WAML "The Microreproduction And Digitization Of Maps"

Western Association of Map Libraries

The Microreproduction And Digitization Of Maps: A Comparative Analysis
by Thomas Corsmeier, University of Texas, School of Library and Information Science

Abstract:

The range of colors found on many maps is difficult, if not impossible, to capture using micrographic materials. Recent advances in digitization have allowed for a more accurate representation of a map's colors and, through the World Wide Web, vastly improved access to the images. As a result, the digitization of maps has been embraced in way that the microreproduction process has never been. Although digital imaging technologies do not provide the life expectancy that microforms do, the benefits of digitization negate many of the advantages microforms offer. However, a closer analysis of two map digitization projects shows that the digitization of maps is still in a pilot stage and progress needs to be met in several areas before the technology can clearly surpass microforms as an ideal media for storage.

Editor's Note: This article is also on WAML's Website at http://www.waml.org/corsmeier.html. The benefit of viewing the article online is that the 14 digitized maps discussed here are linked and available for viewing in full color. Also please see the loose color photocopy of the 1849 Hispania map inserted in this issue.

While an innocuous piece of paper to some, throughout history maps have been utilized as powerful weapons. Maps have been used by people to support claims of autonomy, while on other occasions, nations have used maps to assert hegemony. Yet, maps are not permanent and are continuously challenged and replaced. We live in a period where technological developments have made computer-aided map production prevalent, and, as a result, a multitude of maps is being produced from things such as the solar system to the human brain. At the same time, maps of historical value have been given greater attention. In the past decades advances in photocopying, microreproduction, and digitization have made maps of historical value accessible to a wider audience. However, due to their size, details, and importance of scale, many maps have proven to be difficult to capture accurately. Digitization is attractive as it provides the full color of a map and makes it possible to put a map online where it can be accessed by anyone with a personal computer and a modem. Microfilm and microfiche on the other hand do not always present a faithful representation of a map's colors, are limited in the number of users, and can be awkward to handle. Unlike digital imaging though, microforms are a proven media that have the ability to provide access to an image for centuries and are relatively inexpensive to produce. In comparison, the life expectancy of the hardware and software involved with digital imaging is relatively short and system upgrades are necessary at frequent intervals to keep the images available. This paper analyzes the processes involved in the microreproduction and digitization of maps. More specifically, the paper will examine map microreproduction and imaging projects carried out over the past two decades at the University of Texas at Austin and the University of California at Berkeley. The result of the observation shows the value and pitfalls associated with the microreproduction and digitization of maps. While microreproduction offers a clear advantage in terms of life expectancy, the ability of digital imaging to provide a replication of a map's color and provide wide access to an image are advantages that have tipped the scale in favor of digitization as the media of choice for capturing maps.

The University of California and the University of Texas are two of the world's largest map repositories. The maps at the University of Texas's Perry-Castañeda Library range from USGS topographical maps, to historical maps dating from the early 19^th century, to facsimiles of maps from the 15^th century. The University of California also possesses a wide range of maps, varying from early maps of California and Mexico, to facsimiles of maps from as early as 100 AD, to twentieth century nautical charts. Unfortunately, as is the case with many paper documents, some of the older maps have begun to show signs of deterioration, becoming brittle and covered with spots. Various technologies have been employed over the past decades in an attempt to capture and preserve some of the maps in both collections. With either microforms or digital imaging, maps are difficult to successfully capture.

The problems associated with the imaging of maps are numerous, and no media exists which satisfactorily addresses all the problems. A comparison of the University of California's and University of Texas's approach to capturing maps in its collections furnishes insight into the advantages and disadvantages of both microreproduction and digital imaging and offers an understanding to what extent the two media will be used in the future.

Maps and Microcartography

As a means of preservation, the amenities microforms offer are hard to equal. To be able to take an image that is in danger of slipping out of the human consciousness and preserve it for up to five hundred years is something that cannot be readily matched. However, maps are one of the most difficult items to capture with microforms. Some of the complications maps present are: the large size of some maps, which requires that they be filmed at very high reduction ratios or in sections; inclusion of small lines; and, complicated patterns of color where each variation of color provides specific information and a loss or change in color alters a map's accuracy. Given these difficulties, the use of microforms to capture maps has been embraced only moderately over the past decades.

Maps and Microcartography: Different approaches by two map libraries

Although microfilming has been carried out for over a century, the microfilming of maps was only started on a large scale during the 1970s. The idea for microfilming maps was advanced as early as 1943, but was not more widely explored until the 1960s and 1970s. The Cartographic Archives Division of the United States National Archives and the National Map Collection at the Public Archives of Canada were two pioneering institutions in the establishment of large-scale map filming projects. Also at this time, the term "microcartography" was given to the microfilming of maps by Larry Cruse, head of the Map Section at the University of California-San Diego.

