City Point, Virginia, ca. 1865.
All images are digitized | All jpegs/tiffs display outside Library of Congress | View All
Digitizing the Negatives
During 2002-2003, JJT, Inc., of Austin, Texas, scanned the Civil War negatives. They used an overhead MARC II digital camera to scan the 7,592 glass negatives (measuring in sizes ranging between 2-1/4 x 3-1/2" and 8 x 10 inches). The images were captured in grayscale at a spatial resolution of approximately 10,000 pixels on the long side and a tonal resolution of 16 bits per pixel. The negatives were scanned with the emulsion side up to protect the fragile surface. The negatives display online as they would have been printed. Words sometimes appear in mirror image because they were notes written on the emulsion side for identification purposes, not necessarily to be printed with the image--the words were often cropped out.
With today's resources, these very high-resolution images require significantly increased costs, particularly in time spent capturing, inspecting, and loading the files. For most collections in the Prints and Photographs Division, online digital images, even at lower resolutions, play an important preservation role as surrogates that reduce handling of the original pictures. Digital images of each negative display in each bibliographic record. Two (or more) digital images display separated or variant views of items in stereograph records to facilitate re-creation of original stereoscopic views.
Specifications for the Negatives
Uncompressed Archival TIFF Images
| Spatial Resolution: | 7,500 pixels on the long side with the short side scaled in proportion for file names ending in u.tif (17-20 megabytes). Prior to 2023, this version had been scaled down to 5,000 pixels on the long side. |
| Tonal (pixel depth) resolution: | 8 bits per pixel (grayscale) |
| Image enhancement: | None. |
| File format: | Tagged Image File Format (TIFF) ver. 6.0 |
| Compression: | None |
Highest Resolution TIFF Images
| Spatial Resolution: | 7,500 pixels on the long side with the short side scaled in proportion (up to 100 megabytes) |
| Tonal (pixel depth) resolution: | 16 bits per pixel (grayscale). Note: Some older versions of image viewers and editing software cannot handle 16 bit images. |
| Image enhancement: | None |
| File format: | Tagged Image File Format (TIFF) ver. 6.0 |
| Compression: | None |
Compressed Service Images
| Spatial resolution: | 640 pixels on the long side with the short side scaled in proportion for file names ending r.jpg (25-190 kilobytes); 1024 pixels on the long side with the short side scaled in proportion for file names ending v.jpg (80-460 kilobytes) |
| Tonal (pixel depth) resolution: | 8 bits per pixel (grayscale) |
| Image enhancement: | Mild sharpening |
| File format: | JPEG |
| Compression: | Compressed to yield an average compression ratio of 10:1 |
Thumbnail Images
| Spatial Resolution: | 150 pixels on the long side with the short side scaled in proportion for file names ending in t.gif (approximately 20 kilobytes) |
| Tonal (pixel depth) resolution: | 8 bits per pixel (grayscale) |
| Image enhancement: | Mild sharpening |
| File format: | Archived copy: TIFF - Tagged Image File
Format Online copy: GIF - Graphics Interchange Format |
| Compression: | Archived copy: Uncompressed Online copy: Compression native to the GIF format |
