More NBIS cleanups

[libfprint.git] / libfprint / nbis / mindtct / ridges.c

/*******************************************************************************

License: 
This software was developed at the National Institute of Standards and 
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Disclaimer: 
This software was developed to promote biometric standards and biometric
technology testing for the Federal Government in accordance with the USA
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Specific hardware and software products identified in this software were used
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*******************************************************************************/

/***********************************************************************
      LIBRARY: LFS - NIST Latent Fingerprint System

      FILE:    RIDGES.C
      AUTHOR:  Michael D. Garris
      DATE:    08/09/1999
      UPDATED: 03/16/2005 by MDG

      Contains routines responsible for locating nearest minutia
      neighbors and counting intervening ridges as part of the
      NIST Latent Fingerprint System (LFS).

***********************************************************************
               ROUTINES:
                        count_minutiae_ridges()
                        count_minutia_ridges()
                        find_neighbors()
                        update_nbr_dists()
                        insert_neighbor()
                        sort_neighbors()
                        ridge_count()
                        find_transition()
                        validate_ridge_crossing()
***********************************************************************/

#include <stdio.h>
#include <lfs.h>
#include <log.h>

/*************************************************************************
**************************************************************************
#cat: insert_neighbor - Takes a minutia index and its squared distance to a
#cat:               primary minutia point, and inserts them in the specified
#cat:               position of their respective lists, shifting previously
#cat:               stored values down and off the lists as necessary.

   Input:
      pos       - postions where values are to be inserted in lists
      nbr_index - index of minutia being inserted
      nbr_dist2 - squared distance of minutia to its primary point
      nbr_list  - current list of nearest neighbor minutia indices
      nbr_sqr_dists - corresponding squared euclidean distance of each
                  neighbor to the primary minutia point
      nnbrs     - number of neighbors currently in the list
      max_nbrs  - maximum number of closest neighbors to be returned
   Output:
      nbr_list - updated list of nearest neighbor indices
      nbr_sqr_dists - updated list of nearest neighbor distances
      nnbrs    - number of neighbors in the update lists
   Return Code:
      Zero      - successful completion
      Negative  - system error
**************************************************************************/
static int insert_neighbor(const int pos, const int nbr_index, const double nbr_dist2,
                    int *nbr_list, double *nbr_sqr_dists,
                    int *nnbrs, const int max_nbrs)
{
   int i;

   /* If the desired insertion position is beyond one passed the last     */
   /* neighbor in the lists OR greater than equal to the maximum ...      */
   /* NOTE: pos is zero-oriented while nnbrs and max_nbrs are 1-oriented. */
   if((pos > *nnbrs) ||
      (pos >= max_nbrs)){
      fprintf(stderr,
              "ERROR : insert_neighbor : insertion point exceeds lists\n");
      return(-480);
   }

   /* If the neighbor lists are NOT full ... */
   if(*nnbrs < max_nbrs){
      /* Then we have room to shift everything down to make room for new */
      /* neighbor and increase the number of neighbors stored by 1.      */
      i = *nnbrs-1;
      (*nnbrs)++;
   }
   /* Otherwise, the neighbors lists are full ... */
   else if(*nnbrs == max_nbrs)
      /* So, we must bump the last neighbor in the lists off to make */
      /* room for the new neighbor (ignore last neighbor in lists).  */
      i = *nnbrs-2;
   /* Otherwise, there is a list overflow error condition */
   /* (shouldn't ever happen, but just in case) ...       */
   else{
      fprintf(stderr,
              "ERROR : insert_neighbor : overflow in neighbor lists\n");
      return(-481);
   }

   /* While we havn't reached the desired insertion point ... */
   while(i >= pos){
      /* Shift the current neighbor down the list 1 positon. */
      nbr_list[i+1] = nbr_list[i];
      nbr_sqr_dists[i+1] = nbr_sqr_dists[i];
      i--;
   }

   /* We are now ready to put our new neighbor in the position where */
   /* we shifted everything down from to make room.                  */
   nbr_list[pos] = nbr_index;
   nbr_sqr_dists[pos] = nbr_dist2;

   /* Return normally. */
   return(0);
}

/*************************************************************************
**************************************************************************
#cat: update_nbr_dists - Takes the current list of neighbors along with a
#cat:               primary minutia and a potential new neighbor, and
#cat:               determines if the new neighbor is sufficiently close
#cat:               to be added to the list of nearest neighbors.  If added,
#cat:               it is placed in the list in its proper order based on
#cat:               squared distance to the primary point.

