Adobe PHOTOSHOP 5.0 User Manual page 332

324 CHAPTER 14
Saving and Exporting Images
PCX
The PCX format is commonly used by IBM PC-
compatible computers. Most PC software
supports version 5 of the PCX format. A standard
VGA color palette is used with version 3 files,
which do not support custom color palettes.
The PCX format supports RGB, indexed-color,
grayscale, and Bitmap color modes, and does not
support alpha channels. PCX supports the RLE
compression method. Images can have a bit depth
of 1, 4, 8, or 24.
PDF
Portable Document Format (PDF) is used by
Adobe Acrobat, Adobe's electronic publishing
software for Windows, Mac OS, UNIX
You can view PDF files using the Acrobat Reader
software included on the application CD-ROM.
Identical to PostScript pages, PDF files can
represent both vector and bitmap graphics, and
can contain electronic document search and
navigation features such as electronic links. For
more information on PDF and Adobe Acrobat, see
the Electronic Publishing Guide included on the
Tour & Training CD-ROM.
The Photoshop PDF format supports RGB,
indexed-color, CMYK, grayscale, Bitmap, and Lab
color modes, and does not support alpha
channels. The format supports JPEG and ZIP
compression, except for Bitmap-mode files, which
use CCITT Group 4 compression when saved as
Photoshop PDF. When you open a PDF created by
another application, Photoshop rasterizes the file
(see "Importing Adobe Illustrator, PDF, and EPS
files" on page 55).
PICT File
The PICT format is widely used among Macintosh
graphics and page-layout applications as an inter-
mediary file format for transferring files between
applications. The PICT format supports RGB files
with a single alpha channel, and indexed-color,
grayscale, and Bitmap files without alpha
channels. The PICT format is especially effective at
compressing images with large areas of solid color.
This compression can be dramatic for alpha
channels with their large areas of white and black.
When saving an RGB image in PICT format, you
can choose either a 16-bit or 32-bit pixel
resolution. For a grayscale image, you can choose
from 2, 4, or 8 bits per pixel. In Mac OS with
QuickTime installed, four JPEG compression
, and DOS.
®
options are available.
®
PICT Resource (Mac OS only)
A PICT resource is a PICT file contained in a
Mac OS file's resource fork—for example, an
applications' splash screen or the contents of the
Scrapbook. The PICT Resource format supports
RGB files with a single alpha channel, and
indexed-color, grayscale, and Bitmap files without
alpha channels.
Open a PICT resource by choosing File>Import>
PICT Resource. When saving a file as a PICT
resource, you can specify the resource ID and
resource name. As with other PICT files, you also
specify bit depth and compression options.