facsimile

facsimile or fax, in communications, system for transmitting pictures or other graphic matter by wire or radio. Facsimile is used to transmit such materials as documents, telegrams, drawings, pictures taken from satellites, and even entire newspapers. The surface of the material to be sent is traversed by a light-beam and a photodiode that translates the light and dark areas of the material thus scanned into electric signals for transmission. A receiving station reproduces the transmitted material by a variety of means. Newspapers and television stations have long transmitted and recorded news photographs using a process in which the received electric signals activate a variable lamp that is used to scan a photographic film.

A modern office fax machine scans a page to make an electronic representation of its text or graphics, compresses the data to save transmission time, and transmits it to another fax machine (or computer emulating a fax machine). The receiving machine decrypts the signal and uses a printer (usually built in) to make a facsimile of the original page. Because of the adoption of Group 3 digital standards in 1980 by the CCITT (International Telegraph and Telephone Consultative Committee), facsimile devices have become extremely prevalent in offices. These machines work over the public telephone network; they use digital modems and transmit at data rates up to 9600 bits per second. Images are produced with a resolution of 200 dots per inch. Personal computers can emulate Group 3 facsimile machines if they are equipped with a fax modem, printer, and appropriate software. Facsimile machines that produce higher-resolution images or color and gray-scale images are also available.

in full facsimile

Device for the transmission and reproduction of documents by digitized signals sent over telephone lines. Fax machines scan printed text and graphics and convert the image into a digital code: 1 for dark areas, 0 for white areas. The code is transmitted through the telephone network to similar devices, where the documents are reproduced in close to their original form. Though the concepts for fax technology were developed in the 19th century, widespread use did not occur until the 1970s, when inexpensive means of adapting digitized information to telephone circuits became common.

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A facsimile (From Latin fac simile, "make like") is a copy or reproduction of an old book, manuscript, map, art print or other item of historical value that is as true-to-the-original source as possible using, normally, some form of photographic technique. They differ from other forms of reproduction by attempting to replicate the source as accurately as possible in terms of scale, colour, condition, and other material qualities. For books and manuscripts, this also entails a complete copy of all pages; hence an incomplete copy is known as a "partial facsimile". Facsimiles are used, for example, by scholars to research a source that they do not have access to otherwise and by museums and archives for museum and media preservation. Many are sold commercially.

Facsimiles in the age of mechanical reproduction

Advances in the art of facsimile is closely related to advances in printmaking. Maps, for instance, were the focus of early explorations in making facsimiles, although these examples often lack the rigidity to the original source that is now expected. An early example being Abraham Ortelius's Peutinger map (1598). Innovations during the 18th century, especially in the realms of lithography and aquatint saw an explosion in the number of facsimiles after old master drawings that could be studied from afar.

Facsimiles and conservation

Important illuminated manuscripts like Les Très Riches Heures du duc de Berry are not only on display to the public as facsimiles, but now even scholars may only consult high-quality copies. However, unlike normal book reproduction processes, facsimiles remain truer to the original colours—which is especially important for illuminated manuscripts—as well as defects.

Facsimiles play an important role in the study of history, palaeography and other fields where ready-access to an otherwise unavailable original document is essential for close examination. The copy of Edgar Allan Poe's original manuscript for "The Murders in the Rue Morgue" allows a wider availability of such resources and for researchers to see corrections and changes in the writer's autograph hand in a quality that rivals the original.

Facsimiles are best suited to printed or hand-written documents, and not to items such as three dimensional objects or oil paintings with unique surface texture. Reproductions of those latter objects are often referred to as replicas.

Books of which facsimiles have been made

A very incomplete list includes:

• Gutenberg Bible
• Book of Kells
• Hours of Catherine of Cleves
• Les Très Riches Heures du duc de Berry
• Utrecht Psalter
• Voynich Manuscript

References

External links

• Specialist bookseller, with good information on editions