invert luminance colormap

Let me start by thanking  Nico Schlömer for his development of the cplot library. It has been very useful for me. I would like to know how I can invert the abs colormap: i.e. make the low amplitude bright and the high amplitude dark. My question is maybe related to my limited undestanding on how to work and tune abs_scaling parameter. Example code would be useful.
Thanks.