There is no way to reverse the process to my knowledge. The original luminance information is lost and only the edge transitions are retained, with the luminance determining the amount of offset for the emboss effect. Portions of the original image that were 100% white will be represented with the same color value as portions that were 100% black. -- Not enough info retained to unscramble that egg. Here's another post with some additional info regarding how Poser detects the edges: CYMK & BUM conversions