[ITK] About pipeline recursion
Bradley Lowekamp
blowekamp at mail.nih.gov
Fri Jun 20 09:19:48 EDT 2014
Hello,
There is some code in the pipeline architecture to prevent circular execution. I believe it has been used for more complex circular pipelines. But your case is a bit simplified and has a problem.
For your particular case the input image IS same as the output image. This does not surprise me that it breaks things and causes odd behavior.
I am not sure if the below pipeline is close to what you are trying to do in the end or not. But I'll suggest the following:
1) After getting the output, call tmpImage->DisconnectPipeline().
This will explicitly sever the pipeline, and allow you to manual place the output as a input.
2) Turn on InPlace for the AddImageFilter.
This will copy the buffer of input1 to the output and remove the need to allocate a new output.
Hope that helps,
Brad
On Jun 20, 2014, at 4:35 AM, Nicolas Gallego <nicgallego at gmail.com> wrote:
> Good morning,
>
> I have been coding a filter that implements an iterative procedure on images. I have tried the straight forward implementation of updating a temporal image on the recursion loop but results are wrong. The correct result is obtained when I explicitly unroll the pipeline although it becomes harder to code for more complex pipelines, and I am concerned about the scalability on the number of recursions.
>
> Could you give me some ideas to work this point out. Is there a way to implement a straight forward way in itk? Here the code that illustrates the point on recursively adding images:
>
> ----- code 1 -------------
> std::cout << "Recursion on image pointer" << std::endl;
> ImageType::Pointer image1 = ImageType::New();
> image1->SetRegions( region );
> image1->Allocate();
> image1->FillBuffer( 1 );
> AdderType::Pointer adder = AdderType::New();
> adder->SetInput1( image1 );
> adder->SetInput2( image1 );
> adder->Update();
> ImageType::Pointer tmpImage = adder->GetOutput();
> std::cout << "start: " << image1->GetPixel( index ) << std::endl;
> const unsigned short N = 10;
> for ( unsigned short k = 0; k < N; k++ ) {
> adder->Update();
> tmpImage = adder->GetOutput();
> std::cout << k << " " << tmpImage->GetPixel( index ) << std::endl;
> adder->SetInput1( tmpImage );
> adder->SetInput2( image1 );
> }
> std::cout << std::endl;
> --- end of 1 --------------
>
> Code 1 produces the following output:
> -----------------------------------------------
> Recursion on image pointer
> start: 1
> 0 2
> 1 3
> 2 3
> 3 3
> 4 4
> 5 4
> 6 4
> 7 5
> 8 5
> 9 5
> ---------------------------------------------
>
> The explicit pipeline unroll is illustrated in code 2
>
> --- code 2 -----------------------------------------------
> std::cout << "Pipeline explicit unroll recursion" << std::endl;
> std::vector< AdderType::Pointer > adders( N );
> adders[0] = AdderType::New();
> adders[0]->SetInput1( image1 );
> adders[0]->SetInput2( image1 );
> std::cout << "start: " << image1->GetPixel( index ) << std::endl;
> // connections
> for ( unsigned short k = 1; k < N; k++ ) {
> adders[k] = AdderType::New();
> adders[k]->SetInput1( adders[k-1]->GetOutput() );
> adders[k]->SetInput2( image1 );
> }
> // execution
> adders[N-1]->Update();
> for ( unsigned short k = 0; k < N; k++ ) {
> std::cout << k << " " << adders[k]->GetOutput()->GetPixel( index ) << std::endl;
> }
>
> --- end of code 2 --------------------------------------
>
> Pipeline explicit unroll recursion
> start: 1
> 0 2
> 1 3
> 2 4
> 3 5
> 4 6
> 5 7
> 6 8
> 7 9
> 8 10
> 9 11
> ------------------------------------
>
> Find attached complete code file, thank you for your help
>
> ------
> Nicolás Gallego-Ortiz
> Université catholique de Louvain, Belgium
> <recursionTest.cxx>_______________________________________________
> Community mailing list
> Community at itk.org
> http://public.kitware.com/mailman/listinfo/community
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://public.kitware.com/pipermail/community/attachments/20140620/2ba7fc0f/attachment-0002.html>
More information about the Community
mailing list