The Detroit Publishing Company photographs were originally captured for the Optical Disk Pilot Project (1982-87), an early Library of Congress effort in the development of digitized collections. For the ODPP, the original photographs (except for the mammoth plate photographs) were copied by a contractor using a modified motion picture camera and 35mm color motion picture film in "academy" or "half-frame" format which was then transferred to video on a standard analog film-to-video transfer device.
In 1991, when the American Memory project produced a new version of the videodisc, analog video frames were created from the existing "half-frame" format film and from new 35mm color motion picture "full-frame" format film which was used to capture the mammoth plate photographs. On this occasion, a contractor created intermediate digital images at a resolution of 560x420-pixels by scanning the film. The contractor then used an automated system to write these images to analog video. The current set of images have been reprocessed from this last set of digital intermediates, which had been stored on Digital Audio Tapes (DAT.)
The "half-frame" format 35mm color motion picture frame images reproduce originals that consist of glass negatives and transparencies (about 25,000) ranging in size from 6x8 to 11x14 inches (most are 8x10-inches); large-format Photochroms (72); and Photochroms in albums (241 prints.) In order to provide access to the large mammoth plate negatives that measure up to 18x22 inches, the Library of Congress created duplicate 8x10 inch film negatives (600) from each original and unique mammoth plate. The "full-frame" format 35mm color motion picture frame images reproduce large-format photographs (over 300), and the 8x10 inch copy negatives (600) made from the mammoth plate negatives.
The digital images reproduce the entire original item, and many include the masking and cropping marks, captions, and negative numbers which were used by the publishing company. Mounted photographs and Photochroms were filmed to show the entire mount. All of the objects appear surrounded by a black border.