ITK/Examples/ImageProcessing/ExtractImageFilter

ExtractImageFilter.cxx

<source lang="cpp"> // This is different from CropImageFilter only in the way // that the region to crop is specified.

1. include "itkImage.h"
2. include <itkImageFileReader.h>
3. include <itkExtractImageFilter.h>

int main(int argc, char *argv[]) {

 typedef itk::Image<unsigned char, 2> ImageType;

 ImageType::IndexType start;
 start.Fill(0);

 ImageType::SizeType size;
 size.Fill(10);

 ImageType::RegionType region(start, size);
 
 ImageType::Pointer image = ImageType::New();
 image->SetRegions(region);
 image->Allocate();
 image->FillBuffer(5);

 std::cout << "Image largest region: " << image->GetLargestPossibleRegion() << std::endl;

 ImageType::IndexType desiredStart;
 desiredStart.Fill(3);

 ImageType::SizeType desiredSize;
 desiredSize.Fill(4);

 ImageType::RegionType desiredRegion(desiredStart, desiredSize);

 std::cout << "desiredRegion: " << desiredRegion << std::endl;
 
 typedef itk::ExtractImageFilter< ImageType, ImageType > FilterType;
 FilterType::Pointer filter = FilterType::New();
 filter->SetExtractionRegion(desiredRegion);
 filter->SetInput(image);

1. if ITK_VERSION_MAJOR >= 4

 filter->SetDirectionCollapseToIdentity(); // This is required.

1. endif

 filter->Update();
 
 ImageType::Pointer output = filter->GetOutput();
 output->DisconnectPipeline();
 output->FillBuffer(2);

 itk::Index<2> index;
 index.Fill(5);

 std::cout << "new largest region: " << output->GetLargestPossibleRegion() << std::endl;
 std::cout << "new: " << (int)output->GetPixel(index) << std::endl;
 std::cout << "Original: " << (int)image->GetPixel(index) << std::endl;

 return EXIT_SUCCESS;

} </source>

CMakeLists.txt

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

project(ExtractImageFilter)

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

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

endif()

add_executable(ExtractImageFilter MACOSX_BUNDLE ExtractImageFilter.cxx)

if( "${ITK_VERSION_MAJOR}" LESS 4 )

 target_link_libraries(ExtractImageFilter ITKReview ${ITK_LIBRARIES})

else( "${ITK_VERSION_MAJOR}" LESS 4 )

 target_link_libraries(ExtractImageFilter ${ITK_LIBRARIES})

endif( "${ITK_VERSION_MAJOR}" LESS 4 )

</syntaxhighlight>

Download and Build ExtractImageFilter

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

cd ExtractImageFilter/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:

./ExtractImageFilter

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.