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An image scanner—often abbreviated to just scanner—is a device that optically scans images, printed text,
handwriting Handwriting is the writing done with a writing instrument, such as a pen or pencil, in the hand. Handwriting includes both printing and cursive styles and is separate from formal calligraphy or typeface. Because each person's handwriting is ...
or an object and converts it to a
digital image A digital image is an image composed of picture elements, also known as ''pixels'', each with '' finite'', '' discrete quantities'' of numeric representation for its intensity or gray level that is an output from its two-dimensional functions ...
. Commonly used in offices are variations of the desktop ''flatbed scanner'' where the document is placed on a glass window for scanning. ''Hand-held scanners'', where the device is moved by hand, have evolved from text scanning "wands" to
3D scanner 3D scanning is the process of analyzing a real-world object or environment to collect data on its shape and possibly its appearance (e.g. color). The collected data can then be used to construct digital 3D models. A 3D scanner can be based on ...
s used for industrial design, reverse engineering, test and measurement,
orthotics Orthotics ( el, Ορθός, translit=ortho, lit=to straighten, to align) is a medical specialty that focuses on the design and application of orthoses, or braces. An is "an externally applied device used to influence the structural and functi ...
, gaming and other applications. Mechanically driven scanners that move the document are typically used for large-format documents, where a flatbed design would be impractical. Modern scanners typically use a
charge-coupled device A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are ...
(CCD) or a
contact image sensor Contact image sensors (CIS) are image sensors used in flatbed scanners almost in direct contact with the object to be scanned. Charge-coupled devices (CCDs), the other kind of sensor often used in scanners, use mirrors to bounce light to a stati ...
(CIS) as the image sensor, whereas ''drum scanners'', developed earlier and still used for the highest possible image quality, use a
photomultiplier A photomultiplier is a device that converts incident photons into an electrical signal. Kinds of photomultiplier include: * Photomultiplier tube, a vacuum tube converting incident photons into an electric signal. Photomultiplier tubes (PMTs for ...
tube (PMT) as the image sensor. A ''rotary scanner,'' used for high-speed document scanning, is a type of drum scanner that uses a CCD array instead of a photomultiplier. Non-contact planetary scanners essentially photograph delicate books and documents. All these scanners produce two-dimensional images of subjects that are usually flat, but sometimes solid; 3D scanners produce information on the three-dimensional structure of solid objects.
Digital camera A digital camera is a camera that captures photographs in digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film. Digital cameras are now widely incorporated into mobile devic ...
s can be used for the same purposes as dedicated scanners. When compared to a true scanner, a camera image is subject to a degree of distortion, reflections, shadows, low contrast, and blur due to camera shake (reduced in cameras with
image stabilization Image stabilization (IS) is a family of techniques that reduce blurring associated with the motion of a camera or other imaging device during exposure. Generally, it compensates for pan and tilt (angular movement, equivalent to yaw and pi ...
). Resolution is sufficient for less demanding applications. Digital cameras offer advantages of speed, portability and non-contact digitizing of thick documents without damaging the book spine. In 2010 scanning technologies were combining 3D scanners with digital cameras to create full-color, photo-realistic 3D models of objects. Scans are usually downloaded by a computer the unit is attached to. Some scanners are able to store scans on standalone flash media (e.g. memory cards and USB sticks). In the biomedical research area, detection devices for DNA microarrays are called scanners as well. These scanners are high-resolution systems (up to 1 µm/ pixel), similar to microscopes. The detection is done via CCD or a photomultiplier tubes.

# History of scanners

Modern scanners are considered the successors of early telephotography and fax input devices. The pantelegraph (Italian: ''pantelegrafo''; French: pantélégraphe) was an early form of
facsimile machine Fax (short for facsimile), sometimes called telecopying or telefax (the latter short for telefacsimile), is the telephonic transmission of scanned printed material (both text and images), normally to a telephone number connected to a printer o ...
transmitting over normal telegraph lines developed by
Giovanni Caselli Giovanni Caselli (8 June 1815 – 25 April 1891) was an Italian priest, inventor, and physicist. He studied electricity and magnetism as a child which led to his invention of the pantelegraph (also known as the universal telegraph or all-purpos ...
, used commercially in the 1860s, that was the first such device to enter practical service. It used electromagnets to drive and synchronize movement of pendulums at the source and the distant location, to scan and reproduce images. It could transmit handwriting, signatures, or drawings within an area of up to 150 × 100 mm. Édouard Belin's Belinograph of 1913, scanned using a
photocell Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. There is a wide variety of photodetectors which may be classified by mechanism of detection, such as photoelectric or photochemical effects, or b ...
and transmitted over ordinary phone lines, formed the basis for the AT&T Wirephoto service. In Europe, services similar to a wirephoto were called a Belino. It was used by news agencies from the 1920s to the mid-1990s, and consisted of a rotating drum with a single photodetector at a standard speed of 60 or 120 rpm (later models up to 240 rpm). They send a linear analog AM signal through standard telephone voice lines to receptors, which synchronously print the proportional intensity on special paper. Color photos were sent as three separated RGB filtered images consecutively, but only for special events due to transmission costs.

# Types

## Drum

Drum scanners capture image information with photomultiplier tubes (PMT), rather than the
charge-coupled device A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are ...
