Fast(er) Radon Transform

Stefan van der Walt stefanv at berkeley.edu
Mon Apr 13 03:13:02 EDT 2015


Hi Ross

On 2015-04-10 13:03:57, Ross McKinney <ross.m.mckinney at gmail.com> 
wrote:
> Does anyone know of a more efficient way to implement the 
> skimage.transform.radon() function?

Beylkin's 1987 paper already describes a faster way of computing 
it; this 1993 paper improves further upon those ideas:

http://dx.doi.org/10.1109/83.236530

Unfortunately, we do not have an implementation of that paper 
available.

> I am trying to rotationally align a large series of images 
> (>10,000) by  taking their radon projections and then converting 
> them into the frequency  domain. Unfortunately, this is going to 
> take a really long time using the  current implementation of the 
> radon() function. I've started to take a look  at the code 
> myself, but I'm not an expert on the subject. Also, if there 
> are any alternative methods of rotational alignment (that are 
> computationally efficient), I'd love to hear them!

Rotation correction can be done without the help of the radon 
transform.  E.g., rotation can be estimated directly from the 
Fourier transform.  The log-polar transform allows for estimates 
of rotation and scale.  With offset, it becomes a bit more tricky 
but can still be done.  Perhaps show us the kinds of images you 
have in mind?

Regards
Stéfan



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