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Chapter 4. Creating Web Images > Reducing the Number of Colors

Reducing the Number of Colors

Whether or not you've decided to keep to browser safe colors, you can make compression more efficient by reducing the number of colors in your GIF images. And better compression means faster loading.

To reduce the number of colors in an image:

1.
Open an RGB image with Photoshop.

2.
Choose File > Export > GIF89a Export.

3.
In the GIF 89a Export dialog box, choose Adaptive in the Palette pop-up menu (Figure 4.33).

Figure 4.33. Choose Adaptive for Palette and then enter the desired number of colors in the Colors box. Finally, click the Preview button to see how the illustration will look on the page.


4.
Enter the desired number of colors in the Colors box.

5.
Click Preview to see how the image will look with this number of colors (Figures 4.34 and 4.35). Use the magnifying glass and the hand to examine the image carefully. Click OK to return to the main dialog box.

Figure 4.34. With only eight colors, the dithering is very obvious. Click OK to go back to the GIF89a Export dialog box and try another value.


Figure 4.35. A value of 32 considerably reduces the amount of colors—with minimal dithering.


6.
Repeat steps 4–5 until you find the least number of colors you can live with.

7.
Click OK and save the document.

Tip

If the image is already in indexed color and you wish to reduce the colors further, you have two choices. Either convert the document to RGB mode and then follow the steps above, or convert the image to RGB mode and then choose Image > Mode > Indexed Color and enter a smaller number of colors in the Colors box of the dialog box that appears.


Tip

If you're going to save the image as JPEG, reducing the number of colors results in larger files (see page 77).


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