ITK/Examples/Broken/Statistics/ImageToHistogramFilter

The last entry of the red histogram should contain several values, but it is 0?

ImageToHistogramFilter.cxx

<source lang="cpp">

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

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::InputHistogramMeasurementVectorObjectType  InputHistogramMeasurementVectorObjectType;
 typedef HistogramFilterType::InputBooleanObjectType                     InputBooleanObjectType;
 typedef HistogramFilterType::HistogramSizeType                          HistogramSizeType;
 typedef HistogramFilterType::HistogramType                              HistogramType;

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

 HistogramSizeType histogramSize( MeasurementVectorSize );

 histogramSize[0] = 256;  // number of bins for the Red   channel
 histogramSize[1] =   1;  // number of bins for the Green channel
 histogramSize[2] =   1;  // number of bins for the Blue  channel

 // Compute the bounds of the histrogram automatically
 filter->SetHistogramSize(histogramSize);
 filter->SetMarginalScale(10); // What is this?
 filter->Update();

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

 std::cout << "Histogram of the red component" << std::endl;
 for(unsigned int i = 0; i < histogramSize[0]; i++)
   {
   std::cout << histogram->GetFrequency(i, 0) << " "; // Red channel
   }
 std::cout << 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::RegionType region;
 RGBImageType::SizeType   size;
 RGBImageType::IndexType  start;

 size[0] = 127;
 size[1] = 127;

 start[0] = 0;
 start[1] = 0;

 region.SetIndex(start);
 region.SetSize(size);

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

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

 RGBPixelType pixel;
 RGBImageType::IndexType index;

 while(!iterator.IsAtEnd())
   {
   index = iterator.GetIndex();
   if(index[0] < 70 && index[0] > 50 && index[1] > 50 && index[1] < 70)
     {
     pixel.SetRed(255);
     pixel.SetGreen(0);
     pixel.SetBlue(0);
     iterator.Set(pixel);
     }
   else if(index[0] < 110 && index[0] > 100 && index[1] > 100 && index[1] < 110)
     {
     pixel.SetRed(0);
     pixel.SetGreen(255);
     pixel.SetBlue(0);
     iterator.Set(pixel);
     }
   else
     {
     pixel.SetRed(0);
     pixel.SetGreen(0);
     pixel.SetBlue(0);
     iterator.Set(pixel);
     }

   ++iterator;
   }

} </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>