Microforms offer a number of features that work well with maps. In addition to their durability, microforms can capture the fine detail of an item and are a relatively inexpensive media. Although their collections share similarities in size and breadth, the map libraries at the University of California and the University of Texas took different approaches to capturing their maps with microforms. While the University of California's Bancroft Library modestly embraced the microfilming of maps, the Perry-Castañeda Library did not microfilm any of its collection. The person who oversaw the Bancroft Library's microfilming was Phil Hoehn, the library's map librarian from 1969-1994. According to Mr. Hoehn, the impetus to embark on a microfilming project came in the fall of 1977 when the Bancroft Library received a donation of a reel of 35mm microfilm with roughly 150 18^th and 19^th century maps from the Spanish archives pertaining to Mexico. The filmed maps lacked any clear identification or targets and were eventually cut into individual frames and placed into film jackets. With this, the Bancroft Library slowly began the process of filming maps in its collections.

During the next several years Bancroft Library captured an estimated 250 maps on microfilm. The maps to be microfilmed were chosen by Mr. Hoehn and consisted mainly of nautical charts, Van Dyke negatives, and blueprints. The majority of the maps were filmed by the University of California at Berkeley's Library Photographic Services, Conservation Department. The only exception to this was a collection of nautical charts filmed by an outside vendor (Oakland Blue Print Company) to be used as part of a Western Association of Map Libraries project. Mr. Hoehn was involved in the selection and preparation of the maps. The maps selected were in fair to good condition, with some being torn or having deteriorated color. Maps such as blueprints, blue line prints, and Van Dyke negatives were selected for microfilming partially because they were on deteriorating or poor quality paper. Mr. Hoehn did basic pre-filming preparations, including applying mending tape and flattening maps, but did not have any role in the development of instructions and targets used during the filming. This responsibility was left with the Conservation Department. During the filming, to avoid having to use high reduction ratios, several of the maps were spread out over more than one frame.

After the filming of the maps and the processing of the film, one copy of 35mm silver-gelatin film was given to the Bancroft Library and subsequently sectioned and inserted it into roughly 200 microfilm jackets. The microfilming of maps allowed for a greater access of maps in two ways. First, it made it possible for the Bancroft Library to send some of the original maps to libraries at the University of Alaska and University of Oregon where they would receive greater use. Secondly, copies of the microfilm were made available to other libraries in the University of California system. The microfilming of maps at the Bancroft library was a relatively short lived process, as added job responsibilities decreased the amount of time Mr. Hoehn had available to select and prepare maps for filming. In the early 1980s the Bancroft Library stopped microfilming maps in its collection.

In contrast with the University of California's efforts, the University of Texas's Perry Castañeda Library made no attempt to film the maps in its collections. The map librarian at the Perry-Castañeda Library, James Weiferman, claims that microreproduction of maps was not pursued due to lack of financial resources and the cumbersome nature of microforms, especially when the media is applied to cartographic materials. As noted above, maps are one of the most difficult documents to accurately capture with microforms. Charles Stewart, head of photography at the University of California at Berkeley's Library Photographic Services, Conservation Department identifies several reasons why maps are difficult to capture with microfiche and microfilm. For more than twenty years, Mr. Stewart has filmed a number of maps to be put onto microfiche or microfilm. The maps he has filmed were never part of a large map filming project, but rather, tended to be portions of collections the photolab was filming. He believes microforms are good for capturing the fine detail of a map and offering a means of preservation. However, Mr. Stewart cites difficulties in evenly lighting a map and accurately representing a map's scale and color code as major drawbacks in capturing maps with microforms.

In an attempt to counter the absence of color representation in microfilm, the possibility of using color microfilm has been investigated over the past two decades. Unfortunately, color-microforms have been plagued with difficulties, preventing it from being as reliable as black-and-white microforms. The primary problem with color emulsions tend to be poor resolution, troubles with the dye shifting, and light acting as a catalyst for deterioration among heavily used images. Based on his experience, Mr. Stewart recalls some of the signs of deterioration with color microforms appearing as early as six months after production. As a result, it is difficult to place a life expectancy rating on color microforms. There have been various estimates ranging from one to two hundred years, but not with any degree of certainty.

After experiencing a brief popularity in the 1970s and 1980s, the number of maps being microfilmed declined drastically. Part of the reason for the dropoff are the difficulties involved with the microreproduction of maps and the increasing popularity of digital maps. Many maps are rich, vibrant works of art that are done an injustice with black and white microforms. Furthermore, we live in a society where the benefits of color and digitization are strongly imbued in the public consciousness, while microfilm and black-and-white representation of color images are conveyed as being boring and antiquated. Although the filming of maps for preservation purposes is still carried out on a small-scale, the utilization of microforms as a way to provide greater access to maps has been surpassed by the digitization of maps.

