5.9. Posterize

5.9. Posterize
	5. Color Tools

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 Tools → Color Tools → Posterize or Colors → Posterize.
By clicking on the tool icon in Toolbox, if this tool has been installed there (see Tools dialog).

5.9.2. Options

Figure 13.160. 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.
Preview: The Preview check-box makes all changes dynamically so that they can be viewed straight away.

5.9.3. Example

Figure 13.161. Example for the “Posterize” tool

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