Using the Color Table palette

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.

Using the Color Table palette menu

The Color Table palette menu contains commands for working with colors. To view the menu, click the triangle  above the right corner of the Color Table palette.

Sorting the color table

You can sort colors by hue (neutral colors are assigned a hue of 0 and located with the reds), luminance (the lightness or brightness of a color), or popularity, making it easier to see an image's color range and locate particular colors. Choose a sorting command from the Color Table palette menu.

Adding new colors

Select the eyedropper tool and click a color in the image. (Or, click the color selection box and use the color picker to select a color.) Then click the New Color button , or select New Color from the Color Table palette menu. A small white square with a dark center appears in the lower right corner of the new color, indicating that the color is locked.

Note: If the color table already contains the maximum number of colors (256, or 255 with transparency), you cannot add a new color.

Selecting colors

To select a color in the image, select the eyedropper tool , and click a color in the image. A white border appears around that color in the Color Table palette. To select a color in the Color Table palette, click the color. To select a contiguous group of colors, press Shift and click another color. All colors in the rows between the first and second selected colors are selected. To select a discontiguous group of colors, press Ctrl (Windows) or Command (Mac OS) and click each color that you want to select.

The Color Table palette menu provides commands for selecting colors. Choose Select All Colors, Select All Web-Safe Colors, Select All Non-Web Safe Colors, or Deselect All Colors.

Note: The Select All Web-Safe Colors command is not available when the optimized image does not contain Web-safe colors; likewise, the Select All Non-Web Safe Colors command is not available when the optimized image contains only Web-safe colors.

Editing colors

You can change a selected color in the Color Table palette to any other RGB color value. Double-click the color in the Color Table palette to display the default color picker, and then select a color. A small plus sign appears in the center of each edited color. When you regenerate the optimized image, the selected color changes to the new color wherever it appears in the image.

Shifting to Web-safe colors

You can shift colors to their closest equivalents in the Web palette to prevent the colors from dithering in a browser. Select the colors you want to shift, and click the Web Shift button  in the Color Table palette. (Or, choose Web Shift/Unshift Selected Colors from the Color Table palette menu.) A small white diamond appears in the center of any color that has been Web-shifted (and in any Web-safe color).

Once you've shifted colors, you can revert them to their original values using commands in the Color Table palette menu. Choose Web Shift/Unshift Selected Colors or Unshift All Colors. Or, select a Web-shifted color and click the Web Shift button  to revert it. To specify a tolerance for shifting colors, specify a value for Web Snap in the Settings panel of the Save For Web dialog box. A higher value shifts more colors.

Deleting colors

You can delete selected colors from the color table to decrease the image file size. To delete selected colors, click the Trash button or choose Delete Color from the Color Table palette menu. When you delete a color, areas of the optimized image that previously included that color are rerendered using the closest color remaining in the palette.

Note: Deleting a color changes the color palette type to Custom to prevent the color from being added back to the palette if you reoptimize the image.

Locking and unlocking colors

You can lock selected colors in the color table to prevent them from being dropped or dithered if you reduce the number of colors in the image. Click the Lock button , or choose Lock/Unlock Selected Colors from the Color Table palette menu. A white square with a red center appears in the lower right corner of each locked color.

To unlock all colors, choose Unlock All Colors from the Color Table palette menu.

Saving and loading color tables

You can save color tables from optimized images to use with other images and load color tables created in other applications. To save a color table, choose Save Color Table from the Color Table palette menu. By default, the filename extension .act (Adobe Color Table) is added to the color table file. To load a color table, choose Load Color Table in the Color Table palette menu. You can load a color table from an .act file or a GIF file (to load the file's embedded color table).

Once you load a new color table, the colors in the optimized image change to reflect the new color table.