Digitization of Maps

In 1849 the map "Hispania" was published in A Classical Atlas of Ancient Geography. Over the years a copy of the atlas and its map have sat on the shelf at the Perry-Castañeda Library. Recently the map was scanned and made available on the Perry-Castañeda Library's Web page. The scanned image provides a good example of how maps can be scanned, edited, and made available to millions of potential users through the World Wide Web. While this process is extremely appealing, there is a downside to the scanning of maps: low levels of resolution; lack of standards; the size of memory required to store the files; and, the impermanence associated with the software and hardware used in the process. A closer examination of the process involved in the digitization of maps at the University of California at Berkeley and the University of Texas at Austin offers an insight to the promises and drawbacks digital technologies hold for the imaging of maps.

Maps and digital imaging

Digital imaging technology is a relatively new process, with its widespread use coming only in the 1990s with improvements in high resolution scanning; lower costs for the scanning and storage of images; the spread of high-speed, high-bandwidth networks; and, the emergence of the World Wide Web. The basic tools needed to digitize a document are a computer, scanner, and software to control the scanner and manipulate the images once they are scanned. If the image is going to be put online for wider access, additional software may be required.

The importance of getting a good scan from a document on the initial scan cannot be emphasized strongly enough. In some cases, an item may only be available for one scan, or, the document may be so fragile that it cannot afford to be scanned multiple times. Additionally, a quality scan saved in an archival quality format helps justify future migration costs. From a high-quality scanned image, information can then be transferred to other formats as desired.

In Digital Imaging for Libraries and Archives, Anne Kenney and Stephen Chapman identify the following as the key determinants in obtaining a high-quality scan:

1) Resolution

2) Bit Depth/Dynamic Range

3) Image Enhancement

4) Compression

5) Metadata

Resolution: The number of pixels used to represent an image; often measured as dots per square inch (dpi). In grayscale and color scanning both resolution and bit depth combine to play significant roles in image quality. Resolution is a measurement of clarity, or detail, and can refer either to an image file, or, the device, such as a monitor, used to display an image. Central to image quality is not the capturing of a document at the highest resolution possible, but rather, to scan at a level that ensures adequate capture of the information content of the original document and the creation of a moderately sized file.

Bit Depth/Dynamic Range: Bit depth is the number of colors or shades of gray (grayscale) that can be represented in a digital image. Dynamic range is a measurement of the number of bits used to represent each pixel in an image and is used to express the full range of tonal variations between the lightest and darkest areas of a document. A scanner's capability to capture a complete range of tones is dependent upon its bit depth and dynamic range. The greater the bit depth, the greater number of grayscale or color tones that can be represented. Black and white images are usually scanned using eight or sixteen bits, while twenty-four bits and higher are used for color images.

Image enhancement: The use of software programs to improve image capture. Standard enhancement software allows the user to rotate; crop; alter brightness or contrast; and stitch together Tagged Image File Format (TIFF) images for large documents requiring multiple scans. While the use of some of enhancement features is necessary to provide a suitable image, too much dependence on image altering software raises questions concerning the authenticity and fidelity of an image.

Compression: The reduction of file size in order to save storage space. Digital images captured at high resolutions produce large files. To counter this, several steps are commonly followed to help reduce file size. First is the scanning of an image at the highest feasible resolution and then saving the scanned image to a lossless compression mechanism file, such as TIFF, to create an archival image. Then, from the archival image, a lossy compression mechanism, such as Joint Photographic Experts Group (JPEG) can be used to reduce the size needed for a file's processing, storage, and transmission. A determining factor in defining an appropriate level of compression is the balancing of file size and resulting storage requirements with quality needs and the limits of the display hardware and network speeds. The greater the image quality, the more storage space it will occupy; the scanning process will be costlier and longer; and, more memory will be required to display the image.

The level of compression used may effect the quality of the image. An image decompressed and viewed after lossless compression will be identical to its original compression. Lossy compression results in some loss of data, and therefore image quality is reduced. Images do not respond to compression in an identical way. As an image is compressed, particular kinds of visual characteristics, such as subtle tonal variations, or unintended visual effects may appear. In other instances, no noticeable change results from the use of lossy compression. A point to consider when determining resolution and compression ratios is that the monitor a user views the image with will not be calibrated the same as the monitor used when the image is digitized; thus, any resolution finer than the resolution of the user's monitor is wasted.

