itkHoughTransform2DCirclesImageFilter.txx

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/*=========================================================================

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkHoughTransform2DCirclesImageFilter.txx,v $
  Language:  C++
  Date:      $Date: 2009-04-05 23:09:19 $
  Version:   $Revision: 1.20 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even 
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/

#ifndef __itkHoughTransform2DCirclesImageFilter_txx
#define __itkHoughTransform2DCirclesImageFilter_txx

#include "itkHoughTransform2DCirclesImageFilter.h"
#include "itkImageRegionIteratorWithIndex.h"
#include "itkDiscreteGaussianImageFilter.h"
#include "itkGaussianDerivativeImageFunction.h"
#include "itkMinimumMaximumImageCalculator.h"


namespace itk
{

template<typename TInputPixelType, typename TOutputPixelType>
HoughTransform2DCirclesImageFilter< TInputPixelType, TOutputPixelType>
::HoughTransform2DCirclesImageFilter()
{
  m_Threshold = 0;
  m_MinimumRadius = 0; // by default
  m_MaximumRadius = 10; // by default
  m_SigmaGradient = 1; // Scale of the DoG filter
  m_DiscRadiusRatio = 1;
  m_Variance = 10;
  m_OldModifiedTime = 0;
  m_OldNumberOfCircles = 0;
  m_SweepAngle = 0.0;
  m_NumberOfCircles = 1;
}

template<typename TInputPixelType, typename TOutputPixelType>
void 
HoughTransform2DCirclesImageFilter< TInputPixelType, TOutputPixelType>
::SetRadius(double radius)
{
  this->SetMinimumRadius(radius);
  this->SetMaximumRadius(radius);
}

template<typename TInputPixelType, typename TOutputPixelType>
void 
HoughTransform2DCirclesImageFilter<TInputPixelType,TOutputPixelType>
::EnlargeOutputRequestedRegion(DataObject *output)
{
  Superclass::EnlargeOutputRequestedRegion(output);
  output->SetRequestedRegionToLargestPossibleRegion();
}


template<typename TInputPixelType, typename TOutputPixelType>
void 
HoughTransform2DCirclesImageFilter<TInputPixelType,TOutputPixelType>
::GenerateInputRequestedRegion()
{
  Superclass::GenerateInputRequestedRegion();
  if ( this->GetInput() )
    {
    InputImagePointer image = 
      const_cast< InputImageType * >( this->GetInput() );
    image->SetRequestedRegionToLargestPossibleRegion();
    }
}

template<typename TInputPixelType, typename TOutputPixelType>
void
HoughTransform2DCirclesImageFilter< TInputPixelType, TOutputPixelType>
::GenerateData()
{

  // Get the input and output pointers
  InputImageConstPointer  inputImage = this->GetInput(0);
  OutputImagePointer outputImage = this->GetOutput(0);

  // Allocate the output
  this->AllocateOutputs();
  outputImage->FillBuffer(0);

  typedef GaussianDerivativeImageFunction<InputImageType> DoGFunctionType;
  typename DoGFunctionType::Pointer DoGFunction = DoGFunctionType::New();
  DoGFunction->SetInputImage(inputImage);
  DoGFunction->SetSigma(m_SigmaGradient);

  m_RadiusImage = OutputImageType::New();

  m_RadiusImage->SetRegions( outputImage->GetLargestPossibleRegion() );
  m_RadiusImage->SetOrigin(inputImage->GetOrigin());
  m_RadiusImage->SetSpacing(inputImage->GetSpacing());
  m_RadiusImage->SetDirection(inputImage->GetDirection());
  m_RadiusImage->Allocate();
  m_RadiusImage->FillBuffer(0);

  ImageRegionConstIteratorWithIndex< InputImageType >  image_it( inputImage,  inputImage->GetRequestedRegion() );
  image_it.Begin();

  Index<2> index;
  Point<float,2> point;

  while( !image_it.IsAtEnd() )
    {
    if(image_it.Get()>m_Threshold)
      {   
      point[0] = image_it.GetIndex()[0];
      point[1] = image_it.GetIndex()[1];
      typename DoGFunctionType::VectorType grad = DoGFunction->EvaluateAtIndex(image_it.GetIndex());

      double Vx = grad[0];
      double Vy = grad[1];

      if( (vcl_fabs(Vx)>1) || (vcl_fabs(Vy)>1) ) // if the gradient is not flat
        {
        double norm = vcl_sqrt(Vx*Vx+Vy*Vy);
        Vx /= norm;
        Vy /= norm;
        
        for(double angle = -m_SweepAngle;angle<=m_SweepAngle;angle+=0.05)
          {
          double i = m_MinimumRadius;
          double distance;
        
          do
            {
            index[0] = (long int)(point[0]-i*(Vx*vcl_cos(angle)+Vy*vcl_sin(angle)));
            index[1] = (long int)(point[1]-i*(Vx*vcl_sin(angle)+Vy*vcl_cos(angle)));
            
            distance = vcl_sqrt((index[1]-point[1])*(index[1]-point[1])
                             +(index[0]-point[0])*(index[0]-point[0]) );


            if(outputImage->GetRequestedRegion().IsInside( index ))
              {
              outputImage->SetPixel(index, outputImage->GetPixel(index)+1);
              m_RadiusImage->SetPixel(index, (m_RadiusImage->GetPixel(index)+distance));
              }
            
            i=i+1;
            
            } while( outputImage->GetRequestedRegion().IsInside( index ) 
                     && (distance < m_MaximumRadius) );
          }
        }
      }
    ++image_it;
    }

