[Insight-users] AdaptiveHistgramEqualization too slow

[Zhenchao Li]

Thanks for your reply.
I compiled itk in Debug Mode ! That may very much make a difference. Thank
you for noticing that. I will set the radius to a smaller value later on and
see what happens. Currently I leave radius as default in both itk and
matlab.

On 7 March 2010 08:39, Luis Ibanez <luis.ibanez at kitware.com> wrote:

> Hi Zhenchao,
>
>
> 1) The itkAdaptiveHistogramEqualizationImageFilter took
>
>                        9 minutes 25 seconds
>
>     to run in an input image of size:  3072x2304
>
>     in a laptop LATITUDE E6500, with processor:
>     Intel(R) Core(TM)2 Duo CPU T9600  @ 2.80GHz
>     Running Ubuntu 9.10,
>     with code compiled with gcc 4.4 in Release mode.
>
>
>     with the following parameters:
>
>                 Radius =   10
>                 Alpha   =   1.0
>                 Beta     =   0.25
>
>
>      The radius parameter is obviously critical here.
>
>      You should anticipate that the computation time
>      is proportional to the square of the radius
>      (for 2D images)
>
>      A radius of 10 is using a region of 21x21 pixels
>      for performing the local computations.
>
>
> 2)   As a reference: Using a radius value of 2,
>      leads the filter to run in 25 seconds, on the
>      same input image.
>
>
> What value of radius are you using with the ITK filter ?
>
> What value of radius are you using with Matlab ?
>
> and
>
> Very important:
> have you compiled your code for "Release" mode ?
>
>
>
>     Regards,
>
>
>              Luis
>
>
> ------------------------------------------------
> On Fri, Mar 5, 2010 at 4:32 AM, Zhenchao Li <cockneykevin at gmail.com>
> wrote:
> > Hi,
> >    I'm using itk's builtin adaptive histogram equalization to equalize an
> > image(3000*3000 in size), with the default arguments the process seems to
> > run forever. However if I use matlab's adaptivehisteq function the result
> > returns immediately. After googling I find that matlab uses an algorithm
> > called contrast limited AHE, while itk uses the original AHE. The
> difference
> > is that the former process the image block by block while the latter
> > processes the image globally.(not sure how really it works). So, am I
> stuck?
> > Or is there a way to use CLAHE in itk? The current AHE in itk is really
> > slow, any suggestions?
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