[Insight-users] Questions about Canny edge detector

[qi yang]

Hi All,

Recently I am checking the source code of the Canny filter in ITK, as
I might want to apply the filter to the 3D volume.
It looks like a real 3D Canny edge detector. But I don't quite
understand the method of calculating the 2nd derivative and the
non-maximum suppression.
And now it is programed in the way that only the same sigma value in
each direction is allowed, but actually Gaussion filter allows
different sigma values in different direction.
Can anybody enlighten me, please?

Thanks,
Tina