Adobe illustrator 10 Manuale Utente

1 Click the Layers tab in the Save for Web dialog box.

2 Select Export As CSS Layers. 

3 Choose a layer from the Layer pop-up menu, and set the following options as desired:

Visible to create a visible CSS layer in the resulting HTML file.

Hidden to create a hidden CSS layer in the resulting HTML file.

Do Not Export to not export the layer to the resulting HTML file.

Decreasing the number of colors in an image is a key factor in optimizing GIF and PNG-8 
images. A reduced range of colors will often preserve good image quality while dramati-
cally reducing the file space required to store extra colors.

Illustrator generates a color table for GIF and PNG-8 images based on the color options 
you set for optimization. You choose a method for generating the color table from the 
Color Reduction menu and specify the number of colors you want in the color table in the 
Colors text box. (See 

You can choose from the following methods for generating color tables:

Perceptual Creates a custom color table by giving priority to colors for which the human 
eye has greater sensitivity. 

Selective Creates a color table similar to the Perceptual color table, but favoring broad 
areas of color and the preservation of Web colors. This color table usually produces images 
with the greatest color integrity. Selective is the default option.

Adaptive Creates a custom color table by sampling colors from the spectrum appearing 
most commonly in the image. For example, an image with only the colors green and blue 
produces a color table made primarily of greens and blues. Most images concentrate 
colors in particular areas of the spectrum. 

Web Uses the standard 216-color color table common to the Windows and Mac OS 8-bit 
(256-color) palettes. This option ensures that no browser dither is applied to colors when 
the image is displayed using 8-bit color. (This palette is also called the Web-safe palette.)

Using the Web palette can create larger files, and is recommended only when avoiding 
browser dither is a high priority. 

Custom Preserves the current perceptual, selective, or adaptive color table as a fixed 
palette that does not update with changes to the image.

The Color Table palette in the Save for Web dialog box gives you precise control over 
the colors in optimized GIF and PNG-8 images. With a maximum of 256 colors, you can add 
and delete colors in the color table, shift selected colors to Web-safe colors, and lock 
selected colors to prevent them from being dropped from the palette.