[SciPy-user] canny1d filter?

Zachary Pincus zachary.pincus@yale....
Fri Apr 24 18:30:16 CDT 2009


Hi Davide,

I can send you code for a 2D Canny filter that uses numpy and  
scipy.ndimage to good effect. It's a decent demonstration of the  
filter, and of how to make good use out of the tools in ndimage.

However, I don't think that Canny edge-detection, as I understand it,  
is applicable to 1D signaling. Basically, Canny filtering finds the  
gradient magnitude and direction in an image, and then uses the  
direction information to thin out edges except along their "ridges".  
It then uses a hysteresis thresholding approach to link the edges (by  
finding seeds with a stringent threshold, and then extending the seeds  
out along the edges using a less-stringent threshold). None of this  
stuff makes sense in the 1D case -- there's no "edge direction", etc.

Zach


On Apr 24, 2009, at 3:44 PM, Davide Cittaro wrote:

> Hi all, I'm new to image (and signal processing).
> I have to detect peaks in a 1d signal. I'm collecting documentation
> about this and tested some procedures (actually LoG and DoG in the
> past two days...). I would like now to test the Canny filter which is
> not included in scipy.ndimage filters...
> I've found a bunch of implementations in 2d cases, in many languages,
> but not for the 1d case... Does anybody want to share some hints on
> this? :-)
> Any suggestion is appreciated
>
> Thanks
>
> d
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