C.1.1 The Library of Congress and the National Digital Library Program
The central mission of the Library of Congress (Library/LC) is to assemble, preserve, and provide access to a universal collection representing human knowledge, in order to serve the United States Congress and the American people. During the next several years, the provision of access to this collection will increasingly be accomplished via online networks and the Library of Congress will work cooperatively with other libraries and archives to establish a national digital library.
To support its growing role in online access, the Library has established the National Digital Library Program (NDLP), which has as its primary focus the conversion of historical collections to digital form. During the next five years, the Library plans to convert as many as 5 million of its more than 100 million items. The material to be converted includes books and pamphlets, manuscripts, prints and photographs, motion pictures, and sound recordings. Some are in their original forms while others have been reformatted as microfilm or microfiche.
As America's national library, the Library of Congress is committed to establishing and maintaining standards and practices that will support the development of the national digital library.
The Library of Congress seeks proposals to digitize portions of its retrospective 35mm microfilm collection. The Library notes that one key purpose for scanning is to create an archival copy; distribution of these copies will follow a careful determination of their copyright status. The Library will not require the contractor to perform work if, by so doing, the contractor will infringe upon third-party rights under the Copyright Law of the United States. The Library's archive of master microfilm which reproduces materials from the LC collections has been created largely by the LC Photoduplication Service over the past fifty years. The microfilm of the historical collections which will be selected for scanning within the NDLP was produced between 1950-1994. This time frame encompasses some of the very early microfilm produced by the Library, when preparation and bibliographic practices were often cursory, through a period in the late 1970's, when the Library established standard practices for preparing and filming various collections formats such as serials, monographs, newspapers and manuscripts. Many current LC practices follow these established procedures, or they interpret national standards which currently govern the production of preservation microfilm. The focus for the NDLP will be American holdings, and the microfilms to be digitized contain materials like the following:
The Library may also choose to digitize the content of other microfilms, including such items as government technical reports.
The digital images produced together with their finding aids will be presented as collections, i.e., groupings of primary-source documents. Each digital collection will be accompanied by introductory and explanatory material. Larger collections include the 97,000-image Abraham Lincoln Papers; smaller collections include a 5,000-page group of pamphlets on the growth of the railroads in the nineteenth century.
C.2 SCOPE OF WORK
High-quality digital images that reproduce the microfilm frames shall be created. The Library's microfilms present a number of significant problems in image capture, including frames with a range of tonal values and reels in which the sizes of the document images vary greatly from frame to frame. Successful and efficient capture of these images shall require careful analysis of the microfilm and may require sophisticated special equipment or the customization of the types of equipment most frequently used for microfilm scanning.
The raster-scanned images to be produced shall meet the needs of researchers at the Library and in sites reached by the Internet around the world. (See Section J, Attachment 2, for additional information on the use of collections by researchers) The Library seeks a balance between efficient production and custom work that strikes the best compromise between two competing goals:
The delivered sets of images shall also be coherently and logically named and/or numbered, placed in delivery directories with prescribed characteristics, and accompanied by a carefully maintained scanning log . After the images are loaded into the Library's retrieval system, the named images and directories will link the images to bibliographic records (computer catalog "cards") or to finding aids (not unlike the yellow pages in a telephone directory).
Following the startup and testing activity, all work and production of the digital images shall be performed under individual task orders issued under this contract. Each task order will treat a coherent set of films and shall begin with the contractor analyzing these films and proposing to the Library how they should be digitized. The list of requirements which follows within this Statement of Work references explanatory and descriptive information in Attachments in Section J.
C.2.1 Contract Startup/Testing Phase and Task Order Analysis
Two features of microfilm digitization warrant a startup activity to launch this contract: (1) the variation in Library of Congress microfilms, and (2) the complexity of the Library's requirements for digital images and their delivery. For these reasons, the first task to be carried out under this contract shall entail the study of a representative cross section of microfilms and the production of a set of test images.
