Digitizing the Presidential Portraits Collection

In order to offer extensive reference service to the nation, the Library of Congress will provide online access to more than 500,000 items from its pictorial collections during the next few years. The reproductions will have sufficient quality to meet general reference needs and, in a few instances, higher resolution reproductions will also be created.

Generally speaking, the Library reproduces pictorial items as a set of three digital images:
(1) an uncompressed archival image,
(2) a compressed reference image, and
(3) a thumbnail image.

For the first time with this collection, the Library is providing access to the uncompressed archival image as well as to the compressed reference image. By doing so, the Library hopes to serve patrons who would like a file free of the artifacts that result from the JPEG (Joint Photographic Experts Group) compression algorithm. In this case, since the archival and reference files have the same 1,200-pixel spatial resolution (see specifications below), the differences are very subtle. In the future, however, the Library will produce archival images at significantly higher resolution than the reference images. Then the archival images will have two advantages over the reference images: lack of compression artifacts and greater detail. Of course, the archival images are larger in extent (bytes) and, thus, more cumbersome to transmit and view. The Library would like to hear patron reaction to the provision of access to the archival files; please send us a note at the American Memory Help Desk.

The digital images in the presidents and first ladies reference aid were produced by scanning 8x10-inch copy negatives selected from the Prints and Photographs Division's extensive copy photograph file. (See: By Popular Demand). All but two sets of the digital images were produced by JJT, Incorporated, of Austin, Texas, which scanned the copy negatives with a Kontron digital camera.

Specifications For This Collection

Uncompressed Archival Images

Compressed Reference Images

Thumbnail Images

Presidential Portraits Home Page