upekux/nbis/libmindtct/morph.c

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

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


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

      FILE:    MORPH.C
      AUTHOR:  Michael D. Garris
      DATE:    10/04/1999
      UPDATED: 10/26/1999 by MDG
               To avoid indisciminate erosion of pixels along
               the edge of the binary image.
      UPDATED: 03/16/2005 by MDG

      Contains general support image morphology routines required by
      the NIST Latent Fingerprint System (LFS).

***********************************************************************
               ROUTINES:
                        erode_charimage_2()
                        dilate_charimage_2()
                        get_south8_2()
                        get_north8_2()
                        get_east8_2()
                        get_west8_2()

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

#include "morph.h"
#include <string.h>

/*************************************************************************
**************************************************************************
#cat: erode_charimage_2 - Erodes an 8-bit image by setting true pixels to zero
#cat:             if any of their 4 neighbors is zero.  Allocation of the
#cat:             output image is the responsibility of the caller.  The
#cat:             input image remains unchanged.  This routine will NOT
#cat:             erode pixels indiscriminately along the image border.

   Input:
      inp       - input 8-bit image to be eroded
      iw        - width (in pixels) of image
      ih        - height (in pixels) of image
   Output:
      out       - contains to the resulting eroded image
**************************************************************************/
void erode_charimage_2(unsigned char *inp, unsigned char *out,
                     const int iw, const int ih)
{
   int row, col;
   unsigned char *itr = inp, *otr = out;
 
   memcpy(out, inp, iw*ih);
 
   /* for true pixels. kill pixel if there is at least one false neighbor */
   for ( row = 0 ; row < ih ; row++ )
      for ( col = 0 ; col < iw ; col++ )
      {  
         if (*itr)      /* erode only operates on true pixels */
         {
            /* more efficient with C's left to right evaluation of     */
            /* conjuctions. E N S functions not executed if W is false */
            if (!(get_west8_2 ((char *)itr, col        , 1 ) &&
                  get_east8_2 ((char *)itr, col, iw    , 1 ) &&
                  get_north8_2((char *)itr, row, iw    , 1 ) &&
                  get_south8_2((char *)itr, row, iw, ih, 1)))
               *otr = 0;
         }
         itr++ ; otr++;
      }  
}

/*************************************************************************
**************************************************************************
#cat: dilate_charimage_2 - Dilates an 8-bit image by setting false pixels to
#cat:             one if any of their 4 neighbors is non-zero.  Allocation
#cat:             of the output image is the responsibility of the caller.
#cat:             The input image remains unchanged.

   Input:
      inp       - input 8-bit image to be dilated
      iw        - width (in pixels) of image
      ih        - height (in pixels) of image
   Output:
      out       - contains to the resulting dilated image
**************************************************************************/
void dilate_charimage_2(unsigned char *inp, unsigned char *out,
                      const int iw, const int ih)
{
   int row, col;
   unsigned char *itr = inp, *otr = out;
 
   memcpy(out, inp, iw*ih);
 
   /* for all pixels. set pixel if there is at least one true neighbor */
   for ( row = 0 ; row < ih ; row++ )
      for ( col = 0 ; col < iw ; col++ )
      {  
         if (!*itr)     /* pixel is already true, neighbors irrelevant */
         {
            /* more efficient with C's left to right evaluation of     */
            /* conjuctions. E N S functions not executed if W is false */
            if (get_west8_2 ((char *)itr, col        , 0) ||
                get_east8_2 ((char *)itr, col, iw    , 0) ||
                get_north8_2((char *)itr, row, iw    , 0) ||
                get_south8_2((char *)itr, row, iw, ih, 0))
               *otr = 1;
         }
         itr++ ; otr++;
      }  
}

/*************************************************************************
**************************************************************************
#cat: get_south8_2 - Returns the value of the 8-bit image pixel 1 below the
#cat:                current pixel if defined else it returns  (char)0.

   Input:
      ptr       - points to current pixel in image
      row       - y-coord of current pixel
      iw        - width (in pixels) of image
      ih        - height (in pixels) of image
      failcode  - return value if desired pixel does not exist
   Return Code:
      Zero      - if neighboring pixel is undefined
                  (outside of image boundaries)
      Pixel     - otherwise, value of neighboring pixel
**************************************************************************/
char get_south8_2(char *ptr, const int row, const int iw, const int ih,
                  const int failcode)
{
   if (row >= ih-1) /* catch case where image is undefined southwards   */
      return failcode; /* use plane geometry and return code.           */

   return *(ptr+iw);
}

/*************************************************************************
**************************************************************************
#cat: get_north8_2 - Returns the value of the 8-bit image pixel 1 above the
#cat:                current pixel if defined else it returns  (char)0.

   Input:
      ptr       - points to current pixel in image
      row       - y-coord of current pixel
      iw        - width (in pixels) of image
      failcode  - return value if desired pixel does not exist
   Return Code:
      Zero      - if neighboring pixel is undefined
                  (outside of image boundaries)
      Pixel     - otherwise, value of neighboring pixel
**************************************************************************/
char get_north8_2(char *ptr, const int row, const int iw,
                  const int failcode)
{
   if (row < 1)     /* catch case where image is undefined northwards   */
      return failcode; /* use plane geometry and return code.           */

   return *(ptr-iw);
}

/*************************************************************************
**************************************************************************
#cat: get_east8_2 - Returns the value of the 8-bit image pixel 1 right of the
#cat:               current pixel if defined else it returns  (char)0.

   Input:
      ptr       - points to current pixel in image
      col       - x-coord of current pixel
      iw        - width (in pixels) of image
      failcode  - return value if desired pixel does not exist
   Return Code:
      Zero      - if neighboring pixel is undefined
                  (outside of image boundaries)
      Pixel     - otherwise, value of neighboring pixel
**************************************************************************/
char get_east8_2(char *ptr, const int col, const int iw,
                 const int failcode)
{
   if (col >= iw-1) /* catch case where image is undefined eastwards    */
      return failcode; /* use plane geometry and return code.           */

   return *(ptr+ 1);
}

/*************************************************************************
**************************************************************************
#cat: get_west8_2 - Returns the value of the 8-bit image pixel 1 left of the
#cat:              current pixel if defined else it returns  (char)0.

   Input:
      ptr       - points to current pixel in image
      col       - x-coord of current pixel
      failcode  - return value if desired pixel does not exist
   Return Code:
      Zero      - if neighboring pixel is undefined
                  (outside of image boundaries)
      Pixel     - otherwise, value of neighboring pixel
**************************************************************************/
char get_west8_2(char *ptr, const int col, const int failcode)
{
   if (col < 1)     /* catch case where image is undefined westwards     */
      return failcode; /* use plane geometry and return code.            */

   return *(ptr- 1);
}