Sure I will add some test examples and also make some more change ,you have
suggested ...
and one more thing I have implemented Frei-Chen edge detection also which i
haven't found in the scipy and scikit-image . actually performance wise
this is better than sobel algorithm . so i will update that also .

Regards,
Umesh


On Sun, Apr 21, 2013 at 11:40 AM, Tony S Yu <notifications@github.com>wrote:

> In skimage/filter/edges.py:
>
> > +        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):
> > +    """Find the cross edges of an image using the Roberts' Cross operator.
> > +    The kernel is applied to the input image, to produce separate measurements
> > +    of the gradient component one orientation.
> > +    Parameters
>
> Minor: blank line before Parameters
>
> —
> Reply to this email directly or view it on GitHub<https://github.com/scikit-image/scikit-image/pull/517/files#r3887369>
> .
>