Glossary
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Error diffusion
Method of halftone (pseudo-grayscale) image processing which is based on black & white pixel binarization. It sums the
optical density of a pixel and its adjacent pixels, then relocates black pixels in the order of density to minimize the difference
between scanned and output images. By diffusing the errors onto other pixels, the density data of adjacent pixels can be
binarized. This function suppresses moire patterns of dotted halftone images such as newspapers, and reproduces its
grayscale gradation.
F
Filter
A function that applies a type of filter operation process on a scanned image.
Types of filtering are as follows:
Digital Endorser:
Adds alphanumeric character strings on the scanned image data.
Page Edge Filler:
Fills in the margins of the scanned image in a specified color.
Flatbed
An input device of the scanner.
A user places sheets of documents one by one on the document bed (glass section) and scans each sheet.
Also used to scan documents such as books and magazines.
G
Gamma
A unit which indicates the changes in the brightness of an image. It is expressed as a function of the electric input power to
devices (e.g. scanner, display) and the brightness of the image. If the gamma rate is larger than 1, the brightness of an
image increases and vice versa.
Grayscale
A method which expresses the gradation (density) from black to white in 256 levels. Suitable for scanning images such as
photographs.