(CCD) arrays found in flatbed scanners and inexpensive film scanners. "Reflective and transmissive originals are mounted on an acrylic cylinder, the scanner drum, which rotates at high speed while it passes the object being scanned in front of precision optics that deliver image information to the PMTs. Modern color drum scanners use three matched PMTs, which read red, blue, and green light, respectively. Light from the original artwork is split into separate red, blue, and green beams in the optical bench of the scanner with dichroic filters."Pushkar O.I., (2011), Information systems and technologies. Summary of lectures. /O.I. Pushkar, K.S. Sibilyev. – Kharkiv: Publishing House of KhNUE, p.38 Photomultipliers offer superior dynamic range and for this reason drum scanners can extract more detail from very dark shadow areas of a transparency than flatbed scanners using CCD sensors. The smaller dynamic range of the CCD sensors, versus photomultiplier tubes, can lead to loss of shadow detail, especially when scanning very dense transparency film. While mechanics vary by manufacturer, most drum scanners pass light from
halogen lamps A halogen lamp (also called tungsten halogen, quartz-halogen, and quartz iodine lamp) is an incandescent lamp consisting of a tungsten filament sealed in a compact transparent envelope that is filled with a mixture of an inert gas and a smal ...
though a focusing system to illuminate both reflective and transmissive originals. The drum scanner gets its name from the clear acrylic cylinder, the drum, on which the original artwork is mounted for scanning. Depending on size, it is possible to mount originals up to , but maximum size varies by manufacturer. "One of the unique features of drum scanners is the ability to control sample area and aperture size independently. The sample size is the area that the scanner encoder reads to create an individual pixel. The aperture is the actual opening that allows light into the optical bench of the scanner. The ability to control aperture and sample size separately are particularly useful for smoothing film grain when scanning black-and-white and color negative originals." While drum scanners are capable of scanning both reflective and transmissive artwork, a good-quality flatbed scanner can produce good scans from reflective artwork. As a result, drum scanners are rarely used to scan prints now that high-quality, inexpensive flatbed scanners are readily available. Film, however, is where drum scanners continue to be the tool of choice for high-end applications. Because film can be wet-mounted to the scanner drum, which enhances sharpness and masks dust and scratches, and because of the exceptional sensitivity of the PMTs, drum scanners are capable of capturing very subtle details in film originals. The situation was that only a few companies continued to manufacture and service drum scanners. While prices of both new and used units dropped from the start of the 21st century, they were still much more costly than CCD flatbed and film scanners. Image quality produced by flatbed scanners had improved to the degree that the best ones were suitable for many graphic-arts operations, and they replaced drum scanners in many cases as they were less expensive and faster. However, drum scanners with their superior resolution (up to 24,000 PPI), color gradation, and value structure continued to be used for scanning images to be enlarged, and for museum-quality archiving of photographs and print production of high-quality books and magazine advertisements. As second-hand drum scanners became more plentiful and less costly, many fine-art photographers acquired them.

## Flatbed

This type of scanner is sometimes called a reflective scanner because it works by shining white light onto the object to be scanned and reading the intensity and color of light that is reflected from it, usually a line at a time. They are designed for scanning prints or other flat, opaque materials but some have available transparency adapters, which for a number of reasons, in most cases, are not very well suited to scanning film.

### CCD scanner

"A flatbed scanner is usually composed of a glass pane (or
platen A platen (or platten) is a flat platform with a variety of roles in printing or manufacturing. It can be a flat metal (or earlier, wooden) plate pressed against a medium (such as paper) to cause an impression in letterpress printing. Platen m ...
), under which there is a bright light (often
xenon Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...
,
LED A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light ...
or cold cathode fluorescent) which illuminates the pane, and a moving optical array in
CCD CCD may refer to: Science and technology * Charge-coupled device, an electronic light sensor used in various devices including digital cameras * .ccd, the filename extension for CloneCD's CD image file * Carbonate compensation depth, a property o ...
scanning. CCD-type scanners typically contain three rows (arrays) of sensors with red, green, and blue filters."Pushkar O.I., (2011), Information systems and technologies. Summary of lectures. /O.I. Pushkar, K.S. Sibilyev. – Kharkiv: Publishing House of KhNUE, p.39

### CIS scanner

Contact image sensor (CIS) scanning consists of a moving set of red, green and blue
LED A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light ...
s strobed for illumination and a connected monochromatic
photodiode A photodiode is a light-sensitive semiconductor diode. It produces current when it absorbs photons. The package of a photodiode allows light (or infrared or ultraviolet radiation, or X-rays) to reach the sensitive part of the device. The packag ...
array under a rod lens array for light collection. "Images to be scanned are placed face down on the glass, an opaque cover is lowered over it to exclude ambient light, and the sensor array and light source move across the pane, reading the entire area. An image is therefore visible to the detector only because of the light it reflects. Transparent images do not work in this way, and require special accessories that illuminate them from the upper side. Many scanners offer this as an option."

