core/vil/vil_resample_nearest.txx

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// This is core/vil/vil_resample_nearest.txx
#ifndef vil_resample_nearest_txx_
#define vil_resample_nearest_txx_
//:
// \file
// \brief Sample image with nearest neighbour interpolation in one image and place in another
// \author dac
//
// The vil nearest neighbour source files were derived from the corresponding
// vil bilin files, thus the vil bilin/bicub/nearest source files are very
// similar.  If you modify something in this file, there is a
// corresponding bicub/bilin file that would likely also benefit from
// the same change.

#include "vil_resample_nearest.h"
#include <vil/vil_nearest_interp.h>


#ifdef VCL_VC
// Get rid of double to bool conversion warnings
#pragma warning( disable : 4800 )
#endif

//: This function should not be the same in nearest, bicub and bilin
inline bool vil_resample_nearest_corner_in_image(double x0, double y0,
                                                 const vil_image_view_base& image)
{
  return x0 >= 0.0
      && y0 >= 0.0
      && x0+1 <= image.ni()
      && y0+1 <= image.nj();
}

//: Sample grid of points in one image and place in another, using nearest neighbour interpolation.
//  dest_image(i,j,p) is sampled from the src_image at
//  (x0+i.dx1+j.dx2,y0+i.dy1+j.dy2), where i=[0..n1-1], j=[0..n2-1]
//  dest_image resized to (n1,n2,src_image.nplanes())
//  Points outside image return zero.
// \relatesalso vil_image_view
template <class sType, class dType>
void vil_resample_nearest(const vil_image_view<sType>& src_image,
                          vil_image_view<dType>& dest_image,
                          double x0, double y0, double dx1, double dy1,
                          double dx2, double dy2, int n1, int n2)
{
  bool all_in_image =    vil_resample_nearest_corner_in_image(x0,y0,src_image)
                      && vil_resample_nearest_corner_in_image(x0+(n1-1)*dx1,y0+(n1-1)*dy1,src_image)
                      && vil_resample_nearest_corner_in_image(x0+(n2-1)*dx2,y0+(n2-1)*dy2,src_image)
                      && vil_resample_nearest_corner_in_image(x0+(n1-1)*dx1+(n2-1)*dx2,
                                                              y0+(n1-1)*dy1+(n2-1)*dy2,src_image);
#ifdef DEBUG
  // corners
  vcl_cout<<"src_image= "<<src_image<<vcl_endl
          <<"x0="<<x0<<vcl_endl
          <<"y0="<<y0<<vcl_endl
          <<"x0+(n1-1)*dx1+(n2-1)*dx2="<<x0+(n1-1)*dx1+(n2-1)*dx2<<vcl_endl
          <<"y0+(n1-1)*dy1+(n2-1)*dy2="<<y0+(n1-1)*dy1+(n2-1)*dy2<<vcl_endl;
#endif

  const unsigned ni = src_image.ni();
  const unsigned nj = src_image.nj();
  const unsigned np = src_image.nplanes();
  const vcl_ptrdiff_t istep = src_image.istep();
  const vcl_ptrdiff_t jstep = src_image.jstep();
  const vcl_ptrdiff_t pstep = src_image.planestep();
  const sType* plane0 = src_image.top_left_ptr();

  dest_image.set_size(n1,n2,np);
  const vcl_ptrdiff_t d_istep = dest_image.istep();
  const vcl_ptrdiff_t d_jstep = dest_image.jstep();
  const vcl_ptrdiff_t d_pstep = dest_image.planestep();
  dType* d_plane0 = dest_image.top_left_ptr();

  double x1=x0;
  double y1=y0;

