Region Contrast and DC Offset

All of the region dialogs have Contrast and DC Offset controls. These allow you to indicate that the pattern contained within the region should occupy some sub-range of the color ramp you specified with the Peak and Trough parameters. The Contrast parameter has a range of +-1 and allows you to shrink the range of colors used, or even flip the range's polarity. The DC Offset parameter also has a range of +-1 and allows you to shift the used range up and down within the peak-trough range.