## Film

This type of scanner is sometimes called a slide or transparency scanner and it works by passing a narrowly focused beam of light through the film and reading the intensity and color of the light that emerges. "Usually, uncut film strips of up to six frames, or four mounted slides, are inserted in a carrier, which is moved by a
stepper motor A stepper motor, also known as step motor or stepping motor, is a brushless DC electric motor that divides a full rotation into a number of equal steps. The motor's position can be commanded to move and hold at one of these steps without any po ...
across a lens and CCD sensor inside the scanner. Some models are mainly used for same-size scans. Film scanners vary a great deal in price and quality."Dubey, N.B. (2009), Office Management: Developing Skills for Smooth Functioning, Global India Publications, 312 pp. The lowest-cost dedicated film scanners can be had for less than 50 and they might be sufficient for modest needs. From there they inch up in staggered levels of quality and advanced features upward of five figures. "The specifics vary by brand and model and the end results are greatly determined by the level of sophistication of the scanner's optical system and, equally important, the sophistication of the scanning software." ## Roller scanner Scanners are available that pull a flat sheet over the scanning element between rotating rollers. They can only handle single sheets up to a specified width (typically about 210 mm, the width of many printed letters and documents), but can be very compact, just requiring a pair of narrow rollers between which the document is passed. Some are portable Portable may refer to: General * Portable building, a manufactured structure that is built off site and moved in upon completion of site and utility work * Portable classroom, a temporary building installed on the grounds of a school to provide a ... , powered by batteries and with their own storage, eventually transferring stored scans to a computer over a USB Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply ( interfacing) between computers, peripherals and other computers. A broa ... or other interface. ## 3D scanner 3D scanners collect data on the three-dimensional Three-dimensional space (also: 3D space, 3-space or, rarely, tri-dimensional space) is a geometric setting in which three values (called '' parameters'') are required to determine the position of an element (i.e., point). This is the inform ... shape and appearance of an object. ## Planetary scanner Planetary scanners scan a delicate object without physical contact. ## Hand Hand scanners are moved over the subject to be imaged by hand. There are two different types: document and 3D scanners. ### Hand document scanner Hand-held document scanners are manual devices that are dragged across the surface of the image to be scanned by hand. Scanning documents in this manner requires a steady hand, as an uneven scanning rate produces distorted images; an indicator light on the scanner indicates if motion is too fast. They typically have a "start" button, which is held by the user for the duration of the scan; some switches to set the optical resolution Optical resolution describes the ability of an imaging system to resolve detail, in the object that is being imaged. An imaging system may have many individual components, including one or more lenses, and/or recording and display components. ... ; and a roller, which generates a clock pulse for synchronization with the computer. Older hand scanners were monochrome A monochrome or monochromatic image, object or palette is composed of one color (or values of one color). Images using only shades of grey are called grayscale (typically digital) or black-and-white (typically analog). In physics, monoc ... , and produced light from an array of green LED A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light ... s to illuminate the image"; later ones scan in monochrome or color, as desired. A hand scanner may have a small window through which the document being scanned could be viewed. In the early 1990s many hand scanners had a proprietary interface module specific to a particular type of computer, such as an Atari ST The Atari ST is a line of personal computers from Atari Corporation and the successor to the Atari 8-bit family. The initial model, the Atari 520ST, had limited release in April–June 1985 and was widely available in July. It was the first per ... or Commodore Amiga Amiga is a family of personal computers introduced by Commodore in 1985. The original model is one of a number of mid-1980s computers with 16- or 32-bit processors, 256 KB or more of RAM, mouse-based GUIs, and significantly improved graph ... . Since the introduction of the USB standard, it is the interface most commonly used. As hand scanners are much narrower than most normal document or book sizes, software (or the end user) needed to combine several narrow "strips" of scanned document to produce the finished article. Inexpensive portable Portable may refer to: General * Portable building, a manufactured structure that is built off site and moved in upon completion of site and utility work * Portable classroom, a temporary building installed on the grounds of a school to provide a ... battery-powered "glide-over" hand scanners, typically capable of scanning an area as wide as a normal letter and much longer remain available . ### Hand 3D scanner Handheld 3D scanners are used in industrial design, reverse engineering, inspection and analysis, digital manufacturing and medical applications. "To compensate for the uneven motion of the human hand, most 3D scanning systems rely on the placement of reference markers, typically adhesive reflective tabs that the scanner uses to align elements and mark positions in space." ## Portable Image scanners are usually used in conjunction with a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations ( computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These p ... which controls the scanner and stores scans. Small portable scanners, either roller-fed or "glide-over" hand A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on ea ... -operated, operated by batteries and with storage capability, are available for use away from a computer; stored scans can be transferred later. Many can scan both small documents such as business cards and till receipts, and letter-sized documents. ## Keyboard document scanner A document scanner embedded inside a computer keyboard makes it available when needed yet taking no extra space since it is built inside the computer keyboard. ## Smartphone scanner app The higher-resolution cameras fitted to some smartphones can produce reasonable quality document scans by taking a photograph with the phone's camera and post-processing it with a scanning app, a range of which are available for most phone operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may al ... s, to whiten the background of a page, correct perspective distortion so that the shape of a rectangular document is corrected, convert to black-and-white, etc. Many such apps can scan multiple-page documents with successive camera exposures and output them either as a single file or multiple page files. Some smartphone scanning apps can save documents directly