# ImageAlgorithmFilter

VTKExamples/Cxx/Developers/ImageAlgorithmFilter

### Description

This example demonstrates how to setup the pipeline for a {{class|vtkImageAlgorithm}} filter that takes a {{class|vtkImageData}} as input and produces another vtkImageData as output. This particular example creates a 2x2 image and fills it with "2"s. The filter changes the (0,0) element to a 5.

### Code

ImageAlgorithmFilter.cxx

    #include <vtkSmartPointer.h>

    #include "vtkImageAlgorithmFilter.h"
    #include "vtkImageData.h"

    void PrintImage(vtkImageData* image);

    int main (int argc, char *argv[])
    {
      vtkSmartPointer<vtkImageData> input =
        vtkSmartPointer<vtkImageData>::New();
      // Setup the image
      input->SetDimensions(2,2,1);
      input->AllocateScalars(VTK_DOUBLE,1);

      // Fill every entry of the image data with "2.0"
      int* dims = input->GetDimensions();

      for (int y=0; y<dims[1]; y++)
      {
        for (int x=0; x<dims[0]; x++)
        {
          input->SetScalarComponentFromDouble(x,y,0,0,2.0);
        }
      }

      std::cout << "Input image: " << std::endl;
      PrintImage(input);

      vtkSmartPointer<vtkImageAlgorithmFilter> filter =
        vtkSmartPointer<vtkImageAlgorithmFilter>::New();
      filter->SetInputData(input);
      filter->Update();

      vtkImageData* output = filter->GetOutput();

      std::cout << "Output image: " << std::endl;
      PrintImage(output);

      return 0;
    }

    void PrintImage(vtkImageData* image)
    {
      int* dims = image->GetDimensions();

      for (int y=0; y<dims[1]; y++)
      {
        for (int x=0; x<dims[0]; x++)
        {
          double v = image->GetScalarComponentAsDouble(x,y,0,0);
          std::cout << v << " ";
        }
        std::cout << std::endl;
      }
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(ImageAlgorithmFilter)

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

    add_executable(ImageAlgorithmFilter MACOSX_BUNDLE ImageAlgorithmFilter.cxx)

    target_link_libraries(ImageAlgorithmFilter ${VTK_LIBRARIES})

### Download and Build ImageAlgorithmFilter

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

    cd ImageAlgorithmFilter/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:

    ./ImageAlgorithmFilter

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