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ImageExport

vtk-examples/Cxx/Images/ImageExport

Question

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Code

ImageExport.cxx

#include <vtkImageData.h>
#include <vtkImageExport.h>
#include <vtkNew.h>

#include <memory>

int main(int, char*[])
{
  // Create an image data
  vtkNew<vtkImageData> imageData;

  // Specify the size of the image data
  constexpr int dims[3] = {2, 3, 1};

  imageData->SetDimensions(dims[0], dims[1], dims[2]);
  imageData->AllocateScalars(VTK_UNSIGNED_CHAR, 1);

  unsigned char value = 0;
  for (int row = 0; row < dims[0]; ++row)
  {
    for (int col = 0; col < dims[1]; ++col)
    {
      unsigned char* pixel =
          static_cast<unsigned char*>(imageData->GetScalarPointer(row, col, 0));
      pixel[0] = value;
      value += 10;
    }
  }

  // Create the c-style image to convert the VTK image to
  std::unique_ptr<unsigned char> cImage(
      new unsigned char[dims[0] * dims[1] * dims[2]]);

  vtkNew<vtkImageExport> exporter;
  exporter->SetInputData(imageData);
  exporter->ImageLowerLeftOn();
  exporter->Export(cImage.get());
  exporter->Update();

  // Output the raw c-style image
  for (int row = 0; row < dims[0]; ++row)
  {
    for (int col = 0; col < dims[1]; ++col)
    {
      std::cout << static_cast<int>(cImage.get()[col * dims[0] + row]) << " ";
    }
    std::cout << std::endl;
  }

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(ImageExport)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkIOImage
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping ImageExport: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(ImageExport MACOSX_BUNDLE ImageExport.cxx )
  target_link_libraries(ImageExport PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(ImageExport MACOSX_BUNDLE ImageExport.cxx )
  target_link_libraries(ImageExport PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS ImageExport
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build ImageExport

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

cd ImageExport/build

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./ImageExport

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.