  if (all_in_image)
  {
    if (np==1)
    {
      dType *row = d_plane0;
      for (int j=0;j<n2;++j,x1+=dx2,y1+=dy2,row+=d_jstep)
      {
        double x=x1, y=y1;  // Start of j-th row
        dType *dpt = row;
        for (int i=0;i<n1;++i,x+=dx1,y+=dy1,dpt+=d_istep)
          *dpt = (dType) vil_nearest_interp_unsafe(x,y,plane0,ni,nj,istep,jstep);
      }
    }
    else
    {
      dType *row = d_plane0;
      for (int j=0;j<n2;++j,x1+=dx2,y1+=dy2,row+=d_jstep)
      {
        double x=x1, y=y1; // Start of j-th row
        dType *dpt = row;
        for (int i=0;i<n1;++i,x+=dx1,y+=dy1,dpt+=d_istep)
        {
          for (unsigned int p=0;p<np;++p)
            dpt[p*d_pstep] = (dType) vil_nearest_interp_unsafe(x,y,plane0+p*pstep,ni,nj,istep,jstep);
        }
      }
    }
  }
  else
  {
    // Use safe interpolation
    if (np==1)
    {
      dType *row = d_plane0;
      for (int j=0;j<n2;++j,x1+=dx2,y1+=dy2,row+=d_jstep)
      {
        double x=x1, y=y1;  // Start of j-th row
        dType *dpt = row;
        for (int i=0;i<n1;++i,x+=dx1,y+=dy1,dpt+=d_istep)
          *dpt = (dType) vil_nearest_interp_safe(x,y,plane0,
                                               ni,nj,istep,jstep);
      }
    }
    else
    {
      dType *row = d_plane0;
      for (int j=0;j<n2;++j,x1+=dx2,y1+=dy2,row+=d_jstep)
      {
        double x=x1, y=y1; // Start of j-th row
        dType *dpt = row;
        for (int i=0;i<n1;++i,x+=dx1,y+=dy1,dpt+=d_istep)
        {
          for (unsigned int p=0;p<np;++p)
            dpt[p*d_pstep] = (dType) vil_nearest_interp_safe(x,y,plane0+p*pstep,
                                                           ni,nj,istep,jstep);
        }
      }
    }
  }
}


//: Resample image to a specified width (n1) and height (n2)
template <class sType, class dType>
void vil_resample_nearest(const vil_image_view<sType>& src_image,
                          vil_image_view<dType>& dest_image,
                          int n1, int n2)
{
  double f= 0.9999999; // so sampler doesn't go off edge of image
  double x0=0;
  double y0=0;
  double dx1=f*(src_image.ni()-1)*1.0/(n1-1);
  double dy1=0;
  double dx2=0;
  double dy2=f*(src_image.nj()-1)*1.0/(n2-1);
  vil_resample_nearest( src_image, dest_image, x0, y0, dx1, dy1, dx2, dy2, n1, n2 );
}


//: Sample grid of points in one image and place in another, using bilinear interpolation.
//  dest_image(i,j,p) is sampled from the src_image at
//  (x0+i.dx1+j.dx2,y0+i.dy1+j.dy2), where i=[0..n1-1], j=[0..n2-1]
//  dest_image resized to (n1,n2,src_image.nplanes())
//  Points outside image return zero.
// \relatesalso vil_image_view
template <class sType, class dType>
void vil_resample_nearest_edge_extend(
  const vil_image_view<sType>& src_image,
  vil_image_view<dType>& dest_image,
  double x0, double y0, double dx1, double dy1,
  double dx2, double dy2, int n1, int n2)
{
  bool all_in_image =    vil_resample_nearest_corner_in_image(x0,y0,src_image)
                      && vil_resample_nearest_corner_in_image(x0+(n1-1)*dx1,y0+(n1-1)*dy1,src_image)
                      && vil_resample_nearest_corner_in_image(x0+(n2-1)*dx2,y0+(n2-1)*dy2,src_image)
                      && vil_resample_nearest_corner_in_image(x0+(n1-1)*dx1+(n2-1)*dx2,
                                                              y0+(n1-1)*dy1+(n2-1)*dy2,src_image);
#ifdef DEBUG
  // corners
  vcl_cout<<"src_image= "<<src_image<<vcl_endl
          <<"x0="<<x0<<vcl_endl
          <<"y0="<<y0<<vcl_endl
          <<"x0+(n1-1)*dx1+(n2-1)*dx2="<<x0+(n1-1)*dx1+(n2-1)*dx2<<vcl_endl
          <<"y0+(n1-1)*dy1+(n2-1)*dy2="<<y0+(n1-1)*dy1+(n2-1)*dy2<<vcl_endl;
#endif

  const unsigned ni = src_image.ni();
  const unsigned nj = src_image.nj();
  const unsigned np = src_image.nplanes();
  const vcl_ptrdiff_t istep = src_image.istep();
  const vcl_ptrdiff_t jstep = src_image.jstep();
  const vcl_ptrdiff_t pstep = src_image.planestep();
  const sType* plane0 = src_image.top_left_ptr();

