//integral image (ii) and integral image squared (iiSqr) float VarianceFilter::computeVar(Mat& ii, Mat& iiSqr, BoundingBox& bb) { double area = bb.getArea(); double mX = bb.getArea(ii) / area; //Sum of Area divided by area double mX2 = bb.getArea(iiSqr) / area; return (float) (mX2 - mX*mX); }