   Input:
      nbr_list - current list of nearest neighbor minutia indices
      nbr_sqr_dists - corresponding squared euclidean distance of each
                 neighbor to the primary minutia point
      nnbrs    - number of neighbors currently in the list
      max_nbrs - maximum number of closest neighbors to be returned
      first    - index of the primary minutia point
      second   - index of the secondary (new neighbor) point
      minutiae - list of minutiae
   Output:
      nbr_list - updated list of nearest neighbor indices
      nbr_sqr_dists - updated list of nearest neighbor distances
      nnbrs    - number of neighbors in the update lists
   Return Code:
      Zero      - successful completion
      Negative  - system error
**************************************************************************/
static int update_nbr_dists(int *nbr_list, double *nbr_sqr_dists,
                      int *nnbrs, const int max_nbrs,
                      const int first, const int second, MINUTIAE *minutiae)
{
   double dist2;
   MINUTIA *minutia1, *minutia2;
   int pos, last_nbr;

   /* Compute position of maximum last neighbor stored. */
   last_nbr = max_nbrs - 1;

   /* Assigne temporary minutia pointers. */
   minutia1 = minutiae->list[first];
   minutia2 = minutiae->list[second];

   /* Compute squared euclidean distance between minutia pair. */
   dist2 = squared_distance(minutia1->x, minutia1->y,
                            minutia2->x, minutia2->y);

   /* If maximum number of neighbors not yet stored in lists OR */
   /* if the squared distance to current secondary is less      */
   /* than the largest stored neighbor distance ...             */
   if((*nnbrs < max_nbrs) ||
      (dist2 < nbr_sqr_dists[last_nbr])){

      /* Find insertion point in neighbor lists. */
      pos = find_incr_position_dbl(dist2, nbr_sqr_dists, *nnbrs);
      /* If the position returned is >= maximum list length (this should */
      /* never happen, but just in case) ...                             */
      if(pos >= max_nbrs){
         fprintf(stderr, 
         "ERROR : update_nbr_dists : illegal position for new neighbor\n");
         return(-470);
      }
      /* Insert the new neighbor into the neighbor lists at the */
      /* specified location.                                    */
      if(insert_neighbor(pos, second, dist2,
                         nbr_list, nbr_sqr_dists, nnbrs, max_nbrs))
         return(-471);

      /* Otherwise, neighbor inserted successfully, so return normally. */
      return(0);
   }
   /* Otherwise, the new neighbor is not sufficiently close to be       */
   /* added or inserted into the neighbor lists, so ignore the neighbor */
   /* and return normally.                                              */
   else
      return(0);

}

/*************************************************************************
**************************************************************************
#cat: find_neighbors - Takes a primary minutia and a list of all minutiae
#cat:               and locates a specified maximum number of closest neighbors
#cat:               to the primary point.  Neighbors are searched, starting
#cat:               in the same pixel column, below, the primary point and then
#cat:               along consecutive and complete pixel columns in the image
#cat:               to the right of the primary point.

   Input:
      max_nbrs - maximum number of closest neighbors to be returned
      first    - index of the primary minutia point
      minutiae - list of minutiae
   Output:
      onbr_list - points to list of detected closest neighbors
      onnbrs    - points to number of neighbors returned
   Return Code:
      Zero      - successful completion
      Negative  - system error
**************************************************************************/
static int find_neighbors(int **onbr_list, int *onnbrs, const int max_nbrs,
                   const int first, MINUTIAE *minutiae)
{
   int ret, second, last_nbr;
   MINUTIA *minutia1, *minutia2;
   int *nbr_list, nnbrs;
   double *nbr_sqr_dists, xdist, xdist2;

   /* Allocate list of neighbor minutiae indices. */
   nbr_list = (int *)malloc(max_nbrs * sizeof(int));
   if(nbr_list == (int *)NULL){
      fprintf(stderr, "ERROR : find_neighbors : malloc : nbr_list\n");
      return(-460);
   }

