Omaha Indian Music

Building the Digital Collection

Digitizing the Sound Recordings | Digitizing the Photographs | Digitizing the Manuscripts

Digitizing the Sound Recordings

The wax cylinder recordings presented in the online collection were taken from the Omaha Indian Music: Historical Recordings from the Fletcher/La Flesche Collection (AFC L71) preservation tape copy recordings. The cylinders were played back onto magnetic tape using a modified Edison Home Phonograph. The analog preservation copy tapes were recorded in a half-track format at 7.5 ips. These preservation tape copies served as the source for the digital audio tape (RDAT) copies which were, in turn, used to produce the digital files presented online.

The original recordings for the 1983 Omaha harvest celebration pow-wow, the 1983 interview, and the 1999 interview sound recordings are analog recordings made on Nagra tape recorders, generally in a stereo mode and recorded at 7.5 ips. At the pow-wow, a variety of microphone configurations was used, some of which are documented in photographs and fieldnotes included in this presentation. The original 1985 Neptune Plaza Library of Congress recording is also analog, recorded at the concert on ten-inch open-reel tape. Each of these analog recordings was transferred to digital audio tapes (RDAT) that served as the source for the production of the digital files presented here.

Some background noise may be apparent on the recordings, especially when the original is a cylinder. The transfers from the cylinders to analog tape were carried out by the Motion Picture, Broadcasting and Recorded Sound Division laboratory, using their customary and conservative professional practices regarding adjustments of level, equalization, and noise reduction. The transfers from the 1983, 1985, and 1999 originals were made by the American Folklife Center. No further adjustments or enhancements were made when the RDAT tapes were used to produce the WAVE, MP3, and RealAudio versions provided online for each selection.

The WAVE files were created from the RDAT tapes at a sampling rate of 22,050 samples per second, 16-bit word length, and a single (mono) channel. The RealAudio and MP3 files were derived from the WAVE files by digital processing. The RealAudio files were created for users who have at least a 14.4 modem.

Digitizing the Photographs

The original negatives and color transparencies in the Omaha collection consist primarily of 35mm black-and-white negatives and color slides. In order to provide researchers with access to the entire body of photographic documentation from the 1983 pow-wow and the 1985 concert, the online collection includes both blocks of images and individual selections. For the black-and- white negatives, the blocks represent original camera rolls and are the digital equivalent of a contact sheet. For the color slides, the blocks represent the storage holders used by the American Folklife Center to archive the photographs. Each holder contains up to twenty images as selected and identified by the photographer. These photographer's selections are more or less in "shooting order," with only the most redundant or poor-quality photographs discarded. Taken together, the digital proof sheets and color storage units present all of the 1,090 photographs in the collection. The online collection also includes 326 individually digitized black-and-white and color photographs. These images were selected by the team that assembled the online collection.

Specifications for the photographs

Uncompressed Master Images

Spatial resolution:
For the online proof sheets: About 3,000 pixels on the long side with the short side falling where it may.
For the individual images: About 4,000 pixels on the long side with the short side falling where it may.

Tonal (pixel-depth) resolution:
Grayscale: 8 bits-per-pixel
Color: 24 bits-per-pixel

File format:

Tagged Image File Format (TIFF) ver. 6.0



Compressed Service Images

Spatial resolution:
Medium resolution: 640 pixels on the long side with the short side falling where it may.
Higher resolution: 1,024 pixels on the long side with the short side falling where it may.

Tonal (pixel-depth) resolution:
Grayscale: 8 bits-per-pixel
Color: 24 bits-per-pixel

File format:

JFIF (JPEG File Interchange Format)

Medium resolution: JPEG at a quality setting that yields an average compression of 15:1.
Higher resolution: JPEG at a quality setting that yields an average compression of 8:1.

Thumbnail Images

Spatial resolution:

About 150 pixels on the 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.

File formats:
Archived copy: Tagged Image File Format (TIFF)
Online copy: GIF (Graphics Interchange Format) format

Archived copy: native to the GIF format
Online copy: uncompressed compression

The digital images were produced by JJT, Inc. of Austin, Texas, using their new overhead-capture MARC II digital camera. The initial capture uses matrices with values as high as 7,000 x 7,000 pixels, at 12 bits-per-pixel for grayscale or 36 bits for color. Image processing is then executed at 16-bits-per-pixel for grayscale or 48 bits for color. The bit depth is increased because having two even bytes per channel facilitates post-processing. For the archival or master image as saved, the spatial and tonal resolution is reduced. JJT's post- processing step also creates the three service images that complete the set of four delivered to the Library.

The digital images are intended to serve research. Although aesthetic considerations played a role in determining the look of the digital images, it was also important to retain highlight and shadow detail so the maximum amount of information can be derived from the image. This means that the images are made at lower contrast than might otherwise be the case. Users who require digital images that are cropped, have higher contrast, or are improved by local adjustments, should download the archival versions and manipulate them in graphic arts software.

Digitizing the Manuscripts

Manuscript materials were scanned onsite by the NDLP paper scanning and text conversion contractor, Systems Integration Group of Lanham, Maryland. UMAX flatbed scanners were used to produce the images of most of the manuscripts.

The Library's online presentation of the data pages employs a "page turner" or "electronic binder" that permits the user to navigate the manuscript pages, turning to the next or a previous image, or selecting an image by number. The inline service images displayed in the browser are GIF images with a spatial resolution of about 495 x 640 pixels; a hyperlink on the image provides access to the master image. Using the master images as a source, the Library produces the inline service images in a batch mode that includes five steps:

(1) adding tonality (transform the bitonal image into a 16-color grayscale image),
(2) blurring the image to soften the edges of the characters;
(3) reducing the image from about 1,700 x 2,200 pixels to 495 x 640 pixels;
(4) applying an image-enhancement algorithm to suppress the speckling that sometimes results from the addition of tones and reduction in size; and
(5) sharpening the image to restore more clarity to the characters.

Specifications for the data pages

Archival or master images

Spatial resolution:

300 dpi
Tonal (pixel-depth) resolution: 1 bit-per-pixel
File format: Tagged Image File Format (TIFF) ver. 6.0
Compression: ITU Group IV

Inline service images

Spatial resolution:

About 495 x 640 pixels
Tonal (pixel-depth) resolution: 4 bits-per-pixel
File format: GIF (Graphics Interchange Format)

Typescript materials were converted to machine-readable form at an accuracy rate of 99.95 percent and encoded with Standard Generalized Markup Language (SGML), according to the American Memory Document Type Definition (DTD). This DTD is a markup scheme that conforms to the guidelines of the Text Encoding Initiative (TEI), the work of a consortium of scholarly institutions. The texts of the transcripts have been translated to HTML for indexing and viewing on the World Wide Web.

Omaha Indian Music