C.2.1.1 Variation in Library Microfilm
The fifty years of Library of Congress microfilm production have seen considerable variation in practice and the use of problem-solving for various anomalies encountered during filming. A comprehensive overview of these variations is provided in Section J, Attachment 1. Some of these variations present special difficulties for digitizing and shall require a greater level of effort from the contractor (See Pages J-15 and J-16). There is considerable variation in the types of original materials presented on the microfilms, ranging from handwritten manuscript documents to printed music notation to photographs reproduced as printed halftones. The microfilms also exhibit considerable variation in quality, resolution, tonality, and reduction ratio.
C.2.1.2 Varying Levels of Effort
The microfilm frames that represent the source for contractor-produced digital images may vary from task to task and from reel to reel for a specific task. The following variables which may require the contractor's level of effort to change have been used to develop Section B, The Schedule.Specific variables may include the following:
C.2.1.3 Special Difficulty Factors
The contractor shall identify special difficulty factors during the analysis associated with each task to be performed. This shall be included in each specific task proposal and shall be subject to review and verification by the Library.The special difficulty factors include:
C.2.2 Initial Task Analysis
Due to the complex, interrelated technical elements which may need to be specified for each task, an initial nine week contract startup and testing phase is included. This initial phase is intended to provide a time during which the contractor and NDLP staff shall work together to address and finalize the definition of requirements which require mutually agreed-upon definitions for varying levels of effort and the special difficulty factors.
The outcome of the start-up and testing activity shall (1) establish the specifications for the first task order and (2) provide for the provisional establishment of other key specifications for additional image types likely to be encountered in later tasks under the contract.
During the project's startup/testing phase, the Library will furnish representative examples of the types of microfilms from which digital images shall be produced. They will be positive copies or duplicate negatives based on the contractor preference determined prior to award. The following microfilms and information regarding the appropriate filenaming and directory structure to be employed will be provided:
C.2.2.1 Contract Startup/Testing Phase
The startup phase shall include the following actions:
All follow-on task orders shall require similar contractor analysis of the microfilm prior to the issuance for any given task order. The analysis and resultant proposal shall address all general and specific requirements detailed. Meetings with the COTR may be required to discuss the task, as necessary, throughout the analysis period.
C.2.3 Project Management
At the Library of Congress, the Contracting Officer's Technical Representative (COTR), will manage and coordinate this effort, while the contractor's project leader shall perform a similar function for the contractor. The COTR and the contractor's project leader will serve as the principal points of technical communication between the two organizations.
The objectives of the project management approach are:
In each task proposal, the contractor shall establish milestones against which progress shall be monitored and evaluated during performance of the task order. These milestones must be related to distinct and measurable deliverables. In addition to the scanning log, the contractor shall submit periodic written reports of progress during the course of each task. The timing of such reports shall be determined when the specific task is planned; for longer tasks, monthly reports may be required. The reports shall provide a summary narrative that includes key events or activities, noting special problems or difficulties encountered, and addressing proposed methods for corrections of such problems as the work continues. The reports shall note changes in equipment or procedures and provide statistics that indicate the accomplishments of the period described.
C.2.4 Key Personnel
For purposes of this contract, the contractor's key personnel are defined as the project manager and designated alternate, digital scanning personnel, and quality assurance inspector(s). The contractor's project manager or designated alternate shall have full authority to represent the contractor in all matters regarding the contract. The project manager/designated alternate shall be in contact within a period of 24 hours after receipt of notification (telephone, facsimile, or in writing) from the Library to discuss any technical or contractual matter.
C.2.5 Library Furnished Material/Microfilm For Scanning
The microfilm materials selected for scanning for this project are all 35mm roll microfilm on 100-foot reels. The Library will furnish either duplicate negatives (second generation microfilm) or positive copies (which can also be second generation film or third generation film) based on the contractor's preference (which has been specified in the proposal prior to contract award). In either case, the film will be produced from the existing camera master negative and will be second generation microfilm produced especially for the National Digital Library conversion program. If a duplicate negative exists, however, the positive may be produced from that negative. The film will be made available at no cost to the contractor prior to issuance of task order and shall be returned to the Library upon completion of the task order. The film will be used primarily for scanning but thereafter, it may be incorporated into the Library's collections.
