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ImageSeparableConvolution

vtk-examples/Cxx/Images/ImageSeparableConvolution

Description

Read in a binary image and convolve it with a separable kernel. The input and output are displayed.

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

ImageSeparableConvolution.cxx

#include <vtkFloatArray.h>
#include <vtkImageActor.h>
#include <vtkImageCast.h>
#include <vtkImageMapper3D.h>
#include <vtkImageSeparableConvolution.h>
#include <vtkInteractorStyleImage.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPNGReader.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

int main(int argc, char* argv[])
{
  vtkNew<vtkNamedColors> colors;

  // Handle the arguments.
  if (argc < 2)
  {
    std::cout << "Required arguments: BinaryImage.png e.g. Yinyang.png"
              << std::endl;
    return EXIT_FAILURE;
  }

  // Read the image.
  vtkNew<vtkPNGReader> reader;
  reader->SetFileName(argv[1]);
  reader->Update();

  vtkNew<vtkFloatArray> xKernel;
  xKernel->SetNumberOfTuples(5);
  xKernel->SetNumberOfComponents(1);
  xKernel->SetValue(0, 1);
  xKernel->SetValue(1, 1);
  xKernel->SetValue(2, 1);
  xKernel->SetValue(3, 1);
  xKernel->SetValue(4, 1);

  vtkNew<vtkImageSeparableConvolution> convolutionFilter;
  convolutionFilter->SetInputConnection(reader->GetOutputPort());
  convolutionFilter->SetXKernel(xKernel);
  convolutionFilter->Update();

  vtkNew<vtkImageActor> originalActor;
  originalActor->GetMapper()->SetInputConnection(reader->GetOutputPort());

  vtkNew<vtkImageCast> convolutionCastFilter;
  convolutionCastFilter->SetInputConnection(convolutionFilter->GetOutputPort());
  convolutionCastFilter->SetOutputScalarTypeToUnsignedChar();
  convolutionCastFilter->Update();

  vtkNew<vtkImageActor> convolutionActor;
  convolutionActor->GetMapper()->SetInputConnection(
      convolutionCastFilter->GetOutputPort());

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

  // Setup renderers
  vtkNew<vtkRenderer> originalRenderer;
  originalRenderer->SetViewport(originalViewport);
  originalRenderer->AddActor(originalActor);
  originalRenderer->ResetCamera();
  originalRenderer->SetBackground(
      colors->GetColor3d("CornflowerBlue").GetData());

  vtkNew<vtkRenderer> convolutionRenderer;
  convolutionRenderer->SetViewport(convolutionViewport);
  convolutionRenderer->AddActor(convolutionActor);
  convolutionRenderer->ResetCamera();
  convolutionRenderer->SetBackground(colors->GetColor3d("SteelBlue").GetData());

  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->SetSize(600, 300);
  renderWindow->AddRenderer(originalRenderer);
  renderWindow->AddRenderer(convolutionRenderer);
  renderWindow->SetWindowName("ImageSeparableConvolution");

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  vtkNew<vtkInteractorStyleImage> style;

  renderWindowInteractor->SetInteractorStyle(style);

  renderWindowInteractor->SetRenderWindow(renderWindow);
  renderWindow->Render();
  renderWindowInteractor->Initialize();

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(ImageSeparableConvolution)

find_package(VTK COMPONENTS 
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "ImageSeparableConvolution: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(ImageSeparableConvolution MACOSX_BUNDLE ImageSeparableConvolution.cxx )
  target_link_libraries(ImageSeparableConvolution PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS ImageSeparableConvolution
  MODULES ${VTK_LIBRARIES}
)

Download and Build ImageSeparableConvolution

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

cd ImageSeparableConvolution/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:

./ImageSeparableConvolution

WINDOWS USERS

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