Digitizing the "Votes for Women" Suffrage Pictures

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.

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 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 American Memory Help Desk.

The digital images in the "Votes for Women" reference aid were produced by scanning a few vintage prints and many 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. Library of Congress staff scanned the vintage prints on a Horizon flatbed scanner.

Specifications for this collection

Uncompressed Archival Images

Spatial resolution of about 1,200 pixels on the image's long side; with the short side falling where it may.

Tonal (pixel-depth resolution): Color: 24 bits-per-pixel; black and white: 8 bits-per-pixel

No sharpening

Uncompressed

Tagged Image File Format (TIFF)

NOTE 1: The resolution of 1,200-pixels was selected for the digital images in this collection as consistent with the resolution planned for digital images of other copy negatives and copy transparencies. Some subsequent Library of Congress pictorial collections--especially when original materials rather than copy photographs are being digitized-- will offer archival images at resolutions of 3,000 and 5,000 pixels.

Spatial resolution of about 640 pixels on the image's long side; with the short side falling where it may.

Tonal (pixel-depth resolution): Color: 24 bits-per-pixel; black and white: 8 bits-per-pixel

Sharpened

JPEG compression to yield average compression of 10:1 for grayscale and 15:1 for color

JFIF format/headers

Spatial resolution on the order of 150 pixels on the image's long side; with the short side falling where it may.

Tonal (pixel-depth resolution): 8 bits-per-pixel

Palettes optimized (adaptive palettes) for each image

Sharpened

Uncompressed

Archived copy: Tagged Image File Format (TIFF)

Online copy: GIF format, produced by the Library of Congress. These are the images displayed with the bibliographic records.