   /* Allocate list of squared euclidean distances between neighbors */
   /* and current primary minutia point.                             */
   nbr_sqr_dists = (double *)malloc(max_nbrs * sizeof(double));
   if(nbr_sqr_dists == (double *)NULL){
      free(nbr_list);
      fprintf(stderr,
              "ERROR : find_neighbors : malloc : nbr_sqr_dists\n");
      return(-461);
   }

   /* Initialize number of stored neighbors to 0. */
   nnbrs = 0;
   /* Assign secondary to one passed current primary minutia. */
   second = first + 1;
   /* Compute location of maximum last stored neighbor. */
   last_nbr = max_nbrs - 1;

   /* While minutia (in sorted order) still remian for processing ... */
   /* NOTE: The minutia in the input list have been sorted on X and   */
   /* then on Y.  So, the neighbors are selected according to those   */
   /* that lie below the primary minutia in the same pixel column and */
   /* then subsequently those that lie in complete pixel columns to   */
   /* the right of the primary minutia.                               */
   while(second < minutiae->num){
      /* Assign temporary minutia pointers. */
      minutia1 = minutiae->list[first];
      minutia2 = minutiae->list[second];

      /* Compute squared distance between minutiae along x-axis. */
      xdist = minutia2->x - minutia1->x;
      xdist2 = xdist * xdist;

      /* If the neighbor lists are not full OR the x-distance to current */
      /* secondary is smaller than maximum neighbor distance stored ...  */
      if((nnbrs < max_nbrs) ||
         (xdist2 < nbr_sqr_dists[last_nbr])){
         /* Append or insert the new neighbor into the neighbor lists. */
         if((ret = update_nbr_dists(nbr_list, nbr_sqr_dists, &nnbrs, max_nbrs,
                          first, second, minutiae))){
            free(nbr_sqr_dists);
            return(ret);
         }
      }
      /* Otherwise, if the neighbor lists is full AND the x-distance   */
      /* to current secondary is larger than maximum neighbor distance */
      /* stored ...                                                    */
      else
         /* So, stop searching for more neighbors. */
         break;

       /* Bump to next secondary minutia. */
       second++;
   }

   /* Deallocate working memory. */
   free(nbr_sqr_dists);

   /* If no neighbors found ... */
   if(nnbrs == 0){
      /* Deallocate the neighbor list. */
      free(nbr_list);
      *onnbrs = 0;
   }
   /* Otherwise, assign neighbors to output pointer. */
   else{
      *onbr_list = nbr_list;
      *onnbrs = nnbrs;
   }

   /* Return normally. */
   return(0);
}

/*************************************************************************
**************************************************************************
#cat: sort_neighbors - Takes a list of primary minutia and its neighboring
#cat:               minutia indices and sorts the neighbors based on their
#cat:               position relative to the primary minutia point.  Neighbors
#cat:               are sorted starting vertical to the primary point and
#cat:               proceeding clockwise.

   Input:
      nbr_list - list of neighboring minutia indices
      nnbrs    - number of neighbors in the list
      first    - the index of the primary minutia point
      minutiae - list of minutiae
   Output:
      nbr_list - neighboring minutia indices in sorted order
   Return Code:
      Zero     - successful completion
      Negative - system error
**************************************************************************/
static int sort_neighbors(int *nbr_list, const int nnbrs, const int first,
                   MINUTIAE *minutiae)
{
   double *join_thetas, theta;
   int i;
   static double pi2 = M_PI*2.0;

   /* List of angles of lines joining the current primary to each */
   /* of the secondary neighbors.                                 */
   join_thetas = (double *)malloc(nnbrs * sizeof(double));
   if(join_thetas == (double *)NULL){
      fprintf(stderr, "ERROR : sort_neighbors : malloc : join_thetas\n");
      return(-490);
   }

   for(i = 0; i < nnbrs; i++){
      /* Compute angle to line connecting the 2 points.             */
      /* Coordinates are swapped and order of points reversed to    */
      /* account for 0 direction is vertical and positive direction */
      /* is clockwise.                                              */
      theta = angle2line(minutiae->list[nbr_list[i]]->y,
                         minutiae->list[nbr_list[i]]->x,
                         minutiae->list[first]->y,
                         minutiae->list[first]->x);

