positive diagonal ...
and nd for negative diagonal




On Mon, Apr 22, 2013 at 5:06 AM, Stefan van der Walt <
notifications@github.com> wrote:

> In skimage/filter/edges.py:
>
> > +    image : 2-D array
> > +        Image to process.
> > +    mask : 2-D array, optional
> > +        An optional mask to limit the application to a certain area.
> > +        Note that pixels surrounding masked regions are also masked to
> > +        prevent masked regions from affecting the result.
> > +
> > +    Returns
> > +    -------
> > +    output : ndarray
> > +        The Roberts' Cross edge map.
> > +    """
> > +    return np.sqrt(pdroberts(image, mask)**2 + ndroberts(image, mask)**2)
> > +
> > +
> > +def pdroberts(image, mask=None):
>
> What does "pd" stand for?
>
> —
> Reply to this email directly or view it on GitHub<https://github.com/scikit-image/scikit-image/pull/517/files#r3891736>
> .
>