Fujitsu FI-4530C Operator's Manual page 127

A standard paper size used in the U.S.A. and other countries. Paper size is 11 x 17 inches.
dpi
Dots per inch.
Dropout color
A color which is used in the document but does not appear in the read image.
Duplex reading mode
A reading mode in which both sides of the document are read.
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 bina-
rization. A pixel's optical density and that of adjacent pixels are summed, with black pixels relo-
cated 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 read-
ing, 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.
Halftone processing
Any method used to reproduce a photograph which includes a shade as an image composed of dots,
namely, a binary image. Dithering and error diffusion processing are examples of halftone process-
ing.
Hexadecimal
A base-16 numbering system (also commonly referred to as hex numbers). Since a base-16 system
requires 16 digits, numbers 0 through 9 and letters A through F are used. It is convenient to express
binary numbers in hexadecimal because fewer digits are required.
Image emphasis
Density is decreased for lighter but not completely white areas adjacent to black areas. Weakening
this emphasis eliminates spot noise or produces softened images.
Image processing
An image is read with specified parameters.
GL-2