Computer Encyclopedia - 3

What is Video Capture?

Similar to audio recording, Video Capture is the term used to denote the process of recording video data by using analog devices, like Webcams.

What is TWAIN?

The image capture API (application programming interface) that is needed for an image capture device, like a Webcam to interact with the system.

 What is Resolution?
The number of pixels that can be captured by the CCD is it’s resolution. This is expressed as the number of pixels. Resolution can be actual or interpolated. The webcam can offer the maximum resolution for taking static photos while take videos at a lower resolution. Resolution can be expressed in the number of pixels in the horizontal and vertical axis, for example 640 X 480, or as a total number of pixels on the CCD, for example 1.3 megapixel

What is Megapixel?

A megapixel = 1,000,000 pixels. This refers to the resolution of the camera.

What is Interpolated Resolution?

The colour of the points between two pixels can be estimated by software. This is used to boost the resolution of the camera. Such resolution is called interpolated resolution.

What is Compression?

Uncompressed Video data is quite data intensive, and for transferring this data over the net one would need very high speed internet connections. Compressing the video streams reduced the file size, without causes any significant loss in quality. Different webcams use different codecs to compress the video.

What is FPS?

Frames per second refers to the frequency with which the webcam updates the CCD. A high refresh rate means that the captured motion is smoother. Most webcams capture at speeds of 25 fps.

What is CCD?

Charge Coupled Devices are optical sensors that are needed to convert the optical data into electrical impulses. These can be coloured to capture data related to each colour in the RGB scheme (Red, Green, Blue).

What is AVI?

Audio Video Interlace is a method for storing these two data streams by interleaving them. AVI is a popular file format. Webcams can be used to record video data which is stored in AVI format.

What is Actual Resolution?

This is the actual number of pixels that the camera CCD can capture. This is expressed in pixels (or megapixels).

What is Wireless Keyboard?

This keyboard uses radio waves to carry the data to the system, thus avoiding the need for wires. The keyboard communicates with a base station that is connected to the system, usually through the USB port. Since the keyboard needs additional power to create the radio signals, it uses batteries. Wireless keyboards can also be based on Bluetooth technology and Infra Red technology, the latter requires that the keyboard and sensorbe in visible range.

What is Typematic Rate / Repeat Rate?

This refers to the speed with which letters are repeated when the key is pressed. A high repeat rate causes many letters to be input.

What is RSI?

Repetitive Stress Injury refers to the condition caused by prolonged use of the keyboard and mouse. This is characterised by pain in the wrist and fingers and is attributed to bad posture and insufficient support while typing. Using ergonomic keyboards can reduce chances of RSI.

What is QWERTY / Dvorak keyboard?

Two schemes for key placements on keyboards. The QWERTY scheme is more popular, and gets its name from the arrangement of letters in the first row of the keyboard. The Dvorak scheme was introduced by August Dvorak, who arrived at the placement based on his observations about the frequency of letter usage and human physiology.

What is Multimedia / Internet Keyboard?

These refer to keyboards that have additional keys that are configured to launch special programs or perform certain tasks like increasing or decreasing the volume of the media player or launching a browser.

What is Gaming Keyboard?

These are special keyboards that are built for gamers. In most games a limited set of keys are used, and the position of these keys are is determined keeping a gamer’s needs in mind. A dedicated gaming keyboard offers a more user friendly layout of keys, and each key is programmable.

What is Ergonomic Keyboard?

This keyboard is designed keeping the natural position of the hands. Since the wrists are stressed when the palms are positioned at an angle to the arm, the keyboard was redesigned to place the keys in the form of an arc, with the key switches split down the middle, allowing the user to keep the wrist unbent. Some keyboards also provide a wrist rest for the wrists.

What is Wireless Mouse?

This mouse does away with the need for wires by using radio waves to communicate with a base station that is connected by wires to the system, usually to the USB port. The mouse has an independent power source, usually in the form of batteries, or can be recharged by plugging into the base station. Since radio waves can pass through objects, there is no need to position the mouse in front of the base station to use it.

What is Trackball?

This is seen on some mice as a freely moving sphere that can be used to more accurately position the cursor on the screen.

What is Scroll Wheel?

This is the wheel found in between the main two mouse buttons, and can be used to scroll through a document. This is the default behaviour as set by the default driver. The mouse driver can be used to allocate a different function for the wheel.

What is mouse Refresh Rate?

Refresh rate is the number of images taken by the optical sensor of a mouse. This is variable and usually in the hundreds per second. A higher figure means a quicker response.

What is Optical Mouse?

