source: tags/release-1.1/src/Detection/lutz_detect.cc @ 1391

// -----------------------------------------------------------------------
// lutz_detect.cc: Search a 2D Image for objects.
// -----------------------------------------------------------------------
// Copyright (C) 2006, Matthew Whiting, ATNF
//
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2 of the License, or (at your
// option) any later version.
//
// Duchamp is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License
// along with Duchamp; if not, write to the Free Software Foundation,
// Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
//
// Correspondence concerning Duchamp may be directed to:
//    Internet email: Matthew.Whiting [at] atnf.csiro.au
//    Postal address: Dr. Matthew Whiting
//                    Australia Telescope National Facility, CSIRO
//                    PO Box 76
//                    Epping NSW 1710
//                    AUSTRALIA
// -----------------------------------------------------------------------
#include <Cubes/cubes.hh>
#include <PixelMap/Voxel.hh>
#include <PixelMap/Object2D.hh>
#include <vector>

using namespace PixelInfo;

/** Enumeration to describe status of a pixel or a detected object */
enum STATUS { NONOBJECT, ///< Pixel not above the threshold.
              OBJECT,    ///< Pixel above the threshold.
              COMPLETE,  ///< Object is complete
              INCOMPLETE ///< Object not yet complete
};

/** Simple enumeration to enable obvious reference to current or prior
    row. */
enum ROW { PRIOR=0, CURRENT};

/** A couple of null values: the default starting value for markers,
    and one used for debugging. */
enum NULLS { NULLSTART=-1, ///< Default start/end value, obviously
                           ///   outside valid range.
             NULLMARKER=45 ///< ASCII 45 = '-', which eases printing
                           ///   for debugging purposes
}; 

//---------------------------
/**
 * A simple class local to lutz_detect.cc to help manage detected
 * objects.
 *
 * Keeps a track of a detection, as well as the start and finish
 * locations of the detection on the current row.
 */
class FoundObject{
public:
  /** Basic constructor, setting the start & end to NULL values. */
  FoundObject(){start=NULLSTART; end=NULLSTART;};
  int start; ///< Pixel on the current row where the detection starts.
  int end;   ///< Pixel on the current row where the detection finishes.
  Object2D info; ///< Collection of detected pixels.
};
//---------------------------

std::vector<Object2D> Image::lutz_detect() 
{
/**
 *  A detection algorithm for 2-dimensional images based on that of
 *  Lutz (1980).
 *  
 *  The image is raster-scanned, and searched row-by-row. Objects
 *  detected in each row are compared to objects in subsequent rows,
 *  and combined if they are connected (in an 8-fold sense).
 * 
 *  Note that "detected" here means according to the
 *  Image::isDetection(long,long) function.
 *
 *  Upon return, the detected objects are stored in the
 *  Image::objectList vector.
 *
 */

  // Allocate necessary arrays.
  std::vector<Object2D> outputlist;
  STATUS *status  = new STATUS[2];
  Object2D *store = new Object2D[this->axisDim[0]+1];
  char *marker    = new char[this->axisDim[0]+1];
  for(int i=0; i<(this->axisDim[0]+1); i++) marker[i] = NULLMARKER;
  std::vector<FoundObject> oS;
  std::vector<STATUS>      psS;

  Pixel pix;

  for(int posY=0;posY<(this->axisDim[1]+1);posY++){
    // Loop over each row -- consider rows one at a time
    
    status[PRIOR] = COMPLETE;
    status[CURRENT] = NONOBJECT;

    for(int posX=0;posX<(this->axisDim[0]+1);posX++){
      // Now the loop for a given row, looking at each column individually.

      char currentMarker = marker[posX];
      marker[posX] = NULLMARKER;

      bool isObject;
      if((posX<this->axisDim[0])&&(posY<this->axisDim[1])){ 
        // if we are in the original image
        isObject = this->isDetection(posX,posY);
      }
      else isObject = false;
      // else we're in the padding row/col and isObject=FALSE;

