Micrographics Glossary of Terms

16mm microfilm: microfilm, which is 16mm in width, commonly used to film office documents up to 8 1/2 by 14 inches.

35mm microfilm: microfilm, which is 35mm in width, commonly used to film documents larger than 8 ½ by 14 inches and often used to film archival records.

Acetate Film: 1: A collective name for Cellulose triacetate and Cellulose diacetate film bases. Acetate safety film was first marketed on a large scale in the 1920′s, due largely to a desire on the part of photographic manufacturers to sell 16 mm home movies that did not pose a risk of fire in balky home projectors or hot attics.

Aliasing: 1. A phenomenon in which a sampled signal is degraded by false lower frequency components. Normally caused by sampling data at an insufficient rate. 2. Distortion of an image on a raster scan display caused when the detail of an image exceeds the resolution of the Cathode Ray Tube – CRT. 3. Image defects generally caused by elements of a scanned image being smaller or not registered with the picture element

ANSI: American National Standards Institute formally the United States of American Standards Institute – USASI and the American Standards Association – ASA.

Aperture: 1. In an optical system, an opening through which light can pass. This is frequently referred to as the “lens stop” or “lens opening” or “diaphragm”; 2. An aperture in a microfilm reproduction system is a hole in an aperture card. See also: Hollerith Card which is specifically designed to hold a frame or chip of microfilm of a specified size – ISO.

Aperture card: a card with a rectangular hole or holes specifically designed to hold a frame or frames of microfilm. An aperture card is often used to store frequently accessed large format documents such as building plans.

Aperture Card Scanner: An aperture card scanner reads information about the drawing – such as the title, version, page, etc. that is punched into the card – in what is called Hollerith code. The aperture card scanner reads the punched data and scans the microfilm window. The result is a digital image similar to what is produced from a paper scanner. When the aperture card scanner reads the punched textual information the data is often used to automatically index the scanned image, allowing unattended batch input of thousands of cards at a time.

Archive Writer: A device for converting Digital Data & Images to an Analogue Long Term Archival Media such as microfilm

Array: Any orderly arrangement of individual sensor elements. In digital imaging, there are primarily three array types; two dimensional or area arrays, one dimensional or linear arrays, and tri-linear arrays consisting of three consecutive linear arrays of red, green, and blue sensitive sensor elements

ASCII: American Standard Code for Information Interchange – basic coding method to convert letters, numbers, punctuation, and control codes into digital form ( a sequence of 1′s and 0′s = Zero’s ) so that it can be understood by other computers.

Aspect Ratio: The relationship between the horizontal and vertical dimensions of an image. The horizontal dimension is normally listed first. For example, a 4-inch (vertical) by 6-inch (horizontal) print has an aspect ratio of 3:2

Automatic Coding: Index methods that are machine readable, i.e., digital or bit code.

Automated retrieval: A microfilm, micrographic and microform retrieval system in which the image / s is displayed automatically. Commonly the user interrogates and index, which may be manipulated by a computer, to locate the image / s.

Automated or semi-automated microfilm scanning, digitizing & imaging: The scanning, digitizing & imaging of 16 / 35 mm roll microfilm

Background: The portion of a document, drawing, microfilm, micrographic and microform or print that does not include the line work, lettering or other information.

Bar code: A series of machine-readable lines of varying width used to capture indexing information.

Binary Digital Code: An optical pattern of clear and opaque rectangles machine encoded or random access retrieval used to index one or more images.

Bitonal Digital Image: A single-bit image comprised of a pixel value of 0 or 1 (or, in some circumstances, as 0 and 255), corresponding to either black or white. This type of image is often used for typography (as in a FAX) and for line art graphs and pictorial works

Bleed Line: 1. A line width change or a change in the character of the edge of a line usually due to overexposure or over-development; 2. Lateral spread or diffusion of a dye-formed image.

Bleed-Through: An effect caused when ink or paint has migrated from the surface of one side of a sheet of paper to the other side. This is generally due to the porous nature of the paper

Blips: In micrographics terms this describes the small marks on the edge of the film that indicates a frame or image. Blips come in 3 sizes; large, medium, small, and by default a forth when none is present. The blip sizes normally indicate small page, medium-document and large-folder

Blooming: An overflow behavior of an individual sensor element in a sensor array caused by excessive light, that manifests itself in a finished image file as a relatively large blush (or bloom) of light from the effected pixel into neighboring ones

Blowback: The optical enlargement of a microimage.

