See: graphonomics

Predominant angle of the downward stroke in Western handwriting. A good basis for its estimation is the point of the handwritten curve where the velocity has its peak value in the downward stroke. The polar distribution of the running angle along a handwritten trajectory is another good method for estimating the slant angle. Left-handed writing is often accompanied by a slant value which is larger than 90 degrees, i.e., it is bent backwards, to the left. Figure 1 shows orange lines along strokes in a handwritten sample, marking the slant angle φ. In handwriting recognition, an affine transformation can be used to normalize handwritten input towards a population average or towards 90 degrees.

Also see shear.

Figure 1. Orange lines marking slant angle in a handwritten sample. It is a fragment of the "Kabinet van den Koning", an administrative document collection, of the Dutch Nationaal Archief. The sample dates from the year 1913.