  // Compute the average radius
  ImageRegionConstIterator< OutputImageType >  output_it( outputImage, outputImage->GetLargestPossibleRegion() );
  ImageRegionIterator< OutputImageType >  radius_it( m_RadiusImage, m_RadiusImage->GetLargestPossibleRegion() );
  output_it.Begin();
  radius_it.Begin();
  while( !output_it.IsAtEnd() )
    {
    if(output_it.Get()>0)
      {   
      radius_it.Set(radius_it.Get()/output_it.Get());
      }
    ++output_it;
    ++radius_it;
    }
}


template<typename TInputPixelType, typename TOutputPixelType>
typename HoughTransform2DCirclesImageFilter< TInputPixelType, TOutputPixelType>::CirclesListType & 
HoughTransform2DCirclesImageFilter< TInputPixelType, TOutputPixelType>
::GetCircles(unsigned int n)
{
  if((this->GetMTime() == m_OldModifiedTime) && (n == m_OldNumberOfCircles)) // if the filter has not been updated
    {
    return m_CirclesList;
    }

  m_CirclesList.clear();

  typedef Image<float,2> InternalImageType;
  
  OutputImagePointer  outputImage = OutputImageType::New();
  outputImage->SetRegions( this->GetOutput(0)->GetLargestPossibleRegion() );
  outputImage->SetOrigin(this->GetOutput(0)->GetOrigin());
  outputImage->SetSpacing(this->GetOutput(0)->GetSpacing());
  outputImage->SetDirection(this->GetOutput(0)->GetDirection());
  outputImage->Allocate();
  outputImage->FillBuffer(0);

  ImageRegionConstIteratorWithIndex< OutputImageType >  image_it( this->GetOutput(0),  this->GetOutput(0)->GetRequestedRegion() );
  image_it.GoToBegin();

  ImageRegionIterator< InternalImageType >  it( outputImage,  outputImage->GetRequestedRegion() );
 
  while( !image_it.IsAtEnd() )
    {
    it.Set(image_it.Get());
    ++image_it;
    ++it;
    }


  typedef DiscreteGaussianImageFilter<OutputImageType,InternalImageType> GaussianFilterType;
  typename GaussianFilterType::Pointer gaussianFilter = GaussianFilterType::New();

  gaussianFilter->SetInput(outputImage); // the output is the accumulator image
  double variance[2];
  variance[0] = m_Variance;
  variance[1] = m_Variance;
  gaussianFilter->SetVariance(variance);
  gaussianFilter->Update();
  typename InternalImageType::Pointer postProcessImage = gaussianFilter->GetOutput();

  typedef MinimumMaximumImageCalculator<InternalImageType> MinMaxCalculatorType;
  typename MinMaxCalculatorType::Pointer minMaxCalculator = MinMaxCalculatorType::New();
  ImageRegionIterator<InternalImageType> it_input(postProcessImage,postProcessImage->GetLargestPossibleRegion());

  Index<2> index;

  unsigned int circles=0;
  bool found;

  const double nPI = 4.0 * vcl_atan( 1.0 );

  // Find maxima
  do
    {
    minMaxCalculator->SetImage(postProcessImage);
    minMaxCalculator->ComputeMaximum();
    InternalImageType::PixelType  max = minMaxCalculator->GetMaximum();
    
    found = false;
    for(it_input.GoToBegin();!it_input.IsAtEnd();++it_input)
      {
      if(it_input.Get() == max) 
        { 
        // Create a Line Spatial Object
        CirclePointer Circle = CircleType::New();
        Circle->SetId(circles);
        Circle->SetRadius(m_RadiusImage->GetPixel(it_input.GetIndex()));

        CircleType::VectorType center;
        center[0] = it_input.GetIndex()[0];
        center[1] = it_input.GetIndex()[1];
        Circle->GetObjectToParentTransform()->SetOffset(center);
        Circle->ComputeBoundingBox();

        m_CirclesList.push_back(Circle);
       
        // Remove a black disc from the hough space domain
        for(double angle = 0; angle <= 2*nPI; angle += nPI/1000)
          {
          for(double length = 0; length < m_DiscRadiusRatio*Circle->GetRadius()[0];length += 1)
            {
            index[0] = (long int)(it_input.GetIndex()[0] + length * vcl_cos(angle));
            index[1] = (long int)(it_input.GetIndex()[1] + length * vcl_sin(angle));
            if(postProcessImage->GetLargestPossibleRegion().IsInside( index ))
              {
              postProcessImage->SetPixel(index,0);
              }
            } 
          }
        minMaxCalculator->SetImage(postProcessImage);
        minMaxCalculator->ComputeMaximum();
        max = minMaxCalculator->GetMaximum();
      
        circles++;
        found = true;
        if(circles == m_NumberOfCircles) break;  
        }
      }
    } while((circles<m_NumberOfCircles) && (found));
  
  m_OldModifiedTime = this->GetMTime();
  m_OldNumberOfCircles = m_CirclesList.size();
  return m_CirclesList;
}


template<typename TInputPixelType, typename TOutputPixelType>
void
HoughTransform2DCirclesImageFilter< TInputPixelType, TOutputPixelType>
::PrintSelf(std::ostream& os, Indent indent) const
{
  Superclass::PrintSelf(os,indent);

  os << "Threshold: " << m_Threshold << std::endl;
  os << "Minimum Radius:  " << m_MinimumRadius << std::endl;
  os << "Maximum Radius: " << m_MaximumRadius << std::endl;
  os << "Derivative Scale : " << m_SigmaGradient << std::endl;
  os << "Radius Image Information : " << m_RadiusImage << std::endl;
  os << "Number Of Circles: " << m_NumberOfCircles << std::endl;
  os << "Disc Radius: " << m_DiscRadiusRatio << std::endl;
  os << "Accumulator blur variance: " << m_Variance << std::endl;
  os << "Sweep angle : " << m_SweepAngle << std::endl;
}

} // end namespace

#endif