Good values should probably be 0.2 through 0.6 . Note that effect of this value is expotential. Wave settings dialog Map from image dialog From this dialog you can specify from what image you want to map, how to scale the data from the image and how to map the scaled data to fit your needs. Only RGB and grayscale images are allowed. RGB images will be converted to grayscale on the fly.
Linear mapping uses the data as it is.
Logarithmic takes something like this and turns it into something like this . Sinusoidal transforms it to this . Finally, there's the sphere map.