[ITK-users] Anti-alias filter

[Bill Lorensen]

If you change
 typedef  short PixelType;
to
 typedef  double PixelType;

do the results change.


On Mon, Aug 11, 2014 at 2:47 PM, Tobias Gass <gass at vision.ee.ethz.ch> wrote:
>
>> Can you post your code. The results do not look correct.
>
>
> Sure. The {write,read}Image functions are just convenient wrappers for the
> respective ITK tools.
>
>
> #include <stdio.h>
>
> #include <iostream>
>
> #include "argstream.h"
>
> #include "ImageUtils.h"
>
> #include "itkAntiAliasBinaryImageFilter.h"
>
> using namespace std;
>
> using namespace itk;
>
>
>
>
> int main(int argc, char ** argv)
>
> {
>
>
> feenableexcept(FE_INVALID|FE_DIVBYZERO|FE_OVERFLOW);
>
>     typedef  short PixelType;
>
>     typedef double OutputPixelType;
>
>     const unsigned int D=3;
>
>     typedef Image<PixelType,D> ImageType;
>
>
>
>     typedef ImageType::Pointer ImagePointerType;
>
>
>
>     typedef Image<OutputPixelType,D> OutputImageType;
>
>     typedef OutputImageType::Pointer OutputImagePointerType;
>
>
>
>     argstream * as=new argstream(argc,argv);
>
>     string inFile, outFile;
>
>     double thresh=0.0;
>
>     (*as) >> parameter ("in", inFile, " filename...", true);
>
>     (*as) >> parameter ("out", outFile, " filename...", true);
>
>
>     (*as) >> help();
>
>     as->defaultErrorHandling();
>
>
>     ImagePointerType img = ImageUtils<ImageType>::readImage(inFile);
>
>
>     typedef itk::AntiAliasBinaryImageFilter <ImageType, OutputImageType>
>
>         AntiAliasBinaryImageFilterType;
>
>
>
>     AntiAliasBinaryImageFilterType::Pointer antiAliasFilter
>
>         = AntiAliasBinaryImageFilterType::New ();
>
>     antiAliasFilter->SetInput(img);
>
>     antiAliasFilter->SetNumberOfIterations(5);
>
>     antiAliasFilter->SetMaximumRMSError(0.02);
>
>
>     antiAliasFilter->Update();
>
>
>   // For increased code coverage.  Does nothing.
>
>   antiAliasFilter->GetMaximumRMSError();
>
>
>
>
>   antiAliasFilter->Update();
>
>
>   std::cout << "Maximum RMS change value threshold was: 0.02 " << std::endl;
>
>   std::cout << "Last RMS change value was: " <<
> antiAliasFilter->GetRMSChange() << std::endl;
>
>
>   std::cout<< antiAliasFilter->GetElapsedIterations() <<endl;
>
>
>   std::cout<<antiAliasFilter->GetLowerBinaryValue()<<" "<<
> antiAliasFilter->GetUpperBinaryValue()<<std::endl;
>
>
>     OutputImagePointerType out=antiAliasFilter->GetOutput();
>
>
>     ImageUtils<OutputImageType>::writeImage(outFile,out);
>
>
> return 1;
>
> }
>
>
> I tried different values for maxIter (1,2,3,4,5,10,100,1000) and maxRMSError
> (0.02 0.07 0.08 0.8), and the best visual results are achieved after one
> iteration where RMSE changes by about 0.08. This increases for all following
> iterations, which have an RMSE-change of about 0.25 for all number of
> iterations tested. All this is using ITK 4.5 pulled from the GIT repository
> a while ago, running on an intel i7 on Debian.
>
> Thanks a lot!
> Tobias
>
>>
>>
>> On Mon, Aug 11, 2014 at 12:18 PM, Tobias Gass <gass at vision.ee.ethz.ch>
>> wrote:
>> > Dear all,
>> >
>> > I'm having problems using the anti-alias filter, which I want to use in
>> > order to smooth a binary segmentation volume. I'm using essentially the
>> > example code from the repository, which for my input file seems to start
>> > oscillating after 2 iterations, leading to weird 'pointy' artifacts on
>> > the
>> > surface as can be seen from the attached screenshot (AA filter output is
>> > on
>> > the left, input on the right).
>> >
>> > Is there any parameter to set/implement which could improve the behavior
>> > of
>> > this filter? I'm assuming that my input is reasonable, or is this
>> > something
>> > the filter is expected to have problems with? It is notable that such
>> > errors
>> > seem to mainly appear in 'flat' regions of the volume, and are not
>> > apparent
>> > in the curved shaft of the bone.
>> >
>> > Any help, or pointers to further resources are appreciated,
>> > thanks,
>> > Tobias
>> >
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>>
>>
>>
>> --
>> Unpaid intern in BillsBasement at noware dot com
>
>



-- 
Unpaid intern in BillsBasement at noware dot com