C.2.5.1 Duplicate Negative (printing master)
A negative polarity, direct duplicate, print master microfilm (resulting in a second generation film) from the camera master negative will be provided. It will be silver-gelatin, non-perforated, polyester-base film. There will be no splices at any point in the microfilm roll.
C.2.5.2 Positive Microfilm
A positive polarity microfilm which may be printed from the camera master negative microfilm (producing a second generation film) or printed from an existing duplicate negative (producing a third generation film) will be provided. It will be silver-gelatin, non-perforated, polyester-base film. There will be no splices at any point in the microfilm roll.
C.2.6 Receipt of Microfilm - Shipment List
The Library will generate lists of reels to be included in each task order which will accompany the shipments of microfilm for analysis and subsequent scanning. The contractor shall inventory the shipment within two working days of receipt and report to the Library's Project Officer or alternate by telephone immediately any discrepancies between the shipping list and the microfilm which was shipped.
C.2.7 Quality Control
A quality control program adapted to this contract in accordance with the requirements and standards (See also Section E, Inspection and Acceptance) shall be initiated, documented, and maintained throughout the life of this contract. The quality control plan shall be implemented for each phase of contract performance beginning with capture of the microfilm through delivery and acceptance by the Library of all deliverables. The contractor shall be responsible for performing all inspections or evaluations of the quality of images and accuracy of filenames and directories for all digital images produced under this contract. Inspection equipment shall be of appropriate quality, accuracy, and quantity and appropriate staffing shall be utilized to ensure that all requirements of this contract are met.
The contractor shall document all quality control procedures and any actions taken including correction of problems, etc. and submit a quality review report along with (or as a part of) the scanning log with each delivery to the Library.
C.2.7.1 Scanning Log
The contractor shall keep a scanning log. At a minimum, this log shall indicate the date and general description of the material scanned, as well as noting exceptions, problems, irregularities, and anomalies of the types described in section C.4.3. The scanning log may be in computerized or paper form. If a computerized log is utilized, it shall be in commonly used software (e.g. WordPerfect, DBase, etc.) and/or delivered as a delimited ASCII or a generic wordprocessing file. A sample log (which is currently being maintained on paper of the type used for other Library projects) is provided in Section J, Attachment 1, page J-17).
The Library will actively consult this log as it carries out its quality review of the materials delivered by the contractor. The accuracy of the logs will be especially important in tracking the movement of batches/lots within a larger task order. The Library will also use the log to guide the modification of its cataloging or finding aids by incorporating the log's reports of missing documents, impossible-to-scan documents, and other anomalies.
C.2.8 Deliverables and Delivery Media
The work for each task order executed under the terms of this contract shall be presented in three major deliveries:
C.2.8.1 Test Samples (when applicable).
Those digital images associated with the task analysis and proposal prior to issuance of task order. If the group of samples will fit on 10 floppy disks or less, 3.5-inch, IBM-compatible floppy disks may be used. Alternatively, and as a requirement if the sample data exceeds the capacity of 10 floppy disks, the samples shall be furnished on write-once CD-ROM disks.
C.2.8.2 Main Delivery
This shall consist of one or more write-once CD-ROMs. The task shall entail the scanning and delivery of batches of reels in lots as discussed in Section F. These first-delivery CD-ROMs are referred to as alpha disks, meaning that they are the first delivery of the image sets. The alpha disks will be retained by the Library.
Unacceptable digital images. When performing reworks, the contractor shall follow all contract specifications and specific task specifications as agreed to for the original scanning and for the filename/directory structure, unless otherwise directed by the Library's project manager. If the rework consists of a small number of images, the contractor may deliver them on either floppy disks or on a new write-once CD-ROM. These are referred to as rework disks, meaning that they contain reworked versions of images that failed in the first delivery. Separate floppy rework disks or rework CD-ROMS shall be produced for each collection (to facilitate archiving of the disks by the Library of Congress).
