chapter four

Optical vs Digital zoom

Optical zoom: specification reflect how much the cameral can zoom without losing image quality. This is what should be considered when purchasing a camera. Digital zoom: is some in-camera image processing.

Low vs High resolution

The quality of a scanned image is indicated by optical resolution, usually measured in the number of dots per inch (DPI). The resolution can be reduced if needed (such as to compress an image to reduce its file size before posting it on a Web page). A higher resolution results in a better image but also results in a larger file size.

Function key

used for issuing commands in some programs

Data projector

a display device that projects output to a wall or projection screen.

Ppm (pages per minute)

a measurement of the speed of printing; how many pages can be printed in a minute. It is often different for black printing vs. color printing. There are also often different settings for draft vs high resolution printing.

Wireless keyboard receiver

a way to connect a keyboard to the computer. A keyboard can be built into a device, attached by inserting a keyboard's wired cable or wireless receiver into a USB port, or connected via a wireless networking connection, such as Bluetooth.

Dot-matrix printer

an example of an impact printer that uses a printhead consisting of pins that strike an inked ribbon to transfer the ink to the paper. The appropriate pins are extended as the printhead moves across the paper in order to form the appropriate words or images. If used anymore, they are used typically to product multipart forms.

QR code

an optical code that represents data with a matrix of small squares

Barcode

an optical code that represents data with bars of varying widths or heights

Headphones

can be used instead of speakers when you do not want the audio output to disturb others.

Ink-jet printer

form images by spraying tiny drops of liquid ink from one or more ink cartridges onto the page. They print one line at a time. They are relatively inexpensive, have good-quality output and can print in color. They are the printer of choice for home use. They are also a good choice for printing photograph-quality digital photos.

Headset

headphones with a built-in microphone and are often used when dictating, making phone calls, or are participating in Web conferences using a computer. They can connect wired or wirelessly. Wireless headsets are commonly used in conjunction with mobile phones.

OMRs (Optical mark readers)

input data from optical mark forms to score or tally exams, questionnaires, ballots, etc.

Megapixels

one factor affecting digital camera quality is the number of pixels, measured in megapixels or millions of pixels) used to store the data for each image. A pixel is the smallest colorable area in an electronic image (such as a scanned image, or a digital photograph, or image displayed on a digital screen).

MICR (Magnetic ink character recognition)

technology used primarily by the banking industry to facilitate check processing.

OCRs (Optical character recognition)

the ability of a computer to recognize text characters printed on a document. The characters are read by a compatible scanning device and then OCR software is used to identify each character and convert it to editable text.

Speaker

the most common type of audio output device. They are either built into the computer or connected to it (wired or wirelessly) in order to provide audio output for games, music, videos, etc.

Dpi (dots per inch)

the number of dots per inch which is a measurement of image quality and resolution.

Laser printer

the standard for business documents and come in both personal and network versions. The laser printer uses a laser beam to charge the appropriate locations on a drum to form the page's image, and then toner powder (powdered ink) is released from a toner cartridge and sticks to the drum. Then toner is then transferred to a piece of paper when the paper is rolled over the drum and a heating unit fuses the toner powder to the paper to permanently form the image. Prints one entire page at a time. They are typically faster and better quality output than ink-jet printers.

Biometric readers

used to read biometric data about a person so that the individual's identity can be verified based on particular unique physiological characteristic (such as a fingerprint or a face) or a personal trait (such as a voice or a signature).

Optical resolution

usually measures in the number of dots per inch (DPI), it measures the quality of a scanned image