      /* Make sure the angle is positive. */
      theta += pi2;
      theta = fmod(theta, pi2);
      join_thetas[i] = theta;
   }

   /* Sort the neighbor indicies into rank order. */
   bubble_sort_double_inc_2(join_thetas, nbr_list, nnbrs);

   /* Deallocate the list of angles. */
   free(join_thetas);

   /* Return normally. */
   return(0);      
}

/*************************************************************************
**************************************************************************
#cat: find_transition - Takes a pixel trajectory and a starting index, and
#cat:               searches forward along the trajectory until the specified
#cat:               adjacent pixel pair is found, returning the index where
#cat:               the pair was found (the index of the second pixel).

   Input:
      iptr  - pointer to starting pixel index into trajectory
      pix1  - first pixel value in transition pair
      pix2  - second pixel value in transition pair
      xlist - x-pixel coords of line trajectory
      ylist - y-pixel coords of line trajectory
      num   - number of coords in line trajectory
      bdata - binary image data (0==while & 1==black)
      iw    - width (in pixels) of image
      ih    - height (in pixels) of image
   Output:
      iptr  - points to location where 2nd pixel in pair is found
   Return Code:
      TRUE  - pixel pair transition found
      FALSE - pixel pair transition not found
**************************************************************************/
static int find_transition(int *iptr, const int pix1, const int pix2,
                    const int *xlist, const int *ylist, const int num,
                    unsigned char *bdata, const int iw, const int ih)
{
   int i, j;

   /* Set previous index to starting position. */
   i = *iptr;
   /* Bump previous index by 1 to get next index. */
   j = i+1;

   /* While not one point from the end of the trajectory .. */
   while(i < num-1){
      /* If we have found the desired transition ... */
      if((*(bdata+(ylist[i]*iw)+xlist[i]) == pix1) &&
         (*(bdata+(ylist[j]*iw)+xlist[j]) == pix2)){
         /* Adjust the position pointer to the location of the */
         /* second pixel in the transition.                    */
         *iptr = j;

         /* Return TRUE. */
         return(TRUE);
      }
      /* Otherwise, the desired transition was not found in current */
      /* pixel pair, so bump to the next pair along the trajector.  */
      i++;
      j++;
   }

   /* If we get here, then we exhausted the trajector without finding */
   /* the desired transition, so set the position pointer to the end  */
   /* of the trajector, and return FALSE.                             */
   *iptr = num;
   return(FALSE);
}

/*************************************************************************
**************************************************************************
#cat: validate_ridge_crossing - Takes a pair of points, a ridge start
#cat:               transition and a ridge end transition, and walks the
#cat:               ridge contour from thre ridge end points a specified
#cat:               number of steps, looking for the ridge start point.
#cat:               If found, then transitions determined not to be a valid
#cat:               ridge crossing.

   Input:
      ridge_start - index into line trajectory of ridge start transition
      ridge_end   - index into line trajectory of ridge end transition
      xlist       - x-pixel coords of line trajectory
      ylist       - y-pixel coords of line trajectory
      num         - number of coords in line trajectory
      bdata       - binary image data (0==while & 1==black)
      iw          - width (in pixels) of image
      ih          - height (in pixels) of image
      max_ridge_steps  - number of steps taken in search in both
                         scan directions
   Return Code:
      TRUE        - ridge crossing VALID
      FALSE       - ridge corssing INVALID
      Negative    - system error
**************************************************************************/
static int validate_ridge_crossing(const int ridge_start, const int ridge_end,
                            const int *xlist, const int *ylist, const int num,
                            unsigned char *bdata, const int iw, const int ih,
                            const int max_ridge_steps)
{
   int ret;
   int feat_x, feat_y, edge_x, edge_y;
   int *contour_x, *contour_y, *contour_ex, *contour_ey, ncontour;

   /* Assign edge pixel pair for contour trace. */
   feat_x = xlist[ridge_end];
   feat_y = ylist[ridge_end];
   edge_x = xlist[ridge_end-1];
   edge_y = ylist[ridge_end-1];

