ITK/Examples/ImageProcessing/CropImageFilter

Description

This example demonstrates how to crop an image. The SetBoundaryCropSize( cropSize ) method specifies the size of the boundary to be cropped at both the uppper & lower ends of the image - e.g. cropSize/2 pixels will be removed at both upper & lower extents.

Classes Demonstrated

CropImageFilter

Output

The original image is displayed on the left. The cropped image is displayed on the right.

CropImageFilter.cxx

<source lang="cpp">

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

1. include "itkImageToVTKImageFilter.h"

1. include "vtkImageViewer.h"
2. include "vtkRenderWindowInteractor.h"
3. include "vtkSmartPointer.h"
4. include "vtkImageActor.h"
5. include "vtkInteractorStyleImage.h"
6. include "vtkRenderer.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);

 typedef itk::CropImageFilter <ImageType, ImageType>
   CropImageFilterType;

 CropImageFilterType::Pointer cropFilter
   = CropImageFilterType::New();
 cropFilter->SetInput(image);
 // The SetBoundaryCropSize( cropSize ) method specifies the size of the boundary to 
 // be cropped at both the uppper & lower ends of the image
 // eg. cropSize/2 pixels will be removed at both upper & lower extents

 ImageType::SizeType cropSize = {10,14};
 cropFilter->SetBoundaryCropSize(cropSize);

 // The below three lines are equivalent to the above two lines:
 //ImageType::SizeType halfCropSize = {5,7};
 //cropFilter->SetUpperBoundaryCropSize(halfCropSize);
 //cropFilter->SetLowerBoundaryCropSize(halfCropSize);

 cropFilter->Update();

 // Visualize first image
 typedef itk::ImageToVTKImageFilter<ImageType> ConnectorType;
 ConnectorType::Pointer originalConnector = ConnectorType::New();
 originalConnector->SetInput(image);

 vtkSmartPointer<vtkImageActor> originalActor =
   vtkSmartPointer<vtkImageActor>::New();
 originalActor->SetInput(originalConnector->GetOutput());

 // Visualize permuted image
 ConnectorType::Pointer croppedConnector = ConnectorType::New();
 croppedConnector->SetInput(cropFilter->GetOutput());

 vtkSmartPointer<vtkImageActor> croppedActor =
   vtkSmartPointer<vtkImageActor>::New();
 croppedActor->SetInput(croppedConnector->GetOutput());

 // There will be one render window
 vtkSmartPointer<vtkRenderWindow> renderWindow =
   vtkSmartPointer<vtkRenderWindow>::New();
 renderWindow->SetSize(600, 300);

 vtkSmartPointer<vtkRenderWindowInteractor> interactor =
   vtkSmartPointer<vtkRenderWindowInteractor>::New();
 interactor->SetRenderWindow(renderWindow);

 // Define viewport ranges
 // (xmin, ymin, xmax, ymax)
 double leftViewport[4] = {0.0, 0.0, 0.5, 1.0};
 double rightViewport[4] = {0.5, 0.0, 1.0, 1.0};

 // Setup both renderers
 vtkSmartPointer<vtkRenderer> leftRenderer =
   vtkSmartPointer<vtkRenderer>::New();
 renderWindow->AddRenderer(leftRenderer);
 leftRenderer->SetViewport(leftViewport);
 leftRenderer->SetBackground(.6, .5, .4);

 vtkSmartPointer<vtkRenderer> rightRenderer =
   vtkSmartPointer<vtkRenderer>::New();
 renderWindow->AddRenderer(rightRenderer);
 rightRenderer->SetViewport(rightViewport);
 rightRenderer->SetBackground(.4, .5, .6);

 // Add the sphere to the left and the cube to the right
 leftRenderer->AddActor(originalActor);
 rightRenderer->AddActor(croppedActor);

 leftRenderer->ResetCamera();
 rightRenderer->ResetCamera();

 renderWindow->Render();

 vtkSmartPointer<vtkInteractorStyleImage> style =
   vtkSmartPointer<vtkInteractorStyleImage>::New();
 interactor->SetInteractorStyle(style);

 interactor->Start();

 return EXIT_SUCCESS;

}

void CreateImage(ImageType::Pointer image) {

 // Create an image with 2 connected components
 ImageType::RegionType region;
 ImageType::IndexType start;
 start[0] = 0;
 start[1] = 0;

 ImageType::SizeType size;
 unsigned int NumRows = 200;
 unsigned int NumCols = 300;
 size[0] = NumRows;
 size[1] = NumCols;

 region.SetSize(size);
 region.SetIndex(start);

 image->SetRegions(region);
 image->Allocate();
 image->FillBuffer( 0 );

 // Make a rectangle, centered at (100,150) with sides 160 & 240
 // This provides a 20 x 30 border around the square for the crop filter to remove
 for(unsigned int r = 20; r < 180; r++)
   {
   for(unsigned int c = 30; c < 270; c++)
     {
     ImageType::IndexType pixelIndex;
     pixelIndex[0] = r;
     pixelIndex[1] = c;
     
     image->SetPixel(pixelIndex, 200);
     }
   }

} </source>

CMakeLists.txt

<source lang="cmake"> cmake_minimum_required(VERSION 2.6)

PROJECT(CropImageFilter)

include_directories(/home/doriad/src/ITK/Wrapping/WrapITK/ExternalProjects/ItkVtkGlue/src/)

FIND_PACKAGE(VTK REQUIRED) INCLUDE(${VTK_USE_FILE})

FIND_PACKAGE(ITK REQUIRED) INCLUDE(${ITK_USE_FILE})

ADD_EXECUTABLE(CropImageFilter CropImageFilter.cxx) TARGET_LINK_LIBRARIES(CropImageFilter vtkHybrid ITKBasicFilters ITKCommon ITKIO)

</source>