorporates selected fields from the MARC record, and the conversion was conducted through a customized batch process. In the 856 field of each MARC record, two links appear to the user: one directly to the JPEG image and the second leading to the URL for the web image database if the user prefers incorporating visual browsing with search results. Hidden links allow for the incorporation of thumbnail images in the various summary displays. A sample group of records was mounted in 1998. In 2004, records for the remainder of the 366 posters were mounted.