CHAPTER 12 THE IMPORTANCE OF RESOLUTION 183- Exit the scanning software and save the image with a new name. You can
now edit it and print it, depending on the resolution.
Understanding Bit Depth
A bit is the foundation for all computing: it’s the smallest unit of data—a one or a
zero. Bit depth is directly related to the amount of data (bits) a scanner or camera
captures per pixel. Most scanner software provides several scanning bit depths, such
as 24-, 36-, and 48-bit depth.
Eight bits make up a byte. A byte is a handy way to group bits (1 or 0). Two to the
eighth power equals 256. Therefore, 8 bits of data (a byte) can have 256 different
values (0–255) (see Table 12.3). For simplicity, let’s call each value a brightness.Table 12.3 Bit Depth and Corresponding RGB Colors
Number of
Bit Depth Values Available Values Available in an RGB Image
12 Not applicable
24 2 × 2 ×2 = 8 color values. Only applicable to a GIF image
(indexed color in Photoshop)
416 4 × 4 ×4 = 16 color values. Only applicable to a GIF image
(indexed color in Photoshop)
8 256 8(R)×8(G)×8(B) = 24 bits = 16,777,216 values
12 4096 12(R)×12(G)×12(B) = 36 bits = 68,719,476,736 values
16 16,384 16(R)×16(G)×16(B) = 48 bits = 281,474,976,710,656 valuesFIGURE 12.3
The scan resolu-
tion will show
up in Photo-
shop as the
Image Size.