Ch. 1: Digital Content

Unicode

A 16-bit character-representation code that can represent more than 65,000 characters.

GIF (Graphics Interchange Format)

A bitmap graphics file format, popularized by CompuServe, for use on the Web.

TIFF (Tagged Image File Format)

A bitmap image file format with the .tif extension that automatically compresses the file data.

Digital camera

A camera that takes and stores a digital image instead of recording onto film.

ASCII (American Standard Code for Information Interchange)

A code that represents characters as a series of 1s and 0s. Most computers use ASCII code to represent text, making it possible to transfer data between computers.

True Color

A color image with a color depth of 24 bits or 32 bits. Each pixel in a True Color image can be displayed using any of 16.7 million different colors.

Lossless compression

A compression technique that is able to reconstitute all of the data in the original file; hence, lossless means that this compression technique does not lose data.

Audio player

A device or software program that plays files containing audio data in one or more formats, such as MP3 or WAV.

Scanner

A device that converts a printed image into a bitmap graphic.

Digital-to-analog converter

A device that converts digital data, such as 1s and 0s, in an audio file into continuous data, such as audio sounds.

MPEG (Moving Picture Experts Group)

A family of highly compressed container file formats and codecs for digital multimedia; MPEG-1, MPEG- 2, and MPEG-4.

AAC (Advanced Audio Coding)

A file format that provides highly compressed audio files with very little loss of sound quality and is promoted by Apple on its iTunes Web site.

JPEG (Joint Photographic Experts Group)

A format that uses lossy compression to store bitmap images. JPEG (pronounced ?JAY-peg?) files have a .jpg extension.

Run-length encoding (RLE)

A graphics file compression technique that looks for patterns of bytes and replaces them with messages that describe the patterns.

SVG (Scalable Vector Graphics)

A graphics format designed specifically for Web display that automatically resizes when displayed on different screens.

Binary number system

A method for representing numbers using only two digits: 0 and 1. Contrast to the decimal number system, which uses ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.

MOV

A multimedia file format, popular for digital videos, that works with QuickTime software.

File

A named collection of data (such as a computer program, document, or graphic) that exists on a storage medium, such as a hard disk or CD.

Ogg Theora

A non-proprietary container format (Ogg) and video codec (Theora).

Compression ratio

A ratio such as 5:1 indicating the amount of compression that has been applied to a file. High compression ratios such as 35:1 indicate more compression so data can be contained in smaller files.

Digital video

A series of still frames stored sequentially in digital format by assigning values to each pixel in a frame.

Delimiter

A special character used to separate commands or formatting characters from the rest of the text in a file.

MIDI (Musical Instrument Digital Interface)

A standardized way in which sound and music are encoded and transmitted between digital devices that play music.

Ray tracing

A technique by which light and shadows are added to a 3-D image.

3-D graphics

A type of digital graphics format that displays a three-dimensional image in a two dimensional space.

PNG (Portable Network Graphics)

A type of graphics file format similar to but newer than GIF and JPEG.

Phoneme

A unit of sound that is a basic component of words and is produced by speech synthesizers.

AVI (Audio Video Interleave)

A video file format, developed by Microsoft, that was once the most common format for desktop video on the PC.

Byte

An 8-bit unit of data that represents a single character.

Bitmap graphic

An image, such as a digital photo, that is stored as a gridwork of colored dots.

Image histogram

An interactive graph that can be used to adjust the colors in a digital photo.

Ogg Vorbis

An open source audio file format.

CDDA (Compact Disc Digital Audio)

An optical disc recording format for audio CDs.

Lossy compression

Any data compression technique in which some of the data is sacrificed to obtain more compression.

Analog-to-digital converter

Any device, such as a sound card, that converts analog data into digital data.

Image compression

Any technique that is used to reduce the size of a file that holds a graphic.

Gigabit (Gb or Gbit)

Approximately 1 billion bits; exactly 1,024 megabits.

Gigabyte (GB)

Approximately 1 billion bytes; exactly 1,024 megabytes (1,073,741,824 bytes).

Megabyte (MB)

Approximately 1 million bytes; exactly 1,048,576 bytes.

Kilobyte (KB)

Approximately 1,000 bytes; exactly 1,024 bytes.

Synthesized sound

Artificially created sound, usually found in MIDI music or synthesized speech.

Digital compositing

Assembling parts from multiple digital images into a single image.

Letterbox

Black bars added to a video file to fit it into a different aspect ratio.

Digitization

Converting non-digital information or media to a digital format through the use of a scanner, sampler, or other input device.

Analog data

Data that is measured or represented on a continuously varying scale, such as a dimmer switch or a watch with a sweep second hand.

Pixelation

Describes the effect of increasing the size of an image until smooth edges become jagged.

Resolution dependent

Graphics, such as bitmaps, in which the quality of the image is dependent on the number of pixels constituting the image.

Intraframe compression

In a digital video, compression that takes place within a single frame, similar to the compression used for still images.