The Optical mouse employs a camera or optical sensor to constantly take images of the surface beneath the mouse. Any changes in the surface is detected and the differences in the x and y positions compared to the previously recorded image is transmitted to the OS. A dedicated light emitting diode (LED) is used to illuminate the surface to make detection easier. Since the camera scans the surface for changes, it’s task is made difficult if the surface is devoid of any distinguishing pattern or is highly reflective.

What is Mouse Driver?

Usually the default driver offers the basic functionality of a 2 button scroll wheel mouse. To use the features of the mouse optimally, the driver created specifically for the mouse needs to be installed. The mouse driver allows the buttons on the mouse to be reconfigured.

What is Mechanical Mouse?

This mouse uses a ball to rotate two slit disks placed in the X and Y axis. The slit disks are placed between a set of light source and optical sensor. Any rotation of the disk causes a the slits to cut the beam of light received by the sensor which is translated into changes in the respective axis. Any movement of the ball is thus translated into changes in the X and Y axis. Mechanical mice are on the way out due to the advantages offered by the equally priced optical mice.

What is Laser Mouse?

This is the latest innovation in pointing technology. Moving a step ahead of the optical mouse, which uses normal light, the Laser mouse uses an infrared Laser beam (from a Laser Emitting Diode) to illuminate the surface. A laser sensitive sensor is then used to track changes in the surface. Due to the focussed nature of the laser beam, the Laser mouse can achieve 20 times the sensitivity of the optical mouse, besides being able to detect differences on surfaces that befuddle an optical mouse.

What is CPI / DPI?

Short for Counts per Inch / Dots Per Inch, this is the number of unique points that can be detected by the sensor in one square inch area. The greater this value, the greater the capability of the mouse to detect movements (sensitivity).

What is Multi-function Device?

MFDs or Multi-function Devices combine the functionality of a Printer and Scanner. This allows them to be used also as a copier. Some MFDs also add additional facilities like a dial up modem that can be used to fax images scanned with the scanner. MFDs are also called All in Ones.

What is TWAIN?

A term frequently used with regard to image capturing devices like Scanners and Webcams, TWAIN is the image capture API that is needed to communicate with image capture devices. It is usually bundled with the device drivers.

What is Scan Speed?

This is expressed as the time it takes the scanner to scan an object. This varies with the mode (colour, grey scale) and scan resolution.

What is RGB?

This refers to the scheme which uses Red, Green and Blue (RGB) as the primary colours. The other colours can be expressed as a combination of these colours in varying intensity.
 What is Resolution?
This refers to the number of distinct points in a square inch that can be detected by the scanner. Resolution can be of two types : optical and interpolated.

What is Optical Resolution?

If the resolution can be achieved by the hardware, it is the optical resolution. Optical resolution is the product of the number of CCDs accommodated in one inch of a row on the sensor and the number of times the CCD captures light as the scan head rolls a distance of 1 inch over the subject.

What is OCR?

Optical Character Recognition refers to the process of identifying textual data present in an image file. All scanners come with a bundled OCR software. Good OCR software can identify textual and graphical data and retain the formatting of the original document. For best results, OCR software need a scanning resolution higher than 200 dpi.

What is Negative Scanner?

These scanners are used to scan photographic film negatives. In these scanners the optical sensor and the light source are on opposite sides of the scan subject. The scan result is the developed photo.

What is Interpolated Resolution?

If the hardware is unable to produce the resolution, the software can interpolate the values of two points to arrive at the values of a point in between them. This would be the interpolated resolution. Scanners achieve a higher resolution by Interpolation.

What is Hand Held Scanner?

These are smaller scanners that rely on the user’s movement to scan the document below it. These can be in the form of Bar Code Scanners which are used to record bar codes on packages or as Pen scanners where moving the scanner over the document captures it’s contents.

What is Flatbed Scanner?

These scanners have a sheet of glass over which the object to be scanned is placed. The scan head consisting of the light source, the reflecting mirror and the CCD array is moved under the glass sheet to scan the subject.

What is Document Scanner?

These are special type of Scanners that are designed for scanning large number of documents. Here rather than have a moving scan head, the scan head is fixed and the paper is fed underneath it.

What is CCD?

Charge Coupled Device refers to the optical sensor used to detect the intensity in the reflected light. These devices are capable of converting the light into electric energy with corresponding intensity. Higher intensity of light generates higher voltage electric impulse. For colour scanning the CCDs are coated with either of the colours Red, Green, Blue to register the colour under each filter.

What is Bit Depth?