Blurring: A lack of image clarity in which the image is not sharp or distinct.

Brightness: The balance or contrast of light and dark shades in an image. Colored paper can produce different brightness levels in an image

Camera: A photographic device, employing an optical system, used for exposing light-sensitive material

Calibration: The comparison of instrument performance to a standard of higher accuracy. The standard is considered the reference and the more correct measure. Calibrations should be performed against a specified tolerance

Camera negative: microfilm used in a camera to produce original roll of microfilm. For permanent records the camera negative must have a silver gelatin emulsion to ensure longevity of the film. To minimize damage to the microfilm, the camera negative is only used to produce user copies of the microfilm.

C.A.R.: computer assisted retrieval systems. An automated system that uses a database in conjunction with reading “blip” marks on each frame of 16mm microfilm to speed retrieval of documents on microfilm.

Carriage: The table or stage on a unitized microfilm, micrographic or microform reader or reproduction device that holds the microfilm, micrographic or microform.

Carrier: A device used to hold microfilm, micrographic or microform in place on a viewer, reader, reader / printer or reader / scanner or viewer /scanner.

Cartridge: A roll of microfilm placed in a special plastic case either 16 or 35 mm. This form requires special retrieval equipment but does protect the microfilm from dust and fingerprints. 16 / 35 mm microfilm used in CAR systems are housed in cartridges.

CCD: (Charged Coupled Device) are sensors used in digital scanners or cameras to capture the images. The CCD captures light and converts it to digital data that is recorded by the camera. For this reason, a CCD is often considered the digital version of film.

Chromatic: In common terms, chromatic refers to light having the perceived quality of color, as opposed to achromatic. More specifically, chromatic has the quality of hue. All colors other than the neutral colors of gray, black and white are chromatic

Cine mode: Images arranged on microfilm, micrographic or microform with the bottom of one image above the top of the next – like movie film.

Color Space: A geometric representation of colors in space (generally in three dimensions) can be visually perceived or generated using a particular color model

COM: computer output microfilm. Microfilm produced directly from a computer file to microfilm. COM produces high quality microfilm, often in microfiche format

Comic mode: Images arranged on microfilm, micrographic or microform from left to right like a comic strip

Compression (data): The process of encoding data in a manner that reduces the amount of information required than required for the uncompressed data. Compression techniques can be categorized into two major categories: lossless and lossy.…

Compression Ratio: The ratio of a files uncompressed size over its compressed size. A file compressed ten-fold over its uncompressed size would be described as having a ten-to-one compression, expressed as 10:1. Some formats such as JPEG and JPEG 2000 allow the user to specify the compression ratio

Compression, lossless: Data compressed using a lossless compression technique will allow the decompressed data to be exactly the same as the original data before compression, bit for bit. The compression of data is achieved by coding redundant data in a more efficient manner than in the uncompressed format.

Compression, lossy: Data compressed using a lossy compression technique results in the loss of information. The decompressed data will not be identical to the original uncompressed data. Conservative lossless compression can result in a form of lossy compression referred to as visually lossless compression

Contrast: An expression of the relationship between the high and low brightness of a subject or between high and low density areas of a microfilm, micrographic or microform, a photograph or a screen display.

Crop: To cut off or remove the borders of an image. Scanners usually capture the area (dead space) around the target image. Cropping is the act of removing this unwanted data to a specific margin.

Curvature Correction: When scanning bound works, a natural distortion appears from the curve of the pages into the binding. Curvature Correction is a software that allows one to flatten an image and remove that curve. The end result will create a rectangular image with straight text.

Density: Measures the contrast between the image and the non – image background of the film in the case of microfilm formats. In addition density can refer to the degree of darkness in an image & also the percentage of screen used in an image.

Derivative: A file created as a secondary source to the master file. Many times, projects will require a TIFF master file and a derivative file such as .JPG, .PDF, .GIF, etc.

Deskew: The act of rotating an image to compensate for off balanced or crooked images. The end goal is to make the image edges parallel with the edges of the materials in the image

Despeckle: The act of removing noise (grainy dots throughout an image) through smoothing the image without blurring the edges. It is a filtering process that detects areas with noise and ignores complex smooth areas.

Diazo Film: A slow print film, sensitized by means of diazonium salts, which, after exposure to light that is strong in the blue to ultraviolet spectrum and after development, forms an image. Diazo film generally produces non reversible images, i.e., a positive image will produce a positive image and a negative image will produce a negative image.

