Adobe Dreamweaver CS3 - Manual (Page 388)

DREAMWEAVER CS3
User Guide
381
Matte Allows you to set the image’s background. You can maintain the transparency of a 32-bpc (bits per channel)
PNG by clicking the transparency icon in the Matte dialog box. You can also use Matte to anti-alias soft-edged
objects that lie directly above the canvas by matching the matte color to the target background.
Optimize to Size Specifies the image size, in kilobytes. For 8-bpc images, the wizard attempts to achieve the
requested file size by adjusting the number of colors or dithering.
GIF and PNG image options
In the Options tab, you can set a transparency value for individual colors in GIF and 8-bpc PNG images so that the
background of the web page is visible through areas with those colors. Do this by adjusting the color palette on the
left of the Options tab. PNG images that have 32-bpc format automatically contain transparency, though you won’t
see a transparency option for 32-bpc PNGs in the Optimize panel.
Palette Set to Adaptive by default.
Loss Set to 0 by default. Not applicable to 8-bpc PNG images.
Dither Approximates colors not in the current palette by alternating similar-colored pixels so that they appear to
blend to the missing color. Dithering is especially helpful when exporting images with complex blends or gradients,
or when exporting photographic images to an 8-bpc graphic format such as GIF. Not selected by default.
Note: Dithering can greatly increase file size.
Number Of Colors List Set to 256 by default. The number of colors is dependent on the current behavior of the
palette. For example, the "Web 216" palette only displays 216 colors.
Color Palette The display of colors varies depending on the selected palette behavior and maximum number of
colors.
Palette Tools Click on any pixel in the palette and then click on these icons to change, add, or delete color, or to make
a color transparent, web safe, or locked.
Select Transparency Color Icons These buttons allow you to select, add, or remove a palette color. For example, if you
choose the Select Transparency Color option, you can click on any pixel in the palette or on a point of color in the
preview panel to render it transparent.
Transparency Pop-Up Menu Allows you to set index, alpha, or no transparency. A gray-and-white checkerboard on
document previews denotes transparent areas. To see how your choices affect the image, choose 2-up or 4-up in the
image preview and click on an image other than the original.
• Index Use index transparency when exporting GIF images that contain transparent areas. With index trans-
parency, you set specific colors to be transparent upon export. Index transparency turns on or turns off pixels with
specific color values.
• Alpha Use alpha transparency when exporting 8-bpc PNG images that contain transparent areas. Alpha trans-
parency allows gradient transparency and semi-opaque pixels.
Matte Lets you set the image’s background. You can maintain the transparency of a 32-bpc PNG by clicking the
transparency icon in the Matte dialog box. You can also use Matte to anti-alias soft-edged objects that lie directly
above the canvas by matching the matte color to the target background.
Remove Unused Colors Reduces file size by removing colors not used in the image.
Interlaced Browser Display Displays an interlaced image initially at low resolution and progressively increases to full
resolution during download. Not selected by default.
Optimize To Size Lets you specify a size, in kilobytes, for the image. For 8-bpc images, the wizard attempts to achieve
the requested file size by adjusting the number of colors or dithering.
September 4, 2007