5.9. Posterize

This tool is designed to intelligently weigh the pixel colors of the selection or active layer and reduce the number of colors while maintaining a semblance of the original image characteristics.

5.9.1. Activating the Tool

You can get to this tool in several ways:

  • In the image menu through ToolsColor ToolsPosterize… or ColorsPosterize….

  • By clicking on the tool icon in Toolbox, if this tool has been installed there. For this, please refer to Section 1.7, “Toolbox”.

5.9.2. Options

Figure 14.174. Posterize tool options

Posterize tool options

Posterize Levels

This slider and the input boxes with arrow-heads allow you to set the number of levels (2-256) in each RGB channel that the tool will use to describe the active layer. The total number of colors is the combination of these levels. A level to 3 will give 23 = 8 colors.


The Preview checkbox enables the rendering of changes right on the canvas for immediate evaluation.

5.9.3. Example

Figure 14.175. Example for the Posterize tool

Example for the Posterize tool

Image posterized in 4 levels. The histogram shows the 4 levels and 10 colors, counting black and white also.