Digitize:  To convert data (microfilm, fiche, books, newspapers, etc.) to a digital form for use on a computer.
To convert data (microfilm, fiche, books, newspapers, etc.) to a digital form for use on a computer.

Distortion: An aberration of a lens that causes the imaging of straight lines as curves, usually near the edge of the field of view.

Duo: A method of recording images on each half of the usable width of the roll of microfilm, micrographic or microform. Exposures are made on one half of the roll and then continued on the other half of the roll in the reverse direction.

Duplex: In micrographics, duplex refers to film that contains two images within one frame. Usually stacked one on top of the other, a duplex roll will contain twice as many images as a regular roll.

Duty cycle (scanner): This term generally refers to the percentage of time a machine or piece of equipment can be in operation in relation to the time it must remain out of operation. For instance, a duty cycle of 100 percent means that the equipment will operate continuously (24×7).

Emulsion: a light sensitive layer coated onto a film substrate. The microfilm images are recorded in the emulsion layer of the microfilm.

Fading: The loss in density of photographic images

File format: Set of structural conventions that define a wrapper, formatted data, and embedded metadata, and that can be followed to represent images, audiovisual waveforms, texts, etc., in a digital object. The wrapper component on its own is often colloquially called a file format.

Film size: Film width, generally expressed in millimeters, e.g. 16, 35 or 105 mm.

Finger Masking: In production scanning, the operator may need to use a finger to hold down a page or document. Finger Masking software will detect the finger and remove it from the image so that it appears a finger was never in the original image.

First generation image: An image, generally used as a master, produced directly from a subject or original document

Frame: That area of the film on which radiant energy e.g. a light source can fall during a single exposure.

Frame numbering: number placed by most 16mm cameras next to each image on the microfilm

Gamma Correction: An adjustment to the intensity (brightness) of an image in order to match the output more closely to the original image. Gamma is the relationship between the density of the film image versus the film’s exposure to light. Gamma correction allows us to adjust the scanned images’ contrast for a variety of applications: to produce more natural-looking images, to “lift” or enhance text on dark film to make it more readable, to compensate for under- or over-exposure, etc.

Ghost images: Spurious multiple images of objects caused by reflection from lens surfaces in cameras etc

GIFThe Graphics Interchange Format (GIF) is an 8-bit-per-pixel bitmap image format. The format produces images that are small and efficient through the use of a limited 256 color palette and of the Lempel-Ziv-Welch (LZW) lossless data compression scheme. GIF is widely used for graphics with areas of solid color such as maps, illustrations

Gradation: In photographic originals and reproductions, the rate at which density changes.

Gray Scale or Grayscale: An array of adjacent neutral density areas varying by a predetermined rate or step from black to white and used to expose film to determine its sensitivity curve.

Grid pattern: An array of horizontal and vertical lines – usually imaginary that divides and area of a microfilm, micrographic or microform – usually microfiche into spaces called frames

Heading: An index placed at the top of the microfilm, micrographic or microform – microfiche, jacket or aperture card to identify its content.

Hot spot: An area that appears appreciably lighter than the surrounding area, commonly the result of uneven distribution of light by the reflector, optical system or camera lighting.

ICC: The International Color Consortium (ICC) was established in 1993 to create, promote and encourage the standardization and evolution of an open, vendor-neutral, cross-platform color management system architecture. The resulting ICC specification (ISO 15076-1:2005) provides a cross-platform format to translate color data between devices in order to ensure color fidelity

ICR: ICR is an abbreviation for Intelligent Character Recognition. It is an electronic process similar to OCR, but is designed for the recognition of handwritten characters and their conversion to electronic characters. Because of the highly variable characteristics of handwriting, ICR accuracy tends to be much lower than what is achieved with OCR

Image: A digital representation of a document.

Image arrangement: The placement of microimages within a given microform.

Image orientation: The arrangement of images with respect to the edges of the film

Image scanning: Image scanning, in data processing, the act of optically analyzing a two or three dimensional image and digitally encode it (digitise it) for storage in IT as a computer file. Document Scanning or Image Scanning is the action or process of converting text and graphic paper documents, photographic film, photographic paper or other files to digital images. This “analog” to “digital” conversion process

Index frame: Usually, the first or last frame of a series of images on a 16 or 35 mm microfilm, micrographic or microform or microfiche that records a table of contents or index to facilitate locating the contents of a microform.

