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Digital Imaging Glossary

In the computer industry, the process of bringing information from one device to another. Usually applies to the movement of pictures from a digital camera to a host computer via a USB cable.

Analog (or Analogue)
A signal which changes over a range of values. For example, the video and audio outputs of a VHS videocassette recorder are analog signals [compare Digital].

Back-formation of binary digit. One bit in a file represents either a one or a zero.

Bitmap (BMP)
A file format, in which each pixel of an image is recorded with the same number of bits. No compression is used in bitmap files, so they contain all the detail of the original image. However, bitmap files take up much more space in memory and / or mass storage when they are recorded in a computer.

Color Gamut
A standardized group of colors, used to ensure that an image will retain its same colors as it is acquired, edited, stored and printed.

Compact Flash
A memory-module standard, used in digital cameras. The Compact Flash family is an earlier standard, and is thicker and larger than other newer types of modules.

The process of making an image file take up less memory space, while retaining most of the detail of the original image. The most common compression system used in digital imaging is the JPEG format.

A signal which changes only between two values: on and off, positive and negative. For example, when a digital camera is connected to a USB port, the camera's output is a digital signal [compare Analog].

Digital Zoom
A feature in digital cameras, whereby the outer edges of an image are discarded, and the center of the image is expanded to fill the entire image. Digital zooming simulates what a "zoom lens" does in a film camera, but does not move the camera's lens, and thus saves battery power. However, as with compression, it loses some of the original image's detail. Digital cameras express their digital zoom in terms of how many times closer the image appears (3x, 8x, and so forth) between its "wide-angle" and its "telephoto" setting.

Dye Sublimation
A printing process in which wax-based colored dye is heated to its vapor point (thus becoming "sublime"). The vapor particles cool as they come in contact with the printing paper, and solidify into colored dots. Professional color printers often use dye sublimation, or "dye-sub" for short.

Graphics Interchange File Format. Developed by CompuServe in 1987 as a standard format for graphics in their network. GIF includes the ability to render colors transparent, allowing text and graphics to be layered over one another, making the format popular in website graphics.

Gloss (or Glossy)
A finish on photo-quality paper, which adds a glass-like appearance to the surface of a printed picture [compare Matte].

Inkjet Printer
A printer which sprays microscopic droplets of colored ink onto paper. Epson printers compress the ink by flexing quartz crystals in their print-head nozzles: Canon and Hewlett Packard printers heat their ink nozzles electrically.

The Joint Photographic Experts' Group. A combined effort of the International Standards Organization (ISO) and the International Telecommunications Union (ITU), JPEG creates and codifies standards for use in the photographic industry around the world. The JPEG compression standard is frequently applied to storing image files in digital cameras.

Laser Printer
A printer which uses infrared light from a laser and a powdered toner to form an image on a light-sensitive drum, then transfer the image to paper. Color laser printers repeat this process (basically the same as in a copying machine) four times, with black, cyan, magenta and yellow toner powders.

A finish on photo-quality paper, which adds a soft, slightly reflective appearance to the surface of a printed picture [compare Gloss].

Memory Stick (MS)
A memory-module standard, distinctive to Sony digital cameras.

A sub-miniature hard disk drive, which is sized and shaped to fit in a "Type II" Compact Flash module slot. Microdrives can store more information than Compact Flash modules (up to 4 gigabytes).

Multimedia Card (MMC)
A memory-module standard, used in some digital cameras. Multimedia Cards are smaller and lighter than Compact Flash cards, and are (in most cases) cross-compatible with Secure Digital cards.

Optical Zoom
A feature in either digital or film cameras, whereby the lens is extended or retracted to change the relative size of the image being taken. Digital cameras express their optical zoom in terms of how many times closer the image appears (3x, 8x, and so forth) when the lens is set from "wide angle" to "telephoto".

Back-formation of picture element. An individual point on a digital image, with a given value of brightness (luminance) and color (chrominance).

Portable Network Graphics. PNG offers the same transparency features as GIF, but with greater color depth, better compression and brightness control. PNG is being proposed by some groups as a replacement for GIF.

Secure Digital
A memory-module standard, used in some digital cameras. Using the same encoding method as in DVD Audio media, data stored in Secure Digital cards can be protected from being read in other devices. Most digital cameras do not encode their pictures when taken on a Secure Digital card.

SmartMedia (SM)
A memory-module standard, used in some earlier digital cameras. SmartMedia cards were very thin and lightweight, and consumed less power than early Compact Flash cards.

Tagged Interchange File Format. Developed by the predecessor of Adobe Systems. TIFF is compatible with many different graphics programs, and can compress graphics files with no loss of the original data ("lossless compression"). However, TIFF files are larger, and take longer to open, than other file formats.

The Universal Serial Bus: a computer-industry standard for connecting a host computer (the "root") to one or more peripheral devices. USB peripherals can be connected or disconnected without turning either the computer or the peripheral off.

xD-Picture Card
A memory-module standard, distinctive to Olympus and Fuji digital cameras.

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