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Introduction to Electronic Document Imaging Systems

Number 8.1
Effective: January 1994

Technology Overview

Electronic document imaging systems are computer-based systems that store digitally encoded document images. These systems provide image retrieval and distribution on demand. They are an alternative to paper or microfilm record systems.

In electronic document imaging systems, a scanner converts documents to digitized, electronic images. Each image gets a storage "address," and indexing software finds the image for retrieval. Both paper and microfilm documents can be converted to electronic images.

Electronic document imaging systems are commonly called optical disk systems. Optical disks are frequently used for storage in these systems because of their high storage capacity. However, electronic images can be stored on any digital medium.

An optical disk is made of two glass platters with a vacuum between them. The inner surfaces of the glass platters are coated with a metallic compound. A laser etches digital codes onto this inner surface. The computer reads these codes and translates them into images. The images can then be displayed on a video terminal.

Several kinds of optical disk are available. Some are known as WORM disks (Write Once Read Many). WORM disks cannot be edited or erased. Other types of optical disk include erasable optical disks, magneto disks, and CD-ROM (Read Only Memory). CD-ROM is usually reserved for electronic publishing.

Digital Imaging System Functions

• Input. A scanner brings document images into the system. The document image is digitized and compressed. Document compression normally occurs at ratios of 20:1 or 30:1, corresponding to CCITT Group 3 and Group 4 compression algorithms. CCITT algorithms have become standards for electronic document image storage.
• Indexing. Images are usually temporarily stored magnetically until the accuracy of the scanning has been verified. A video terminal displays the scanned image with an indexing data entry screen. An operator enters indexing information or verifies OCR/ICR indexing. The document image is then recorded on the storage medium -optical disk- and its address is recorded in the indexing database. The indexing database usually remains on the hard disk of the retrieval station or on a fileserver. The index information can be recorded directly on the optical disk. However, many users record the index only on the security copy of the optical disk.
• Storage. Storage subsystem choices include:
  • Direct Optical Disk Drives, in which a single disk is connected directly to the host computer workstation via a peripheral drive
  • Library Units or Jukeboxes, in which multiple optical disks provide mass storage and retrieval, usually over a network of stations
  • Off-Line Optical Disks, in which a single disk or multiple disks are stored "on-the-shelf" and inserted into a disk drive when access to the images on the disk is required.
• Information Processing. Electronic document imaging systems integrate all of the functions necessary for the processing of document information. Data entry into a mainframe or minicomputer, document annotation, referral, on-demand printing or routing to other stations, dual image display, image reduction, enlargement or enhancement, electronic mail, and graphics are all enabled in an electronic document imaging system.

  The ability of several persons at different stations to access a document simultaneously offers the opportunity to review and redesign workflow procedures, in order to increase productivity and output of processed information.

• Output. Images stored in electronic document imaging systems can be printed on a high-resolution laser printer. The images may be printed from multiple printers on a network, or may be directed to a dedicated printer. The images are decompressed or converted back to the original size, and software may allow the user to enhance the image before printing, resulting in a print that is better than the original.
• Communication. Images may be routed over a Local Area Network (LAN) in a work environment, or may be transmitted to remote stations using a fax/modem gateway. This allows immediate access to documents which may be physically distant.

Management of Digitized Public Records

At first glance, EDI systems seem more closely related to electronic records systems than to human-readable records systems. The reverse is really the case. First, EDI systems are imaging systems. These systems store digitally encoded pictures of human-readable records. It might help to think of digital imaging as a media conversion process, rather than a record creation process. Second, digital images are fixed images. Unlike databases, spreadsheets, and word processing documents, digitized images are not dynamic documents. To change them into editable data, they must be converted using some sort of OCR/ICR software in much the same way that a paper document would have to be converted. Third, an index must be used to locate records in an EDI system; images do not have internal access information like electronic records.

When managing EDI systems, users must remember that the digital images are only one part of the system. Paper records are converted to digital images and in many cases the images are output to paper. Any consideration of records management must include the paper elements of an EDI system as well as its digitized portions.

There are four major steps in the life cycle of EDI records - creation, use, storage, and disposition.

• Creation. Records creation usually occurs outside the EDI system. Paper records are created and at some point are converted to digital images. When this conversion takes place depends on the purpose of an organization's EDI system. EDI systems typically are either front-office, or "mail room" applications, and back-office, or "file room" applications.

  In front-office applications, all documents are scanned into the system as soon as they are received. Workflow software may then direct the images to the appropriate workstations for action and response. The images can be directed to several stations simultaneously, allowing multiple tasks to be performed at the same time. The system can automatically prioritize the documents, queuing them at each workstation in a preset manner. This type of application is usually more task-oriented; that is, all subsequent processing of the information contained in the records is performed electronically. Conversion happens very early in the record life cycle in front-office applications.

  In back-office applications, documents are scanned into the system following the processing of the information by traditional methods. The documents are scanned into the system as a substitute for sending them to inactive files storage. Conversion happens relatively late in the records life cycle — usually just before storage — in back-office applications.

• Use. Records management priorities for active records insure that records are reliable and accurate and that they will be accessible as long as they are needed. First, quality control procedures — for scanning verification, medium recording verification, and indexing verification — must insure that documents being recorded are accurate, accessible, and of sufficient quality. Second, proper indexing procedures must be designed to meet the application's access and retrieval requirements. Poor indexing may result in inaccessible images. Third, back-up procedures must be developed to guard against catastrophic loss of documents. Off-site storage of back-up copies is necessary. Fourth, records retention schedules must be observed. Oregon Administrative Rule 166-30-080 states that:

  Public records with a scheduled retention period of less than ten years may be stored on optical disk devices. The original record may be disposed of following verification of acceptable optical image quality. Public records with a scheduled retention period of ten years or more may be stored on optical disk devices provided that the original records are retained in hard copy or on microfilm for the entire scheduled retention period

  Note that the retention is set for the source documents in an EDI system. A commitment to an EDI system may well mean a commitment to preserving paper documents for a significant period of time.
• Storage. Commitment to an EDI system means commitment to providing secure and accessible storage for digital images. The storage characteristics of the disks used must be able to meet the access and retention requirements of the documents they hold. If retention and access requirements exceed the capability of the storage medium, the disks must be duplicated regularly in order to extend and defend the retention and access capability.

  EDI applications should include a migration strategy which provides the ability to retrieve documents recorded on optical disk as hardware and software change. The information recorded by any technology is only as good as the ability to retrieve it.

  Standards for electronic document imaging systems are constantly evolving. Standards are critical in designing and implementing EDI systems. Compliance with standards as they develop is the single best assurance that valuable information will migrate into successive electronic document environments.

• Disposition. The disposition of EDI system documents may take place intellectually or physically. If the system uses erasable optical disks as storage media, outdated information can be overwritten. If the system uses a WORM disk as a storage medium, the index information can be destroyed (effectively making the image inaccessible) or the disk itself can be destroyed. If a disk contains confidential information or information expunged by court order, the media itself and any index entries must usually be destroyed.

What will an electronic digital imaging system deliver?

Without careful planning, the most likely result of installing an EDI system will be very expensive headaches.

Most back-end applications do not warrant the expense — records center storage or microfilming are not as trendy, but will serve the same information needs at a reduced cost. Front-end applications are better candidates, but only if EDI can improve workflow and office efficiency.

If an EDI system is planned carefully, implemented correctly, and maintained constantly, it can provide better information management capabilities than other information processing systems. If not, the public records it stores may not be accessible to tomorrow's users.

Adapted from the Oregon State Archives Records Management Manual (1994).