extract.c

/*
*				extract.c
*
* Extract connected pixels from an image raster.
*
*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*
*	This file part of:	SExtractor
*
*	Copyright:		(C) 1993-2020 IAP/CNRS/SorbonneU
*
*	License:		GNU General Public License
*
*	SExtractor 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 3 of the License, or
*	(at your option) any later version.
*	SExtractor 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 SExtractor. If not, see <http://www.gnu.org/licenses/>.
*
*	Last modified:		15/07/2020
*
*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/

#ifdef HAVE_CONFIG_H
#include        "config.h"
#endif

#include	<math.h>
#include	<stdlib.h>
#include	<string.h>

#include	"define.h"
#include	"globals.h"
#include	"prefs.h"
#include	"extract.h"
#include	"plist.h"

/*------------------------- Static buffers for lutz() -----------------------*/

static infostruct	*info, *store;
static char		*marker;
static status		*psstack;
static int		*start, *end, *discan, xmin,ymin,xmax,ymax;

PIXTYPE			*dumscan;

/******************************* lutzalloc ***********************************/
/*
Allocate once for all memory space for buffers used by lutz().
*/
void	lutzalloc(int width, int height)
  {
   int	*discant,
	stacksize, i;

  stacksize = width+1;
  xmin = ymin = 0;
  xmax = width-1;
  ymax = height-1;
  QMALLOC(info, infostruct, stacksize);
  QMALLOC(store, infostruct, stacksize);
  QMALLOC(marker, char, stacksize);
  QMALLOC(psstack, status, stacksize);
  QMALLOC(start, int, stacksize);
  QMALLOC(end, int, stacksize);
  QMALLOC(discan, int, stacksize);
  discant = discan;
  for (i=stacksize; i--;)
    *(discant++) = -1;

  return;
  }


/******************************* lutzfree ************************************/
/*
Free once for all memory space for buffers used by lutz().
*/
void	lutzfree()
  {
  free(discan);
  free(info);
  free(store);
  free(marker);
  free(psstack);
  free(start);
  free(end);

  return;
  }


/********************************** lutz *************************************/
/*
C implementation of R.K LUTZ' algorithm for the extraction of 8-connected pi-
xels in an image
*/
int	lutz(objliststruct *objlistroot, int nroot, objstruct *objparent,
	objliststruct *objlist)

  {
   static infostruct	curpixinfo,initinfo;
   objstruct		*obj, *objroot;
   pliststruct		*plist,*pixel, *plistin, *plistint;

   char			newmarker;
   int			cn, co, luflag, objnb, pstop, xl,xl2,yl,
			out, minarea, stx,sty,enx,eny, step,
			nobjm = NOBJ,
			inewsymbol, *iscan;
   short		trunflag;
   PIXTYPE		thresh;
   status		cs, ps;

  out = RETURN_OK;

  minarea = prefs.deb_maxarea;
  plistint = plistin = objlistroot->plist;
  objroot = &objlistroot->obj[nroot];
  stx = objparent->xmin;
  sty = objparent->ymin;
  enx = objparent->xmax;
  eny = objparent->ymax;
  thresh = objlist->dthresh;
  initinfo.pixnb = 0;
  initinfo.flag = 0;
  initinfo.firstpix = initinfo.lastpix = -1;
  cn = 0;
  iscan = objroot->submap + (sty-objroot->suby)*objroot->subw
	+ (stx-objroot->subx);
/* As we only analyse a fraction of the map, a step occurs between lines */
  step = objroot->subw - (++enx-stx);
  eny++;

/*------Allocate memory to store object data */

  free(objlist->obj);
  if (!(obj=objlist->obj=(objstruct *)malloc(nobjm*sizeof(objstruct))))
    {
    out = RETURN_FATAL_ERROR;
    plist = NULL;			/* To avoid gcc -Wall warnings */
    goto exit_lutz;
    }

/*------Allocate memory for the pixel list */

  free(objlist->plist);
  if (!(objlist->plist
	= (pliststruct *)malloc((eny-sty)*(enx-stx)*plistsize)))
    {
    out = RETURN_FATAL_ERROR;
    plist = NULL;			/* To avoid gcc -Wall warnings */
    goto exit_lutz;
    }

  pixel = plist = objlist->plist;