Indexing: Alphabetic or numeric list of items that serve as a measure or indicator of something.

Interpolation:  To put it simply, Interpolation is the use of software or hardware to scale the resolution of an image up or down. This is not the ideal technique as the software is adding or removing pixels to meet the desired resolution. Generally scaling down is acceptable, scale up is frowned upon.

Jacketed microfiche or Jackets: A flat transparent plastic or polyester carrier with single or multiple channels made to hold single or multiple microfilm, micrographic or microform images of 16 mm or 35 mm film strips that are sleeved or inserted into plastic or polyester jackets containing three to eight sleeves or channels.

JPEG: JPEG (Joint Photographic Experts Group) compression is superior to other formats such as GIF for reproducing full-color and greyscale images, but JPEG is still a ‘lossy’ form of compression, meaning that parts of the image are discarded in the process of converting it to a JPEG file. Conservative levels of JPEG compression can have negligible impact on the resulting image as far as the human eye is concerned, and still reduce the file to a fraction of its original size. At higher levels of compression however image blurring and ‘artifacts’ can appear, though this is the compromise necessary to achieve very small file sizes.

JPEG 2000The Joint Photographic Experts Group developed JPEG 2000 as an open imaging compression and file format standard (ISO/IEC 15444-1:2000) with the intention of superseding their original JPEG standard. JPEG 2000 is a wavelet-based image compression method that provides much better image quality at smaller file sizes than the original JPEG method.

JPEG XR: JPEG XR (JPEG Extended Range) is a still-image compression standard and file format for continuous tone photographic images, based on technology originally developed and patented by Microsoft under the name HD Photo (formerly Windows Media Photo).  It supports both lossy and lossless compression.

Lens: The optical instrument or arrangement of light refracting elements designed to collect and distribute rays of light in the formation of an image.

Magnification ratio: The expression of the relative degree of enlargement by an optical instrument; usually expressed in diameters of times, e.g. 16X = 1:16, 24X = 1:24, 30X = 1:30 etc

Megapixel: A megapixel is one million pixels, and is commonly abbreviated “MP.” The megapixel count of a camera sensor is one of the most common characteristics used in describing and comparing digital cameras

Metadata: Information about an analog or digital object, a component of an object, or a coherent collection of objects. Metadata describing digital content is often structured (e.g., with tagging or markup) and it may be embedded (Metadata, embedded) within a single file, incorporated within the “packaging” that is associated with a group of files

Microfiche: a sheet of microfilm containing multiple images in a grid pattern.

Microfilm: fine grain, high-resolution photographic film capable of recording images.

Microfilm / microfiche readers: equipment used to read microforms and whose primary components include a lens, a light source, and a viewing screen. Microfilm is normally enlarged to original size for reading.

Microfilm/microfiche reader/printers: equipment used to read and produce paper copies of documents from microfilm.

Micrographics: The techniques associated with the production, handling and use of microforms or the science of recording images on microfilm, or microform.

Mirror image: Characterizing a reversal of orientation, as the image of an object formed by a plane reflecting surface. Right to left change, as seen in a flat mirror.

Modulation Transfer Function: The sharpness of an imaging system can be characterized by its Modulation Transfer Function (MTF), which is generally equivalent to the Spatial Frequency Response (SFR). One approach to measuring this parameter employs a target with black and white bands of increasing spatial frequency

Monochromatic: Light characterized by having a single wavelength. In more general usage, light or an image composed of a single hue

Multi-Page File: Most images are captured as individual files and therefore need to be opened separately for viewing. A multi-page document is combining multiple images into one file. This is most commonly seen as a multi-page PDF or TIFF. Multi-page documents allow for easier viewing and searching for particular text over a number of different documents.

Negative Film: In micrographics terms this indicates the polarity of film. Negative film is black with white letters on the documents. When scanning microfilm this is the film poliarity of choice.

OCR: (Optical Character Recognition) The process by which a scanned document is electronically analyzed, so that the text information can be extracted from the image and reproduced as a text file. Text generated by OCR is often input into text search databases, allowing retrieval of the original scanned image based on its content. This text information can also be embedded in your PDF or Word file to make these documents fully searchable as if they were pure text files.