   /* Adjust pixel pair if they neighbor each other diagonally. */
   fix_edge_pixel_pair(&feat_x, &feat_y, &edge_x, &edge_y,
                       bdata, iw, ih);

   /* Trace ridge contour, starting at the ridge end transition, and */
   /* taking a specified number of step scanning for edge neighbors  */
   /* clockwise.  As we trace the ridge, we want to detect if we     */
   /* encounter the ridge start transition.  NOTE: The ridge end     */
   /* position is on the white (of a black to white transition) and  */
   /* the ridge start is on the black (of a black to white trans),   */
   /* so the edge trace needs to look for the what pixel (not the    */
   /* black one) of the ridge start transition.                      */ 
   ret = trace_contour(&contour_x, &contour_y,
                       &contour_ex, &contour_ey, &ncontour,
                       max_ridge_steps,
                       xlist[ridge_start-1], ylist[ridge_start-1],
                       feat_x, feat_y, edge_x, edge_y,
                       SCAN_CLOCKWISE, bdata, iw, ih);
   /* If a system error occurred ... */
   if(ret < 0)
      /* Return error code. */
      return(ret);

   /* Otherwise, if the trace was not IGNORED, then a contour was */
   /* was generated and returned.  We aren't interested in the    */
   /* actual contour, so deallocate it.                           */
   if(ret != IGNORE)
      free_contour(contour_x, contour_y, contour_ex, contour_ey);

   /* If the trace was IGNORED, then we had some sort of initialization */
   /* problem, so treat this the same as if was actually located the    */
   /* ridge start point (in which case LOOP_FOUND is returned).         */
   /* So, If not IGNORED and ridge start not encounted in trace ...     */
   if((ret != IGNORE) &&
      (ret != LOOP_FOUND)){

      /* Now conduct contour trace scanning for edge neighbors counter- */
      /* clockwise.                                                     */
      ret = trace_contour(&contour_x, &contour_y,
                          &contour_ex, &contour_ey, &ncontour,
                          max_ridge_steps,
                          xlist[ridge_start-1], ylist[ridge_start-1],
                          feat_x, feat_y, edge_x, edge_y,
                          SCAN_COUNTER_CLOCKWISE, bdata, iw, ih);
      /* If a system error occurred ... */
      if(ret < 0)
         /* Return error code. */
         return(ret);

      /* Otherwise, if the trace was not IGNORED, then a contour was */
      /* was generated and returned.  We aren't interested in the    */
      /* actual contour, so deallocate it.                           */
      if(ret != IGNORE)
         free_contour(contour_x, contour_y, contour_ex, contour_ey);

      /* If trace not IGNORED and ridge start not encounted in 2nd trace ... */
      if((ret != IGNORE) &&
         (ret != LOOP_FOUND)){
         /* If we get here, assume we have a ridge crossing. */
         return(TRUE);
      }
      /* Otherwise, second trace returned IGNORE or ridge start found. */
   }
   /* Otherwise, first trace returned IGNORE or ridge start found. */
   
   /* If we get here, then we failed to validate a ridge crossing. */
   return(FALSE);
}

/*************************************************************************
**************************************************************************
#cat: ridge_count - Takes a pair of minutiae, and counts the number of
#cat:               ridges crossed along the linear trajectory connecting
#cat:               the 2 points in the image.

   Input:
      first     - index of primary minutia
      second    - index of secondary (neighbor) minutia
      minutiae  - list of minutiae
      bdata     - binary image data (0==while & 1==black)
      iw        - width (in pixels) of image
      ih        - height (in pixels) of image
      lfsparms  - parameters and thresholds for controlling LFS
   Return Code:
      Zero or Positive - number of ridges counted
      Negative         - system error
**************************************************************************/
static int ridge_count(const int first, const int second, MINUTIAE *minutiae,
                unsigned char *bdata, const int iw, const int ih,
                const LFSPARMS *lfsparms)
{
   MINUTIA *minutia1, *minutia2;
   int i, ret, found;
   int *xlist, *ylist, num;
   int ridge_count, ridge_start, ridge_end;
   int prevpix, curpix;

   minutia1 = minutiae->list[first];
   minutia2 = minutiae->list[second];