Metadata: Data that describes an information resource and which assists in the locating and accessing of information about the resource. Metadata includes a number of elements, such as title, author, and date and place of creation.

Problems in the digitization of Maps

Maps are considered one of the most difficult items to scan. In Digital Imaging for Libraries and Archives, Kenney and Chapman recommend that any library beginning a scanning project not "begin with oversize maps, as the combination of large dimensions and fine detail will challenge the best of scanning systems and will defy effective presentation on the highest resolution monitors available today." Many maps are too large to capture with one scan and it is often difficult to scan a map in sections and then paste it together. Regarding the fine detail of maps, contour lines and text are sometimes as small as 1mm, meaning little contrast between the print and the background. Another major difficulty is that maps usually lose their scale when digitized and, as a result, the viewer is left without a firm understanding of the distance between points on the map.

It cannot be denied that the potential for the digital imaging of maps is great. However, the technology is still relatively new and in the experimental phase, and there exist a number of drawbacks that curb its use as a means of preservation. Among some of the primary downsides with digital imaging are: the lack of standards, and, a quickly changing technological base that necessitates a migration policy and a financial commitment for future transfer of files Despite the problems, there are currently an amazing array of digital maps available via the Web and digital imaging holds great potential for capturing maps in the future. What follows below is an overview of the imaging systems used to digitize maps at the University of California and the University of Texas.

Imaging Maps at the University of California

The Earth Sciences Library at the University of California has made an estimated 300 of its maps available through its home page on the Web. Under the auspices of John Creaser, a electronic reference specialist, the scanning of maps at the Earth Sciences Library began in August of 1997. In addition to the Earth Science Library's Web page, some of the library's maps are available via the University of California's online catalog, Gladis. Mr. Creaser is responsible for all the details associated with putting the maps online, from the selection and preparation; to the scanning and editing; to writing the HTML; to cataloging the digital image. To scan the maps he uses a 133 MHZ PC Pentium with 8 MB of RAM; a Windows 3.1 operating system; and a legal-size Hewlet Packard Scanjet 4c flatbed scanner operated with Hewlet Packard DeskScan II v2.4 software.

During scanning, the images are captured using an eight-bit setting for black and white maps and a twenty-four bit setting for color maps. The dpi on average ranges from 75 dpi to 300 dpi. As this project is still in its infancy, Mr. Creaser is still experimenting in accurately determining the resolution requirements for each map and often does two or more scans to get the proper setting. Mr. Creaser says that he attempts to scan a map at a resolution that will allow the user to read the fine print. A restriction on resolution is the file size, as to keep the file small Mr. Creaser at times finds it necessary to sacrifice some clarity in readability and resolution. Once the maps are scanned, Paint Shop Pro, Corel Photo Paint v.5F4 and LView Pro 1.B2 are used to edit the images. Files are saved to TIFF format and then posted on the World Wide Web using Graphic Interchange Format (GIF) or JPEG compression, whichever is smallest. Mr. Creaser prefers not to compress images too much, believing that the process distorts the texture of the map. The average file size is 150k and the TIFF images are stored on the hard drive of its UNIX server, which is backed up on a weekly basis.

After the scanning process, some adjustment of the image is often required. In his experience, Mr. Creaser has adjusted the color only rarely. The majority of tonal adjustments, he says, occur with black and white maps. During the editing process he also makes physical adjustments such as correcting paper folds and removing spots from a map. In response to questions about any qualms he may have over using computer software to change the appearance of a scanned image, Mr. Creaser responded that his primary goal is to produce a legible map, not preservation. Once the maps have been scanned they are returned to the collection, with a few being sent to off-site storage. Mr. Creaser does not yet have a firm migration plan for his files.

In his selection of maps for digitization, Mr. Creaser faces several barriers. The size of the scanner's platform limits the size of maps that can be scanned. With larger maps it is sometimes possible to scan the map in sections and then piece it together. With some large maps Mr. Creaser has been unable to piece the map together and has ended up posting the map in sections. An example of this can be found with the oldest map Mr. Creaser has put online, "Plano de la Notable Ciudad de Sevilla, 1848." The map was too large to capture with one scan and Mr. Creaser had difficulty in piecing it together, so he put it online in eight sections and provided a thumbnail of the eight sections put together. Another restraint cited by Mr. Creaser in his selection of maps is copyright. Due to copyright restrictions, only maps before 1922 can be scanned and made accessible on the Web. An exception to this are maps produced by the United States government, which do not fall under copyright restriction.

In a relatively short period of time Mr. Creaser has made a number of impressive maps available to millions of potential users. His project is still in the experimental phase, but it has already shown the enormous potential, as well as problems, that exist in the digitizing of maps. The Perry-Castañeda Library has shared many of the same experiences and an analysis of its program provides further insight into the processes involved in the digitizing of maps.