C.2.8.4 Write-once CD-ROM disks for delivery
As outlined in the subsections that follow, deliveries other than those of small sample batches/lots shall be made on write-once CD-ROM disks compatible with ISO 9660 specifications and containing DOS files in DOS directories. The disks shall be in a single session format. Each CD-ROM and accompanying jewel case shall be labeled with the collection or job names, disk (volume) name (within the job series), date completed, and the indicator "Library of Congress-NDLP."
C.2.8.5 Alternate Delivery Media
Alternate delivery media, e.g., 8mm TAR tapes readable on IBM RS-6000 computers running AIX version 3.2.5 operating system, or delivery of images by file transfer protocol (ftp) which would permit images to be loaded into directories and subdirectories in servers at the Library may be acceptable as negotiated and determined prior to contract award. The Library's consideration of the alternatives will take into account compatibility with the Library's existing systems.
C.2.8.6 Shipping/Packing List Form, Scanning Log, Directory and Filename Lists
Each shipment of digital images delivered to the Library shall include an itemized packing list. When the shipment includes the return of microfilm reels, it should be accompanied by the Library's original shipping list for the job. Each shipment of digital files on CD-ROMs shall be accompanied by the scanning log covering that shipment together with directory and filename lists for the disk.
C.2.8.7 Return of Government Furnished Materials
All products developed under this contract shall belong to the U.S. Government, including the proprietary rights therein. (See H.1, Release, Publication, and Use of Government Furnished Data, page H-1) The contractor shall return to the Library all original materials supplied, including the microfilms. The films shall be returned in reasonable condition, in the correct original labeled boxes with their button and string ties and with the film properly wound head of the reel out. The Library understands that scanning equipment will produce a modest level of wear. The returned films may be incorporated into the Library's microfilm collections after scanning.
If the film is damaged during return shipment, at the contractor facility, or the contractor damages an item during the scanning process, the contractor shall be liable for the cost of the duplicate negative or positive copy. The Library will have a replacement copy produced and the contractor shall be liable for the full cost.
Although the contractor may retain copies of the digital scanned files created as working backups, at the end of the contract period, the contractor shall erase or destroy all backup or duplicate files and materials.
C.2.8.8 Intermediate Production Formats
The contractor shall deliver to the Library any intermediate materials produced in the course of preparing the required images. This may include intermediate film copies, or other output. These intermediate materials shall be labeled in a systematic way. Documentation in the form of logs or inventory sheets shall be supplied.
C.3 IMAGE QUALITY AND FORMAT REQUIREMENTS
Image-quality and format specifications are defined as 1) general and/or functional and 2) specific. After the analysis of the film provided for each defined task order, the contractor shall propose the final set of image requirements and the methods to be used to obtain them. This proposal will be reviewed and approved by the Library prior to the issuance of the task order.
C.3.1 General/Functional Image Requirements
C.3.1.1 Retain Significant Data
It is required that digital images contain all of the significant data in the microfilm image. Success in retaining significant data will be the determined by the legibility of the materials to be digitized under performance of this contract; i.e., when all of the words, drawings or other markings, or musical notes can be read in the digital image as could be read in the document on the microfilm. The Library will further define the significant data to be captured for each task order.
C.3.1.2 Spatial Resolution and Translation of Film Tonality
The scanning system to be utilized shall be capable of producing images with varied spatial resolutions. The system shall also be able to translate film frames with low, moderate, and high levels of tonality into digital images as described below. These digital images may be either bitonal (black-and-white; one bit-per-pixel) or grayscale (typically eight bits-per-pixel) based on an analysis performed by the contractor and approved by the Library prior to issuance of each task order. (See additional discussion in Section J, Attachment 3)
C.184.108.40.206 Low Tonality. Film images for which tonality in the original is not significant, e.g., printed matter illustrated with line art, or where tonality in the original has been lost when microfilmed. This category also includes printed matter with halftone illustrations that are reproduced with excessively high contrast (or too dark) on the microfilm. In the latter case, the assumption is that the illustrations are so poorly reproduced on the film as to render futile any attempt to create high-quality reproductions.
