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segment.c

Go to the documentation of this file.

#include        "sadie.h"

/*-Copyright Information------------------------------------------------------*/
/* Copyright (c) 1990 by the University of Arizona Digital Image Analysis Lab */
/*----------------------------------------------------------------------------*/
/*-General Information--------------------------------------------------------*/
/*                                                                            */
/*   This function optionally resamples an image, creates a label map of      */
/*   the image by segmenting it into regions of similar graylevels, and,      */
/*   if the input image was resampled, refines the label map back to the      */
/*   original resolution of the input image.                                  */
/*                                                                            */
/*----------------------------------------------------------------------------*/
/*-Background Information-----------------------------------------------------*/
/*                                                                            */
/*   Mehldau, G.:                                                             */
/*   "An Image Segmentation Algorithm."                                       */
/*   University of Arizona, DIAL, Technical Report No. 90-3                   */
/*                                                                            */
/*----------------------------------------------------------------------------*/
/*-Interface Information------------------------------------------------------*/
void
SEGMENT (IMAGE * in,            /*  I   Pointer to the input image.                           */
         short steps,           /*  I   Number of reduction steps.                            */
         double sigma,          /*  I   Greylevel variance threshold.                         */
         PIXEL thresh,          /*  I   Greylevel difference threshold.                       */
         IMAGE ** out           /*  O   Address of a pointer to the output image.             */
/*----------------------------------------------------------------------------*/
  )
{
  register short i;
  char msg[SLEN];
  IMAGE **scratch = 0, *img[3];

  if (TIMES)
    TIMING (T_SEGMENT);
  if (NAMES)
    {
      MESSAGE ('I', "");
      MESSAGE ('I', "SEGMENT");
      MESSAGE ('I', "");
      sprintf (msg, " Input image:                      %s", in->text);
      MESSAGE ('I', msg);
      sprintf (msg, " Graylevel difference threshold: %12.4e", thresh);
      MESSAGE ('I', msg);
      sprintf (msg, " Graylevel variance threshold:   %12.4e", sigma);
      MESSAGE ('I', msg);
      sprintf (msg, " Number of reduction steps:        %d", steps);
      MESSAGE ('I', msg);
      MESSAGE ('I', " ...............");
    }

  /* check input */
  if (!CHECKIMG (in))
    {
      MESSAGE ('E', " Can't identify image.");
      goto the_end;
    }
  else if (steps < 0)
    {
      MESSAGE ('E',
               " Number of reduction steps must be equal to or greater than zero.");
      goto the_end;
    }

  /* allocate and initialize image vector */
  if (!(scratch = (IMAGE **) malloc ((2 * steps + 2) * sizeof (IMAGE *))))
    {
      MESSAGE ('E', " Memory request failed.");
      goto the_end;
    }
  for (i = 0; i < 2 * steps + 2; scratch[i++] = 0);

  /* reduce image */
  scratch[0] = in;
  for (i = 0; i < steps; i++)
    {
      RESAMPL (scratch[i], 2, 2, 2, 2, scratch + i + 1);
      if (ABORT || !scratch[i + 1])
        goto the_end;
      sprintf (scratch[i + 1]->text, "Scratch");
    }

  /* label image */
  LABEL (scratch[steps], sigma, thresh, scratch + steps + 1);
  if (ABORT || !scratch[steps + 1])
    goto the_end;
  sprintf (scratch[steps + 1]->text, "Scratch");

  /* refine image */
  for (i = 0; i < steps; i++)
    {
      img[0] = scratch[steps + i + 1];
      img[1] = scratch[steps - i];
      img[2] = scratch[steps - i - 1];
      REFINE (img, scratch + steps + i + 2);
      if (ABORT || !scratch[steps + i + 2])
        goto the_end;
      sprintf (scratch[steps + i + 2]->text, "Scratch");
      RELMEM (scratch[steps - i]);
      scratch[steps - i] = 0;
    }
  *out = scratch[2 * steps + 1];

the_end:
  if (scratch)
    {
      for (i = 1; i < 2 * steps + 1; i++)
        {
          if (scratch[i])
            RELMEM (scratch[i]);
        }
      free (scratch);
    }
  if (TIMES)
    TIMING (T_EXIT);
}

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