Microfilm Today


8. Hybrid systems


The increasing popularity of hybrid systems, combining the best features of electronic imaging and micrographics, has created a demand for equipment to link the two technologies. This chapter examines methods of scanning film and converting film-images to digital data and also the reverse process by which digital formats, including text and raster graphics, can be converted to microfilm for archival storage with the advantages of established storage life, freedom from technological obsolescence and established legal acceptability.

Many permutations are viable. It is possible to microfilm paper input and digitise it simultaneously to create both a film and a bit-map image of each page. Alternatives include filming and scanning the film image to provide digital input, or scan but delay filming until all processing work is completed, at which point Computer Output on Microfilm (COM) techniques can be employed to convert the digital data to any microform. A wide range of hardware has been developed to enable these operations.

Digital reader-printers

Digital reader-printers can usually optically enlarge film images on to an integral screen for reference or verification but they also incorporate a facility to scan the images for input to an electronic document management system, printout via a laser-printer or send it for direct fax transmission. Versions are available for all microforms and some models can accept more than one film format.

Factors such as the choice of lenses, film carrier options and the image retrieval methods available are similar to optical microfilm reader-printers, but a much wider range of printout is available via a laser or inkjet printer. Options typically include the ability to mask any part of the image, correction of skewed images, superimposition of repetitive data on prints and electronically variable enlargement.

These units are suitable for applications when there is a need for a method of enlarging images from film but only occasional necessity to convert them to electronic format.

Production film scanners

Production scanners for roll film, fiche or aperture cards are intended for the rapid digitising of high volumes of data from film rather than reference to or enlargement from specific images. A screen may be provided for verification purposes, but if a facility for full size display is required it is usually provided via a CRT monitor in order to show the quality of the digitised data rather than an optical enlargement of the microfilm image.

 Applications include file conversion of microfilm archives to electronic document management systems and the automation of document scanning when assorted input is involved. If documents of different sizes and quality are to be input to an electronic document management system it may not be possible to batch scan and input may be very slow. By microfilming the mixed input to produce standard images on roll film it is possible to digitise the entire roll automatically at high speed. An additional advantage of this method is the production of a film showing the input in its original form which serves as a legally acceptable archival record.

Engineering drawings can be handled in a similar manner by first filming them on to 35mm roll and then scanning the roll. Special film scanners are also available with hoppers which accept batches of aperture cards. These units automatically scan the film, and extract data from punching or marks on the cards.

Production film scanners are fast and relatively expensive. It is necessary to have a long-term requirement for the scanning of fairly high volumes of input to justify an in-house unit, but many microfilm bureaux now offer film scanning services at prices which make even low-volume input economic.

COM recording

When documents need to be available for instant access it is logical to hold them in digital format within electronic document management systems, but the period of peak activity is usually of relatively short duration. Thereafter the need for retrieval remains a possibility, but in many applications the majority of the documents will never be referenced again.

Despite advances in the capacity of digital storage, it is still usually impractical to hold archival information on instant access devices. Another problem is that as systems evolve it is time-consuming and expensive to ensure that all digital archives held on outdated media or in abandoned formats are converted. Repetitive conversion also carries an attendant risk of data loss. The need to cater for large quantities of archival material can act as a brake on system development.

COM (Computer Output Microfilm, also known as IOM - Image Output Microfilm) offers a fast and economical method of converting digital files to proven and archival microformats. In many cases it is sensible to do this as part of the input process to ensure that an absolutely secure back-up is always available. The master films should be preserved in a remote archive, but exact copies can be produced inexpensively for use when access from digital storage is terminated.

If a microfilmed document, thought to be archival, needs to be re-input to an electronic document management system, it can easily be scanned and digitised. Reader-scanners suitable for such applications can also produce prints via a laser-printer if hard copy is preferable.

CAD plotting

CAD applications are often "print bound" because paper plotters are relatively slow. An alternative is to print direct to microfilm, either in 35mm roll format or set into aperture cards. When aperture cards are employed, the recorder normally contains its own film processor in order to deliver fully processed and titled aperture cards at speeds of up to 35 cards per hour.

Specifications for hybrid equipment are included on this site under film scanners for aperture cards, for fiche & jackets, for roll formats and for multiple formats.  COM recorders for all formats and film plotters are listed under digital to film recorders.

UK bureaux offering COM recording facilities are listed under "COM and other media conversion services"

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1. Introduction

2. Microfilm today

3. Getting started

4. Input and output methods

5. Indexing and retrieval

6. Management and control

7. Storage and preservation

8. Hybrid systems

9. Services available

10. Standards

Webmaster: Gerald Baker     Last update 19/7/2018     G G Baker & Associates 2018