   /* If the 2 mintuia have identical pixel coords ... */
   if((minutia1->x == minutia2->x) &&
      (minutia1->y == minutia2->y))
      /* Then zero ridges between points. */
     return(0);

   /* Compute linear trajectory of contiguous pixels between first */
   /* and second minutia points.                                   */
   if((ret = line_points(&xlist, &ylist, &num,
                        minutia1->x, minutia1->y, minutia2->x, minutia2->y))){
      return(ret);
   }

   /* It there are no points on the line trajectory, then no ridges */
   /* to count (this should not happen, but just in case) ...       */
   if(num == 0){
      free(xlist);
      free(ylist);
      return(0);
   }

   /* Find first pixel opposite type along linear trajectory from */
   /* first minutia.                                              */
   prevpix = *(bdata+(ylist[0]*iw)+xlist[0]);
   i = 1;
   found = FALSE;
   while(i < num){
      curpix = *(bdata+(ylist[i]*iw)+xlist[i]);
      if(curpix != prevpix){
         found = TRUE;
         break;
      }
      i++;
   }

   /* If opposite pixel not found ... then no ridges to count */
   if(!found){
      free(xlist);
      free(ylist);
      return(0);
   }

   /* Ready to count ridges, so initialize counter to 0. */
   ridge_count = 0;

   print2log("RIDGE COUNT: %d,%d to %d,%d ", minutia1->x, minutia1->y,
                                               minutia2->x, minutia2->y);

   /* While not at the end of the trajectory ... */
   while(i < num){
      /* If 0-to-1 transition not found ... */
      if(!find_transition(&i, 0, 1, xlist, ylist, num, bdata, iw, ih)){
         /* Then we are done looking for ridges. */
         free(xlist);
         free(ylist);

         print2log("\n");

         /* Return number of ridges counted to this point. */
         return(ridge_count);
      }
      /* Otherwise, we found a new ridge start transition, so store */
      /* its location (the location of the 1 in 0-to-1 transition). */
      ridge_start = i;

      print2log(": RS %d,%d ", xlist[i], ylist[i]);

      /* If 1-to-0 transition not found ... */
      if(!find_transition(&i, 1, 0, xlist, ylist, num, bdata, iw, ih)){
         /* Then we are done looking for ridges. */
         free(xlist);
         free(ylist);

         print2log("\n");

         /* Return number of ridges counted to this point. */
         return(ridge_count);
      }
      /* Otherwise, we found a new ridge end transition, so store   */
      /* its location (the location of the 0 in 1-to-0 transition). */
      ridge_end = i;

      print2log("; RE %d,%d ", xlist[i], ylist[i]);

      /* Conduct the validation, tracing the contour of the ridge  */
      /* from the ridge ending point a specified number of steps   */
      /* scanning for neighbors clockwise and counter-clockwise.   */
      /* If the ridge starting point is encounted during the trace */
      /* then we can assume we do not have a valid ridge crossing  */
      /* and instead we are walking on and off the edge of the     */
      /* side of a ridge.                                          */
      ret = validate_ridge_crossing(ridge_start, ridge_end,
                                    xlist, ylist, num, bdata, iw, ih,
                                    lfsparms->max_ridge_steps);

      /* If system error ... */
      if(ret < 0){
         free(xlist);
         free(ylist);
         /* Return the error code. */
         return(ret);
      }

      print2log("; V%d ", ret);

      /* If validation result is TRUE ... */
      if(ret){
         /* Then assume we have found a valid ridge crossing and bump */
         /* the ridge counter.                                        */
         ridge_count++;
      }

      /* Otherwise, ignore the current ridge start and end transitions */
      /* and go back and search for new ridge start.                   */
   }

   /* Deallocate working memories. */
   free(xlist);
   free(ylist);

   print2log("\n");

   /* Return the number of ridges counted. */
   return(ridge_count);
}

/*************************************************************************
**************************************************************************
#cat: count_minutia_ridges - Takes a minutia, and determines its closest
#cat:                neighbors and counts the number of interveining ridges
#cat:                between the minutia point and each of its neighbors.