  dest_image.set_size(n1,n2,np);
  const vcl_ptrdiff_t d_istep = dest_image.istep();
  const vcl_ptrdiff_t d_jstep = dest_image.jstep();
  const vcl_ptrdiff_t d_pstep = dest_image.planestep();
  dType* d_plane0 = dest_image.top_left_ptr();

  double x1=x0;
  double y1=y0;

  if (all_in_image)
  {
    if (np==1)
    {
      dType *row = d_plane0;
      for (int j=0;j<n2;++j,x1+=dx2,y1+=dy2,row+=d_jstep)
      {
        double x=x1, y=y1;  // Start of j-th row
        dType *dpt = row;
        for (int i=0;i<n1;++i,x+=dx1,y+=dy1,dpt+=d_istep)
          *dpt = (dType) vil_nearest_interp(x,y,plane0,ni,nj,istep,jstep);
      }
    }
    else
    {
      dType *row = d_plane0;
      for (int j=0;j<n2;++j,x1+=dx2,y1+=dy2,row+=d_jstep)
      {
        double x=x1, y=y1; // Start of j-th row
        dType *dpt = row;
        for (int i=0;i<n1;++i,x+=dx1,y+=dy1,dpt+=d_istep)
        {
          for (unsigned int p=0;p<np;++p)
            dpt[p*d_pstep] = (dType) vil_nearest_interp(x,y,plane0+p*pstep,ni,nj,istep,jstep);
        }
      }
    }
  }
  else
  {
    // Use safe interpolation
    if (np==1)
    {
      dType *row = d_plane0;
      for (int j=0;j<n2;++j,x1+=dx2,y1+=dy2,row+=d_jstep)
      {
        double x=x1, y=y1;  // Start of j-th row
        dType *dpt = row;
        for (int i=0;i<n1;++i,x+=dx1,y+=dy1,dpt+=d_istep)
          *dpt = (dType) vil_nearest_interp_safe_extend(
            x,y,plane0,ni,nj,istep,jstep);
      }
    }
    else
    {
      dType *row = d_plane0;
      for (int j=0;j<n2;++j,x1+=dx2,y1+=dy2,row+=d_jstep)
      {
        double x=x1, y=y1; // Start of j-th row
        dType *dpt = row;
        for (int i=0;i<n1;++i,x+=dx1,y+=dy1,dpt+=d_istep)
        {
          for (unsigned int p=0;p<np;++p)
            dpt[p*d_pstep] = (dType) vil_nearest_interp_safe_extend(
              x,y,plane0+p*pstep,ni,nj,istep,jstep);
        }
      }
    }
  }
}


//: Resample image to a specified width (n1) and height (n2)
template <class sType, class dType>
void vil_resample_nearest_edge_extend(const vil_image_view<sType>& src_image,
                                      vil_image_view<dType>& dest_image,
                                      int n1, int n2)
{
  double f= 0.9999999; // so sampler doesn't go off edge of image
  double x0=0;
  double y0=0;
  double dx1=f*(src_image.ni()-1)*1.0/(n1-1);
  double dy1=0;
  double dx2=0;
  double dy2=f*(src_image.nj()-1)*1.0/(n2-1);
  vil_resample_nearest_edge_extend(
    src_image, dest_image, x0, y0, dx1, dy1, dx2, dy2, n1, n2 );
}
#define VIL_RESAMPLE_NEAREST_INSTANTIATE( sType, dType ) \
template void vil_resample_nearest(const vil_image_view<sType >& src_image, \
                                   vil_image_view<dType >& dest_image, \
                                   double x0, double y0, double dx1, double dy1, \
                                   double dx2, double dy2, int n1, int n2); \
template void vil_resample_nearest(const vil_image_view<sType >& src_image, \
                                   vil_image_view<dType >& dest_image, \
                                   int n1, int n2); \
template void vil_resample_nearest_edge_extend(const vil_image_view<sType >& src_image, \
                                               vil_image_view<dType >& dest_image, \
                                               double x0, double y0, double dx1, double dy1, \
                                               double dx2, double dy2, int n1, int n2); \
template void vil_resample_nearest_edge_extend(const vil_image_view<sType >& src_image, \
                                               vil_image_view<dType >& dest_image, \
                                               int n1, int n2)

#endif // vil_resample_nearest_txx_