Adobe Photoshop CS3 - Manual (Page 65)

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Chapter 3: Opening and importing
images
Adobe® Photoshop® CS3 can open and import many types of graphic files. To work effectively, you should under-
stand basic imaging concepts, and how to acquire, import, and resize images.
Photoshop images
About bitmap images
Bitmap images—technically called raster images—use a rectangular grid of picture elements (pixels) to represent
images. Each pixel is assigned a specific location and color value. 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 more efficiently 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 to high magnifications 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
Bitmap images sometimes require large amounts of storage space, and often need to be compressed to keep file sizes
down when used in certain Creative Suite components. For instance, you compress an image file in its original appli-
cation before you import it into a layout.
Note: In Adobe Illustrator, you can create bitmap effects in your artwork using filters, effects, and graphic styles.
See also
“About vector graphics” on page 58
About vector graphics
Vector graphics (sometimes called vector shapes or vector objects) are made up of lines and curves defined by mathe-
matical objects called vectors, which describe an image according to its geometric characteristics.
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