to online storage locations, such as Dropbox Dropbox is a file hosting service operated by the American company Dropbox, Inc., headquartered in San Francisco, California, U.S. that offers cloud storage, file synchronization, personal cloud, and client software. Dropbox was founded in 2 ... and Evernote Evernote is a note-taking and task management application. It is developed by the Evernote Corporation, headquartered in Redwood City, California. It is intended for archiving and creating notes in which photos, audio and saved web content can ... , send via email or fax documents via email-to-fax gateways. Smartphone scanner apps can be broadly divided into three categories: # Document scanning apps primarily designed to handle documents and output PDF, and sometimes JPEG, files # Photo scanning apps that output JPEG files, and have editing functions useful for photo rather than document editing; # Barcode-like QR code A QR code (an initialism for quick response code) is a type of matrix barcode (or two-dimensional barcode) invented in 1994 by the Japanese company Denso Wave. A barcode is a machine-readable optical label that can contain information about th ... scanning apps that then search the internet for information associated with the code. # Scan quality Color scanners typically read RGB ( red-green-blue color) data from the array. This data is then processed with some proprietary algorithm to correct for different exposure conditions, and sent to the computer via the device's input/output In computing, input/output (I/O, or informally io or IO) is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signal ... interface (usually USB Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply ( interfacing) between computers, peripherals and other computers. A broa ... , previous to which was SCSI Small Computer System Interface (SCSI, ) is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, electrical, optical and logical interfac ... or bidirectional parallel port In computing, a parallel port is a type of interface found on early computers ( personal and otherwise) for connecting peripherals. The name refers to the way the data is sent; parallel ports send multiple bits of data at once ( parall ... in older units). Color depth Color depth or colour depth (see spelling differences), also known as bit depth, is either the number of bits used to indicate the color of a single pixel, or the number of bits used for each color component of a single pixel. When referring ... varies depending on the scanning array characteristics, but is usually at least 24 bits. High quality models have 36-48 bits of color depth. Another qualifying parameter for a scanner is its '' resolution'', measured in pixels per inch In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the sm ... (ppi), sometimes more accurately referred to as Samples per inch (spi). Instead of using the scanner's true optical resolution, the only meaningful parameter, manufacturers like to refer to the ''interpolated resolution'', which is much higher thanks to software interpolation In the mathematical field of numerical analysis, interpolation is a type of estimation, a method of constructing (finding) new data points based on the range of a discrete set of known data points. In engineering and science, one often ha ... . , a high-end flatbed scanner can scan up to 5400 ppi and drum scanners have an optical resolution of between 3,000 and 24,000 ppi. "Effective resolution" is the true resolution of a scanner, and is determined by using a resolution test chart. The effective resolution of most all consumer flatbed scanners is considerably lower than the manufactures' given optical resolution. Example is the Epson V750 Pro with an optical resolution given by manufacturer as being 4800dpi and 6400dpi (dual lens), but tested "According to this we get a resolution of only about 2300 dpi - that's just 40% of the claimed resolution!" Dynamic range is claimed to be 4.0 Dmax, but "Regarding the density range of the Epson Perfection V750 Pro, which is indicated as 4.0, one must say that here it doesn't reach the high-quality ffilm scanners either." Manufacturers often claim interpolated resolutions as high as 19,200 ppi; but such numbers carry little meaningful value, because the number of possible interpolated pixels is unlimited and doing so does not increase the level of captured detail. The size of the file created increases with the square of the resolution; doubling the resolution quadruples the file size. A resolution must be chosen that is within the capabilities of the equipment, preserves sufficient detail, and does not produce a file of excessive size. The file size can be reduced for a given resolution by using "lossy" compression methods such as JPEG JPEG ( ) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and i ... , at some cost in quality. If the best possible quality is required lossless compression should be used; reduced-quality files of smaller size can be produced from such an image when required (e.g., image designed to be printed on a full page, and a much smaller file to be displayed as part of a fast-loading web page). Purity can be diminished by scanner noise, optical flare, poor analog to digital conversion, scratches, dust, Newton's rings, out of focus sensors, improper scanner operation, and poor software. Drum scanners are said to produce the purest digital representations of the film, followed by high end film scanners that use the larger Kodak Tri-Linear sensors. The third important parameter for a scanner is its density range (Dynamic Range) or Drange (see Densitometry Densitometry is the quantitative measurement of optical density in light-sensitive materials, such as photographic paper or photographic film, due to exposure to light. Overview Optical density is a result of the darkness of a developed pictur ... ). A high density range means that the scanner is able to record shadow details and brightness details in one scan. Density of film is measured on a base 10 log scale and varies between 0.0 (transparent) and 5.0, about 16 stops. Density range is the space taken up in the 0 to 5 scale, and Dmin and Dmax denote where the least dense and most dense measurements on a negative or positive film. The density range of negative film is up to 3.6d, while slide film dynamic range is 2.4d. Color negative density range after processing is 2.0d thanks to compression of the 12 stops into a small density range. Dmax will be the densest on slide film for shadows, and densest on negative film for highlights. Some slide films can have a Dmax close to 4.0d with proper exposure, and so can black-and-white negative film. Consumer-level flatbed photo scanners have a dynamic range in the 2.0–3.0 range, which can be inadequate for scanning all types of photographic film Photographic film is a strip or sheet of transparent film base coated on one side with a gelatin emulsion containing microscopically small light-sensitive silver halide crystals. The sizes and other characteristics of the crystals determin ... , as Dmax can be and often is between 3.0d and 4.0d with traditional black-and-white film. Color film compresses its 12 stops of a possible 16 stops (film latitude) into just 2.0d of space via the process of dye coupling and removal of all