Multimedia and File Compression

Flashcards covering multimedia concepts including bit-map images, vector graphics, sound files, video, and file compression techniques.

Bit-map image

System that uses pixels to make up an image.

Pixel

Smallest picture element that makes up an image.

Colour depth

Number of bits used to represent the colours in a pixel.

Bit depth

Number of bits used to represent the smallest unit in a sound or image file.

Image resolution

Number of pixels that make up an image.

Screen resolution

Number of horizontal and vertical pixels that make up a screen display.

Resolution (screen)

Number of pixels per column and per row on a monitor or television screen.

Pixel density

Number of pixels per square centimetre.

Vector graphics

Images that use 2D points to describe lines and curves and their properties, grouped to form geometric shapes.

Sampling resolution

Number of bits used to represent sound amplitude (also known as bit depth).

Sampling rate

Number of sound samples taken per second.

Frame rate

Number of video frames that make up a video per second.

Lossless file compression

File compression method where the original file can be restored following decompression.

Lossy file compression

File compression method where parts of the original file cannot be recovered during decompression, so some of the original detail is lost.

JPEG

Joint Photographic Expert Group – a form of lossy file compression based on the inability of the eye to spot certain colour changes and hues.

MP3/MP4 files

File compression method used for music and multimedia files.

Audio compression

Method used to reduce the size of a sound file using perceptual music shaping.

Perceptual music shaping

Method where sounds outside the normal range of hearing of humans are eliminated from the music file during compression.

Bit rate

Number of bits per second that can be transmitted over a network; a measure of the data transfer rate.

Run length encoding (RLE)

Lossless file compression technique used to reduce text and photo files in particular.