[SciPy-user] canny1d filter?

Davide Cittaro davide.cittaro@ifom-ieo-campus...
Mon Apr 27 07:28:53 CDT 2009


Hi Zach,

>
> This has the effect of "growing out" the regions that pass the  
> higher threshold out into regions above the lower threshold. (I'm  
> pretty sure this is a standard operation, given that it's available  
> in ndimage, but like I said, it was not obvious to me at first.)  
> Other than that, the implementation is basically straight from the  
> wikipedia entry.
>

Got it! Indeed this is much more elegant than other implementations  
I've seen (where each magnitude is tested for being higher, lower or  
within...)

> I just looked over the paper -- there are plenty of 1D examples and  
> calculations, but I think the results from that part aren't that  
> useful: basically it says that there's a theoretical reason to use a  
> DoG as the edge filter. It's probably interesting to read through  
> the logic, because if your problem setting is different, then you  
> could see if a different filter shape is optimal for what you're  
> looking for. But as far as the "canny filter" as anyone would  
> implement it, it's a 2D-only thing, because his real contribution  
> was the 2D post-processing after doing a DoG.


I've asked to my institution to get the paper (it is not in our  
library... you know, here's all about biology ^__^) so I can figure  
how it works.
BTW, I'm testing a 1d implementation (basically a 2d with only W  
footprint and no angles), I still have some doubt on choosing the  
thresholds...	bah... I'll take some time to think about it.

Thanks

d


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