silver from the emulsion. Kodak Vision 3 has 18 stops. So, color negative film scans the easiest of all film types on the widest range of scanners. Because traditional black-and-white film retains the image creating silver after processing, density range can be almost twice that of color film. This makes scanning traditional black-and-white film more difficult and requires a scanner with at least a 3.6d dynamic range, but also a Dmax between 4.0d to 5.0d. High-end (photo lab) flatbed scanners can reach a dynamic range of 3.7, and Dmax around 4.0d. Dedicated film scanners have a dynamic range between 3.0d–4.0d. Office document scanners can have a dynamic range of less than 2.0d. Drum scanners have a dynamic range of 3.6–4.5. By combining full-color imagery with 3D models, modern hand-held scanners are able to completely reproduce objects electronically. The addition of 3D color printers enables accurate miniaturization of these objects, with applications across many industries and professions. For scanner apps, the scan quality is highly dependent on the quality of the phone camera and on the framing chosen by the user of the app. # Computer connection Scans must virtually always be transferred from the scanner to a computer or information storage system for further processing or storage. There are two basic issues: (1) how the scanner is physically connected to the computer and (2) how the application retrieves the information from the scanner. ## Direct physical connection to a computer The file size of a scan can be up to about 100 megabyte The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB. The unit prefix ''mega'' is a multiplier of (106) in the International System of Units (SI). Therefore, one megabyte is one million bytes ... s for a (9"x11") (slightly larger than A4 paper ISO 216 is an international standard for paper sizes, used around the world except in North America and parts of Latin America. The standard defines the "A", "B" and "C" series of paper sizes, including A4, the most commonly available paper size ... ) uncompressed 24-bit Notable 24-bit machines include the CDC 924 – a 24-bit version of the CDC 1604, CDC lower 3000 series, SDS 930 and SDS 940, the ICT 1900 series, the Elliott 4100 series, and the Datacraft minicomputers/ Harris H series. The term SWORD ... image. Scanned files must be transferred and stored. Scanners can generate this volume of data in a matter of seconds, making a fast connection desirable. Scanners communicate to their host computer using one of the following physical interfaces, listing roughly from slow to fast: * Parallel port In computing, a parallel port is a type of interface found on early computers ( personal and otherwise) for connecting peripherals. The name refers to the way the data is sent; parallel ports send multiple bits of data at once ( parall ... - Connecting through a parallel port is the slowest common transfer method. Early scanners had parallel port connections that could not transfer data faster than 70 kilobyte The kilobyte is a multiple of the unit byte for digital information. The International System of Units (SI) defines the prefix '' kilo'' as 1000 (103); per this definition, one kilobyte is 1000 bytes.International Standard IEC 80000-13 Quanti ... s/ second The second (symbol: s) is the unit of time in the International System of Units (SI), historically defined as of a day – this factor derived from the division of the day first into 24 hours, then to 60 minutes and finally to 60 seconds ... . The primary advantage of the parallel port connection was economic and user skill level: it avoided adding an interface card to the computer. * GPIB Glycoprotein Ib (GPIb), also known as CD42, is a component of the GPIb-V-IX complex on platelets. The GPIb-V-IX complex binds von Willebrand factor, allowing platelet adhesion and platelet plug formation at sites of vascular injury. It is def ... - General Purpose Interface Bus. Certain drumscanners like the Howtek D4000 featured both a SCSI and GPIB interface. The latter conforms to the IEEE-488 standard, introduced in the mid 1970s. The GPIB interface has only been used by a few scanner manufacturers, mostly serving the DOS/Windows environment. For Apple Macintosh systems, National Instruments provided a NuBus NuBus (pron. 'New Bus') is a 32-bit parallel computer bus, originally developed at MIT and standardized in 1987 as a part of the NuMachine workstation project. The first complete implementation of the NuBus was done by Western Digital f ... GPIB interface card. * Small Computer System Interface (SCSI), rarely used since the early 21st century, supported only by computers with a SCSI interface, either on a card or built-in. During the evolution of the SCSI standard, speeds increased. Widely available and easily set up USB and Firewire largely supplanted SCSI. * Universal Serial Bus (USB) scanners can transfer data quickly. The early USB 1.1 standard could transfer data at 1.5 megabytes per second (slower than SCSI), but the later USB 2.0/3.0 standards can transfer at more than 20/60 megabytes per second in practice. * FireWire IEEE 1394 is an interface standard for a serial bus for high-speed communications and isochronous real-time data transfer. It was developed in the late 1980s and early 1990s by Apple in cooperation with a number of companies, primarily Son ... , or IEEE-1394, is an interface of comparable speed to USB 2.0. Possible FireWire speeds are 25, 50, and 100, 400 and 800 megabits per second, but devices may not support all speeds. * Proprietary {{Short pages monitor In practice, there are often problems with an application communicating with a scanner. Either the application or the scanner manufacturer (or both) may have faults in their implementation of the API. Typically, the API is implemented as a dynamically linked library. Each scanner manufacturer provides software that translates the API procedure calls into primitive commands that are issued to a hardware controller (such as the SCSI, USB, or FireWire controller). The manufacturer's part of the API is commonly called a device driver In computing, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabling operating systems and ... , but that designation is not strictly accurate: the API does not run in kernel mode and does not directly access the device. Rather the scanner API library translates application requests into hardware requests. Common scanner software API interfaces: SANE (Scanner Access Now Easy) is a free Free may refer to: Concept * Freedom, having the ability to do something, without having to obey anyone/anything * Freethought, a position that beliefs should be formed only on the basis of logic, reason, and empiricism * Emancipate, to procu ... / open-source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ... API for accessing scanners. Originally developed for Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, ... and Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, wh ... operating systems, it has been ported to OS/2 OS/2 (Operating System/2) is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci. As a result of a feud between the two companies over how to position OS/2 ... , Mac OS X macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac (computer), Mac computers. Within the market