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Adobe Photoshop Help
Getting Images into Photoshop and ImageReady
Using Help
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Contents
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Index
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61
Getting Images into Photoshop
and ImageReady
About bitmap images and vector graphics
Computer graphics fall into two main categories—
bitmap
and
vector
. You can work
with both types of graphics in Photoshop and ImageReady; moreover, a Photoshop file
can contain both bitmap and vector data. Understanding the difference between the two
categories helps as you create, edit, and import artwork.
Bitmap images
Bitmap images—technically called
raster images—
use a grid of colors
known as pixels to represent images. Each pixel is assigned a specific location and color
value. For example, a bicycle tire in a bitmap image is made up of a mosaic of pixels in that
location. When working with bitmap images, you edit pixels rather than objects or shapes.
Bitmap images are the most common electronic medium for continuous-tone images,
such as photographs or digital paintings, because they can represent subtle gradations of
shades and color. Bitmap images are resolution-dependent—that is, they contain a fixed
number of pixels. As a result, they can lose detail and appear jagged if they are scaled
on-screen or if they are printed at a lower resolution than they were created for.
Example of a bitmap image at different levels of magnification
Vector graphics
Vector graphics are made up of lines and curves defined by mathe-
matical objects called
vectors
. Vectors describe an image according to its geometric
characteristics. For example, a bicycle tire in a vector graphic is made up of a mathematical
definition of a circle drawn with a certain radius, set at a specific location, and filled with a
specific color. You can move, resize, or change the color of the tire without losing the
quality of the graphic.
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