.. index:: Parameters; 2D Symmetry NCS-70

2D Symmetry NCS-70
==================

Returns the maximum difference between the IFA and the IFA rotated 180 degrees,
normalised to the average of the IFA according to NCS-70 eq 3-6.

.. math:: {maximum \left [ abs(D(x,y) - D(-x,-y)) \right ]} \cdot \cfrac {100} {ave}

Where D(x,y) is the pixel value at x,y and *ave* is the average value of the IFA.

**Protocol invocation name**: 2D Symmetry NCS-70