Adobe PHOTOSHOP 6.0 Manual page 332

CHAPTER 12
322
Optimizing Images for the Web
In ImageReady, you can control which options
show in the Optimize palette by clicking the Show
Options control ( ) on the Optimize palette tab.
To show all options, choose Show Options from
the Optimize palette menu.
To optimize an image in JPEG format:
Select a view in which to apply the
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optimization setting.
2 Select the slice or slices to which you want to
apply the optimization setting. (See "Selecting
slices" on page 276.)
3 In the Optimize panel/palette, choose JPEG
from the File Format menu.
4 Do one of the following to specify the image
quality:
• Choose an option from the Quality menu.
• Drag the Quality pop-up slider.
Enter a value in the Quality text box.
•
The higher the Quality setting, the more detail the
compression algorithm preserves. However, using
a high Quality setting results in a larger file size
than using a low Quality setting. View the
optimized image at several quality settings to
determine the best balance of quality and file size.
5 To vary the Quality setting across the selected
slices using an alpha channel, click the channel
button ( ). In the Modify Quality Setting dialog
box, choose an alpha channel from the pop-up
menu, set a quality range, and click OK.
(See "Using channels to modify JPEG quality" on
page 327.)
6 To create an enhanced JPEG with a slightly
smaller file size, select Optimized. The Optimized
JPEG format is recommended for maximum file
compression; however, some older browsers do
not support this feature.
7 Select Progressive to create an image that
displays progressively in a Web browser. The image
will display as a series of overlays, enabling viewers
to see a low-resolution version of the image before
it downloads completely. The Progressive option
requires use of the Optimized JPEG format.
Progressive JPEGs require more RAM for viewing,
and are not supported by some browsers.
To apply a blur to the image to smooth
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rough edges, enter a value for Blur or drag the
pop-up slider.
The Blur option applies an effect identical to that
of the Gaussian Blur filter and allows the file to be
compressed more, resulting in a smaller file size.
A setting of 0.1 to 0.5 is recommended.
9 To preserve the ICC profile of the image with
the file, select ICC Profile.
ICC profiles are used by some browsers for color
correction. The ICC profile option preserves ICC
profiles embedded by Photoshop. This option is
only available after you've saved an image with an
ICC profile—it is not available for unsaved images.
(See "Setting up color management" on page 124).
If the original image contains transparency,
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select a Matte color that matches the background
of your Web page. (See "Making transparent and
matted images" on page 339.)