of ... , and Microsoft Windows. Unlike TWAIN, SANE does not handle the user interface. This allows batch scans and transparent network access without any special support from the device driver. TWAIN Twain may refer to: People * Mark Twain Samuel Langhorne Clemens (November 30, 1835 – April 21, 1910), known by his pen name A pen name, also called a ''nom de plume'' or a literary double, is a pseudonym (or, in some cases, a var ... is used by most scanners. Originally used for low-end and home-use equipment, it is now widely used for large-volume scanning. ISIS Isis (; ''Ēse''; ; Meroitic: ''Wos'' 'a''or ''Wusa''; Phoenician: 𐤀𐤎, romanized: ʾs) was a major goddess in ancient Egyptian religion whose worship spread throughout the Greco-Roman world. Isis was first mentioned in the Old King ... (Image and Scanner Interface Specification) created by Pixel Translations, which still uses SCSI-II for performance reasons, is used by large, departmental-scale, machines. WIA (Windows Image Acquisition) is an API provided by Microsoft for use on Microsoft Windows. ## Bundled applications Although no software beyond a scanning utility is a feature of any scanner, many scanners come bundled with software. Typically, in addition to the scanning utility, some type of image-editing application (such as Adobe Photoshop Adobe Photoshop is a raster graphics editor developed and published by Adobe Inc. for Windows and macOS. It was originally created in 1988 by Thomas and John Knoll. Since then, the software has become the industry standard not only in r ... ), and optical character recognition Optical character recognition or optical character reader (OCR) is the electronic or mechanical conversion of images of typed, handwritten or printed text into machine-encoded text, whether from a scanned document, a photo of a document, a s ... (OCR) software are supplied. OCR software converts graphical images of text into standard text that can be edited using common word-processing and text-editing software; accuracy is rarely perfect. # Output data Some scanners, especially those designed for scanning printed documents, only work in black-and-white but most modern scanners work in color. For the latter, the scanned result is a non-compressed RGB image, which can be transferred to a computer's memory. The color output of different scanners is not the same due to the spectral response of their sensing elements, the nature of their light source and the correction applied by the scanning software. While most image sensors have a linear response, the output values are usually gamma compressed. Some scanners compress and clean up the image using embedded firmware In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide ... . Once on the computer, the image can be processed with a raster graphics upright=1, The Smiley, smiley face in the top left corner is a raster image. When enlarged, individual pixels appear as squares. Enlarging further, each pixel can be analyzed, with their colors constructed through combination of the values for ... program (such as Adobe Photoshop Adobe Photoshop is a raster graphics editor developed and published by Adobe Inc. for Windows and macOS. It was originally created in 1988 by Thomas and John Knoll. Since then, the software has become the industry standard not only in r ... or the GIMP GIMP ( ; GNU Image Manipulation Program) is a free and open-source raster graphics editor used for image manipulation (retouching) and image editing, free-form drawing, transcoding between different image file formats, and more specialize ... ) and saved on a storage device (such as a hard disk A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with mag ... ). Images are usually stored on a hard disk A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with mag ... . Pictures are normally stored in image formats such as uncompressed Bitmap In computing, a bitmap is a mapping from some domain (for example, a range of integers) to bits. It is also called a bit array or bitmap index. As a noun, the term "bitmap" is very often used to refer to a particular bitmapping application: t ... , "non-lossy" (lossless) compressed TIFF Tag Image File Format, abbreviated TIFF or TIF, is an image file format for storing raster graphics images, popular among graphic artists, the publishing industry, and photographers. TIFF is widely supported by scanning, faxing, word process ... and PNG, and "lossy" compressed JPEG JPEG ( ) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and i ... . Documents are best stored in TIFF or PDF Portable Document Format (PDF), standardized as ISO 32000, is a file format developed by Adobe in 1992 to present documents, including text formatting and images, in a manner independent of application software, hardware, and operating systems. ... format; JPEG is particularly unsuitable for text. Optical character recognition Optical character recognition or optical character reader (OCR) is the electronic or mechanical conversion of images of typed, handwritten or printed text into machine-encoded text, whether from a scanned document, a photo of a document, a s ... (OCR) software allows a scanned image of text to be converted into editable text with reasonable accuracy, so long as the text is cleanly printed and in a typeface and size that can be read by the software. OCR capability may be integrated into the scanning software, or the scanned image file can be processed with a separate OCR program. # Document processing Document imaging Document imaging is an information technology category for systems capable of replicating documents commonly used in business. Document imaging systems can take many forms including microfilm, on demand printers, facsimile machines, copiers, mul ... requirements differ from those of image scanning. These requirements include scanning speed, automated paper feed, and the ability to automatically scan both the front and the back of a document. On the other hand, image scanning typically requires the ability to handle fragile and or three dimensional objects as well as scan at a much higher resolution. Document scanners have document feeders, usually larger than those sometimes found on copiers or all-purpose scanners. Scans are made at high speed, from 20 up to 280 or 420 pages per minute, often in grayscale, although many scanners support color. Many scanners can scan both sides of double-sided originals (duplex operation). Sophisticated document scanners have firmware In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide ... or software Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consis ... that cleans up scans of text as they are produced, eliminating accidental marks and sharpening type; this would be unacceptable for photographic work, where marks cannot reliably be distinguished from desired fine detail. Files created are compressed as they are made. The resolution used is usually from 150 to 300 dpi A Daytona Prototype International (DPi) was a type of sports prototype racing car developed specifically for the International Motor Sports Association's WeatherTech SportsCar Championship, as their top class of car, acting as a direct replacem ... , although the hardware may be capable of 600 or higher resolution; this produces images of text good enough to read and for