Contex SD One+ - Page 59

Service Guide SD One+ 59
Foreground:
Foreground when scanning raster data (black and white, or monochrome data) refers to the pixels that represent data
of interest (background refers to everything else). Typically, lines and shapes are represented by black pixels
(foreground) and empty space is represented by white pixels (background). When scanning greyscale data,
background means the grey level of a region of pixels that surrounds some desired foreground data.
Gamma Adjustment:
An adjustment that makes the tone distribution lighter or darker in an image.
Gamut Transformation:
Color Management System function, where out-of-gamut colors are converted to colors within the gamut of the
targeted device, e.g., a printer.
Gamut:
The color range scanable, printable or displayable by a device; e.g., if some of the displayable colors are outside of
the gamut of the printer they cannot be printed.
GCR:
Grey component replacement. A color separation setting used on color photographs where cyan, magenta and yellow
inks are replaced by black ink (in a balance that would yield a grey value). The advantages are a reduction in overall
ink usage and some increase in image detail.
Greyscale:
A term for a black and white photographic image or a scanner setting. Refers to the range of 256 greytones that make
up the image.
Halftoning:
The processes of offset printing and laser printing are intrinsically bi-level. However, these devices can reproduce a
range of tone levels by halftoning; e.g., an array of widely spaced dots produces the perception of light grey, and an
array of tightly spaced dots produces dark grey. Halftone dots are usually placed in a regular grid. In color printing it is
conventional to use cyan, magenta, yellow and black grids that have exactly the same dot pitch but different carefully-
chosen screen angles.
Hardware id:
Is a unique ID no for the scanner, based on the scanners serial no and MAC address.
Highlights:
The lightest part of a picture reproduced as white on the screen or when printed.
Histogram:
A bar graph representing the statistical distribution of Greytones or colors in an image. Each column represents the
number of pixels at that grey level or color.
HLS:
A color space with the three variables of Hue, Lightness, Saturation. See HSV.