Use the Posterize command to reduce the number of levels for each channel in the image and create interesting effects. With this command, Paint Shop Pro divides the range of channel levels (from 2 to 255) into a number of equal increments that you specify. As you lower the number, you increase the effect.
Important: To apply this command to a selection, the image must be a 16 million (24-bit) color image (otherwise the command is applied to the entire image). In addition, adjustment layers are available for 16 million (24-bit) color or greyscale images only. To increase the color depth of an image, see Increasing the Color Depth of an Image
To use the Posterize command:
To limit the correction to a specific area, make a selection in the image. See Using the Selection Tools.
Do one of the following:
To modify the image pixels directly, choose Effects > Artistic Effects > Posterize.
To create a Levels adjustment layer, choose Layers > New Adjustment Layer > Posterize. For information on adjustment layers, see Using Adjustment Layers.
In the Levels edit box, select the number of channel levels (2 to 255) for the adjusted image. To create a dramatic effect, the number of levels typically must be below 10.
Click OK.
Creating Black and White Images