optical character recognition Optical character recognition or optical character reader (OCR) is the electronic or mechanical conversion of images of typed, handwritten or printed text into machine-encoded text, whether from a scanned document, a photo of a document, a s ... (OCR), without the higher demands on storage space required by higher-resolution images. Document scans are often processed using OCR technology to create editable and searchable files. Most scanners use ISIS Isis (; ''Ēse''; ; Meroitic: ''Wos'' 'a''or ''Wusa''; Phoenician: 𐤀𐤎, romanized: ʾs) was a major goddess in ancient Egyptian religion whose worship spread throughout the Greco-Roman world. Isis was first mentioned in the Old King ... or TWAIN Twain may refer to: People * Mark Twain Samuel Langhorne Clemens (November 30, 1835 – April 21, 1910), known by his pen name A pen name, also called a ''nom de plume'' or a literary double, is a pseudonym (or, in some cases, a var ... device drivers to scan documents into TIFF Tag Image File Format, abbreviated TIFF or TIF, is an image file format for storing raster graphics images, popular among graphic artists, the publishing industry, and photographers. TIFF is widely supported by scanning, faxing, word process ... format so that the scanned pages can be fed into a document management system A document management system (DMS) is usually a computerized system used to store, share, track and manage files or documents. Some systems include history tracking where a log of the various versions created and modified by different users is r ... that will handle the archiving and retrieval of the scanned pages. Lossy JPEG compression, which is very efficient for pictures, is undesirable for text documents, as slanted straight edges take on a jagged appearance, and solid black (or other color) text on a light background compresses well with lossless compression formats. While paper feeding and scanning can be done automatically and quickly, preparation and indexing are necessary and require much work by humans. Preparation involves manually inspecting the papers to be scanned and making sure that they are in order, unfolded, without staples or anything else that might jam the scanner. Additionally, some industries such as legal and medical may require documents to have Bates Numbering or some other mark giving a document identification number and date/time of the document scan. Indexing involves associating relevant keywords to files so that they can be retrieved by content. This process can sometimes be automated to some extent, but it often requires manual labour performed by data-entry clerks. One common practice is the use of barcode A barcode or bar code is a method of representing data in a visual, machine-readable form. Initially, barcodes represented data by varying the widths, spacings and sizes of parallel lines. These barcodes, now commonly referred to as linear or o ... -recognition technology: during preparation, barcode sheets with folder names or index information are inserted into the document files, folders, and document groups. Using automatic batch scanning, the documents are saved into appropriate folders, and an index is created for integration into document-management systems. A specialized form of document scanning is book scanning Book scanning or book digitization (also: magazine scanning or magazine digitization) is the process of converting physical books and magazines into digital media such as images, electronic text, or electronic books (e-books) by using an ima ... . Technical difficulties arise from the books usually being bound and sometimes fragile and irreplaceable, but some manufacturers have developed specialized machinery to deal with this. Often special robotic Robotics is an interdisciplinary branch of computer science and engineering. Robotics involves design, construction, operation, and use of robots. The goal of robotics is to design machines that can help and assist humans. Robotics integrat ... mechanisms are used to automate the page turning and scanning process. # Document camera scanners Another category of document scanner is the document camera. Capturing images on document cameras differs from that of flatbed and Automatic document feeder (ADF) scanners in that there are no moving parts required to scan the object. Conventionally either the illumination/reflector rod inside the scanner must be moved over the document (such as for a flatbed scanner), or the document must be passed over the rod (such as for feeder scanners) in order to produce a scan of a whole image. Document cameras capture the whole document or object in one step, usually instantly. Typically, documents are placed on a flat surface, usually the office desk, underneath the capture area of the document camera. The process of whole-surface-at-once capturing has the benefit of increasing reaction time for the work flow of scanning. After being captured, the images are usually processed through software which may enhance the image and perform such tasks like automatically rotating, cropping and straightening them. It is not required that the documents or objects being scanned make contact with the document camera, therefore increasing flexibility of the types of documents which are able to be scanned. Objects which have previously been difficult to scan on conventional scanners are now able to be done so with one device. This includes in particular documents which are of varying sizes and shapes, stapled, in folders or bent/crumpled which may get jammed in a feed scanner. Other objects include books, magazines, receipts, letters, tickets etc. No moving parts can also remove the need for maintenance, a consideration in the Total cost of ownership Total cost of ownership (TCO) is a financial estimate intended to help buyers and owners determine the direct and indirect costs of a product or service. It is a management accounting concept that can be used in full cost accounting or even ecolog ... , which includes the continuing operational costs of scanners. Increased reaction time whilst scanning also has benefits in the realm of context-scanning. ADF scanners, whilst very fast and very good at batch scanning, also require pre- and post- processing of the documents. Document cameras can be integrated directly into a Workflow A workflow consists of an orchestrated and repeatable pattern of activity, enabled by the systematic organization of resources into processes that transform materials, provide services, or process information. It can be depicted as a sequence of ... or process, for example a teller at a bank. The document is scanned directly in the context of the customer, in which it is to be placed or used. Reaction time is an advantage in these situations. Document cameras usually also require a small amount of space and are often portable. Whilst scanning with document cameras may have a quick reaction time, large amounts of batch scanning of even, unstapled documents is more efficient with an ADF scanner. There are challenges which face this kind of technology regarding external factors (such as lighting) which may have influence on the scan results. The way in which these issues are resolved strongly depends on the sophistication of the product and how it deals with these issues. # Infrared