Bit depth
- Creighton Barrett
In digital imaging and digital video systems, bit depth is the number of bits used to define each pixel in an image or frame. Digital images can be be bitonal, grayscale, or colour.Â
In digital audio systems, bit depth is the number of bits used to define each sound sample (see sampling rate). The following table provides binary calculations for the number of tones (i.e., colour) or sounds represented by common bit depths:
| Number of bits | Number of tones or sounds |
|---|---|
| 1 bit (21) | 2 |
| 2 bits (22) | 4 |
| 3 bits (23) | 8 |
| 4 bits (24) | 16 |
| 8 bits (28) | 256 |
| 16 bits (216) | 65,536 |
| 24 bits (224) | 16,777,216 million |
Bit depth directly corresponds to the resolution of a digital image or digital audio or video file. The greater the bit depth, the greater the number of tones (i.e., colours) that can be represented in a pixel. The greater the bit depth, the greater the possible dynamic range that can be represented in the bitstream of a digital audio file.