Graphics Programs Reference
In-Depth Information
The second is to create the smallest possible fi le size so that the image loads in a user's
browser quickly while still maintaining good image quality so that the image looks like
you intended it to look in the Web page.
Figure 5-23 describes the basic optimization settings available for each format. The
Image Preview dialog box also enables you to resize a graphic, but it is better to do that
in Photoshop.
Figure 5-23
Basic image optimization settings
Format
Setting
Description
JPEG
Quality
Adjusts the quality of the image. A setting of 80 provides very good
quality with a fairly low file size, but you can adjust to find the optimal
setting for the image.
Smoothing
Blurs the edges of the image, making it look softer or slightly out of
focus. Also decreases the image's file size. Unless you want the soft
look that smoothing provides, leave it off.
Progressive
browser display
Displays the image in a Web page at a low resolution and then pro-
gressively increases the image to high resolution. With slower connec-
tions, the image will begin to appear sooner in the user's browser.
Sharpen color
edges
Makes the edges of the image sharper, creating the illusion that the
image is more in focus. This setting increases the image's file size sig-
nificantly and should be used sparingly.
Matte
Sets the color that will fill in any transparent areas of the image.
Remove unused
colors
Deletes any unused colors, reducing the image's file size. Use this setting
unless the resulting image has a blocky color display instead of smooth.
GIF/PNG8
Palette
Sets the colors used in the image's compression. Because GIF/PNG8
images can include a maximum of 256 colors, you must select the
specific colors used to display the image. Adaptive often provides best
results because it enables Dreamweaver to select the best 256 colors
for the image's compression.
Loss
Removes spots of color, decreasing the image's file size. This usually
looks more like an image effect and should be avoided unless you want
a stylized look.
Maximum num-
ber of colors
Adjusts the image's quality/file size because GIF and PNG8 formats
compress images by adjusting the number of colors in the image. The
maximum number of colors is 256, but you can decrease the number of
colors in the color palette as long as the image retains its visual quality
in the preview.
Dither
Simulates additional colors that are not included in the palette by cre-
ating patterns of related colors that resemble the desired color. This
usually does a poor job and increases the image's file size.
Transparency
Enables you to set index, alpha, or no transparency for the image. The
gray/white checked pattern in the background of the image denotes
the transparent area.
Remove unused
colors
Deletes any unused colors from the image color palette, reducing
the image's file size. Use this setting unless the resulting image has a
blocky color display instead of smooth.
Interlaced
browser display
Displays the image in a Web page at a low resolution and then pro-
gressively increases the image to high resolution. Although this setting
can decrease the image's file size, it might not provide the desired look
when the user loads the page.
PNG24
No real settings for this format.
PNG32
No real settings for this format.
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