C.220.127.116.11 Moderate Tonality. Film images for which tonality is somewhat significant in the original and which has been successfully brought into the microfilm. For example, a manuscript document with ink and pencil markings may be reproduced in a film image that retains some of the tonal differentiation. In a moderate tonality example, bleed-through will be minimal and paper shade/texture is not pronounced. This category also includes manuscripts with moderate frame-to-frame variation in brightness and contrast.
C.18.104.22.168 High Tonality. Film images are those for which tonality is very significant, e.g., manuscript documents with ink and pencil markings that vary greatly in intensity and/or manifest pronounced bleed-through (or print-through), very dark paper colors, and/or visible paper texture. This category also includes manuscripts with significant frame-to-frame variation in brightness and contrast and printed matter with gravure, litho, or fine-dot halftone illustrations. In all cases, the assumption is that the microfilm has a good (long) tonal range.
C.3.1.3 Ease of Printing
Individual researchers wish to print copies of Library of Congress digital documents on paper. It is anticipated that these individuals will be using personal computers connected to the Library's Internet World Wide Web resource via local and remote computer networks. Typically, a researcher's personal computer will have a laser printer as a peripheral device; the images must be conveniently printed within this system. (See Section J, Attachment 2) The images to be produced shall be printable, as outlined in the following functional terms:
C.3.2 Specific Image Requirements
Irrespective of the polarity of the film that is provided for scanning, all delivered images shall reproduce the polarity of the original item, i.e., paper is white and ink is black.
In the delivered digital image, the top of the original document shall appear at the top of the display screen, regardless of the orientation of the document in the film frame. Note that "right side up" for printed matter is defined as "the top of the book or magazine page" (portrait mode). However, often an illustration or table in a book or magazine may be printed "sideways" (landscape) to fit the page, thus aligning the top of the page with the side of the illustration or table. In these cases, the top of the image shall be the top of the page and not the top of the illustration.
In the microfilms of many Library collections, especially manuscripts, the documents proper are photographed within a larger film frame. It is not uncommon to find documents that occupy about one half of the area of the frame. The following requirements shall apply for cropping of specified frames.
C.22.214.171.124 Within Frame Cropping. Some microfilm frames that consist of a two-page pair (e.g., large books or periodicals that have been filmed in the 2A or 2B positions using reduction ratios greater than 14:1 or when fine print is present) do not produce legible printouts when reduced to 8x11-inch paper. The contractor shall have the capability to crop individual pages from a single microfilm frame that reproduces pair of pages ("two up") filmed in a 2A or 2B position and produce single-page images. These will be defined during task-specific planning.
Note: It shall not be considered acceptable to simply scan the two-page pair, cut the image in half, and then enlarge. Enlarging is defined as interpolating or filling-in pixels to create apparent high resolution.
C.3.2.4 Bitonal Images: Formates and Compression
Bitonal images shall:
C.126.96.36.199 TIFF Version. TIFF version 5.0 has been determined to be satisfactory and shall be acceptable; however, subject to testing, version 6.0 (or later) may be acceptable.
C.188.8.131.52 TIFF Header. It is required that "typical" or "expected" data be provided for most TIFF tags (normally, the data supplied by software default settings). Appropriate values shall be utilized to produce images that meet printing requirements and prevent printing anomalies. The tags currently in use are listed below. Exceptions or options that may not conform to "typical" or default data are noted in the comments column.Description Tag Comments New Subfile Type 254 Image Width 256 actual pixel count Image Length 257 actual pixel count Bits Per Sample 258 Compression 259 Photometric Interpretation 262 Strip Offsets 273 Samples Per Pixel 277 Rows Per Strip 278 Strip Byte Counts 279 Document Name 269 pathname (directory name and file name) as used for delivery of image Artist 315 Library of Congress Date Time 306 date and time scanned
C.184.108.40.206 TIFF Tags 282, 283, and 296. Library practice for TIFF tags 282, 283, and 296 tags may or may not be appropriate for images scanned from microfilm. For a large number of grayscale digital images that reproduce photographs, the Library has employed these TIFF tags as follows:XResolution 282 actual pixel count YResolution 283 actual pixel count Resolution Unit 296 1 (no unit specified) For printed matter scanned directly from paper, the following values appeared in these same tags: XResolution 282 300 YResolution 283 300 Resolution Unit 296 2 In other cases, the Library has received TIFF images for which no values have been supplied for these tags.
