Fujitsu i-4990C, Operator'S Manual

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GL-2
Dither
Technique for producing halftone images representing grayscale by using a pattern of the two pixel levels
black and white.
dpi
Dots per inch.
Drop-out color
A color which is used to illuminate the document but does not appear in the read image.
Duplex reading mode
Both sides of the document are read in this mode.
Endorser
The unit for printing characters before or after scanning. These character may be used for collation of the
documents and the image data.
Equipment Error
An error that is not recoverable by operator. Call an authorized maintenance engineer.
Error diffusion
High-quality halftone (pseudo-grayscale) image production based on black-and-white pixel binarization.
A pixel’s optical density and that of adjacent pixels are summed, with black pixels relocated in their order
of density as they relate to adjacent pixels.
The purpose of this technique is to minimize the average error between read and printed densities.
Density data for adjacent pixels is modified by diffusing errors on the objective pixel into several pixels,
which are then binarized. This maintains high grayscale levels and resolution during reading, while
suppressing more patterns by dotted halftone images such as newspaper photo graphs.
Filtering
The quality of images written in pencil or ball-pointed pen and read depends on the reflective light
characteristics of the ink or lead.
Dropped pixel’s may produce out lines, gaps or thin, barely connected lines due to even optical density.
Filtering detects areas lighter than their surroundings and increases their density to improve image clarity.
16GL.P65 01.2.17, 5:47 PM 2