9.1 Data Representation: Images and Sound

Vocabulary flashcards covering key definitions and formulas for data sizes, digital image representation, and digital sound sampling from topic 9.1 Data Representation.

Bit

Short for binary digit; each 1 or 0.

Byte

A unit of digital data consisting of 8 bits.

Binary units in ascending order

Bit, Nibble, Byte, Kilobyte, Megabyte, Gigabyte, Terabyte, Petabyte.

Pixel

Short for picture element; typically a tiny dot that can normally only be seen when zoomed in, which makes up an image.

Image resolution

The total number of pixels ($\text{row} \times \text{columns}$) in an image.

Colour depth

The number of bits used for each pixel in an image.

1-bit colour depth

A colour depth that allows for 2 colours.

2-bit colour depth

A colour depth that allows for 4 colours.

24-bit colour (RGB) depth

A colour depth that allows for 16 million colours.

Image file size formula

$$\text{resolution } (\text{columns} \times \text{rows}) \times \text{colour depth}$$

Metadata

The data stored in an image file which helps the computer recreate the image on screen (e.g., file format, height, width, colour-depth, resolution, time/date/location). Without it, devices would not be able to display images.

Image manipulation

The use of various techniques to alter and adjust an image.

Sampling

The process of converting analogue signals to digital signals so that they can be processed by a computer.

Sample interval

The time gap between taking a sample (e.g., sampled every 5 milliseconds).

Sample rate

How many samples are taken in a second (e.g., 44.1 kHz means 44,100 samples are taken per second).

Sample size

How many bits are recorded for each measurement.

Sound file size formula

$$\text{sampling rate} \times \text{Sample size} \times \text{duration of clip}$$