Oki ES3640eMFP, Справочное руководство

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A-104 Desktop Color Primer
ES3640e MFP Color Reference Guide - 104
A raster image, also referred to as a bitmap, is composed of a grid
of
pixels , each assigned a particular color value (as shown in
example a in the following figure). The grid, when sufficiently
enlarged, resembles a mosaic made from square tiles. Examples
of raster images include scans and images created in painting or
pixel-editing applications, such as Photoshop and Corel Painter.
The amount of data found in a raster image depends on its
resolution and bit depth . The resolution of a raster describes the
compactness of the pixels and is specified in pixels per inch (ppi).
The bit depth is the number of bits of information assigned to
each pixel. Black and white raster images require only one bit of
information per pixel. Grayscale images require 8 bits per pixel.
For photographic quality color, 24 bits of RGB color information
are required per pixel, yielding 256 levels of red, green, and blue.
For CMYK images, 32 bits per pixel are required.
When printing raster artwork, the quality of the output depends
on the resolution of the source raster. If the raster resolution is
too low, individual pixels become visible in the printed output as
small squares. This effect is sometimes called “pixelation.”
In vector graphics , picture objects are defined mathematically as
lines or curves between points—hence the term “vector” (see
example b). Picture elements can have solid,
gradient , or
patterned color fills. Vector artwork is created in illustration and
drawing applications, such as Illustrator and CorelDRAW. Page
layout applications, such as QuarkXPress, also allow you to create
simple vector artwork with their drawing tools. PostScript fonts
are vector-based, as well.