Bit Depth

Bit depth describes the number of bits used to store a value, with the number of possible values growing exponentially with the number of bits (Table 2.2). A single bit can store up to two possible values (black or white) while 2 bits can store up to four possible values (black, white, and two shades of gray), and so on (Figure 2.6). Digital image files are stored using either 8 or 16 bits for each of the three color channels that define pixel values (see “Color Modes” later in this chapter).

Table 2.2. Bit Depth
BitsTonal Values Possible
24
416
664
8256
101024
124096
1416,384
1665,536
Figure 2.6. As the bit depth increases, the number of possible tonal values grows exponentially.

8 Bit vs. 16 Bit

The difference between an 8-bit and a 16-bit ...

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