CHAPTER 13
230
Saving Images
4
Select Save Transparency if you want to preserve
transparency when the file is opened in another
application that supports PDF transparency.
5
Select Image Interpolation if you want to
anti-alias the printed appearance of a low-
resolution image.
6
Click OK.
Saving in PICT File format
PICT File format is widely used among Mac OS
graphics and page-layout applications to transfer
images between applications. PICT File format is
especially effective at compressing images with
large areas of solid color.
When saving an RGB image in PICT File format,
you can choose either 16-bit or 32-bit pixel
resolution. For a grayscale image, you can choose
from 2, 4, or 8 bits per pixel. On Mac OS, you can
save 32-bit PICT or PICT Resource files with four
levels of JPEG compression. To retain a saved
selection with the file, choose the 32-bit option.
Saving in PIXAR format
PIXAR format is designed specifically for
exchanging files with PIXAR image computers.
PIXAR workstations are designed for high-end
graphics applications, such as those used for three-
dimensional images and animation. PIXAR
format supports RGB and grayscale images.
Saving in PNG format
Developed as a patent-free alternative to GIF,
Portable Network Graphics (PNG) format is used
for lossless compression and for display of images
on the World Wide Web. Unlike GIF, PNG
supports 24-bit images and produces background
transparency without jagged edges; however, some
Web browsers do not support PNG images. PNG
preserves transparency in grayscale and RGB
images. For information on when to use PNG
format to optimize images, see “Choosing a file
format for the Web” on page 207.
To save a file in PNG format:
1
Choose File > Save As, and choose PNG from
the format list.
2
Specify a filename and location, select saving
options (as described in “Saving images” on
page 225), and click Save.
3
Select an Interlace option:
•
None to create an image that displays in a Web
browser only after downloading is complete.
•
Interlaced to create an image that displays
low-resolution versions in a browser while the
full image file is downloading. Interlacing can
make downloading time seem shorter and
assures viewers that downloading is in progress.
However, interlacing also increases file size.
4
Click OK.
