IS 310 Chapter 4

What is digital input?

Discrete input with a finite number of possible values that computers ultimately represent as 1s and 0s.

What is analog data?

Continuous data, such as sound, images, fan speed, volume, or brightness.

What converts analog data into digital values?

An analog-to-digital converter.

What is metadata?

Data that describes or interprets the meaning of other data.

What are the two data types listed in the Data Types slide?

Numeric and alphanumeric.

What is numeric data?

Data used for mathematical calculations.

What is alphanumeric data?

Characters, digits, and symbols.

What standards are used to represent alphanumeric data?

Unicode, ASCII, and EBCDIC.

What is ASCII?

American Standard Code for Information Interchange; a 7-bit code representing 128 characters.

What is Unicode?

A multilingual character-coding system developed for worldwide use.

Why is Unicode useful?

It defines codes for nearly every character-based alphabet and many other language characters.

What is UTF-8?

The most widely used Unicode coding scheme on the Web.

What is UTF-16?

A Unicode format used by Windows and Java.

What is EBCDIC associated with?

Legacy IBM mainframes.

What are printing characters?

Characters produced on a screen or printer.

What are control characters?

Characters that control output, cause actions, or communicate status with I/O devices.

What are examples of control characters?

VT, LF, BEL, DEL, and ESC.

What are common representations for bitmapped images?

JPEG, GIF, TIFF, and PNG.

What are common representations for object images?

PostScript and SVG.

What are common sound formats?

MP3, WAV, MIDI, and WMA.

What are common page-description formats?

PDF, HTML, XML, and PostScript.

What are common video formats or standards?

MPEG-2, MPEG-4, WMV, and H.264.

What is a bitmap or raster image?

An image represented as a map of individual pixels.

What is an object or vector image?

An image made from geometrically defined lines, curves, and shapes.

What is a pixel?

A small area of an image with an associated coordinate location.

What is a major difference between bitmap and vector images?

Bitmaps use pixels; vectors use geometrically defined shapes.

What happens when bitmap images are enlarged?

They can develop jagged edges.

What happens when vector images are scaled?

They scale smoothly without losing their shape or identity.

What factors should be considered when representing data?

Accuracy, resolution, compactness, storage/transmission needs, and standardization.

What is resolution?

The amount of detail affecting the clarity and sharpness of an image.

What happens when greater accuracy and resolution are required?

More data is required.

What is a color palette?

A color translation table that uses a code for each pixel instead of the actual color value.

What factors affect bitmap file size?

Resolution, color levels, palette, and data compression.

What is compression?

Recoding data so that it requires fewer bytes of storage space.

What is a compression ratio?

The amount by which a file's size is reduced.

What is lossless compression?

Compression that allows the original data to be restored exactly.

What are examples of lossless compression formats?

GIF, PCX, TIFF, and ZIP.

What is lossy compression?

Compression that sacrifices some data quality to reduce file size.

What are examples of lossy compression formats?

JPEG and MP3.

What is JPEG mainly suited for?

Highly detailed photographs and paintings.

What type of compression does JPEG use?

Lossy compression.

What type of compression does GIF use?

Lossless compression.

What type of compression does PNG use?

Lossless compression.

What is a codec?

An encoder/decoder that determines a video format.

What is streaming video?

Video displayed in real time as it is downloaded from a Web server.

Why does video require large amounts of data?

It contains many high-resolution images displayed as frames over time.

How can video file size be reduced?

Compression, decreasing image size, reducing frame rate, or limiting colors.

What does an analog-to-digital converter do with audio?

Converts analog sound into digital values.

What is MIDI?

Musical Instrument Digital Interface; instructions used to recreate or synthesize sounds.

What is sampling rate?

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

What is the typical audio sampling rate listed in the slides?

44.1 KHz.

What is MP3?

A digital audio format that uses lossy compression to reduce storage requirements.

What is WAV?

A general-purpose audio format using uncompressed 8-bit or 16-bit sound samples.

What is standardization in data representation?

Using common standards so data formats can be consistently represented and used.

What are open standards and proprietary formats?

Two approaches to standardizing data formats.