This Collection:
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- About this Collection
- Arrangement and Access
- Background and Scope
- Selected Bibliography
- Cataloging the Collection
- Digitizing the Collection
- Bringing an NCLC Photo into Focus
- Related Resources
- Reporting on Labor Conditions
- Rights And Restrictions
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All images are digitized | All jpegs/tiffs display outside Library of Congress | View All
Digitizing the Collection
During 2003, JJT, Inc., of Austin, Texas, scanned the National Child Labor Committee Collection. They used an overhead Sinar 54 digital camera to scan the 5127 photographic prints (measuring in sizes ranging between 3.5 x 3.5 inches and 5 x 7 inches) and the 355 glass negatives (measuring either 4 x 6 inches or 5 x 7 inches). The images of photographic prints were captured in color (and the glass negatives captured in grayscale) at a spatial resolution of approximately 5,000 pixels on the long side and a tonal resolution of 8 bits per pixel.
With today's resources, these 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. The high-quality master and derivative files are available online. One digital image of each photographic print displays in each bibliographic record. Two digital images display for items that have a both a photographic print and a negative.
Jump to: Specifications for the Photographic Prints | Specifications for the Glass Negatives
Specifications for the Photographic Prints
Uncompressed Archival Images
Spatial Resolution: | 5,000 pixels on the long side with the short side scaled in proportion for file names ending in u.tif (31-72 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 |
Compressed Service Images
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 |
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 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 |
Specifications for the Glass Negatives
Uncompressed Archival 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 |
Compressed Service Images
Spatial resolution: | 640 pixels on the long side with the short side scaled in proportion for file names ending r.jpg (28-81 kilobytes); 1024 pixels on the long side with the short side scaled in proportion for file names ending v.jpg (62-206 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 15 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 |