Almost ready to issue pull for Canny?

[Dan Farmer]

Hi Group,

I merged Cell Profiler's Canny over last weekend and spent this week
"dogfooding" it on my own project, I had a few questions and ideas to
run by before I push it back to github.

1. Organization: In general the CP filter code is mostly in one file,
I tried to follow the example of the constant time median filter merge
that was already done. I just wanted to make sure that you guys want
one filter per file?
2. API: So I used the function in part of a project I've been doing
this semester and my call to canny looks like this: canny(img,
np.ones(img.shape, dtype=bool), 5, 0.005, 0.01), the np.ones bit is
because the Cell Profiler canny (as far as I can tell) requires a
binary mask, and the 0.005 and 0.01 are the low and high thresholds
for hysteresis thresholding. As you can image that took me quit a bit
of fiddling to get those values. It seems that since it's thresholding
the magnitude values you wind up with strange values. So my thoughts
were: can we add a default parameter for the mask so that end-users of
the library don't have to think about it unless they want to (I do
think it's a nice functionality to have), and secondly should anything
be done (like normalizing between 0 and 1) about the pixel values so
that there can be some intuition about threshold values?
3. As far as the pull request goes, do I just merge my local canny
branch back into master locally and then push that to github or do I
actually push the branch to github and issue a pull against that?

Thanks,
Dan