Imaging maps at the University of Texas

In contrast to the University of California's nascent digital map effort, the Perry-Castañeda Library has been scanning maps for the past four years and currently has over 2,500 maps available online. The site is one of the most popular map sites on the Web, receiving over 50,000 hits a day. A comparison of the scanning process at the Perry-Castañeda Library with the Earth Science Library's reveals both similarities and differences between the two programs; provides a clearer understanding into the difficulty involved in scanning maps; and, gives further indication in which direction the map digitization is heading.

Paul Rascoe, a documents librarian at the library, initiated the map digitization program at the Perry-Castañeda Library four years ago. Beginning with Central Intelligence Agency (CIA) maps, the Perry-Castañeda Library site now offers a wide variety of maps, ranging from 19^th century maps to USGS maps. Currently, Mr. Rascoe and three part-time employees are responsible for the preparation, scanning, editing, and HTML write-up of the maps. Similar to John Creaser's setup, the scanning arrangement for maps at the Perry-Castañeda Library is relatively simple. Maps are scanned using a Power Macintosh 7100 and an Apple Color One Macintosh Scanner. The resolution of the scanned maps vary, usually falling between 150-250 dpi. A newer USGS or CIA map is usually scanned at 150 dpi, while an older historical map is ordinarily scanned between 200 to 250 dpi. Images are modified for size and resolution, and edited and compressed using Adobe Photoshop 3.0 or 4.0 The maps are saved as TIFF files and posted online in JPEG or GIF, with the average online file size ranging between 200k to 400k. After the JPEG images are uploaded to the server, they are visually checked using a Power Macintosh running Netscape 3.0. According to Mr. Rascoe, the TIFF formats will soon be available to online users in addition to the JPEG and GIF images.

One of the part time employees responsible for the scanning, editing, and posting of the maps is Joe Arnone. Many of the maps in the Perry-Castañeda Library's collection are too large to capture in one scan, necessitating several scans of the map and then piecing it together. Once an oversize map is scanned, Photoshop is used to piece a map together and to clean up any blemishes on the map. Mr. Arnone cites the capturing of a map's text and countering the deterioration of the paper and ink as areas of difficulty he often encounters when editing a scanned image. A section of the Perry-Castañeda Library maps are from the 19^th and early 20^th centuries. With maps more than fifty years old, deterioration of the paper and fading of the ink, in addition to the treatment of a map over the years, can present problems in capturing a quality image. Paper may become brittle or start to yellow; the color may begin to fade; or, in some cases, folds and wrinkles are present. With Photoshop, a filter can be used to render text more compact and legible. Additionally, the yellowing of paper can be countered, and a color code can possibly be restored. In cases where maps have been folded, the folded area often appears to be darker on the scanned image. This problem can sometimes be corrected by placing a piece of paper behind the map. When problems such as the ones listed above are too much to correct with Photoshop, the map is not put online. Although he alters the scanned image to a certain degree, Mr. Arnone holds reservations about altering too much of the original content, as his main focus his providing an accurate image of the map.

While the array of images available on Perry-Castañeda Library's site is impressive, there are several problems that need to be addressed for online maps to be highly effective. One problem is that many of the maps are not shown to scale, making it difficult to ascertain true representation between points on the map. Mr. Rascoe states that the main objective of the map digitization project is to make an image available, not to provide a one hundred percent faithful representation of a map. He offers the example of a grade school student looking for a USGS topographic map of a particular area. The Perry-Castañeda Library's site provides the student with an easy way to acquire information on what that particular map would look like. Then, if an accurate reading of the scale is desired, a student could go to a library or the USGS and obtain a copy of the map. Mr. Rascoe states that in the near future the USGS maps on the Perry-Castañeda Library site will have some indication of scale.

One area of difficulty Mr. Rascoe cites as providing problems for his digital map site, is the issue of bibliographic control. According to Mr. Rascoe, the problem is currently being addressed, and as a partial solution to the problem, the Perry-Castañeda Library site will soon have a searchable database. Further problems exist with the place names on some of the maps, particularly the CIA maps. On occasion people wrote in mentioning that a geographic name on one of the CIA maps is inaccurate and demanding that the library insert the correct name. Understandably, Mr. Rascoe and his staff do not comply with such a request.

