Select these parameters to compute the geometrical skewness of objects. The skewness descriptors are derived from the rotational binary moments of the object (M30,M21, M12,M03) normalized for scale and orientation independency.
SkewMajor is derived from the rotational binary moment M30. It describes the skewness of the object along the major axis of the equivalent ellipse. An object symmetrical relative to its minor axis has this value close to zero. If the bulk of the object lies on one side of the major axis, this value is greater than zero. Due to the rotational normalization the SkewMajor is always positive (the major axis is considered to be pointed in the direction of the narrower part of the object).
SkewMinor is derived from the rotational binary moment M03 It describes the skewness of the object along the minor axis of the equivalent ellipse. An object symmetrical relative to its major axis has this value close to zero. The lack of symmetry causes this value to increase. The sign of the SkewMinor depends on which side of the minor axis the bulk of the object is found
Skew12 and Skew 21 are derived from the rotational binary moments M12 and M21 respectively. They describe the general asymmetry of the object and along with two other parameters serve as shape descriptors invariant to the scale and rotation.