/usr/include/ITK-4.5/itkMomentsThresholdCalculator.hxx is in libinsighttoolkit4-dev 4.5.0-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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*
* Copyright Insight Software Consortium
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*=========================================================================*/
#ifndef __itkMomentsThresholdCalculator_hxx
#define __itkMomentsThresholdCalculator_hxx
#include "itkMomentsThresholdCalculator.h"
#include "itkProgressReporter.h"
#include "vnl/vnl_math.h"
namespace itk
{
/*
* Compute the Moments's threshold
*/
template<typename THistogram, typename TOutput>
void
MomentsThresholdCalculator<THistogram, TOutput>
::GenerateData(void)
{
const HistogramType * histogram = this->GetInput();
// histogram->Print(std::cout);
if ( histogram->GetTotalFrequency() == 0 )
{
itkExceptionMacro(<< "Histogram is empty");
}
ProgressReporter progress(this, 0, histogram->GetSize(0) );
if( histogram->GetSize(0) == 1 )
{
this->GetOutput()->Set( static_cast<OutputType>( histogram->GetMeasurement(0,0) ) );
}
unsigned int size = histogram->GetSize(0);
double total = histogram->GetTotalFrequency();
double m0=1.0, m1=0.0, m2 =0.0, m3 =0.0, sum =0.0, p0=0.0;
double cd, c0, c1, z0, z1; /* auxiliary variables */
int threshold = -1;
std::vector<double> histo(size);
for (unsigned i=0; i<size; i++)
histo[i]=(double)(histogram->GetFrequency(i,0)/total); //normalised histogram
/* Calculate the first, second, and third order moments */
for ( unsigned i = 0; i < size; i++ )
{
double m = histogram->GetMeasurement(i,0);
m1 += m * histo[i];
m2 += m * m * histo[i];
m3 += m * m * m * histo[i];
progress.CompletedPixel();
}
//
// First 4 moments of the gray-level image should match the first 4 moments
// of the target binary image. This leads to 4 equalities whose solutions
// are given in the Appendix of Ref. 1
//
cd = m0 * m2 - m1 * m1;
c0 = ( -m2 * m2 + m1 * m3 ) / cd;
c1 = ( m0 * -m3 + m2 * m1 ) / cd;
z0 = 0.5 * ( -c1 - vcl_sqrt ( c1 * c1 - 4.0 * c0 ) );
z1 = 0.5 * ( -c1 + vcl_sqrt ( c1 * c1 - 4.0 * c0 ) );
p0 = ( z1 - m1 ) / ( z1 - z0 ); /* Fraction of the object pixels in the target binary image */
// The threshold is the gray-level closest
// to the p0-tile of the normalized histogram
sum=0;
for (unsigned i = 0; i<size; i++)
{
sum += histo[i];
if (sum>p0)
{
threshold = i;
break;
}
}
this->GetOutput()->Set( static_cast<OutputType>( histogram->GetMeasurement( threshold, 0 ) ) );
}
} // end namespace itk
#endif
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