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 "itkImageFileReader.h"
4. include "itkCropImageFilter.h"

1. include "itksys/SystemTools.hxx"

1. include "QuickView.h"

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

static void CreateImage(ImageType::Pointer image);

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

 ImageType::Pointer image = ImageType::New();
 ImageType::SizeType cropSize;
 std::stringstream desc;

 if (argc > 1)
   {
   typedef itk::ImageFileReader<ImageType> ReaderType;
   ReaderType::Pointer reader = ReaderType::New();
   reader->SetFileName( argv[1] );
   if (argc > 2)
     {
     cropSize[0] = atoi(argv[2]);
     cropSize[1] = atoi(argv[3]);
     }
   reader->Update();
   image = reader->GetOutput();
   desc << itksys::SystemTools::GetFilenameName(argv[1]);
   }
 else
   {
   CreateImage(image);
   cropSize[0] = 10;
   cropSize[1] = 14;
   desc << "Synthetic 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

 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);

 QuickView viewer;
 viewer.AddRGBImage(
   image.GetPointer(),
   true,
   desc.str());  

 std::stringstream desc2;
 desc2 << "CropImageFilter, crop size = {"
       << cropSize[0] << ", " << cropSize[1] << "}";
 viewer.AddRGBImage(
   cropFilter->GetOutput(),
   true,
   desc2.str());  

 viewer.Visualize();

 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( itk::NumericTraits<ImageType::PixelType>::Zero);

 // 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

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

project(CropImageFilter)

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

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

endif()

add_executable(CropImageFilter MACOSX_BUNDLE CropImageFilter.cxx)

if( "${ITK_VERSION_MAJOR}" LESS 4 )

 target_link_libraries(CropImageFilter ITKReview ${ITK_LIBRARIES})

else( "${ITK_VERSION_MAJOR}" LESS 4 )

 target_link_libraries(CropImageFilter ${ITK_LIBRARIES})

endif( "${ITK_VERSION_MAJOR}" LESS 4 )

</syntaxhighlight>

Download and Build CropImageFilter

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

cd CropImageFilter/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:

./CropImageFilter

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.