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Choosing a color palette



All 8-bit images contain a color palette of up to 256 available colors. The image uses only these colors, but it might not use all of them.

 In the Optimize panel, select one of the following options from the Indexed Palette pop-up menu:
Adaptive
A custom palette derived from the actual colors in the document. Most often produces the highest quality image.

Web Adaptive
An adaptive palette in which colors are converted to the closest websafe color. Websafe colors are those that come from the Web 216 palette.

Web 216
A palette of the 216 colors common to both Windows and Mac OS computers. This palette is often called a websafe or browser-safe palette because it produces fairly consistent results in various web browsers on either platform when viewed on 8-bit monitors.

Exact
Contains the exact colors used in the image. Only images containing 256 or fewer colors may use the Exact palette. Otherwise, the palette switches to Adaptive.

Windows and Mac OS
Each contains the 256 colors defined by the Windows or Mac OS platform standards, respectively.

Grayscale
A palette of 256 or fewer shades of gray. Choosing this palette converts the image to grayscale.

Black and White
A two-color palette consisting only of black and white.

Uniform
A mathematical palette based on RGB pixel values.

Custom
A palette that has been modified or loaded from an external palette (ACT file) or a GIF file.

You can optimize and customize color palettes using the color table in the Optimize panel.

Import a custom palette

  1. Do one of the following:

    • Select Load Palette from the Optimize panel options menu.

    • Select Custom from the Optimize panel Indexed Palette pop-up menu.

  2. Navigate to an ACT or GIF palette file and click Open.

    The colors from the ACT or GIF file are added to the color table in the Optimize panel.

    Note: Windows users must select GIF Files from the Files Of Type pop-up menu to see files with a .gif extension in the Open dialog box.

Select a color depth for an 8-bit image

Color depth is the number of colors in the graphic. Reducing color depth makes a smaller file size, but it can also reduce the image quality. When you reduce color depth, some colors in the image are discarded, beginning with those used least. Pixels containing discarded colors convert to the closest color remaining in the palette.

 Do one of the following:

  • In the Optimize panel, select an option from the Colors pop-up menu.

  • Type a value (from 2 to 256) in the text box.

    Note: The number at the bottom of the color table indicates the actual number of colors visible in the image. If no number is visible, click the Rebuild button.

Remove unused colors in an 8-bit image

This makes the file size smaller.

 From the Optimize panel Options menu, select Remove Unused Colors.

Include all palette colors, including those not present in the saved image

 Deselect Remove Unused Colors.