   Input:
      minutia   - input minutia
      bdata     - binary image data (0==while & 1==black)
      iw        - width (in pixels) of image
      ih        - height (in pixels) of image
      lfsparms  - parameters and thresholds for controlling LFS
   Output:
      minutiae  - minutia augmented with neighbors and ridge counts
   Return Code:
      Zero     - successful completion
      Negative - system error
**************************************************************************/
static int count_minutia_ridges(const int first, MINUTIAE *minutiae,
                      unsigned char *bdata, const int iw, const int ih,
                      const LFSPARMS *lfsparms)
{
   int i, ret, *nbr_list, *nbr_nridges, nnbrs;

   /* Find up to the maximum number of qualifying neighbors. */
   if((ret = find_neighbors(&nbr_list, &nnbrs, lfsparms->max_nbrs,
                           first, minutiae))){
      free(nbr_list);
      return(ret);
   }

   print2log("NBRS FOUND: %d,%d = %d\n", minutiae->list[first]->x,
              minutiae->list[first]->y, nnbrs);

   /* If no neighors found ... */
   if(nnbrs == 0){
      /* Then no list returned and no ridges to count. */
      return(0);
   }

   /* Sort neighbors on delta dirs. */
   if((ret = sort_neighbors(nbr_list, nnbrs, first, minutiae))){
      free(nbr_list);
      return(ret);
   }

   /* Count ridges between first and neighbors. */
   /* List of ridge counts, one for each neighbor stored. */
   nbr_nridges = (int *)malloc(nnbrs * sizeof(int));
   if(nbr_nridges == (int *)NULL){
      free(nbr_list);
      fprintf(stderr, "ERROR : count_minutia_ridges : malloc : nbr_nridges\n");
      return(-450);
   }

   /* Foreach neighbor found and sorted in list ... */
   for(i = 0; i < nnbrs; i++){
      /* Count the ridges between the primary minutia and the neighbor. */
      ret = ridge_count(first, nbr_list[i], minutiae, bdata, iw, ih, lfsparms);
      /* If system error ... */
      if(ret < 0){
         /* Deallocate working memories. */
         free(nbr_list);
         free(nbr_nridges);
         /* Return error code. */
         return(ret);
      }

      /* Otherwise, ridge count successful, so store ridge count to list. */
      nbr_nridges[i] = ret;
   }

   /* Assign neighbor indices and ridge counts to primary minutia. */
   minutiae->list[first]->nbrs = nbr_list;
   minutiae->list[first]->ridge_counts = nbr_nridges;
   minutiae->list[first]->num_nbrs = nnbrs;

   /* Return normally. */
   return(0);
}

/*************************************************************************
**************************************************************************
#cat: count_minutiae_ridges - Takes a list of minutiae, and for each one,
#cat:                determines its closest neighbors and counts the number
#cat:                of interveining ridges between the minutia point and
#cat:                each of its neighbors.

   Input:
      minutiae  - list of minutiae
      bdata     - binary image data (0==while & 1==black)
      iw        - width (in pixels) of image
      ih        - height (in pixels) of image
      lfsparms  - parameters and thresholds for controlling LFS
   Output:
      minutiae  - list of minutiae augmented with neighbors and ridge counts
   Return Code:
      Zero     - successful completion
      Negative - system error
**************************************************************************/
int count_minutiae_ridges(MINUTIAE *minutiae,
                      unsigned char *bdata, const int iw, const int ih,
                      const LFSPARMS *lfsparms)
{
   int ret;
   int i;

   print2log("\nFINDING NBRS AND COUNTING RIDGES:\n");

   /* Sort minutia points on x then y (column-oriented). */
   if((ret = sort_minutiae_x_y(minutiae, iw, ih))){
      return(ret);
   }

   /* Remove any duplicate minutia points from the list. */
   if((ret = rm_dup_minutiae(minutiae))){
      return(ret);
   }

   /* Foreach remaining sorted minutia in list ... */
   for(i = 0; i < minutiae->num-1; i++){
      /* Located neighbors and count number of ridges in between. */
      /* NOTE: neighbor and ridge count results are stored in     */
      /*       minutiae->list[i].                                 */
      if((ret = count_minutia_ridges(i, minutiae, bdata, iw, ih, lfsparms))){
         return(ret);
      }
   }

   /* Return normally. */
   return(0);
}