C.3.2.5 Grayscale Images: Formats and Compression Grayscale images shall:
C.4 IMAGE FILENAMES AND DELIVERY DIRECTORIES
The contractor shall assign a digital-image filename to each image captured as part of the initial image-capture process and deliver these files to the Library in an arrangement of directories and subdirectories following the specifications outlined below and in Section J, Attachment 4. These are called delivery directories which may consist of as few as 1 image file (e.g., 1 frame); however, no more than 300 images files shall be placed in any one delivery directory.
The filename and directory structure is essential as it will facilitate future access to the images. The contractor shall delivery the images in delivery directories which the Library will archive in repositories that parallel those created for delivery. These directories and the names of the files they contain shall provide the structure for the Library's digital repository, the institution's archive of digital information. The directory names and filenames link the images to elements in the Library's collection-retrieval system.
The content of the digital repository is stored in UNIX-based servers at the Library of Congress. The Library, however, anticipates production and delivery content using equipment that employs the MS-DOS operating system. In addition, sets of images may be delivered to third parties who use IBM-compatible, DOS-based computers. For this reason, the directory names and filenames shall conform to DOS naming conventions. In order to accommodate UNIX needs, any alphabet letters in the file or directory names shall be lower case. Since filename extensions shall be assigned according to file type (e.g., .tif, .jif or .jpg), the first eight characters--the file name proper--become very important.
C.4.1 Identifiers Used to Name Directories
The particular file- and directory names shall be assigned from interpretation of these general specifications.
The Library will specify an identifier for a delivery directory. An identifier is the prefix or left-side (right-truncated) portion of a name that may contain as many as eight characters. For example, the identifier is bj06 might be used as the basis for assigning the directory names bj06001 (for the first 300 files), bj06002 (for the second 300 files), bj06003 (for the third 300 files), and bj06004 (for the fourth 300 files). Other, similar patterns may also be specified for other identifiers.
The identifiers used to name directories also appear in the cataloging or finding-aid data the Library employs in its retrieval systems. When a researcher has found an item of interest in a catalog or finding aid and executes a fetch command, the retrieval system uses the identifier to locate the appropriate repository directory in the Library's digital archive and proceeds to retrieve the appropriate set of image files.
C.4.2 Five File and Directory Structures
Assigning filenames and naming directories for the collections shall be performed according to the five structures identified below and in accordance with detailed specifications regarding these requirements provided in Section J, Attachment 4. In addition, the Scanning Guidelines Summary Table provided in Section J, Attachment 5 provides a summary of features to be recognized and acted upon, missing images to be recorded, and unscannable images to be noted and left unnamed.
C.4.3 Feature Recognition and Missing-and Unscannable-Image Tracking
In order to properly assign file and directory names and enter data into the scanning log, the contractor shall have the capability to:
C.4.3.1 Numbered Documents in Manuscript Collections - 100 Percent Accuracy Required
Numbers printed or stamped on documents shall be identified and used in the assignment of directory names and/or filenames.
C.4.3.2 New Folders in Manuscript Collections - 100 Percent Accuracy Required
The start of a new file folder shall be identified by noticing that the film includes a file folder target or that a file folder label has been photographed in lieu of a target, or by following changes of pencilled numbers on the documents proper (digits that indicate the folder number). These numbers or names shall be used to properly assign names to delivery directories.
C.4.3.3 New Documents in Manuscript Folders - 80 Percent Accuracy Required
The beginning of a new documents (report, letter, etc.) shall be identified and "new document" shall be indicated as a feature.
C.4.3.4 Features and Page Numbers in Printed Matter - 80 Percent Accuracy Required
For some books or other printed matter, the presence of at least four types of features: title pages, tables of contents, lists of illustrations, indexes, and cumulative tables of contents or indexes (for serials) shall be identified. In addition, the actual printed page numbers (when present) for certain books or magazines shall also be identified. Special codes shall be utilized to imbed feature-identifiers in the filenames, as described below.
