Thanks for the comments Fran. I actually both pre and post processed the image in GIMP (my crutch). I concocted GIMP specific techniques that would blow away anything that you could get from using LAB colorspace techniques to do; trust me. One of the cool things you can do easily with GIMP is change amplication. Say you make an ever so slight modification between original layer and top layer. You can copy the original over the change and set that result to Grain Extract, merge and set the result to grain merge and duplicate to amplify the change (I don't actually do it this way anymore; I just set to grain extract, copy visible and invert then set the resulting layer to grain merge). Anyway, not sure if there is a way to to layer change amplication is PS.