Optimizing Images For Chapter 12 About Optimization; The Web - Adobe PHOTOSHOP 6.0 Manual

Chapter 12: Optimizing Images for

the Web

reating small graphics files is key to
C
distributing images on the World Wide
Web. With smaller files, Web servers can
store and transmit images more efficiently, and
viewers can download images more quickly.
Likewise, when preparing images for CD-ROM or
other multimedia viewing, it's important to make
the image files as small as possible. This conserves
file storage space and decreases the amount of
RAM needed for image display.
About optimization
Optimization is the process of fine- tuning the
display quality and file size of an image for use on
the Web or other online media. Adobe Photoshop
and Adobe ImageReady give you an effective range
of controls for compressing the file size of an
image while optimizing its online display quality.
You can optimize images in the three major
graphic file formats used on the Web: GIF
(Graphics Interchange Format), JPEG (Joint
Photographic Experts Group), and PNG-8 or
PNG-24 (Portable Network Graphics, with 8-bit
or 24-bit color).
There are two methods of optimizing images:
For basic optimization, the Photoshop Save As
•
command lets you save an image as a GIF, JPEG,
or PNG file. Depending on the file format, you can
specify image quality, background transparency or
matting, color display, and downloading method.
However, any Web features—such as slices, links,
animations, and rollovers—that you've added to a
file are not preserved.
For complete information on using the Save As
command to save an image as a GIF, JPEG, or PNG
file, see "Saving images" on page 357.
• For precise optimization, you can use the
optimization features in Photoshop or
ImageReady to preview optimized images in
different file formats and with different file
attributes. You can view multiple versions of an
image simultaneously and modify optimization
settings as you preview the image to select the best
combination of settings for your needs. You can
also specify background transparency and
matting, select options to control dithering, and
resize the image to specified pixel dimensions or a
specified percentage of the original size.
When you save an optimized file using the Save for
Web (Photoshop) or Save Optimized
(ImageReady) command, you can choose to
generate an HTML file for the image. This file
contains all the necessary code to display your
image—as well as links, rollovers, and anima-
tions—in a Web browser.
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