OMR: Optical Mark Recognition (OMR) is a technology for extracting data from marked fields, such as checkboxes on printed tests, surveys or ballots. Since OMR technology only recognizes the mark and not the context of a form, positional data where marks are expected to appear must be pre-established

PDF: PDF is a file format developed by Adobe to allow documents to be viewed regardless of the original software, hardware, or operating system which the document was created on. This makes PDF a truly portable format, and as such it has become the de facto standard for the exchange of electronic documentation.

Polarity: Microfilm, micrographic or microform has either negative polarity – white lettering on a dark background or a positive polarity – black lettering on a light background.

Positive Film: In micrographics terms this is the reverse of negative film and has white document and black letters. Although a microfilm scanner can scan positive film, the image quality is normally less than that of negative film.

Post Process: Any adjustments that will be made to an image after the scanning process. This includes but is not limited to cropping, curvature correction, deskew, despeckle, OCR, file compression, and finger masking.

PPI/DPI: (Pixels per Inch or Dots per Inch) is a measurement of resolution in a digital image. You can determine the true resolution of an image by dividing the image size in pixels by the size of the document.

Raster data: Data in which a grid or raster of picture elements (pixels) has been mapped to represent a visual subject, e.g., the page of a book or a photograph. The term is derived from the Latin word for rake, suggesting the way in which that tool can be used to inscribe a grid pattern

Reduction Ratio: The ratio between the size of the original document and the size at which it appears on your rollfilm. For example, an 8.5″ x 11″ document filmed at a 25x reduction ratio will appear as a 0.34″ x 0.44″ frame on the microfilm. It is helpful for the scanner operator to know the reduction ratio of the documents on the rollfilm as it makes setup time much faster.

Resolution: The amount of pixels in an image that are captured during the scanning process. Images that are captured at a higher resolution will contain more data and use more disc space, but not necessarily produce a better image. Ideal resolution will depend on a particular project and the images are intended to be used. 300 dpi is the minimum resolution for OCR, 200 dpi is usually ideal for web presentation, 300+ is typically used as an archival standard.

Rollfilm: microfilm, micrographic or microform that can be placed on a reel, spool or core

Rotation: Images on film can be placed sideways or upside down. Rotation is the act of turning the image 90°, 180°, or 270° so that the image can be easily viewed and read.

Sharpening: This is a filter that will increase the sharpness of microfilmed images. Images that were originally filmed out of focus can be blurry or fuzzy. With proper use of a sharpen filter, the readability of text can increase. However, care must be used when using sharpen filters as too much of the effect can produce unwanted, exaggerated edges or “halos.”

Simplex: In micrographics this refers to film that contains a single image within one frame.

Stitching: An image processing method combining multiple overlapping images to create a single image. Stitching can be used in scanning where a single scan of a large object is not able to produce sufficiently high resolution.

Threading: The action of transferring the leading edge of the film from the supply spool or reel, cartridge etc into photographic or micrographic equipment. The threading path may go around all idlers, rollers, sprockets, etc through to the take-up device of the particular equipment.

Thresholding: An image processing method that creates a bitonal (aka binary) image based on setting a threshold value on the pixel intensity of the original image. While most commonly applied to grayscale images, it can also be applied to color images.

Thresholding, adaptive: Adaptive thresholding, also called dynamic or local thresholding, establishes the threshold level for determining whether to convert to white or black at a regional level. The region sampled and method of evaluation vary between applications. Adaptive thresholding at a pixel level (in comparison with neighboring pixels) can yield highly superior results

Thumbnail image: A small, low resolution file normally used as a preview of an image. A thumbnail image is often linked to a higher resolution version of the same image

TIFF: TIFF (Tagged Image File Format) is a flexible standard that it is widely supported by many image processing applications. We use TIFF for black & white images as the TIFF compression algorithm used is best suited to this application. JPEG on the other hand is used for its ability to compress color image file sizes.

Trailer: That portion of the film beyond the last images recorded

TWAIN: Although represented in all upper-case lettering, the word TWAIN is not an acronym, and was derived from Rudyard Kipling’s The Ballad of East and West which contains the line “and never the twain shall meet.” TWAIN is a freely available open protocol that manages the communication between imaging devices and software applications.

Vector data: Data that consists of mathematically described lines and curves. These mathematical representations are not composed of data that is mapped to individual pixels, as is bitmapped or raster data). For this reason, vector data can be scaled (changed in size) without loss of image quality.

Vesicular microfilm: microfilm used to create user copies of microfilm. This duplicating film is sometimes preferred because duplication process does not require the use of chemicals.