When choosing maps to scan, the Perry-Castañeda Library tries to present government maps of areas of current international political interest, ones of historical value, and maps requested by the public. Both Mr. Rascoe and his staff make the selection of which maps will be put online. Some of the maps selected by Mr. Arnone are from pre-1920 books and atlases sitting on the Perry-Castañeda Library's shelves. A large number of these maps are in books and atlases that are slowly deteriorating, and it is unlikely that efforts will be made to preserve the information they contain. According to Mr. Rascoe, in order to free up shelf space many of the older books and atlases on the Perry-Castañeda Library's shelves are being relocated to offsite storage. On the average, the offsite storage does not have strict environmental controls, and the books and its contents will continue to deteriorate. While scanning may be an imperfect technology in terms of permanence, it provides a temporary way to save a map's image and at the same time offer widespread access to that image.

Although the files that contain a map's image may one day be unreadable, it is apparent that the maps in the 19^th century atlases will likely be lost one day as well. Technological obsolescence is a problem Mr. Rascoe realizes he will have to address in the future, and he is prepared to rescan some of the maps if it is not possible to transfer the files. At the present time, to save room on the server, some of the TIFF files have already been transferred to CD-ROMs. Although the digitizing of maps may be an imperfect preservation tool, it does offer several preservation advantages.

Digital Maps: An upclose analysis

In the Appendix are black and white prints of several maps that provide a better understanding of: how digitized maps compare to microforms; problems associated with the scanning of deteriorating maps; how the compression ratio and level of resolution affect digitized maps; and, finally, the remarkable potential digitization offers. The originals that the maps in the Appendix were drawn from vary in color, size, and purpose. (See WAML Website at http://www.waml.org/ to view online color images of these maps.) As mentioned above, many of the older maps cannot be completely restored to their original state. A good example of this condition is found with the 1849 "Hispania" map (see the loose color photocopy insert in this issue of the 1849 Hispania map reduced). The original 10" x 12" map in the atlas is in poor shape. The paper is deteriorating and losing color; the color code of the map has begun to fade; and someone has written extensively on the edge of the map. With the digitized image, the paper deterioration is less noticeable; the color has been slightly restored; and, the handwriting has been erased. One area where the scanning failed to correct a problem is in the center of the map, where a dark streak appears where the map was in the binding. The same problem is evident with the map of the "British Isles," where a dark streak appears down the center where the map was in a binding. When considering a problem of this nature, it is necessary to look at the end result: an aged map that is slowly deteriorating was scanned, cleaned up to the fullest extent possible, and its image made available to millions of users. Although both scanned images are not perfect, having them available online is preferable to having them sit, neglected, on a shelf in the library.

An examination of several additional digital maps provides further insight into the problems involved with digitizing maps. The "Map of the Battlefield of Gettysburg" shows a noticeable contrast in the tone of the surface. An analysis of prints of the "Estonia," and "Conflagration in San Francisco" maps show the difficulties involved in picking up small characters of text and thin lines.

In contrast to the "Estonia" and "Conflagration in San Francisco" maps, the prints of topographic maps for "Crater Lake" and "Aspen" perform well in capturing the small text and thin, closely associated, contour lines. The same characteristics are evident in the "Stalinabad, USSR" map, which in addition to providing fine detail, presents a wide range of colors. The map "Japan: The Chinese Factory Street of Teng-chan at Nagasaki" provides fine detail of a wide range of colors and small characters. An even more impressive display of colors is found on the "Portion of Northern California Map." While the array of colors is visually appealing, they have nothing but artistic value if some sort of color code is not included with the map.

As discussed above, the impact of lossy compression may or may not be noticeable when viewing an image. To allow for a better appreciation of the subtle changes involved with compression, the appendix has two versions of the same map, "Principato citra olim Picentia," set apart by the different compression methods used to store the file. An example of differences in resolution levels can be found in a comparison of the two copies of "Plan et attaque d L'Isle Ste. Lucie."

While it cannot be denied that digitized maps have their problems, a comparison with photocopies gleaned from microfilmed maps provide insight into the way digitized maps offer more attractive benefits than microfilm. In the appendix are two photocopies of maps found on an uncataloged roll of microfilm in Perry-Castañeda's map library. Although the quality of the photocopies does not provide a completely faithful reproduction of the microfilmed image, it does allow for a cursory understanding of how maps look on microfilm. Both photocopies give examples of how microforms can pick up fine detail such as contour lines and small fonts. Obviously, the lack of color is one of the first things noticeable about the photocopies and microfilm in general. Although problems with the durability of color microforms may be improved upon in the future, trends seem to indicate that digitization will be the media of choice for capturing maps in the years to come.

