Digitizing Microfilm
Microfilm collections of historical documents present a number of challenges to digitization because of the quality of the microfilm being scanned. In addition, there are problems of original document condition, a wide range of tonal values, and differing document sizes and document orientations on the microfilm. For optimal capture of detail, all thirty-four reels of the Frederick Douglass Papers microfilm was raster-scanned from a duplicate negative microfilm copy. The negative was printed directly from the master microfilm, which was scanned by Preservation Resources using a Sunrise Proscan III microfilm scanner.
The digital images scanned from microfilm were produced in JPEG File Interchange Format (JFIF), a compressed grayscale format often used in digitizing historical manuscript documents because of its ability to capture and display a wide range of tonal variations, from those in the document paper to diverse qualities of pencil and ink. This 8-bit grayscale capture also suppresses the bleedthrough typical of handwritten documents in the microfilm collection. Preservation Resources also created 4-bit grayscale GIF (Graphics Interchange Format) images for quicker access than the larger JPEG images permit.
Microfilm frames of individual manuscript leaves that were originally folded to make two pages or writing surfaces have not been split. Smaller volumes were generally microfilmed in open-book format with two pages to a frame, a presentation that has been retained online. Larger volumes and ledger books, originally filmed as two pages to a frame, have been split into single-page images to improve legibility. Some single-page items were microfilmed in sections over two or more frames. When appropriate, many of these separate images were stitched together electronically by Preservation Resources. They also used Photoshop's "unsharp mask filter" tool throughout the collection to enhance ink-to-background contrast in the images.
The varying formats in the Douglass Papers, which range from individual manuscripts, scrapbooks, diaries, and printed speeches to full-sized newspaper sheets, received custom cropping. Manuscript leaves or bound volume pages containing text not oriented for reading on the microfilm were reoriented for reading as digital images. Microfilm images containing multiple texts oriented in a variety of directions were left in their original orientations as they were microfilmed.
Database Access
Access to this collection is through search and browse pages that link to a database created from the finding aid Frederick Douglass: A Register and Index of His Papers in the Library of Congress. The entire microfilm collection was reviewed frame by frame and the database modified and corrected to reflect the microfilm images. The original manuscript collection was also reviewed. In the Correspondence series (to be placed online in a later release), folder date ranges were added to the database, providing new information not in the Register or included on the microfilm.