Photosites

In digital photography, each photosite is a single point on an image capture chip, equivalent to one pixel.

Rendering

In graphics software, the process of creating a 3-D solid image by covering a wireframe drawing and applying computer-generated highlights and shadows.

Data

In the context of computing and data management, refers to the symbols that a computer uses to represent facts and ideas.

RAW

In the context of digital graphics, a file that contains unprocessed image data directly from a digital camera's sensors.

Cloning

In the context of digital graphics, the process of replicating a section of an image, often used to cover blemishes or fill in backgrounds.

Frame

In the context of digital video, one of the sequential images that are combined to produce video footage.

Character data

Letters, symbols, or numerals that will not be used in arithmetic operations (name, Social Security number, etc.).

ASF (Advanced Systems Format)

Microsoft's proprietary container format for streaming digital multimedia; typically holds WMV and WMA files.

Digital audio

Music or voice that has been digitized into files using sampling techniques; sometimes referred to as waveform audio.

Numeric data

Numbers that represent quantities and can be used in arithmetic operations.

CCD (charge-coupled device)

One of the components in a digital camera that captures light from an image and converts it into color data.

Codec

Short for compressor/decompressor; a hardware or software routine that compresses and decompresses digital graphics, sound, and video files.

Pixel

Short for picture element; the smallest unit in a graphic image. Computer display devices use a matrix of pixels to display text and graphics.

Interframe compression

Shrinking the size of a video by removing redundant data that is the same in two successive frames.

Extended ASCII

Similar to ASCII but with 8-bit character representation instead of 7-bit, allowing for an additional 128 characters.

Text-to-speech software

Software that generates speech based on written text that is played back through a computer's sound card.

Audio plugin

Software that works in conjunction with a browser to play audio that is accessed from Web sites.

Live stream

Streaming data that carries an event happening in real time.

On-demand stream

Streaming media that starts and stops when requested, as opposed to a live stream.

Audio compression

Techniques used to reduce the size of files that contain audio data.

ASCII text

Text files that contain no embedded formatting codes.

Digital data

Text, numbers, graphics, or sound represented by discrete digits, such as 1s and 0s.

OCR (optical character recognition)

The ability of a device or software to digitize text from printed sources.

File name extension

The characters in a file name after the period, such as .exe and .txt.

MIDI messages

The commands that create MIDI music by specifying the note to play, its duration, and the instrument that plays it.

Container formats

The formats for files that hold multiple types of media files, such as video and audio.

File format

The method of organization used to encode and store data in a computer. Text formats include DOCX and TXT. Graphics formats include BMP, TIFF, GIF, and PNG.

BMP

The native bitmap graphics file format of Microsoft Windows.

Bit rate

The number of bits that are transmitted or processed per unit of time (usually per second); usually measured as bps (bits per second).

Color depth

The number of bits that determines the range of possible colors that can be assigned to each pixel. For example, an 8-bit color depth can create 256 colors.

Frame rate

The number of frames that are displayed in a video per second.

Image resolution

The number of pixels in an image, usually expressed as horizontal pixels × vertical pixels.

Sampling rate

The number of times per second a sound is measured during the recording process.

Clipping path

The outline of an object in a digital image that can be used to cut out the object from its background.

Speech synthesis

The process by which computers produce sound that resembles spoken words.

Speech recognition

The process by which computers recognize voice patterns and words, and then convert them to digital data.

Alpha blending

The process of combining a foreground color with background colors as when an image is pasted onto a background and the edges are blended to look more natural.

Transcoding

The process of converting audio and video files from one digital format to another, such as converting an MOV file into a Flash video file.

Digital audio extraction

The process of copying files from an audio CD and converting them into a format that can be stored and accessed from a computer storage device, such as a hard disk; sometimes referred to as ripping.

Inpainting

The process of reconstructing missing parts of digital images, usually by means of an algorithm built into graphics software.

Data compression

The process of shrinking the size of a file by removing data or recoding it more efficiently.

Rasterization

The process of superimposing a grid over a vector image and determining the color depth for each pixel.

Download

The process of transferring a copy of a file from a remote computer to a local computer's storage device.

Aspect ratio

The ratio of the width and height of an image or display screen.

Binary

The representation of data using two states, such as off-on or 1-0.

Bit

The smallest unit of information handled by a computer. A bit is one of two values, either a 0 or a 1. Eight bits constitute a byte, which can represent a letter or a number.

Digital cinematography

The use of digital cameras and storage to produce high-quality digital films.

Data representation

The use of electronic signals, marks, or binary digits to represent character, numeric, visual, or audio data.

RGB color model

The use of red, green, and blue light that can be combined to create the full spectrum of colors.

Interlaced scan

The way a display device builds an image by showing every other row of pixels, and then going back and filling in the remaining rows.

Megabit (Mb or Mbit)

1,048,576 bits.

Kilobit (Kbit or Kb)

1024 bits.