[SciPy-user] circumference in raster image
Wed Jul 8 10:53:40 CDT 2009
Zachary Pincus wrote:
>>>> Attached is find_contours, an extension module that finds all
>>>> in a 2D array at a specified iso-value. The contour position is
>>>> interpolated between pixels. Let me know if you have any
>>>> questions, etc.
>>>> (Looking over the code, I'm surprised how well I documented and
>>>> commented it... lucky break for anyone who wants to use or modify
>>>> it, I
>>>> guess.) It's GPL because it comes from a larger GPL'd project of
>>>> but just ask me and I'll send it under a different license.
>>> Thank you very much, I will try your code. This is the way I
>>> thought I
>>> might try (interpolating by a smooth function/polynomial), so it's
>>> I do not have to dive into it :-)
>> ok, I have tried find_contours() - it seems very suitable for my
> Note of course that if the image starts out as binary, the exact same
> problems that Gary described will apply: the contour segments will all
> point in one of eight directions...
It does starts out as binary, so its the best I can get, IMHO. Anyway,
it is going to be better than my gradient based approach. I will post
here the results soon (soon in rc's time = next week).
> If the image originates as non-binary on the other hand, and instead
> of thresholding at value X, you find the iso-contours at value X, you
> might be able to get better values.
Maybe some decent blurring by ndimage filters would help, but I guess
that the accuracy is going to be ok without that.
> Probably worth doing some ground-truth testing with mockup images. I'd
> be interested in the results.
Basically, all my images are mockup (and binary), I can, however,
increase their resolution at will, as they correspond to slices of
objects with an analytical description. I will do some accuracy tests.
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