Example 6: (posterize)

Color effects are also possible
<PARAM name="or_color_mask" value="#222222">
A little posterize effects are possible
Note: not used here but with the and_color_mask you can reduce some colors
<PARAM name="and_color_mask" value=*quot;#FFFFFF">

They aren't that usefull its better to adjust the picture with some photo editing software.

Other examples:
Some function
Parabolic bent on x axis
Parabolic bent on x and y axis
lens effect (small)
lens effect (large)
Posterize effect.
Very large lens.
Parabolic bent on y axis.