Posterize
The Posterize effect reduces the number of brightness levels in an image.
Customized settings can be saved as a preset for future use. Presets can be selected from the Presets drop-down, or saved by clicking the adjacent Save icon.
To apply a Posterize effect:
- Select Filter | Add | Special Effects from the main menu, or press Shift + Alt + S.
- In the Effects dialog, navigate to the Color group.
- Select Posterize.
- Set the options as described below.
- Do one of the following:
- Click OK to accept your changes and close the panel.
- Click Cancel to discard your changes and close the panel.
Posterize Options
|
Brightness levels |
Slide to adjust the variance of colors in the image. The lower the value, the fewer colors used in the image. |
Right-click a slider to reset to the default value.
Use the Edit Brush to paint this effect onto specific areas of the image. 
Use the Gradient tool to transition this effect across specific areas of the image. 
Use the Radial Gradient tool to apply effects around, or directly to, a center point. 