GaussianStretch.cpp

 
/* SPDX-License-Identifier: CC0-1.0 */
#include "GaussianStretch.h"
#include "GaussianDistribution.h"
#include "Stretch.h"
#include "Message.h"
#include <string>
#include <iostream>
#include <iomanip>
 
using namespace std;
namespace Isis {
  GaussianStretch::GaussianStretch(Histogram &histogram, const double mean, const double standardDeviation) {
    GaussianDistribution dis(mean, standardDeviation);
 
    p_stretch.ClearPairs();
    p_stretch.AddPair(histogram.Minimum(), histogram.Minimum());
    double lastvalue = histogram.Minimum();
    for(int i = 1; i <= histogram.Bins() - 1; i++) {
      double percent = 100.0 * (double)i / (double)histogram.Bins();
      double input = histogram.Percent(percent);
      // stretch pairs must be monotonically increasing
      if(lastvalue + DBL_EPSILON > input) continue;
      if(fabs(input - lastvalue) < 100.0 * DBL_EPSILON) continue;
      double output = dis.InverseCumulativeDistribution(percent);
      p_stretch.AddPair(input, output);
      lastvalue = input;
    }
 
    if(histogram.Maximum() > lastvalue) {
      if(abs(histogram.Maximum() - lastvalue) > 100 * DBL_EPSILON) {
        p_stretch.AddPair(histogram.Maximum(), histogram.Maximum());
      }
    }
  }

  double GaussianStretch::Map(const double value) const {
    return p_stretch.Map(value);
  }
}