Emulsion layer(s)—image or image-forming layer(s) of photographic films, papers, and plates.
Film base—the plastic support for the emulsion and backing layers.
Halation—halo or ghost around the desired image on a photographic emulsion. (This is caused by the reflection of rays of light from the base to the emulsion or by internal scattering of light within the film.)
Nitrate film—a photographic film with a base consisting of cellulose nitrate. Nitrate-base films decompose with age and are not suitable for permanent records. The manufacture of nitrate film by Eastman Kodak Company in the United States of America was discontinued in 1951, but older nitrate motion-picture films are often found in storage. It is not always possible to determine by visual examination if a film has a nitrate base. However, neither KODAK nor RECORDAK Microfilms in any width were ever made on nitrate base.
Non-curl backing layer—a layer, usually made of gelatin, applied to the side of the film base opposite to that of the emulsion layer, for the purpose of preventing curl.
NOTE:It is comparable to the emulsion layer in thickness and is not removed in processing. (Antihalation or other layers removed in processing are excluded from this definition.)
Polyester film—a photographic film having a polyester base. This type of base manufactured by Eastman Kodak Company is called Estar Base. It is exceptionally tough and strong and has excellent dimensional stability. Microfilm emulsions on Estar Base are currently supplied for many purposes. Kodak currently manufactures only microfilms on Estar Base.
Safety photographic film—photographic film which passes the ignition time test and burning time test as specified in ANSI and ISO Standards.
Safety poly(ethylene terephthalate) base— a polyester film base for recording materials composed mainly of a polymer of ethylene glycol and terephthalic acid. All safety films (both acetate and polyester) manufactured by Eastman Kodak Company meet these requirements. This means that they are difficult to ignite and are slow burning.
All silver-gelatin Kodak Microfilms on Estar Base, when processed as recommended by Kodak, meet the current specifications established by the American National Standards Institute, Inc., (ANSI) for films intended for use as LE 500.
Substratum (subbing or precoat)—the layer that bonds the emulsion to the base.
Electronic Imaging
With the coming of electronic digital imaging systems, the need for continuing the quality concepts already established in the micrographics arena has evolved. Following are a few
key concepts.
Digitization—use of a scanner to convert documents (on paper or microforms) to digitally coded electronic images suitable for electronic storage.
Digital—the use of binary code to record information. “Information” can be text in a binary code (e.g., ASCII), images in bitmapped form, or sound in a sampled digital form or video.
NOTE:Information is recorded digitally for accuracy in storage and transmission. Some types of data manipulation are easier in digital form.
Scanning—1.) In electronic imaging, scanning is the operation which precedes digitization, where the surface of a document is divided into pixels and analog values are collected representing the optical density (brightness and possibly color) of each pixel.
2.) In electronic imaging, OCR scanning is the conversion of marks that represent symbols into symbols for use in a data processing system. The paper or microfilm with the human-readable marks is first scanned as an image, then is analyzed to recognize the intended symbol. The result is the set of symbolic information,
in a machine-readable code such as ASCII (also known as handprint character recognition, intelligent character recognition, and optical character recognition).
3.) In micrographics, scanning is the movement of an image on a reader screen in a direction perpendicular to the direction of roll-film transport.
4.) Scanning is the systematic examination of data (ISO).
