ITK/Examples/Broken/Statistics/ImageToHistogramFilter

Pending some bug fixes: http://public.kitware.com/Bug/view.php?id=11481 http://public.kitware.com/Bug/view.php?id=11480

ImageToHistogramFilter.cxx

<source lang="cpp">

1. include "itkImageToHistogramFilter.h"
2. include "itkImage.h"
3. include "itkRGBPixel.h"
4. include "itkImageRegionIteratorWithIndex.h"

1. include <fstream>

typedef itk::RGBPixel<unsigned char> RGBPixelType; typedef itk::Image< RGBPixelType, 2> RGBImageType;

void CreateImage(RGBImageType::Pointer image);

int main(int, char *[]) {

 const unsigned int MeasurementVectorSize = 3; // RGB

 RGBImageType::Pointer image = RGBImageType::New();
 CreateImage(image);

 typedef itk::Statistics::ImageToHistogramFilter< RGBImageType >         HistogramFilterType;
 typedef HistogramFilterType::HistogramMeasurementVectorType             HistogramMeasurementVectorType;
 typedef HistogramFilterType::HistogramSizeType                          HistogramSizeType;
 typedef HistogramFilterType::HistogramType                              HistogramType;

 HistogramFilterType::Pointer filter = HistogramFilterType::New();
 filter->SetInput(image);
 filter->SetAutoMinimumMaximum(true);

 HistogramSizeType histogramSize( MeasurementVectorSize );

 histogramSize[0] = 2;  // number of bins for the Red   channel
 histogramSize[1] = 2;  // number of bins for the Green channel
 histogramSize[2] = 2;  // number of bins for the Blue  channel

 filter->SetHistogramSize(histogramSize);
 filter->SetMarginalScale(10); // Required (could this be set in the filter?)
 filter->Update();

 const HistogramType * histogram = filter->GetOutput();

 HistogramType::ConstIterator histogramIterator = histogram->Begin();

 while( histogramIterator  != histogram->End() )
   {
   std::cout << "Index = " << histogram->GetIndex(histogramIterator.GetMeasurementVector())

<< " Histogram cell center = " << histogramIterator.GetMeasurementVector() << " Frequency = " << histogramIterator.GetFrequency() << std::endl;

   ++histogramIterator ;
   }

 HistogramType::MeasurementVectorType mv(3);
 mv[0] = 255;
 mv[1] = 0;
 mv[2] = 0;
 std::cout << "Frequency = " << histogram->GetFrequency(histogram->GetIndex(mv)) << std::endl;
 return EXIT_SUCCESS;

}

void CreateImage(RGBImageType::Pointer image) {

 // Create a black image with a red square and a green square.
 // This should produce a histogram with very strong spikes.
 RGBImageType::SizeType   size;
 size[0] = 3;
 size[1] = 3;

 RGBImageType::IndexType  start;
 start[0] = 0;
 start[1] = 0;

 RGBImageType::RegionType region;
 region.SetIndex(start);
 region.SetSize(size);

 image->SetRegions(region);
 image->Allocate();

 itk::ImageRegionIteratorWithIndex< RGBImageType > iterator( image, image->GetLargestPossibleRegion() );
 iterator.GoToBegin();

 RGBPixelType redPixel;
 redPixel.SetRed(255);
 redPixel.SetGreen(0);
 redPixel.SetBlue(0);

 RGBPixelType blackPixel;
 blackPixel.SetRed(0);
 blackPixel.SetGreen(0);
 blackPixel.SetBlue(0);

 itk::ImageRegionIterator<RGBImageType> imageIterator(image,region);

 while(!imageIterator.IsAtEnd())
   {
   imageIterator.Set(blackPixel);
   ++imageIterator;
   }

 RGBImageType::IndexType index;
 index[0] = 0; index[1] = 0;
 image->SetPixel(index, redPixel);

 index[0] = 1; index[1] = 0;
 image->SetPixel(index, redPixel);  

} </source>

CMakeLists.txt

<source lang="cmake"> cmake_minimum_required(VERSION 2.6)

PROJECT(ImageToHistogramFilter)

FIND_PACKAGE(ITK REQUIRED) INCLUDE(${ITK_USE_FILE})

ADD_EXECUTABLE(ImageToHistogramFilter ImageToHistogramFilter.cxx) TARGET_LINK_LIBRARIES(ImageToHistogramFilter ITKBasicFilters ITKCommon ITKIO ITKStatistics)

</source>