Dithering with Websafe colors

Sometimes you may need to use a color that is not a Websafe color. For example, your company logo may use a color that is not in the Web 216 color palette.

To approximate a Websafe color that will neither shift nor dither when exported with a Websafe palette, use a Web Dither fill.

Web Dither is the method whereby two colors in the palette are combined to most closely replicate a color that is not in the palette. Web Dither can increase the file size.

Two Websafe colors create a Web Dither fill.
 

To use the Web Dither fill:

1 Select an object containing a non-Websafe color.
2 In the Fill panel, choose Web Dither as the fill category.
The object's non-Websafe fill appears in the Fill color well next to the fill type.
The two Websafe dither colors appear in the checkerboard color wells beneath.
The Web Dither appears on the object and becomes the active fill color.

Note: Setting the edge of a Web Dither fill to Anti-Alias or Feather results in colors that are not Websafe.

To create the illusion of a true transparent fill in a Web browser:

1 In the Fill panel, apply a Web Dither fill to a selected object.
2 Select Transparent.
3 Export the object as a GIF or PNG with Index Transparency or Alpha Channel Transparency set.

When you view the graphic in a Web browser, the Web page background shows through every other pixel of the transparent Web Dither fill, creating the appearance of transparency.