cleaning ''Infrared cleaning'' is a technique used to remove the effects of dust and scratches on images scanned from film; many modern scanners incorporate this feature. It works by scanning the film with infrared light; the dyes in typical color film emulsions are transparent to infrared light, but dust and scratches are not, and block infrared; scanner software can use the visible and infrared information to detect scratches and process the image to greatly reduce their visibility, considering their position, size, shape, and surroundings. Scanner manufacturers usually have their own name attached to this technique. For example, Epson Seiko Epson Corporation, or simply known as Epson, is a Japanese multinational electronics company and one of the world's largest manufacturers of computer printers and information- and imaging-related equipment. Headquartered in Suwa, Nagano ... , Minolta was a Japanese manufacturer of cameras, camera accessories, photocopiers, fax machines, and laser printers. Minolta Co., Ltd., which is also known simply as Minolta, was founded in Osaka, Japan, in 1928 as . It made the first integrated autofoc ... , Nikon (, ; ), also known just as Nikon, is a Japanese multinational corporation headquartered in Tokyo, Japan, specializing in optics and imaging products. The companies held by Nikon form the Nikon Group. Nikon's products include cameras, camer ... , Konica Minolta is a Japanese multinational technology company headquartered in Marunouchi, Chiyoda, Tokyo, with offices in 49 countries worldwide. The company manufactures business and industrial imaging products, including copiers, laser printers, multi- ... , Microtek Microtek International Inc. () is a Taiwan-based multinational manufacturer of digital imaging products and other consumer electronics. It produces imaging equipment for medical, biological and industrial fields. It occupies 20 percent of the glo ... , and others use Digital ICE, while Canon Canon or Canons may refer to: Arts and entertainment * Canon (fiction), the conceptual material accepted as official in a fictional universe by its fan base * Literary canon, an accepted body of works considered as high culture ** Western ca ... uses its own system FARE A fare is the fee paid by a passenger for use of a public transport system: rail, bus, taxi, etc. In the case of air transport, the term airfare is often used. Fare structure is the system set up to determine how much is to be paid by various p ... (Film Automatic Retouching and Enhancement system). Plustek Plustek Inc. () is a computer hardware company established in 1986 that manufactures image scanners, as well as surveillance devices in recent years. They have the MobileOffice, SmartOffice, OpticBook, OpticPro, OpticFilm, and OpticSlim line of pr ... uses LaserSoft Imaging LaserSoft Imaging AG is a software developer designing software such as SilverFast for scanners and large format printers. The company's headquarters are located in Kiel, Germany, north of Hamburg, and another office in Sarasota, Florida, Uni ... iSRD. Some independent software developers design infrared cleaning tools. # Other uses Flatbed scanners have been used as digital backs for large-format Large format refers to any imaging format of or larger. Large format is larger than "medium format", the or size of Hasselblad, Mamiya, Rollei, Kowa, and Pentax cameras (using 120- and 220-roll film), and much larger than the frame o ... camera A camera is an optical instrument that can capture an image. Most cameras can capture 2D images, with some more advanced models being able to capture 3D images. At a basic level, most cameras consist of sealed boxes (the camera body), with ... s to create high-resolution digital images of static subjects. A modified flatbed scanner has been used for documentation and quantification of thin layer chromatograms detected by fluorescence quenching on silica gel Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other ... layers containing an ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ... (UV) indicator. 'ChromImage' is allegedly the first commercial flatbed scanner densitometer A densitometer is a device that measures the degree of darkness (the optical density) of a photographic or semitransparent material or of a reflecting surface. The densitometer is basically a light source aimed at a photoelectric cell. It deter ... . It enables acquisition of TLC plate images and quantification of chromatograms by use of Galaxie-TLC software. Other than being turned into densitometers, flatbed scanners were also turned into colorimeters using different methods.Joyce Farrell, Doron Sherman, Brian W. (1994). How to turn your scanner into a colorimeter, Proc. of IS&T 10th Int. Congress on Adv. in Non-Impact Printing Technol, pp579-581. Trichromatic Color Analyser is allegedly the first distributable system using a flatbed scanner as a tristimulus colorimetric device. # See also * Barcode reader A barcode reader is an optical scanner that can read printed barcodes, decode the data contained in the barcode to a computer. Like a flatbed scanner, it consists of a light source, a lens and a light sensor for translating optical impulses into ... * Book scanning Book scanning or book digitization (also: magazine scanning or magazine digitization) is the process of converting physical books and magazines into digital media such as images, electronic text, or electronic books (e-books) by using an ima ... * Cintel Cintel was a British digital cinema company founded in 1927 by John Logie Baird and based in Ware, Hertfordshire. The early company was called ''Cinema Television Ltd''. Cinema Television was sold to J Arthur Rank Organization renamed Rank Cinte ... telecine equipment * Display resolution The display resolution or display modes of a digital television, computer monitor or display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution ... * Gamma correction Gamma correction or gamma is a nonlinear operation used to encode and decode luminance or tristimulus values in video or still image systems. Gamma correction is, in the simplest cases, defined by the following power-law expression: : V_\text ... * Imaging Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of an image). Imaging technology is the application of materials and methods to create, preserve, or duplicate images. ... * Telecine Telecine ( or ) is the process of transferring film into video and is performed in a color suite. The term is also used to refer to the equipment used in the post-production process. Telecine enables a motion picture, captured originally on f ... # References # External links * Photocopy is an open-source software Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. ... to apply a photocopier A photocopier (also called copier or copy machine, and formerly Xerox machine, the generic trademark) is a machine that makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Most modern photocopiers ... effect to scanned images. "Is Drum Scanning Really Alive and Well?" from ''Digital Output'' by Jim Rich "Can a Fine-Art Large-Format Photographer Find Happiness With a30,000 Scanner?"
by Bill Glickman {{Authority control Image scanners Information management Office equipment Records management Records management technology Italian inventions