Fujitsu fi-4120C Operator's Manual page 168

Equipment Error
An error that cannot be corrected by the operator. Call CE.
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 pix-
els is modified by diffusing errors on the objective pixel into several
pixels, which are then binarized. This maintains high grayscale lev-
els and resolution during reading, while suppressing more patterns
by dotted halftone images such as newspaper photographs.
Filtering
A correction method that improves the read quality of handwritten
documents. The read quality of images written in pencil or ball-
pointed pen depends on the reflective light characteristics of the
specific ink or lead used. Dropped pixels may produce outlines,
gaps, or thin, barely connected lines due to uneven optical density.
Filtering detects areas lighter than their surroundings and
increases their density to improve image clarity.
Front-side reading = Front-side scanning
Refers to reading the front side of the document, specifically in
Duplex reading mode.
GL-3