The amount of bits dedicated to capturing information from the scan subject. For greater detail, more bits need to be captured. A 24 bit depth allocates 8 bits or 1 byte per colour in RGB.

What is ADF?

Automatic document Feeder is an attachment seen in some scanners that can load the pages that need to be scanned, automatically into the scanner. This allows scanning without any manual intervention.

What is ADC?

Analogue-to-Digital Converter refers to the device employed to convert analogue signals into digital form. In a scanner the voltages (analogue) from the CCD are passed to the ADC to be converted into binary (digital format).

What is Print Head?

In inkjet printers, the cartridges and associated circuitry are loaded on a block that is moved along the width of the page during the printing process. This is called the print head. Some manufacturers like HP fuse the print head and the cartridge into a single unit which needs to be discarded once the cartridge is depleted. Others like Canon, separate the print head from the cartridge, allowing just the cartridge to be replaced when it is depleted.

What is Photo Printer?

While many normal inkjet printers can also print photos, Photo Printers are printers specially created to print photos. Presently all of these are inkjet printers. They are of a smaller size and use special photo paper in the usual photo sizes like 4 X 6 etc. They allow printing without connecting through the PC by using PictBridge. They also have interfaces to connect digital camera or memory cards, and a screen to preview the photo. Some also allows rudimentary editing of the photo before printing.

What is Cartridge?

In inkjet printers, the colour is stored in reservoirs called cartridges. Cartridges can be individual where a single cartridge carries just one colour of ink or Combined, where each cartridge carries more than one ink within. Needless to say, if one of the colours in the combined cartridge is depleted, the entire cartridge needs to be discarded.

What is Bubble Jet / Thermal Inkjet Printer?

This is a type of Inkjet printer that uses heat to cause ink droplets to be sprayed on to the paper. This is the most widely used technology in Inkjet printers. The droplet size in the latest printers is advertised as 2 picolitre. (1 litre = 1,000,000,000,000 picolitres).

What is Toner?

This refers to the fine electrostatically charged powder that is used as the medium in a laser printer. It consists of minute particles of pigment and plastic. Monochrome printers have just a black toner. Multi colour printers have toners for each of the colours Cyan, Magenta and Yellow (besides black). The toner is packed into a receptacle called the Toner Hopper.

What is Printer Drum?

In laser printers, the drum is used to transfer the file image onto paper. The surface of the drum is charged selectively by a laser, based on the pattern to be printed. When brought in contact with the Toner, the charged areas attract the toner particles to complete the pattern on the drum. When the paper is rolled over the drum, the pattern is transferred on to it. In many entry level models, the Drum and Fuser are combined with the toner hopper, so when the toner is depleted all the components have to be discarded.

What is Multicolour Printer?

These printers have toners for each of the colours Cyan, Magenta, Yellow, and Black. In most printers, the paper passes through all the four toners in sequence, accepting each colour component to complete the print image.

What is Fuser?

After the pattern on the drum has been passed on to the paper by rolling, it passes through the fuser, where heat is applied to fuse the pigment particles to the paper.

What is Toner / Cartridge Refilling?

Budget laser printers and all inkjet printers have ink reservoirs that need to be discarded once the ink is depleted, as recommended by the manufacturers. Refilling usually involves using crude methods (undertaken by the user) to replenish the ink / toner levels, and can be achieved at a fraction of the cost of buying a new cartridge. But doing so usually voids the manufacturer warranty, and can result in reduced print quality..

What is Toner / Cartridge capacity?

The number of pages that can be printed on a single cartridge/toner. This figure is subjective and differs with test conditions. Usually, text printing capacity figures are based on a “5 per cent coverage”, meaning the printed matter only covers 5 per cent of the total paper surface.

What is Resolution?

This refers to the number of dots per square inch that a printer can print. The greater the resolution, the better the smoothness and clarity of the printed matter. Most current inkjet printers offer resolutions of up to 1200 x 1200 dpi, while the photo printers go up to 4800 x 4800 dpi. Laser printers usually offer 600 x 600 dpi with the better ones touching 1200 x 1200 dpi.

What is Print Queue?

Documents can be sent to a printer even while it is already printing a document. These documents are stored in the print queue. Depending on the size of the printer buffer, the print queue can be on the printer or in the system. If the queue is in the printer, disconnecting the PC after a document has been sent to the queue will not cause the queued documents to be lost.

What is Print Quality?

Printers support printing at different quality settings, usually termed Draft, Normal, and Best. The quality setting influences the print speed. In draft mode, the print resolution is lower, as is the amount of ink or toner used. Best mode gives the highest possible resolution, with a normal amount of ink, as in Normal mode. The time required for printing increases along with the resolution.

