All images are digitized | All jpegs/tiffs display outside Library of Congress | View All
Digitizing the Negatives
CSC of Chantilly, Virginia, scanned the original glass plate negatives using an overhead capture Sinar 54 digital camera beginning in 2008. Each negative was scanned at a resolution of 10,000 pixels on the long side with the short side scaled in proportion.
Specifications for the Collection
Uncompressed Archival TIFF Images
| Spatial Resolution: | 5,000 pixels on the long side with the short side scaled in proportion for file names ending in u.tif (17-20 megabytes) |
| 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: | 10,000 pixels on the long side with the short side scaled in proportion (approximately 153 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 (20-100 kilobytes); 1024 pixels on the long side with the short side scaled in proportion for file names ending v.jpg (80-210 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 10 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 |
