ITK/Examples/Segmentation/ContourExtractor2DImageFilter

ContourExtractor2DImageFilter.cxx

<source lang="cpp">

1. include "itkImage.h"
2. include "itkImageFileWriter.h"
3. include "itkContourExtractor2DImageFilter.h"
4. include "itkApproximateSignedDistanceMapImageFilter.h"

typedef itk::Image<unsigned char, 2> UnsignedCharImageType; typedef itk::Image<float, 2> FloatImageType;

static void CreateImage(UnsignedCharImageType::Pointer image);

int main(int, char *[]) {

 UnsignedCharImageType::Pointer image = UnsignedCharImageType::New();
 CreateImage(image);

 typedef  itk::ApproximateSignedDistanceMapImageFilter< UnsignedCharImageType, FloatImageType  > ApproximateSignedDistanceMapImageFilterType;
 ApproximateSignedDistanceMapImageFilterType::Pointer approximateSignedDistanceMapImageFilter = ApproximateSignedDistanceMapImageFilterType::New();
 approximateSignedDistanceMapImageFilter->SetInput(image);
 approximateSignedDistanceMapImageFilter->SetInsideValue(255);
 approximateSignedDistanceMapImageFilter->SetOutsideValue(0);
 approximateSignedDistanceMapImageFilter->Update();
 
 typedef itk::ContourExtractor2DImageFilter <FloatImageType>
         ContourExtractor2DImageFilterType;
 ContourExtractor2DImageFilterType::Pointer contourExtractor2DImageFilter
         = ContourExtractor2DImageFilterType::New();
 contourExtractor2DImageFilter->SetInput(approximateSignedDistanceMapImageFilter->GetOutput());
 contourExtractor2DImageFilter->SetContourValue(0);
 contourExtractor2DImageFilter->Update();
 
 std::cout << "There are " << contourExtractor2DImageFilter->GetNumberOfOutputs() << " contours" << std::endl;

 ContourExtractor2DImageFilterType::VertexListType::ConstIterator vertexIterator = contourExtractor2DImageFilter->GetOutput()->GetVertexList()->Begin();
 
 for(unsigned int i = 0; i < contourExtractor2DImageFilter->GetNumberOfOutputs(); ++i)
   {
   std::cout << "Contour " << i << ": " << std::endl;
   while(vertexIterator != contourExtractor2DImageFilter->GetOutput(i)->GetVertexList()->End())
     {
     std::cout << vertexIterator->Value() << std::endl;
     ++vertexIterator;
     }
   std::cout << std::endl;
   }

 return EXIT_SUCCESS;

}

void CreateImage(UnsignedCharImageType::Pointer image) {

 // Create an image
 itk::Index<2> start;
 start.Fill(0);

 itk::Size<2> size;
 size.Fill(100);

 itk::ImageRegion<2> region(start, size);
 image->SetRegions(region);
 image->Allocate();
 image->FillBuffer(0);

 // Create a line of white pixels
 for(unsigned int i = 40; i < 60; ++i)
   {
   itk::Index<2> pixel;
   pixel.Fill(i);
   image->SetPixel(pixel, 255);
   }
   
 // Create another line of pixels
 for(unsigned int i = 10; i < 20; ++i)
   {
   itk::Index<2> pixel;
   pixel[0] = 10;
   pixel[1] = i;
   image->SetPixel(pixel, 255);
   }

 typedef  itk::ImageFileWriter< UnsignedCharImageType  > WriterType;
 WriterType::Pointer writer = WriterType::New();
 writer->SetFileName("image.png");
 writer->SetInput(image);
 writer->Update();

}

</source>

CMakeLists.txt

<syntaxhighlight lang="cmake"> cmake_minimum_required(VERSION 3.9.5)

project(ContourExtractor2DImageFilter)

find_package(ITK REQUIRED) include(${ITK_USE_FILE}) if (ITKVtkGlue_LOADED)

 find_package(VTK REQUIRED)
 include(${VTK_USE_FILE})

endif()

add_executable(ContourExtractor2DImageFilter MACOSX_BUNDLE ContourExtractor2DImageFilter.cxx)

if( "${ITK_VERSION_MAJOR}" LESS 4 )

 target_link_libraries(ContourExtractor2DImageFilter ITKReview ${ITK_LIBRARIES})

else( "${ITK_VERSION_MAJOR}" LESS 4 )

 target_link_libraries(ContourExtractor2DImageFilter ${ITK_LIBRARIES})

endif( "${ITK_VERSION_MAJOR}" LESS 4 )

</syntaxhighlight>

Download and Build ContourExtractor2DImageFilter

Click here to download ContourExtractor2DImageFilter and its CMakeLists.txt file. Once the tarball ContourExtractor2DImageFilter.tar has been downloaded and extracted,

cd ContourExtractor2DImageFilter/build

• If ITK is installed:

cmake ..

• If ITK is not installed but compiled on your system, you will need to specify the path to your ITK build:

cmake -DITK_DIR:PATH=/home/me/itk_build ..

Build the project:

make

and run it:

./ContourExtractor2DImageFilter

WINDOWS USERS PLEASE NOTE: Be sure to add the ITK bin directory to your path. This will resolve the ITK dll's at run time.

Building All of the Examples

Many of the examples in the ITK Wiki Examples Collection require VTK. You can build all of the the examples by following these instructions. If you are a new VTK user, you may want to try the Superbuild which will build a proper ITK and VTK.

ItkVtkGlue

ITK >= 4

For examples that use QuickView (which depends on VTK), you must have built ITK with Module_ITKVtkGlue=ON.

ITK < 4

Some of the ITK Examples require VTK to display the images. If you download the entire ITK Wiki Examples Collection, the ItkVtkGlue directory will be included and configured. If you wish to just build a few examples, then you will need to download ItkVtkGlue and build it. When you run cmake it will ask you to specify the location of the ItkVtkGlue binary directory.