ITK/Examples/Images/ShrinkImageFilter

Note: The shrink factors must be greater than zero. That is, you cannot use this filter to enlarge an image.

ShrinkImageFilter.cxx

<source lang="cpp">

1. include "itkImage.h"
2. include "itkImageFileWriter.h"
3. include "itkRescaleIntensityImageFilter.h"
4. include "itkShrinkImageFilter.h"

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

static void CreateImage(ImageType::Pointer image);

int main(int, char *[]) {

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

 std::cout << "Original size: " << image->GetLargestPossibleRegion().GetSize() << std::endl;

 typedef itk::ShrinkImageFilter <ImageType, ImageType>
         ShrinkImageFilterType;

 ShrinkImageFilterType::Pointer shrinkFilter
         = ShrinkImageFilterType::New();
 shrinkFilter->SetInput(image);
 shrinkFilter->SetShrinkFactor(0, 2); // shrink the first dimension by a factor of 2 (i.e. 100 gets changed to 50)
 shrinkFilter->SetShrinkFactor(1, 3); // shrink the second dimension by a factor of 3 (i.e. 100 gets changed to 33)
 shrinkFilter->Update();

 std::cout << "New size: " << shrinkFilter->GetOutput()->GetLargestPossibleRegion().GetSize() << std::endl;

 return EXIT_SUCCESS;

}

void CreateImage(ImageType::Pointer image) {

 // Create an image with 2 connected components
 ImageType::IndexType start;
 start.Fill(0);

 ImageType::SizeType size;
 size.Fill(100);

 ImageType::RegionType region(start, size);
 image->SetRegions(region);
 image->Allocate();
 image->FillBuffer(0);

 // Make a white square
 for(unsigned int r = 20; r < 80; r++)
   {
   for(unsigned int c = 20; c < 30; c++)
     {
     ImageType::IndexType pixelIndex;
     pixelIndex[0] = r;
     pixelIndex[1] = c;

     image->SetPixel(pixelIndex, 255);
     }
   }

} </source>

CMakeLists.txt

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

project(ShrinkImageFilter)

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

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

endif()

add_executable(ShrinkImageFilter MACOSX_BUNDLE ShrinkImageFilter.cxx)

if( "${ITK_VERSION_MAJOR}" LESS 4 )

 target_link_libraries(ShrinkImageFilter ITKReview ${ITK_LIBRARIES})

else( "${ITK_VERSION_MAJOR}" LESS 4 )

 target_link_libraries(ShrinkImageFilter ${ITK_LIBRARIES})

endif( "${ITK_VERSION_MAJOR}" LESS 4 )

</syntaxhighlight>

Download and Build ShrinkImageFilter

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

cd ShrinkImageFilter/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:

./ShrinkImageFilter

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.