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fi-4220C Image Scanner Operator’s Guide GL-3
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 com-
posed of dots, namely, a binary image. Dithering and error diffusion processing are
examples of halftone processing.
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.
Interface
The connection that allows communication from one part of a system to another. For
example, electrical signals are transferred between the computer and scanner over an
interface cable.
Inversion (Reverse-image reading)
In reverse-image reading, data is changed from black to white and vice versa.