speed of iradon transform
Stefan van der Walt
stefanv at berkeley.edu
Mon Apr 20 13:48:45 EDT 2015
Hi Matt
On 2015-04-20 04:59:06, Matthew Newville <matt.newville at gmail.com>
wrote:
> Some preliminary timing results:
Thank you very much for your detailed investigation!
> numpy skimage workspace? Best, Worst of 5 (s)
> |---------+-----------+------------+---------------------|
> 1.9.2 master N/A 6.085 6.132 master
> master N/A 1.784, 1.813 master PR1474
> No 1.788, 1.809 master PR1474 Yes
> 1.103, 1.160
> |---------+-----------+------------+---------------------|
It looks like one gets about 1.5x for using the workspace. I am
always careful about added code complexity for a relatively small
gain, but in this case your refactoring *improves* legibility of
the code--so +1 from me.
> Oddly, iradon() is now faster than radon() on this machine/image
> size (radon() takes about 3.5 sec). I don't understand why
> that would be. Anybody understand why radon() is so slow?
I'm afraid we don't implement an optimized version of the forward
radon transform, such as
Brady, "A Fast Discrete Approximation Algorithm for the Radon
Transform", SIAM J. Comput., 27(1), 2006
A fast digital Radon transform--An efficient means for evaluating
the Hough transform WA Götz, HJ Druckmüller - Pattern Recognition,
1996
This overview from William Press of Numerical Recipes fame is
helpful:
http://www.pnas.org/content/103/51/19249.full
Regards
Stéfan
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