I stumbled across a very effective technique tonight. But first a little background. The image I was working on was a 4 photo HDR shot. I processed each of the four first in DXO, then LR and finally Photomatix. The first pass resulted in a sky that was very strange. The word that best describes it is ‘posterization.’ No other area of the image had this problem, just the sky. Where it transitioned from a darker blue to a lighter hue the transition was splotchy and pixelated.