Digitizing the Collection |
During 2003-4, JJT, Inc., of Austin, Texas, scanned the original transparencies and slides from the Farm Security Administration/Office of War Information Color Photographs Collections. They used an overhead Sinar 54 digital camera to scan each of the color slides at 3600 dpi and the color transparencies at 1800 dpi.
In converting these photographs to digital form, the Library of Congress attempts to capture all of the visual content of the images and to create a reasonable representation of the qualities of the film. Some of the original images may have been under or overexposed or may exhibit some color deterioration as they have aged. The scans are not color corrected or adjusted to create an optimized view of the photographic scene, rather they represent the qualities of the images as they exist in the collection at the time they are scanned.
Digital images from this collection were available previously at lower resolutions from the original electronic imaging project in the mid 1980s. The images presented here have replaced the earlier scans.
| Spatial Resolution: | 3,600 dpi for each original slide, 1,800 dpi for each original transparency for file names ending in u.tif (59-210 megabytes) |
| Tonal (pixel depth) resolution: | 8 bits per pixel (color) |
| Image enhancement: | None. |
| File format: | Tagged Image File Format (TIFF) ver. 6.0 |
| Compression: | None |
| Spatial resolution: | 640 pixels on the long side with the short side scaled in proportion for file names ending r.jpg (19-89 kilobytes); 1024 pixels on the long side with the short side scaled in proportion for file names ending v.jpg (48-318 kilobytes) |
| Tonal (pixel depth) resolution: | 8 bits per pixel (color) |
| Image enhancement: | Mild sharpening |
| File format: | JPEG |
| Compression: | Compressed to yield an average compression ratio of 10:1 |
| Spatial Resolution: | 150 pixels on the long side with the short side scaled in proportion for file names ending in t.gif (approximately 15 kilobytes) |
| Tonal (pixel depth) resolution: | 8 bits per pixel (color) |
| 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 |
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