vl_quickshift.c

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/*
Copyright (C) 2009-11 Andrea Vedaldi and Brian Fulkerson.
All rights reserved.

This file is part of the VLFeat library and is made available under
the terms of the BSD license (see the COPYING file).
*/

#include <mexutils.h>

#include <vl/quickshift.h>
#include <string.h>

enum {
  opt_medoid,
  opt_verbose
} ;

vlmxOption options [] = {
  {"Medoid",              0,   opt_medoid         },
  {"Verbose",             0,   opt_verbose        },
  {0,                     0,   0                  }
} ;

void
mexFunction(int nout, mxArray *out[],
            int nin, const mxArray *in[])
{
  enum {
    IN_I=0,     /* Input image */
    IN_KERNEL_SIZE,  /* The bandwidth parameter for density estimation */
    IN_MAX_DIST,     /* The maximum distance to a neighbor which increases
                   the density */
    IN_END
  } ;
  enum {
    OUT_PARENTS=0, /* parents (same size as I) */
    OUT_DISTS,     /* dists (same size as I) */
    OUT_DENSITY    /* density (same size as I) */
  } ;

  int             verb = 0 ;
  int             opt ;
  int             next = IN_END ;
  mxArray const  *optarg ;

  double const *I ;
  double *parents, *dists, *density ;
  int *parentsi;
  double sigma ;
  double tau ;

  int K,N1,N2;

  int medoid = 0 ;

  mwSize const *dims ;
  int ndims ;

  int i;

  VlQS * q;

  VL_USE_MATLAB_ENV ;

  /* -----------------------------------------------------------------
   *                                                   Check arguments
   * -------------------------------------------------------------- */

  if (nin < 2) {
    mexErrMsgTxt("At least two arguments.") ;
  }

  if (nout > 3) {
    mexErrMsgTxt("At most three output arguments.") ;
  }

  ndims = mxGetNumberOfDimensions(in[IN_I]) ;
  dims  = mxGetDimensions(in[IN_I]) ;

  if (ndims > 3) {
    mexErrMsgTxt("I must have at most 3 dimensions.") ;
  }

  if (mxGetClassID(in[IN_I]) != mxDOUBLE_CLASS) {
    mexErrMsgTxt("I must be DOUBLE.")  ;
  }

  N1 = dims [0] ;
  N2 = dims [1] ;
  K = (ndims == 3) ? dims [2] : 1 ;

  I     =  mxGetPr (in[IN_I]) ;
  sigma = *mxGetPr (in[IN_KERNEL_SIZE]) ;
  tau   = 3*sigma;
  if (nin > 2)
    tau = *mxGetPr (in[IN_MAX_DIST]) ;

  while ((opt = vlmxNextOption (in, nin, options, &next, &optarg)) >= 0) {
    switch (opt) {
    case opt_medoid: /* Do medoid shift instead of mean shift */
      medoid = 1 ;
      break ;
    case opt_verbose :
      ++ verb ;
      break ;
    }
  } /* while opts */

  /* Create outputs */
  out[OUT_PARENTS] = mxCreateDoubleMatrix(N1, N2, mxREAL) ;
  parents          = mxGetPr (out[OUT_PARENTS]) ;

  out[OUT_DISTS]   = mxCreateDoubleMatrix(N1, N2, mxREAL) ;
  dists            = mxGetPr (out[OUT_DISTS]) ;

  out[OUT_DENSITY] = mxCreateDoubleMatrix(N1, N2, mxREAL) ;
  density          = mxGetPr (out[OUT_DENSITY]) ;

  if (verb) {
    mexPrintf("quickshift: [N1,N2,K]: [%d,%d,%d]\n", N1,N2,K) ;
    mexPrintf("quickshift: type: %s\n", medoid ? "medoid" : "quick");
    mexPrintf("quickshift: kernel size:  %g\n", sigma) ;
    mexPrintf("quickshift: maximum gap:  %g\n", tau) ;
  }

  /* Do job */
  q = vl_quickshift_new(I, N1, N2, K);

  vl_quickshift_set_kernel_size (q, sigma) ;
  vl_quickshift_set_max_dist     (q, tau) ;
  vl_quickshift_set_medoid      (q, medoid) ;

  vl_quickshift_process(q);

  parentsi = vl_quickshift_get_parents(q);
  /* Copy results */
  for(i = 0; i < N1*N2; i++) parents[i] = parentsi[i] + 1;
  memcpy(dists, vl_quickshift_get_dists(q), sizeof(double)*N1*N2);
  memcpy(density, vl_quickshift_get_density(q), sizeof(double)*N1*N2);

  /* Delete quick shift object */
  vl_quickshift_delete(q);
}