Conclusion: The Future of Map Reproduction

What does the future hold for the imaging of maps? Is it too early to proclaim "microcartography" dead? As evident by the 50,000 hits a day the Perry-Castañeda's map library site receives, it is apparent that digitization offers amenities that micoforms cannot. Digitization offers color and an improved range of access options. Images of maps captured at high resolution with 24-bit color or 8-bit black and white provide a detailed copy of the map, which can be saved in lossless TIFF format as an archival record. A wide variety of uses can then be derived using JPEG compression or other space saving compression methods. Once a file is placed on a server, anyone with a computer and a modem can have access to a map.

Despite their impressive traits, digital images cannot yet be considered the clear choice for digitizing maps. Shortcomings still exist with cost, resolution, and the always troubling question of permanence. However, headway is being made with the above problems. The cost of memory is decreasing; methods of compression are improving; and advances are continuously being made with scanning and resolution. In the future it could very well be possible to use digital cameras to image maps. Recently the Lawrence Livermore National Laboratory modified its digital camera to photograph large maps. Their results were mixed, as the file sizes were all over 100MB each. Mr. Rascoe has also experimented in using digital cameras for imaging maps, but encountered difficulty in capturing smaller fonts.

With the increase in the digital imaging of library and archival collections has come the lament that money is being diverted from a proven preservation media (microforms) and rerouted to less-stable digital technologies. While the microfilming of maps offers considerable advantages as a means of preservation, is it that much of an advantage when it is an image that is missing essential detail such as color? Digital imaging captures color and via the Web raises awareness of the existence of older maps, which, as a result, could increase the chances that heightened efforts will be made to preserve the original map. Also, as evident in the University of Texas's map imaging project, maps that would never be microfilmed, or, made the focus of preservation efforts, are being digitized and, at least for the present, their images are being saved. Despite shortcomings with digitization, the technology will continue to be the choice for capturing the intricate detail found on maps.

ENDNOTES

1 The term microreproduction will be used to describe the process of making microcopies of documents on either opaque or transparent materials. Digitization refers to the converting of an image into binary code.

2 Capture: to preserve in permanent form.

3 The term microforms is a broad term used in reference to either microfilm or microfiche.

4 Life expectancy: length of time that information is retrievable.

5 The University of Texas's Perry-Castañeda Library holds over 225,000 maps. The University of California's Earth Sciences and Map Library houses over 340,000 maps. The above numbers are conservative estimates, as there as maps in atlases and books that are not counted towards each library's holdings.

6 Gilles Langelier, "Microfilming of Cartographic Documents," ACML Bulletin 30 (1979): 1-8.

7 Early map photo reproduction projects were carried out by the United States Army Map Service and the Office of Strategic Services during World War II. Michael Bruno, "Maps on Microfilm; Some Factors Affecting Resolution," Journal of the Society of Motion Picture Engineers 41 (1943): 412-425. Bruno's article details results of the reproduction of maps in 35mm color and 35mm black and white film; Gerrit E. Relstra. "Photoreproduction of Maps: Practical?" Library Journal 76:6 (15 March 1950): 464-465.

8 R.E. Ehrenberg, "Conserving a cartographic heritage: microfilming at the National Archives of the US" International Council on Archives. Microfilm Committee. Bulletin 6 (1977): 21-27; Langelier, 1-8.

9 Larry Cruse and Sylvia B. Warren ed., Microcartography: Applications for Archives and Libraries (Santa Cruz, California: Western Association of Map Libraries, 1981), 2. Mr Cruse defines microcartography as "cartographic related materials registered on film in such a way as to require magnification or enhancement for their full utilization."

10 Philip Hoehn, "A Simple Map Microfilm Program," in Microcartography: Applications for Archives and Libraries, ed. Larry Cruse with Sylvia B. Warren, (Santa Cruz, CA.: Western Association of Map Libraries, 1981), 47-52.

11 Hoehn, Phil. phoehn@sulmail.stanford.edu 27 March 1998, 2 April 1998, re: microfilming of maps, (email to Tom Corsmeier); Stewart, Charles cstewart@library.berkeley.edu 22 April 1998, re: microfilming of maps (email to Tom Corsmeier).

12 Hoehn, Phil. Phoehn@sulmail.stanford.edu 24 April 1998, re: University of California/imaging of maps, (email to Tom Corsmeier); Stewart, Charles, 22 April 1998.

13 James Weiferman, Map Librarian, Perry-Castañeda Library, interview by author, 5 April 1998.

14 Charles Stewart, interview by author, 13 April 1998, via telephone.

15 Charles Stewart, 13 April 1998; Ted Hodur, "Color-Color-Color: The Micrographic Potential," Special Libraries Association, Geography and Map Bulletin 142 (December 1985): 48-55. Mr. Hodur places the dye stability of color microforms between eight and thirty years.

