The digital images of the panoramas were produced by scanning intermediate 35 mm copy film at approximately 900 dpi. This translates into a digital image resolution ranging from approximately 50 to 100 dpi if one were attempting to reproduce the image at the same size as the original panorama. See The Digitization Process below, for further details.
The quality of a digital image reproduction cannot be pre-determined; users will need to experiment to see whether adequate results can be achieved for their specific purpose from these digital images. Factors that can affect reproduction quality include:
The panoramic photographs have been digitized from 35mm film produced by a contractor in 1992-93 using a modified motion picture camera. The full-frame 35 mm exposures were made on color motion picture film stock. The contractor, Stokes Imaging, Inc., constructed a computer controlled table that moved the panorama under the camera, producing a sequence of exposures that represent overlapping segments of the original photograph. (Imagine a comic strip with overlaps.) The computer program tracked the number of segments and the amount of overlap to permit the "reassembly" of the panorama in digital postprocessing, where match lines were identified for each segment, the overlap cropped away, and the segments blended. The digital images were created at a resolution appropriate for video production, e.g., the individual segments were scanned at 560x480 pixels. In 1993, the resulting digital images (both the assembled whole views and all of the individual segments) were converted to analog video and copied to videodisc media.
In 1996, the 35mm copy film was rescanned for this digital presentation by another contractor, JJT, Inc., of Austin, Texas. Once again, the images for each segment were captured from the film in a computer controlled process that tracked the information needed for later assembly, with a base capture resolution of about 1000x700 pixels. Once again, the frames were assembled, this time to produce an archival or master digital image of the panoramic photograph. All other images used in the display (e.g., the thumbnail reference image) are derived from this master image. The master image is available for download as an "uncompressed archival tiff."
Minimal computer enhancements were applied to the archival image during the production process. In contrast, the enhancement called sharpening has been applied to the reference image and, as a result, it may look better in some display settings than the archival master.
The header of the master image indicates that the file carries a resolution of 900 dots per inch (dpi). This represents the approximate resolution of the scanning of the 35mm intermediate copy film. The resolution as related to the size of the original prints ranges from approximately 50 to 100 dpi. The dimensions of each original panorama can be found in the bibliographic record in the MEDIUM field.
Initial segment capture:
| Spatial resolution: | about 1000x700 pixels |
| Tonal resolution: | color, 24 bits per pixel |
| Compression: | none |
| Enhancement: | none |
Archival (master) image:
| Spatial resolution of short side (typically the vertical): | about 700 pixels |
| Spatial resolution of long side (typically the horizontal): | about 500 pixels times the number of original segments (approximate range: 1000-5000 pixels) |
| Tonal resolution: | color, 24 bits per pixel |
| Compression: | none |
| Enhancement: | none |
Reference image:
| Spatial resolution of short side (typically the vertical): | 420 pixels |
| Spatial resolution of long side (typically the horizontal): | approximate range: 700-3000 pixels |
| Tonal resolution: | color, 24 bits per pixel |
| Compression: | JPEG |
| Enhancement: | sharpening |
Thumbnail image:
| Spatial resolution of short side (typically the vertical): | 150 pixels or less |
| Spatial resolution of long side (typically the horizontal): | not to exceed about 600 pixels |
| Tonal resolution: | 8 bits per pixel |
| Compression: | native to GIF |
| Enhancement: | color indexing, sharpening |
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