Further to my original question and in response to the request to include example images, usually the concept I've worked to elsewhere was that anything that is 50% grey (128,128,128 in a 0-255 scenario) would be unaffected, anything lighter will apply in one direction, (ie up and left) and anything darker will apply in the opposite direction (ie down and right) and within that you can adjust how much this is affected either vertically and horizontally, the problem I'm having is that using a displacement map of 50% grey with darker blurred vertical strokes it is applying it in both the vertical and horizontal directions equally so I wasn't sure if there was a workaround to this?