      // 
      // ------------------------------ START SEGMENT ------------------------
      // If the current pixel is object and the previous pixel is not, then
      // start a new segment.
      // If the pixel touches an object on the prior row, the marker is either
      // an S or an s, depending on whether the object has started yet.
      // If it doesn't touch a prior object, this is the start of a completly
      // new object on this row.
      // 
      if ( (isObject) && (status[CURRENT] != OBJECT) ){

        status[CURRENT] = OBJECT;
        if(status[PRIOR] == OBJECT){
          
          if(oS.back().start==NULLSTART){
            marker[posX] = 'S';
            oS.back().start = posX;
          }
          else  marker[posX] = 's';
        }
        else{
          psS.push_back(status[PRIOR]);  //PUSH PS onto PSSTACK;
          marker[posX] = 'S';
          oS.resize(oS.size()+1);        //PUSH OBSTACK;
          oS.back().start = posX;

          status[PRIOR] = COMPLETE;
        }
      }

      // 
      // ------------------------------ PROCESS MARKER -----------------------
      // If the current marker is not blank, then we need to deal with it. 
      // Four cases:
      //   S --> start of object on prior row. Push priorStatus onto PSSTACK 
      //         and set priorStatus to OBJECT
      //   s --> start of a secondary segment of object on prior row.
      //         If current object joined, pop PSSTACK and join the objects.
      //         Set priorStatus to OBJECT.
      //   f --> end of a secondary segment of object on prior row.
      //         Set priorStatus to INCOMPLETE.
      //   F --> end of object on prior row. If no more of the object is to 
      //          come (priorStatus=COMPLETE), then finish it and output data.
      //         Add to list, but only if it has more than the minimum number
      //           of pixels.
      // 
      if(currentMarker != NULLMARKER){

        if(currentMarker == 'S'){
          psS.push_back(status[PRIOR]);      // PUSH PS onto PSSTACK
          if(status[CURRENT] == NONOBJECT){
            psS.push_back(COMPLETE);         // PUSH COMPLETE ONTO PSSTACK;
            oS.resize(oS.size()+1);          // PUSH OBSTACK;
            oS.back().info = store[posX];
          }
          else oS.back().info = oS.back().info + store[posX];
          
          status[PRIOR] = OBJECT;
        }

        /*---------*/
        if(currentMarker == 's'){

          if( (status[CURRENT] == OBJECT) && (status[PRIOR] == COMPLETE) ){
            status[PRIOR] = psS.back();
            psS.pop_back();                   //POP PSSTACK ONTO PS

//          oS.at(oS.size()-2).info.addAnObject( oS.back().info );
//          if(oS.at(oS.size()-2).start == NULLSTART) 
//            oS.at(oS.size()-2).start = oS.back().start;
//          else marker[oS.back().start] = 's';

            oS[oS.size()-2].info = oS[oS.size()-2].info + oS.back().info;
            if(oS[oS.size()-2].start == NULLSTART) 
              oS[oS.size()-2].start = oS.back().start;
            else marker[oS.back().start] = 's';

            oS.pop_back();
          }

          status[PRIOR] = OBJECT;
        }

        /*---------*/
        if(currentMarker == 'f') status[PRIOR] = INCOMPLETE;

        /*---------*/
        if(currentMarker == 'F') {

          status[PRIOR] = psS.back();
          psS.pop_back();                    //POP PSSTACK ONTO PS

          if( (status[CURRENT] == NONOBJECT) && (status[PRIOR] == COMPLETE) ){

            if(oS.back().start == NULLSTART){ 
              // The object is completed. If it is big enough, add to
              // the end of the output list.          
              if(oS.back().info.getSize() >= this->minSize){ 
        //oS.back().info.calcParams(); // work out midpoints, fluxes etc
                outputlist.push_back(oS.back().info);
              }
            }
            else{
              marker[ oS.back().end ] = 'F';
              store[ oS.back().start ] = oS.back().info;
            }

            oS.pop_back();

            status[PRIOR] = psS.back();
            psS.pop_back();
          }
        }

      } // end of PROCESSMARKER section ( if(currentMarker!=NULLMARKER) )

      if (isObject){
        oS.back().info.addPixel(posX,posY);
      }
      else{
        // 
        // ----------------------------- END SEGMENT -------------------------
        // If the current pixel is background and the previous pixel was an 
        // object, then finish the segment.
        // If the prior status is COMPLETE, it's the end of the final segment 
        // of the object section.
        // If not, it's end of the segment, but not necessarily the section.
        // 
        if ( status[CURRENT] == OBJECT) {

          status[CURRENT] = NONOBJECT;

          if(status[PRIOR] != COMPLETE){
            marker[posX] = 'f';
            oS.back().end = posX;
          }
          else{
            status[PRIOR] = psS.back();
            psS.pop_back();                   //POP PSSTACK onto PS;
            marker[posX] = 'F';
            store[ oS.back().start ] = oS.back().info;
            oS.pop_back();
          }
        }
        
      } //-> end of END SEGMENT else{ clause

    }//-> end of loop over posX

  }//-> end of loop over posY

  // clean up and remove declared arrays
  delete [] marker;
  delete [] store;
  delete [] status;

  return outputlist;

}