LC National Digital Library Program announces American Revolution

From: Tamara Swora-Gober (tswo@LOC.GOV)
Date: Mon Aug 07 2000 - 11:53:29 CDT

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    Message-Id: <200008071654.JAA09742@dns.ccit.arizona.edu>
Date:         Mon, 7 Aug 2000 12:53:29 -0400
From: Tamara Swora-Gober <mailto:tswo@LOC.GOV>
Subject:      LC National Digital Library Program announces American Revolution
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    ************************ The Library of Congress National Digital Library Program and the Geography and Map Division announce collection number eighty-three at the American Memory online collections Web site:

    ”The American Revolution and Its Era: Maps and Charts of North America and the West Indies, 1750-1789” at: http://memory.loc.gov/ammem/gmdhtml/armhtml/armhome.html

    The collection presents an important historical record of the mapping of North America and the Caribbean online. Advancements in mapmaking tools and the onset of the French and Indian War and, later, the American Revolution, created a flurry of activity in European and North American mapmaking and publishing. This online collection will include well over two thousand different maps and manuscripts, with easily as many or more unnumbered copies, many with distinct colorations and annotations. Over the next several years many of the maps and charts in this bibliography will be added to the online collection each month. At this time, approximately 100 maps are being released.

    Almost six hundred of the items in this collection are original manuscript drawings, a large number of which are the work of such famous mapmakers as John Montresor, Samuel Holland, Claude Joseph Sauthier, John Hills and William Gerard De Brahm.. Historical cartographers can compare multiple editions, states, and impressions of several of the most important maps of the period, follow the development of a particular map from the manuscript sketch to the finished printed version and its foreign derivatives, and examine the cartographic styles and techniques of surveyors and mapmakers from six different countries Great Britain, France, Germany, Spain, Holland, Italy, and the United States.

    Most of the items presented here are documented in “Maps and Charts of North America and the West Indies, 1750-1789: A Guide to the Collections in the Library of Congress”. The online essay ”Mapping the American Revolution and Its Era” is taken from this bibliography.

    Map specifications and scanning The digital images were created by staff in the Geography and Map Division by scanning the original map on a large-format (24 x 34 inches) flatbed scanner using RGB (red- green-blue) color separation. The scanner was loaned to the Division by Tangent Color Systems. Each raster image was produced by scanning the item at a resolution of 300 dots- per-inch and converting the resulting proprietary file format to TIFF format. These TIFF files, which average approximately 180Mb, are moved over a network to Surestore jukebox 1.3Gb magnetic optical platters for temporarily offline storage. The Surestore jukebox and the associated servers and workstations were donated by the Hewlett Packard Company.

    Following scanning, the TIFF files were enhanced using the WindowsNT version of xRes, an image processing software, to rotate, crop, adjust brightness or contrast, and stitch together TIFF images for items requiring multiple scans. This software was donated by Macromedia. The TIFF files were compressed, using a wavelet-based image compressing software called Multi-Resolution Seamless Image Database, or MrSID. The final step was the creation of a small GIF file for use as the initial thumbnail display of the item. After completing the scanning, the Archive TIFF file along with the SID and GIF files are stored on the Library's RS6000 World Wide Web server.

    Specifications: Master image: Scanning resolution: 300 dpi. Tonal resolution: 24 bit color, RGB separation. File format: TIFF. Compression: none

    Reference image: Scanning resolution: 300 dpi. Tonal resolution: 24 bit color, RGB separation. File format: SID. Compression: Wavelet

    Thumbnail image: Viewing resolution: 72 dpi. Tonal resolution: 8 bit color, RGB separation. File format: GIF. Compression:none

    Map files delivery The Library's world-wide-web delivery of very large digital files of maps is accomplished by using a wavelet compression technology made available to the Library of Congress by LizardTech of Seattle, Washington. The multiresolution seamless image database --MrSID-- software for the storage and retrieval of large digital images is derived from the research efforts of Los Alamos National Laboratory, New Mexico. In contrast to other compression software that relies on tiling, MrSID gets all its sharp resolution from within a single compressed image, and it does not require any special hardware. File size does not matter. MrSID allows immediate access to any part of an image, of any size, at any resolution. This software integrates multiple resolutions of an image in a single file which enables Internet users to zoom in, getting more and more detail.

    Although MrSID is a "lossy" compressor, the images were compressed at a ratio of 22:1, depending on image content and color depth, without experiencing any loss of information. Because fast easy access is provided via networks and the Internet to vast amounts of geographic information, MrSID is ideal for viewing maps, or photos, terrain models, and satellite data.

    Please direct any questions about this collection to mailto:ndlpcoll@loc.gov

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