C.4.3.5 Irregularities Targets - 100 Percent Accuracy Required
Irregularities targets, e.g., targets that are present in the microfilm and indicate anomalies such as "pages missing," "issues missing," "Library of Congress copy missing title page," or "missing pages 14-17" shall be identified and their presence recorded in the scanning log with a summary of the information they impart.
When irregularities targets indicate anomalies within an item, e.g., missing pages in a book, the target shall be scanned and the image inserted in the stream of images being produced a though they represented a page in the original document. The scanned target serves as a place holder for the missing image/page to be inserted in the future. The filenaming shall also proceed as though an additional page has been scanned. When they indicate a whole item to be missing, the target shall not be scanned, but a notation shall be made in the scanning log that the material is missing.
C.4.3.6 Magazine Covers for Two Issues on Same Frame -100 Percent Accuracy Required
Many microfilms of serials in the 2A and 2B positions include the outside back cover of the "last issue" on the same film frame as the outside front cover of the "next issue." In this document, this is called a double-issue serial-cover frame. Two images of each double-issue serial-cover frame shall be captured for each frame and each shall be placed in the appropriate directory. As noted in Attachment 5, Section J, each issue of serial is to be placed in a directory of its own. A notation of the action shall be made in the scanning log.
C.4.3.7 Repeating Images -50 Percent Accuracy Required
Two succeeding images that reproduce the same document page may be accidental or, more often, represent the microphotographer's recognition that the first attempt did not adequately capture the document, e.g., by a wrong exposure. If the microphotographer did notice the problem, he or she will have corrected it on the following exposure. In other cases, to successfully capture both the text and the illustrations, camera settings are often changed. Therefore, when text and tonal materials exist in a single image, such frames are often exposed twice.
When a repeated page is identified, the contractor may at his option either (1) capture both versions of the image or (2) capture the best image. In either case, a notation of the existence of the repeating image and the action taken shall be made in the scanning log.
C.4.3.8 Recording the Occurrence of Unscannable Images -100 Percent Accuracy Required
All instances of images that cannot be scanned shall be recorded in the scanning log. Unscannable microfilm images will usually be those with very low or very high densities or contrasts, representing density or contrast values beyond the capability of the image-capture system. In the future, the Library may desire to locate the paper original for the page represented by unscannable microfilm image and to create a new digital image directly from the paper original to insert in the digital collection. For this reason, the contractor shall leave open the filename that would have been assigned to this image so that it can be assigned in the future.
C.4.3.9 Head-and End-of-Reel Information - 80 Percent Accuracy Required
Many reels, especially those for manuscript collections, begin with a number of explanatory head-of-reel frames. They may also have information at the end of the reel. End-of-the-reel information often repeats information appearing at the beginning of the reel, and information in both locations may repeat for each reel in a multi-reel collection. These frames can be easily distinguished from the content proper since they are typically images of explanatory targets, guides, lists, which provide information or guidance about the content of the microfilm. They do not look like the older documents one expects to find in a historical collection since most times they were produced only for the microfilm edition. Additional information pertaining to the identification of head-of-reel information and which frames are to be scanned will be provided by the Library when a job is assigned. (See Section J, Attachment 1)
C.4.3.10 Identifying Segmented Materials/Images - 100 Percent Accuracy Required
When materials such as foldouts and maps are too large to be accommodated on the 35mm in either 1A or 1B position, they are often filmed in segments or sections in order to maintain the same reduction ratio as the text or other content contained on the microfilm reel. The frame sequence presents the item in segments arranged/ filmed from left to right and top to bottom. An overlap is also filmed between adjacent sections to facilitate associating the frames. A target may be filmed preceding a sequence of segmented frames to alert the user that the item has been filmed in segments (See Section J, Attachment 1). Each segment shall be scanned separately, and the proper sequencing shall be maintained in the resulting scanned images.