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HD Ultra X Service Guide
The set of colors available for an image.
PICT
A file format for pictures used primarily on the Macintosh.
Pixels Per Inch (ppi)
A measurement of resolution for scanners, where the individual element is a square picture element
(pixel).
Pixels
The word pixel is a combination of the two words picture and element. It is the smallest building block
within a scanned line-art or photographic image. A pixel is the small square picture element that is filled
with a color, black or white. The value of a pixel depends on the luminance of the area, and is either a
single bit for a black and white image, or multi-bit for a color or gray-tone image. Pixels come in various
sizes and their size is expressed in terms of resolution. Resolution is measured in pixels per inch (ppi) or
the equivalent dots per inch (DPI.)
PostScript
A computer language developed by Adobe (R) Systems, Inc. for printing text, graphics, and scanned
images. PostScript (R) is a vector format that can include scanned bitmapped images.
Raster File
Also called Raster Image or Bitmapped Image. A picture composed of individual dots (picture elements,
pixels) the way a scanner perceives it. The rows in a high-resolution raster file typically contain 200 or 300
dots per horizontal inch of the original drawing, and there are typically 200 or 300 rows per vertical inch.
As each of these dots is defined by location, and by whether it is on or off, raster images generally result
in large data files.
Resolution of a Scanner
Expressed as DPI (dots per inch) or the equivalent ppi (pixels per inch). The higher the resolution of a
scanner, the smoother the scanned images.
Resolution
A measure of how many pixels per inch are scanned. Generally, more pixels per inch means more detail
in the picture and a larger file when saved. Defines the level of detail that can be captured or shown by a
scanner, display, or output device. For scanners, the resolution is defined by the number of dots (pixels)
per inch (DPI) that can be captured horizontally and vertically, e.g. 300 DPI equals 90,000 pixels per
square inch. Screen Resolutions are normally 72 pixels per inch of screen. Additional detail is thrown
away by the screen display driver, anyway. For Printer Resolution scans, you need 150 dots per inch and
above for good results on the printed output. One must find the level of detail that is still visible in printed
output on the printer in question, and not dramatically increase the size of a saved file without bettering
the result.
RGB
Red, Green, Blue. These additive primary colors are the basic elements of white light. By mixing them on
a computer monitor or in a scanned image file, other colors can be created. For instance, Red and Green
produces Yellow, and equal amounts of all three produce gray.
RIP
Raster Image Processor. A RIP is a special software that converts scanned images into a color dithered
(halftone) image that can be output directly. An image must be 'ripped' before it can be output on a CMYK
device, e.g., an inkjet printer.
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