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To reduce pixel depth in an image

  1. Open the image or frame you want to convert.

  2. Choose Palette > Set Pixel Depth and select a choice from the submenu (Figure 1). Table 1 shows how pixel depth relates to the number of colors in an image.

    icon If the Palette Commands toolbar is active, you also can click icon.

Fig. 1

    Figure 1   To reduce pixel depth in an image, choose Palette > Set Pixel Depth and select a choice from the submenu. (In this case, the Mac menu appears on the left and the Windows one on the right.)

     
  1. Release the cursor and the image is converted to the pixel depth you chose.

 

Table 1

Pixel (Bit) depth and number of colors

HUNDREDS OF COLORS—INDEXED TO A PALETTE

1 bit

2 bits

3 bits

4 bits

5 bits

6 bits

7 bits

8 bits

2 colors

4 colors

8 colors

16 colors

32 colors

64 colors

128 colors

256 colors

 
THOUSANDS OF COLORS—NOT INDEXED TO A PALETTE

15 bits

16 bits

32,768 colors

32,768 colors +
alpha channel

RGB
MILLIONS OF COLORS—NOT INDEXED TO A PALETTE

24 bits

32 bits

17 million colors

17 million colors

RGB

RGB or CMYK +
alpha channel

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