directed orientations in the orientation
histograms. The angle [0,pi) is divided in to NumOrientation
equal parts.
</p></dd><dt>
DirectedPolarField
</dt><dd><p>
By specifying this flag the image IM is interpreted as samples
from a 2D vector field specified by their argument IM(:,:,2) and
modulus IM(:,:,1).
</p></dd><dt>
UndirectedPolarField
</dt><dd><p>
Same as above, but wraps angles in [0,pi).
</p></dd><dt>
BilinearOrientations
</dt><dd><p>
This flags activates the use of bilinear interpolation to assign
