Chapter 1 - Data Representation

Hexadecimal

a base-16 number system that uses the values 0-9 and characters A-F.

Binary

a base-2 number system that uses the values 0 and 1.

Denary

Base 10 number system, how we normally count, uses digits 0 to 9.

ASCII

a code for representing English characters as numbers, with each letter assigned a number from 0 to 127

Unicode

A character code that enables most of the languages of the world to be symbolized with a special character identification.

overflow

error that results when the number of bits is not enough to hold the number.

two's complement

A method of representing negative numbers in the binary system.

resolution

the dimensions of an image

metadata

additional data that is stored with an image that can provide information such as the dimensions of the image and the time and date the image was taken

colour depth

the number of bits that are used to create each colour in an image

sound sampling

a little piece of sound that is recorded at regular time intervals.

sample rate

the number of samples recorded each second.

sample resolution

the number of bits that are used to record each sound sample.

Bitmap

an image composed of pixels with a fixed resolution

Bit

This is the smallest measurement for data

Nibble

4 bits or half a byte (1 hex digit)

Byte

8 bits = 1 byte enough for one letter in English

Kibibyte (KiB)

1024 bytes

Mebibyte (MiB)

1024 kibibytes

Gibibyte (GiB)

1024 mebibytes

Tebibyte (TiB)

1024 gibibytes

Pebibyte (PiB)

1024 tebibytes

Exbibyte (EiB)

1024 pebibytes

Compression

a method that uses an algorithm to reduce the size of a file

lossy

a compression method that reduces the size of a file by permanently removing data.

lossless

a compression method that reduces the size of a file by temporarily altering the data.

perceptual music shaping

a process that is used in lossy compression that removes sounds that are not normally heard by the human ear.

Run Length Encoding (RLE)

an algorithm that groups together repeating patterns and indexes them.

PDF

Fixed layout document that maintains its original appearance regardless of the software used to view it

JPG

Lossy compressed files commonly used for website images

GIF

Lossy compressed images using only 256 colours, used for simple web graphics

PNG

Lossless compressed format using an alpha channel to preserve transparent backgrounds

MP3

Lossy compressed music format

MP4

a lossy compressed file format that can be used for audio and video; appropriate for streaming