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HD Ultra X Service Guide
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 Graytones or colors in an image. Each column
represents the number of pixels at that gray level or color.
HLS
A color space with the three variables of Hue, Lightness, Saturation. See HSV.
HSV
A color space with the three variables of Hue, Saturation, Value. Hue means color (as in the color wheel.)
Saturation is an indication relating to the richness or vibrancy of the color. Value is a term best related to
the intensity of light illuminating the object.
Hue
A named color. In discussions of color that relate to photography, scanning, and printing, six hues are
especially important: red, yellow, green, cyan, blue, and magenta. These hues make up every color we
can see, and are the designated hues on color wheels. Hue is also a measurement of color that can be
related by pointing towards a certain color on the color wheel. Hue indicates the relative redness,
blueness, greenness, yellowness, etc., of a color.
ICC
The International Color Consortium (ICC) was formed to address the need for a common color framework.
The ICC has developed a standard device profile that contains information about how various devices
render color. This concept is supported by Apple (Colorsync), Microsoft for Windows 95, Sun for Solaris,
and by Silicon Graphics for Irix.
Image Editor
A program used to edit pictures to change colors, increase detail, scale or otherwise alter the picture.
Indexed color
Indexed color (or pseudo-color) is the provision of a relatively small number, say 256, of discrete colors in
a colormap or palette. For each pixel in the image, the index number of a color is then stored. When
retrieving the image, a lookup table uses the index to retrieve red, green and blue components that are
then sent to the display. In graphic file for-mats such as PCX of TIFF, an indexed color image is
accompanied by its colormap.
Interpolation
Using the interpolation method of resampling generates values for points in between the actual pixels by
looking at the surrounding colors or intensities. In a scanner resolution is increased beyond the actual
number of CCD cells. As each line of pixel data arrives from the cameras, new interpolated pixels are
added between original pixels. The added pixels enhance line edge definition.
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