To create your own effects (or filters, as they are also known), use the User Defined command.
The easiest way to create your own effects: On the User Defined Filter dialog, click the Randomize button to automatically adjust the coefficients and create unusual effects. Just keep clicking the Randomize button until you find an effect that you like
To create your own effects:
Choose Effects >
User Defined to open the User Defined Filter dialog.
The edit boxes in the Filter matrix group
box show coefficients that process pixels to create the effect.
In the Presets drop-down list, select a filter to use as a starting point. Choose Default for default settings or select one of the other filters.
After you make changes, click OK. Paint Shop Pro applies the effect to the image.
Mathematically Combining Two Images