Web / Internet Colors; Colors (Default) / 256 Colors (Custom); Line Art; Black-And-White Diffusion - Microtek ArtixScan 4500t Reference Manual

Web / Internet Colors

This mode is useful for displaying images on the Web or Internet. Output for the
Web / Internet color mode in ScanWizard Pro is 8-bit, 256 indexed color images
in the sRGB color space.

256 Colors (Default) / 256 Colors (Custom)

These are single-channel images (8 bits per pixel) that use a color lookup table
containing up to 256 colors. The file size is smaller for images in this mode. As
an initial setting, selecting 256 Colors (Default) uses an Adaptive palette with
Diffusion. If the 256 Colors (Custom) option is selected, the dialog box below
appears.
2) Dither: The Dither option can improve the color quality of the 256-indexed
color image for photographs or continuous-tone images, using a technique of
mixing available colors to simulate missing colors. None provides no dithering.
Pattern uses a structured pattern to simulate missing colors. Diffusion (default)
uses the error diffusion technique to dither colors and produces the best quality
for 256 colors.

Line art

Line Art images are made up of one bit of color (black or white) per pixel. Few
editing options are available in this mode, but this mode is useful for images
consisting purely of black and white or even single colors, such as mechanical
drawings, blueprints, or fine-line illustrations.

Black-and-White Diffusion

This is a single-bit black-and-white image dithered with error diffusion. The
black and white pixels are arranged in a way as to "fool" the eye into seeing gray.
1) Palette: The Palette option lets you
choose the method for creating the
color palette table. Uniform uses a 6-6-6
fixed color palette table. Adaptive
(default) creates a color palette table
from the more commonly used areas of
the color spectrum that appears in the
image.
Reference: The Settings Window 61