ITK/Examples/ImageProcessing/RGBResampleImageFilter

RGBResampleImageFilter.cxx

<source lang="cpp">

1. include "itkImage.h"
2. include "itkIdentityTransform.h"
3. include "itkImageFileReader.h"
4. include "itkVectorResampleImageFilter.h"
5. include "itkVectorNearestNeighborInterpolateImageFunction.h"
6. include "itkRGBPixel.h"

1. include "QuickView.h"

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

static void CreateImage(ImageType::Pointer image);

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

 double factor = 2.0;

 // Create input image
 ImageType::Pointer input;
 if(argc < 2)
   {
   input = ImageType::New();
   CreateImage(input);
   }
 else
   {
   typedef itk::ImageFileReader<ImageType> ReaderType;
   ReaderType::Pointer reader = ReaderType::New();
   reader->SetFileName(argv[1]);
   reader->Update();
   input = reader->GetOutput();
   if (argc > 2)
     {
     factor = atof(argv[2]);
     }
 }

 ImageType::SizeType inputSize = input->GetLargestPossibleRegion().GetSize();

 std::cout << "Input size: " << inputSize << std::endl;

 // Resize
 ImageType::SizeType outputSize;
 outputSize[0] = inputSize[0] * factor;
 outputSize[1] = inputSize[1] * factor;

 ImageType::SpacingType outputSpacing;
 outputSpacing[0] = input->GetSpacing()[0] * (static_cast<double>(inputSize[0]) / static_cast<double>(outputSize[0]));
 outputSpacing[1] = input->GetSpacing()[1] * (static_cast<double>(inputSize[1]) / static_cast<double>(outputSize[1]));
 
 typedef itk::IdentityTransform<double, 2> TransformType;
 typedef itk::VectorResampleImageFilter<ImageType, ImageType> ResampleImageFilterType;
 ResampleImageFilterType::Pointer resample = ResampleImageFilterType::New();
 resample->SetInput(input);
 resample->SetSize(outputSize);
 resample->SetOutputSpacing(outputSpacing);
 resample->SetTransform(TransformType::New());
 resample->UpdateLargestPossibleRegion();
 
 typedef itk::VectorNearestNeighborInterpolateImageFunction<
                      ImageType, double >  NearestInterpolatorType;
 NearestInterpolatorType::Pointer nnInterpolator =
   NearestInterpolatorType::New();

 ResampleImageFilterType::Pointer resampleNN =
   ResampleImageFilterType::New();
 resampleNN->SetInput(input);
 resampleNN->SetSize(outputSize);
 resampleNN->SetOutputSpacing(outputSpacing);
 resampleNN->SetTransform(TransformType::New());
 resampleNN->SetInterpolator(nnInterpolator);
 resampleNN->UpdateLargestPossibleRegion();
 
 ImageType::Pointer output = resample->GetOutput();
 
 std::cout << "Output size: " << output->GetLargestPossibleRegion().GetSize() << std::endl;

 QuickView viewer;

 viewer.AddRGBImage(input.GetPointer(),
                 true,
                 "Original");
 viewer.AddRGBImage(output.GetPointer(),
                 true,
                 "Resampled");

 viewer.AddRGBImage(resampleNN->GetOutput(),
                 true,
                 "Resampled NN");

 viewer.Visualize();

 return EXIT_SUCCESS;

}

void CreateImage(ImageType::Pointer image) {

 // Create a black image with 2 white regions
 
 ImageType::IndexType start;
 start.Fill(0);

 ImageType::SizeType size;
 size.Fill(200);

 ImageType::RegionType region(start,size);
 image->SetRegions(region);
 image->Allocate();
 image->FillBuffer( itk::NumericTraits< ImageType::PixelType >::Zero);
 
 ImageType::PixelType pixel;
 pixel.SetRed(200);
 pixel.SetGreen(50);
 pixel.SetBlue(50);

 // Make a square
 for(unsigned int r = 20; r < 80; r++)
   {
   for(unsigned int c = 30; c < 100; c++)
     {
     ImageType::IndexType pixelIndex;
     pixelIndex[0] = r;
     pixelIndex[1] = c;

     image->SetPixel(pixelIndex, pixel);

     }
   }

} </source>

CMakeLists.txt

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

project(RGBResampleImageFilter)

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

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

else()

 find_package(ItkVtkGlue REQUIRED)
 include(${ItkVtkGlue_USE_FILE})
 set(Glue ItkVtkGlue)

endif()

add_executable(RGBResampleImageFilter MACOSX_BUNDLE RGBResampleImageFilter.cxx) target_link_libraries(RGBResampleImageFilter

 ${Glue}  ${VTK_LIBRARIES} ${ITK_LIBRARIES})

</syntaxhighlight>

Download and Build RGBResampleImageFilter

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

cd RGBResampleImageFilter/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:

./RGBResampleImageFilter

WINDOWS USERS PLEASE NOTE: Be sure to add the VTK and ITK bin directories to your path. This will resolve the VTK and 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.