Microtek ScanMaker E3 SCSI Manuel d'utilisateur télécharger pdf (Page 12)

1-6 Microtek User's Guide for Windows

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 or 36 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, to 68.7 billion colors for 36-bit scanners. The extra

amount of information that can be processed by 36-bit scanners

translates to more vivid color reproduction, as the scanner is able

to accommodate more subtle gradations of color approaching

lifelike accuracy.

Grayscale

Grayscale images contain more than just black and white, and

include actual shades of gray. In a grayscale image, each pixel or

dot 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.

256 grays16 grays

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Microtek ScanMaker E3 SCSI Manuel d'utilisateur Page 12