Bit

A single numeric character. 1 binary digit 1 bit.

One mathematical bit can define two levels or states, on/off, black/white, etc.; two bits can define four levels, three bits eight, and so on. In image terms eight bits can define 256 shades of gray between black and white.

Each bit of a binary number can either be 0 or 1. An n-bit number is composed of exactly n numeric characters. An n-bit binary number can have 2n distinct values. For example, an 8-bit binary number has 28%6 distinct values, namely all the numbers between 00000000 (0 in decimal) and 11111111 (255 in decimal), inclusive. 8-bit quantization would discretely sample a signal and assign each sampling a value between 0 and 255, permitting 256 possible values.

Bit Rate

The amount of data transported in a given amount of time, usually defined in Mega (Million) bits per second (Mbps). Bit rate is one means used to define the amount of compression used on a video signal. Uncompressed D1 has a rate of 270 Mbps. MPEG 1 has a bit rate of 1.2 Mbps.

Bit Packing Density

The number of bits recorded per track length unit, usually expressed in terms of kilobits per inch (KBPI) or bits permillimeter (BPMM).