Task 3 How to Optimize GIF Color Sets

The more you work with GIF conversion, the more you realize that the most critical step is in mapping the original colors to a minimal yet representative table set. To most people, it sounds inconceivable that 32 colors can replace the thousands of colors in an image. Although you can do it, you must be careful about which colors you keep and which you throw away.

1. Open and Save File in Photoshop

With your image open in Photoshop, select File, Save for Web. The Save For Web dialog box opens and Photoshop creates a duplicate image, leaving the original image untouched. Click the Optimized tab to select it.

2. Set Basic GIF Settings

Refer to Task 2 and set the compression type (GIF) and the Dither and Lossy settings. From the Colors list, select the lowest number of colors while keeping the file's integrity intact.

3. Lock Important Colors

Click the Color Table tab. Click the Eyedropper tool located at the upper-left side in the Save for Web dialog box, and click a prominent color in the image. The corresponding color in the Color Table is highlighted. Lock the selected color by clicking the Lock button at the bottom of the Color Table; locking a color prevents it from being removed or dithered. Repeat this step for other critical colors in the image.

4. Eliminate Close Colors

With the image showing on the Optimized tab, select Sort by Luminance from the Color Table palette menu. In the Color Table, select a color close to a locked color and click the Trash Can icon in the Color Table section. The screen redraws to delete the selected color from the image. Continue deleting colors until you get a core set that represents the image well.

5. Changing Individual Table Colors

With the important colors locked down, determine whether you need to change other colors. To change color swatches, double-click the color in the Color Table; the Color Picker dialog box opens. Change the current color, paying close attention to the web-safe icon in the picker (the three-sided box icon), which shows you the nearest web-safe color.

6. Save the Color Table

If you're working with the same kind of image or want a series of images to use the same color set, save the color table you just fine-tuned. Select Save Color Table from the Color Table palette menu. In the Save As dialog box that appears, type a name for the color table and click OK.

How-To Hints

Using a Saved Color Table

To load a saved Color Table profile, open the Save for Web dialog box and select Load Color Table from the Color Table palette menu.

Using Web-Safe Colors

Use the Web Snap slider in the upper-right corner of the Save for Web dialog box to convert existing colors to web-safe colors. Change the slider and monitor the results in the preview. The higher the value in the Web Snap slider, the more exactly colors are transformed to the web-safe palette. The web-safe palette refers to a subset of colors that can be reproduced exactly the same on all platforms and with all browsers. Use these colors to ensure that people who view your web graphics see exactly the colors you intended them to see.