VTK/Examples/Developers/vtkImageAlgorithm Filter

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This example demonstrates how to setup the pipeline for a filter that takes a vtkImageData as input and produces a 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.

Contents

vtkImageAlgorithmFilterExample.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->SetNumberOfScalarComponents(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->SetInput(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;
    }
}

vtkImageAlgorithmFilter.h

#ifndef __vtkImageAlgorithmFilter_h
#define __vtkImageAlgorithmFilter_h
 
#include "vtkImageAlgorithm.h"
 
class vtkImageAlgorithmFilter : public vtkImageAlgorithm 
{
public:
  static vtkImageAlgorithmFilter *New();
  vtkTypeMacro(vtkImageAlgorithmFilter,vtkImageAlgorithm);
 
  vtkImageAlgorithmFilter(){}
 
protected:
 
  int RequestData(vtkInformation *, vtkInformationVector **, vtkInformationVector *);
 
private:
  vtkImageAlgorithmFilter(const vtkImageAlgorithmFilter&);  // Not implemented.
  void operator=(const vtkImageAlgorithmFilter&);  // Not implemented.
};
 
#endif

vtkImageAlgorithmFilter.cxx

#include "vtkImageAlgorithmFilter.h"
 
#include "vtkImageData.h"
#include "vtkObjectFactory.h"
#include "vtkStreamingDemandDrivenPipeline.h"
#include "vtkInformationVector.h"
#include "vtkInformation.h"
#include "vtkDataObject.h"
#include "vtkSmartPointer.h"
 
vtkStandardNewMacro(vtkImageAlgorithmFilter);
 
int vtkImageAlgorithmFilter::RequestData(vtkInformation *vtkNotUsed(request),
                                             vtkInformationVector **inputVector,
                                             vtkInformationVector *outputVector)
{
  // Get the info objects
  vtkInformation *inInfo = inputVector[0]->GetInformationObject(0);
  vtkInformation *outInfo = outputVector->GetInformationObject(0);
 
  // Get the input and ouptut
  vtkImageData *input = vtkImageData::SafeDownCast(
      inInfo->Get(vtkDataObject::DATA_OBJECT()));
 
  vtkImageData *output = vtkImageData::SafeDownCast(
      outInfo->Get(vtkDataObject::DATA_OBJECT()));
 
  vtkSmartPointer<vtkImageData> image =
    vtkSmartPointer<vtkImageData>::New();
  image->ShallowCopy(input);
 
  image->SetScalarComponentFromDouble(0,0,0,0, 5.0);
 
  output->ShallowCopy(image);
 
  // Without these lines, the output will appear real but will not work as the input to any other filters
  output->SetExtent(input->GetExtent());
  output->SetUpdateExtent(output->GetExtent());
  output->SetWholeExtent(output->GetExtent());
 
  return 1;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.6)
PROJECT(vtkImageAlgorithmFilterExample)
 
FIND_PACKAGE(VTK REQUIRED)
INCLUDE(${VTK_USE_FILE})
 
ADD_EXECUTABLE(vtkImageAlgorithmFilterExample vtkImageAlgorithmFilterExample.cxx vtkImageAlgorithmFilter.cxx)
TARGET_LINK_LIBRARIES(vtkImageAlgorithmFilterExample vtkHybrid)
Retrieved from "http://www.itk.org/Wiki/VTK/Examples/Developers/vtkImageAlgorithm_Filter"
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