/*----------------------------------------*/

  for (xl=stx; xl<=enx; xl++)
    marker[xl] = 0 ;

  objnb = objlist->nobj = 0;
  co = pstop = 0;
  curpixinfo.pixnb = 1;

  for (yl=sty; yl<=eny; yl++, iscan += step)
    {
    ps = COMPLETE;
    cs = NONOBJECT;
    trunflag =  (yl==0 || yl==ymax) ? OBJ_TRUNC : 0;
    if (yl==eny)
      iscan = discan;

    for (xl=stx; xl<=enx; xl++)
      {
      newmarker = marker[xl];
      marker[xl] = 0;
      if ((inewsymbol = (xl!=enx)?*(iscan++):-1) < 0)
        luflag = 0;
      else
        {
        curpixinfo.flag = trunflag;
        plistint = plistin+inewsymbol;
        luflag = (PLISTPIX(plistint, cdvalue) > thresh?1:0);
        }
      if (luflag)
        {
        if (xl==0 || xl==xmax)
          curpixinfo.flag |= OBJ_TRUNC;
        memcpy(pixel, plistint, (size_t)plistsize);
        PLIST(pixel, nextpix) = -1;
        curpixinfo.lastpix = curpixinfo.firstpix = cn;
        cn += plistsize;
        pixel += plistsize;
        if (cs != OBJECT)
/*------------------------------- Start Segment -----------------------------*/
          {
          cs = OBJECT;
          if (ps == OBJECT)
              {
              if (start[co] == UNKNOWN)
                {
                marker[xl] = 'S';
                start[co] = xl;
                }
              else  marker[xl] = 's';
              }
          else
            {
            psstack[pstop++] = ps;
            marker[xl] = 'S';
            start[++co] = xl;
            ps = COMPLETE;
            info[co] = initinfo;
            }
          }
        }
/*---------------------------------------------------------------------------*/
      if (newmarker)
/*---------------------------- Process New Marker ---------------------------*/

        {
        if (newmarker == 'S')
          {
          psstack[pstop++] = ps;
          if (cs == NONOBJECT)
            {
            psstack[pstop++] = COMPLETE;
            info[++co] = store[xl];
            start[co] = UNKNOWN;
          }
          else
            update (&info[co],&store[xl], plist);
          ps = OBJECT;
          }
        else if (newmarker == 's')
          {
          if ((cs == OBJECT) && (ps == COMPLETE))
            {
            pstop--;
            xl2 = start[co];
            update (&info[co-1],&info[co], plist);
          if (start[--co] == UNKNOWN)
              start[co] = xl2;
            else
              marker[xl2] = 's';
            }
          ps = OBJECT;
          }
        else if (newmarker == 'f')
          ps = INCOMPLETE;
        else if (newmarker == 'F')
          {
          ps = psstack[--pstop];
          if ((cs == NONOBJECT) && (ps == COMPLETE))
            {
          if (start[co] == UNKNOWN)
              {
              if ((int)info[co].pixnb >= minarea)
                {
                if (objlist->nobj>=nobjm)
                  if (!(obj = objlist->obj = (objstruct *)
  			realloc(obj, (nobjm+=nobjm/2)* sizeof(objstruct))))
                    {
                    out = RETURN_FATAL_ERROR;
                    goto exit_lutz;
                    }
                lutzsort(&info[co], objlist);
                }
              }
            else
              {
              marker[end[co]] = 'F';
              store[start[co]] = info[co];
              }
            co--;
            ps = psstack[--pstop];
            }
          }
        }
  
/*---------------------------------------------------------------------------*/

      if (luflag)
        update (&info[co],&curpixinfo, plist);
    else
        {
        if (cs == OBJECT)
/*-------------------------------- End Segment ------------------------------*/
          {
          cs = NONOBJECT;
          if (ps != COMPLETE)
            {
            marker[xl] = 'f';
            end[co] = xl;
            }
          else
            {
            ps = psstack[--pstop];
            marker[xl] = 'F';
            store[start[co]] = info[co];
            co--;
            }
          }
        }
/*---------------------------------------------------------------------------*/
      }
    }

exit_lutz:

   if (objlist->nobj && out == RETURN_OK)
    {
    if (!(objlist->obj=(objstruct *)realloc(obj,
		objlist->nobj*sizeof(objstruct))))
      error(EXIT_FAILURE,"problem with mem. realloc. in lutz()","");
    }
  else
    {
    free(obj);
    objlist->obj = NULL;
    }

  if (cn && out == RETURN_OK)
    {
    if (!(objlist->plist=(pliststruct *)realloc(plist,cn)))
      error(EXIT_FAILURE,"problem with mem. realloc. in lutz()","");
    }
  else
    {
    free(objlist->plist);
    objlist->plist = NULL;
    }

  return  out;
  }


/********************************* lutzsort ***********************************/
/*
Build the object structure.
*/
void  lutzsort(infostruct *info, objliststruct *objlist)

  {
  objstruct  *obj = objlist->obj+objlist->nobj;

  memset(obj, 0, (size_t)sizeof(objstruct));
  obj->firstpix = info->firstpix;
  obj->lastpix = info->lastpix;
  obj->flag = info->flag;
  objlist->npix += info->pixnb;

  preanalyse(objlist->nobj, objlist, ANALYSE_FAST);

  objlist->nobj++;

  return;
  }