16 Imaging: the process in which a document is electronically captured or created as an electronic picture without the interpretation of the actual content, and stored as a sequence of 1s and 0s. Definition taken from Preservation Microfilming: A Guide for Librarians and Archivists, 2nd ed. Lisa L. Fox, ed. (Chicago and London: American Library Association, 1996), 364.

17 Anne Kenney and Stephen Chapman, Digital Imaging for Libraries and Archives. (Itacha, New York: Cornell University Library, 1996), 2, 8.

18 Kenney and Chapman, 8. Archival quality: an image meant to have lasting utility. An "archival" digital image is commonly an image kept off-line in a safe place. An archival quality digital image is often of higher quality than the digital image delivered to the user.

19 Kenney and Chapman, 5-8, 111-112..

20 Kenney and Chapman, 5-6, 9. For example, 100dpi = 100², or, 10,000 dots per inch. Howard Besser and Jennifer Trent. Introduction to Imaging: Glossary; available at http://www.getty.edu/gri/standard/introimages/Gloss.html, accessed 11 April 1998.

21 8 bit image: a digital image where 8 bits are allocated for the storage of each pixel. An 8 bit image can include up to 256 possible colors. With a 24 bit image, 24 bits are set aside for the storage of each pixel and the image can include up to 16 million possible colors. Definition found in Besser and Trent's Introduction to Imaging: Glossary; accessed 11 April 1998; Kenney and Chapman, 5-6.

22 Kenney and Chapman 7-8.

23 Kenney and Chapman, 8.; Besser and Trent. Introduction to Imaging; accessed 13 April 1998. Jennifer Durran, Developments in Electronic Image Databases for Art History; available at http://palimpsest.stanford.edu/bytopic/imaging/durran1.html, accessed 12 April 1998. The JPEG compression algorithm regularly attains compression ration of between 10:1 and 20:1. The compression process reduces the size needed for a file's processing, storage and transmission by methods such as abbreviating repeated information, or eliminating information that is difficult for the human eye to see.

24 Kenney and Chapman, v.

25 Joint Task Force on Text and Image Management. Preserving the Illustrated the Illustrated Text (Washington, D.C, 1992).

26 The University of California's Earth Science Library Web site is available at http://www.lib.berkeley.edu/EART.

27 John Creaser, jcreaser@library.berkeley.edu; 6 April 1998, re: Map Scanning at the University of California, (email to Tom Corsmeier). Mr. Creaser places the amount of time required to select, scan, and write the HTML for a map at between fifteen minutes and one hour. He estimates that on the average another twenty minutes is required to catalog a relatively easy map.

28 John Creaser, 6 April 1998, (email to Tom Corsmeier)

29 John Creaser, 6 April 1998, (email to Tom Corsmeier); 23 April 1998, re: Map Scanning at the University of California, (email to Tom Corsmeier)

30 John Creaser, 6 April 1998, (email to Tom Corsmeier).

31 The map is available at http://library.berkeley.edu/EART/maps/svilla.html.

32 John Creaser, 6 April 1998 (email to Tom Corsmeier), 23 April 1998, (email to Tom Corsmeier).

33 The Perry-Castañeda map site is available at: http://www.lib.utexas.edu/Libs/PCL/Map_collection/Map_collection.html

34 Paul Rascoe, interview by author, 23 April 1998; Joe Arnone, interview by author, 8 April 1998 and 22 April 1998.

35 Joe Arnone, 8 April 1998

36 Paul Rascoe, 23 April 1998.

37 Paul Rascoe, 23 April 1998. Mr. Rascoe cites the most common complaint coming with the CIA maps identifying the body of water off the Korean Coast as the Sea of Japan. This designation has drawn the ire of many, who resent the name and believe the body of water should be referred to as the East Sea. An example can be found with the "Korean Peninsula" map, available at: http://www.lib.utexas.edu/Libs/PCL/Map_collection/middle_east_and_asia/Korean_Peninsula.GIF.

38 Paul Rascoe, 22 April 1998

39 Paul Rascoe, 22 April 1998.

Appendix

A Sample of maps from the Perry-Castañeda Library's Web site

Hispania (also in this issue on a loose color photocopy insert)

Available at: http://www.lib.utexas.edu/Libs/PCL/Map_collection/historical/Ancient_hispania_1849.jpg

Aspen

Available at: http://www.lib.utexas.edu/Libs/PCL/Map_collection/united_states/Aspen_Co_1987.jpg

Crater Lake

Available at: http://www.lib.utexas.edu/Libs/PCL/Map_collection/National_parks/Crater_Lake_88.jpg

Japan: The Chinese Factory Street of Teng-chan at Nagasaki, founded in 1868

Available at: http://www.lib.utexas.edu/Libs/PCL/Map_collection/historical/Titsingh_Chinese.jpg