Frequently Used Imaging Terms and Definition
Optical Terms
AIIM (Association for Information and Image Management) - A Maryland-based organization dedicated to promoting development of systems that store, retrieve and manage document images.
Barcode - Array of vertical rectangular marks and spaces in a predetermined pattern.
CD (Compact Disc) - The trademarked name for the laser read digital audio disk, 12cm. In diameter, developed jointly by Phillips and Sony.
CD-R (Compact disk-recordable) - A standard and technology that enables users to write on and read from a compact disc. This new technology is compatible with existing CDs and CD players.
CD-ROM (Compact Disc Read-Only Memory) - A version of the standard compact disc intended to store general-purpose digital data; provides 556-Mbyte user capacity at 10-13 corrected bit error rate compared to 635 Mbyte at 10-9 for the standard CD.
COLD (Computer Output to Laser Disk) - Microfiche replacement system. COLD systems offer economies as a replacement medium when rapid and/or frequent access to archived documents is necessary. Typically, a 12-inch optical disk platter holds approximately 1.4 million 8.5-by-11-inch pages of information, equal to 7,000 fiche masters.
COM (Computer Output Microfilm) - A system in which digital data is converted into an image on dry processed microfilm.
Compression - In the specific context of digital image representation, compression refers to the process of compacting the data based on the presence of large white or black areas in common business documents, printed pages, and engineering drawings.
The International Telecommunications Union Telecommunications Standards Sector digital facsimile standards contain standard one and two dimensional compression/decompression algorithms.
Data Compression - Conversion of a digital image to a lower number of bits for storage.
Digital - Use of binary code to record information. Information can be text in a binary code (e.g., ASCII), images in a bitmapped form, sound in a sampled digital form, or video.
Dots per Inch (dpi) - Measure of output device resolution and quality. For example, the number of pixels per inch on a display device. Measures the number of dots horizontally and vertically.
Enhancement - Technique for processing an image so that the result is visually clearer than the original image.
Gray Scale - A range of gray tones from black to white used to create an image.
Image - A digital representation of a document.
Image Support - Hardware (scanner, workstation, printer) and software support for image as a system-recognized information type. Typically, although not necessarily, support for optical storage devices is included.
Intelligent Scanner - Scanner with additional image processing capabilities, such as OCR, bar code reading, etc.
OCR (Optical Character Recognition) - The ability of a computer to recognize written characters through some optical-sensing device and pattern recognition software. Characters are read and then converted into computer-processable codes (e.g., ASCII, EBCDIC).
Optical Disk - A disk read or written by light, generally laser light; such a disk may store video, audio, or digital data.
Optical Memory - Memory in which data is recorded and/or read by optical means.
Pixel - Smallest element of a display surface that independently can be assigned color or intensity.
Raster - Description of a rectangular or square array formed by a number of horizontal scan lines comprising a number of picture elements. The number of scan lines establishes the vertical dimension of the array, and the number of picture elements form vertical rows that establish the horizontal dimension of the array.
Resolution - (1) The ability of a scanning or image generation device to reproduce the details of an image. (2) The measure of capability to delineate picture detail.
Scanner - A device that electro-optically converts a document into binary (digital) code by detecting and measuring the intensity of light reflected or transmitted.
Scanner Threshold - Setting that determines whether a pixel is white or black.
Scan Size - The length and width dimensions of the part of a document that can be digitized.
Scan Time - The total time to convert text or graphical information into electronic raster form.
TIFF (Tag Image File Format) - A de facto standard format for image files.
Film Terms
Acetate Film - Safety film with a base composed principally of cellulose acetate or triacetate.
ANSI - American National Standards Institute
Archival Quality - The degree to which a processed print or film will retain its characteristics during a period of use and storage; the ability to resist deterioration for a lengthy specified time.
Base, Film - The transparent plastic on which the photographic emulsion is coated.
Computer Output Microfilm (COM) - Microfilm containing data produced by a recorder from computer-generated electrical signals. A computer output microfilmer is a recorder that coverts data from a computer into human-readable language and records it on microfilm.
Densitomer - A device used to measure the optical transmittance or reflectance density of an image or base by measuring the amount of incident light reflected or transmitted.
Developer - A chemical reagent used to produce a visible image on an exposed photographic layer. It may take many forms for different materials, such as conventional formulas for silver emulsions; plain water used to develop blueprints; or a gas, such as ammonia vapor, used to develop diazo films and prints.
Diazo Film - A slow print film, sensitized by means of diazonium salts, which, after exposure to light strong in the blue to ultraviolet spectrum and after development, forms an image. Diazo film generally produces nonreversible images, i.e., a positive image will produce a positive image and a negative image will produce a negative image.
Dry Silver Film - A nongeletin silver film that is developed by application of heat.
Emulsion - A single or multilayered coating of gelatinous material on a transparent base carrying radiant energy reactive chemicals that create a latent image upon exposure. Processing techniques produce a final, visible, usable image.
Exposure - The act of subjecting sensitized materials to radiant energy.
Film - Any sheet or strip of transparent plastic coated with a light-sensitive emulsion.
Fixer - A solution used to remove undeveloped silver halides from photosensitized emulsions. The fixer usually contains sodium or ammonium thiosulfate (hypo), a hardening agent and an acid or acid salt.
Frame - That area of the film on which radiant energy can fall during a single exposure.
Halide - Any compound of chlorine, iodine, bropane or fluorine and another element. Silver bromide, silver chloride and silver iodine are the light-sensitive materials in most silver emulsions.
Hardcopy - A reproduction of a document usually enlarged and on paper.
Image - A unit of information.
Indexing - Alphabetic or numeric list of items that serve as a measure or indicator of something.
Microfilm - 1) A fine-grain film containing an image greatly reduced in size from the original or the raw film to be used for microphotographs. 2) The process of recording microphotographs on film.
Mil Spec - Filming to government filming standards.
Negative- Appearing Image - A photographic image with light lines, characters and neutral tones on a dark background.
pH - A measure of the acidity of alkalinity of chemical substances, expressed as the logarithm of the reciprocal of the hydrogen ion concentration.
Reduction - A reproduction smaller than the master, expressed as the number of times a given linear dimension of an object is reduced, e.g., 16x.
Resolution - The ability of optical systems and photographic materials to render visible fine detail of an object; a measure of sharpness of an image, expressed as the number of lines per millimeter, discernible in an image. Resolution is measured by examining a microfilmed resolution test chart under a microscope to determine the smallest pattern in which lines cam be distinguished both horizontally and vertically.
Silver Film - Film that is coated with a silver-halide emulsion.
Silver Halide - A compound of silver and one of the following elements known as halogens: chlorine, bromine, iodine, fluorine. See Silver Film.
Spool - The device used to wind up film in a camera or processor after it has been exposed; also called a receiving or take-up spool.
Step Test - 1) A series of orderly varied exposures made to determine the optimum exposure of either film or paper prints. 2) To test contrast for latitude, a step tablet is used in a single exposure.
