P&P ONLINE CATALOG - BRADY-HANDY
COLLECTION
Digitizing the Collection |
During 2002-2003, JJT, Inc.,
of Austin, Texas, scanned the Brady-Handy
Collection. They used an overhead MARC
II digital camera to scan the 4993 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.
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.
Specifications for the Collection
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 (17-23 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: |
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 (22-140 kilobytes); 1024 pixels
on the long side with the short side scaled
in proportion for file names ending v.jpg
(42-290 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 |
[START
OVER] [ NEW
SEARCH] [ "ABOUT" MENU] [ HELP]
Library
of Congress (January 9, 2009
) |