Example 5: (large lens)

allmost the same as the previous example
Except added this
<PARAM name="mask_color" value="#FF0000">

This is the lens effect <PARAM name="mapping" value="lens|100|2">

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.