What is Print Media?

The surface on which a printout is taken. Most printers allow printing on normal paper sheets as well as thicker envelope covers. Photo printing requires the much thicker photo paper which is specially treated to prevent ink blot. The paper path influences the print media that is supported by the printer.

What is Print Job?

The pages sent to the printer at one time together constitute a job.

What is PPM?

This refers to the maximum pages that can be printed by the printer in a unit time, expressed as pages per minute (ppm). Printing speed varies with the content, coverage, and colour qualities. Printing pictures takes more time than text, printing closely-typed text takes more time than printing double spaced text, and printing a colour image takes more time than printing the same image in monochrome.

What is PostScript?

A device-independent printing language. Documents sent for printing from any system are first converted into Postscript.

What is PictBridge?

A protocol that allows digital cameras and photo printers to directly interact without the need to connect through a PC.

What is Paper Path?

This refers to the route the paper travels in the printer during the printing process. Complicated paper paths make it difficult to print of thicker media, besides increasing the chances of paper jams. Some printers print on the reverse side of the page, with reference to how the paper is placed in the tray, indicating a Ushaped paper path.

What is Paper Jam?

A paper jam refers to when a sheet of paper gets stuck in the printer. This can happen due to many factors, like page curl, page moisture, the roller not being clean, etc.

What is Paper Capacity / Tray Capacity?

The number of pages that can be stored in the printer tray. Most printers come with at least a 100-page tray capacity.

What is Printer Buffer?

Every printer has some memory on board, called the buffer, where content that needs to be printed is stored if the printer is currently printing. If the buffer is full, the printer will use the system RAM. Some printers come with upgradeable memory options. Using the printer buffer relieves the PC’s resources.

What is Network Printer / Workgroup Printer?

Such printers have a LAN port and can be plugged into a hub or switch and used by any PC on the network. Since it is not connected to any particular system, a PC is not needed to control the printer.

What is Duty Cycle?

A printer’s construction is capable of withstanding only a certain workload, expressed in the number of pages that can be printed in a unit of time. The Monthly Duty Cycle is the workload that a printer is designed to handle in a month, and is expressed in terms of pages per month.

What is Duplex Printing?

Refers to the ability to print on both sides of a page. This is managed by the printer by ordering the pages in the print queue so that only alternate pages are printed first. After the first print cycle, the pages are inverted and printed on the reverse. In automatic duplex printing, the printer manages all the steps without requiring user intervention. In manual duplex printing, after the first print cycle, the user must reinsert the pages in the paper tray.

What is Draft Mode / Ink Saving mode / Toner Saving Mode?

These refer to an alternative mode of printing where the printer uses less ink or toner to print. This is also the fastest mode of printing, and is ideal for trial prints.

What is CMYK?

This is the colour scheme used in printing technology. The name is derived from the four constituents of the scheme—Cyan, Magenta, Yellow, and Black. Colour inkjet printers have reservoirs for each of the colours. Some photo printers also carry additional colours like red, green, light cyan and light magenta to offer better colour fidelity.

What is Borderless Printing?

This feature is commonly seen in printers that also offer photo printing. Normally, all printers restrict the user from printing the entire width and length of a paper, leaving a small border. But this can be manually overridden. Borderless printing is a feature that allows the creation of photos that look similar to those available from professional labs. When this setting is selected, the printer prints the entire width and length of the paper.

What is Y-Splitter?

This is used to increase the number of free power connectors. The Y-splitter consists of two pins on one end and a socket on the other. The socket is used to connect to any Molex converter. This is usually seen associated with additional cabinet fans.

What is SMPS Fan?

The fan is used to cool the components in the SMPS. Since it sucks air out of the cabinet, it also helps reduce the temperature of the system.

What is SATA power connector?

SATA drives require a different 15-pin power connector. Most motherboards bundle a 4- pin Molex-to 15-pin SATA converter.

What is 6-pin PCIE Connector?

Powerful graphics cards require more power than the 75 watts that can be provided by the PCIE bus, so there are additional power sockets on the card. Power supplies with the 6-pin connector are labelled SLI / CrossFire Ready.

What is Bidirectional Printing?

In older printers, data could be only be sent from the PC to the printer. This meant no information about the status of the print job could be transmitted to the user. Bidirectional printing allowed the printer to convey messages to the PC, which made it easier for the user to track print progress, and be informed about the status of various parameters of the printer—ink level, for example.