total variation denoising

[Emmanuelle Gouillart]

>    have you been able to do some benchmarks to see if the performance hit
>    from Python is reasonnable?

I had done a rapid benchmark when I translated the C code into Python,
and found that the Python code was 3 times slower compared to the C with
Cython wrapping. But now I have improved the performance with a stop
criterion on the energy, instead of a fixed number of iterations; hence
it is difficult to compare now (of course, the stop criterion could be
implemented in C too, but I was much more comfortable to do it in
Python!).

The performance has to be reasonable, because I have a student who is
using this code to denoise large 3D images (512^3)! 

Emmanuelle �