Microtek ScanMaker 5 User's Guide download pdf (Page 192)

Basic Concepts E-5

Grayscale

Grayscale images contain more than just black and white, and include actual

shades of gray. In a grayscale image, each pixel has more bits of information

encoded in it, allowing more shades to be recorded and shown.

For instance, four bits are needed to reproduce up to 16 levels of gray. Going

higher, eight bits can reproduce the 256 levels of gray required to represent

most black-and-white photos accurately.

Color

Color images contain the most complex information. To capture color images,

scanners use a process based on the RGB (Red, Green, and Blue) color model,

where every color is composed of a varying amount of the three colors. In the

RGB model, the absence of white light creates black, the complete saturation of

light creates white (100% of red, green, and blue), and equal amounts of red,

green, and blue create intermediate shades of gray.

Depending on the type of scanner you have, your scanner can record 24 bits for

the three RGB channels. This means your scanner can record and reproduce an

enormous amount of color information — anywhere from 16.7 million colors

for 24-bit scanners.

256 grays16 grays

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Microtek ScanMaker 5 User's Guide Page 192