images/imageBasicSubsampling.cpp

Examples of 2D and 3D basic image subsampling.

Illustration of the resulting subsampling produced by this example.

#include <iostream>
#include "ConfigExamples.h"
#include "DGtal/helpers/StdDefs.h"
#include "DGtal/base/Common.h"

#include "DGtal/kernel/BasicPointFunctors.h"
#include "DGtal/images/ConstImageAdapter.h"

#include "DGtal/images/ImageContainerBySTLVector.h"

#include "DGtal/io/readers/GenericReader.h"
#include "DGtal/io/writers/GenericWriter.h"


using namespace std;
using namespace DGtal;


int main( int /*argc*/, char** /*argv*/ )
{
  
  typedef ImageContainerBySTLVector < Z2i::Domain, unsigned char> Image2D;
  typedef ConstImageAdapter<Image2D,  Image2D::Domain, 
                            functors::BasicDomainSubSampler<Image2D::Domain>,  
                            Image2D::Value,
                            functors::Identity > ConstImageAdapterForSubSampling;


  typedef ImageContainerBySTLVector < Z3i::Domain, unsigned char> Image3D;
  typedef ConstImageAdapter<Image3D,  Image3D::Domain, 
                            functors::BasicDomainSubSampler<Image3D::Domain>,
                            Image3D::Value, 
                            functors::Identity > ConstImageAdapterForSubSampling3D;


  trace.beginBlock ( "Example imageBasicSubsampling" );

  std::string imageFilename3D = examplesPath + "samples/Al.100.vol";
  std::string imageFilename2D = examplesPath + "samples/church.pgm";
  Image3D image3D = GenericReader<Image3D>::import( imageFilename3D );
  Image2D image2D = GenericReader<Image2D>::import( imageFilename2D );

  for (unsigned int i=1; i<=20; i*=2){
    std::vector<Z2i::Domain::Size> aGridSize2D;
    aGridSize2D.push_back(i);
    aGridSize2D.push_back(i);
    // Construction of the functor for the 2D domain subsampling from a given grid size and shift.
    DGtal::functors::BasicDomainSubSampler<Image2D::Domain> subSampler2D(image2D.domain(), aGridSize2D, Z2i::Point(0 ,0));

    functors::Identity df;
    // Get the new domain produces from the subsampler and define the ConstImageAdapter:
    Image2D::Domain subSampledDomain2D  = subSampler2D.getSubSampledDomain();
    ConstImageAdapterForSubSampling subsampledImage2D (image2D, subSampledDomain2D, subSampler2D, df);

    stringstream outputname; 
    outputname << "subSampledImage"<< i<< "x"<< i << ".pgm" ;
    GenericWriter<ConstImageAdapterForSubSampling>::exportFile(outputname.str(), subsampledImage2D );
    trace.info() << "Exporting 2D subsampled image by grid size :" << i << "x"<< i<< " in "<< outputname.str() << std::endl;
  } 

  for (unsigned int i=1; i<=20; i*=2){
    std::vector<Z3i::Domain::Size> aGridSize3D;
    aGridSize3D.push_back(i);
    aGridSize3D.push_back(i);
    aGridSize3D.push_back(i);

        // Construction of the functor for the 3D domain subsampling from a given grid size and shift.
    DGtal::functors::BasicDomainSubSampler<Image3D::Domain> subSampler3D(image3D.domain(), aGridSize3D, Z3i::Point(0 ,0, 0));

    DGtal::functors::Identity df;
    // Get the new domain produces from the subsampler and define the ConstImageAdapter:
    Image3D::Domain subSampledDomain3D  = subSampler3D.getSubSampledDomain();
    ConstImageAdapterForSubSampling3D subsampledImage3D (image3D, subSampledDomain3D, subSampler3D, df);

    stringstream outputname3D; 
    outputname3D << "subSampledImage3D"<< i<< "x"<< i << ".vol" ;
    GenericWriter<ConstImageAdapterForSubSampling3D>::exportFile(outputname3D.str(), subsampledImage3D );
    trace.info() << "Exporting 3D subsampled image by grid size :" << i << "x"<< i<< "x"<< i<< " in "<< outputname3D.str() << std::endl;
  }

  
  trace.endBlock();
  return 0;
}
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