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contour.c

Go to the documentation of this file.

#include        "sadie.h"

/*-Copyright Information------------------------------------------------------*/
/* Copyright (c) 1988 by the University of Arizona Digital Image Analysis Lab */
/*----------------------------------------------------------------------------*/
/*-General Information--------------------------------------------------------*/
/*                                                                            */
/*   This function produces a contour map of an image.                        */
/*                                                                            */
/*----------------------------------------------------------------------------*/
/*-Interface Information------------------------------------------------------*/
void
CONTOUR (IMAGE * in,            /*  I   Pointer to the input image.                           */
         short nlev,            /*  I   Number of contour lines.                              */
         double width,          /*  I   Width of contour lines, fraction less than one.       */
         IMAGE ** out           /*  O   Address of a pointer to the output image.             */
         /*      The input image may be overwritten (out = &in).       */
/*----------------------------------------------------------------------------*/
  )
{
  register short i, j, k;
  char msg[SLEN];
  double delta, class;

  if (TIMES)
    TIMING (T_CONTOUR);
  if (NAMES)
    {
      MESSAGE ('I', "");
      MESSAGE ('I', "CONTOUR");
      MESSAGE ('I', "");
      sprintf (msg, " Input image:               %s", in->text);
      MESSAGE ('I', msg);
      sprintf (msg, " Number of contour lines:   %d", nlev);
      MESSAGE ('I', msg);
      sprintf (msg, " Width of contour lines: %7.2f", width);
      MESSAGE ('I', msg);
      MESSAGE ('I', " ...............");
    }

  /* check input */
  if (!CHECKIMG (in))
    {
      MESSAGE ('E', " Can't identify image.");
      goto the_end;
    }
  else if (nlev <= 0)
    {
      MESSAGE ('E', " Number of contours must be greater than zero.");
      goto the_end;
    }
  else if (0.0 >= width || width >= 1.0)
    {
      MESSAGE ('E',
               " Width of contour lines must be greater than zero and less than one.");
      goto the_end;
    }

  /* create image of appropriate size */
  if (!CHECKIMG (*out))
    GETMEM (in->nbnd, in->nlin, in->npix, out);
  if (!*out)
    goto the_end;

  /* compute contours */
  RANGE (in);
  width = (1.0 - width) / 2.0;
  delta = (double) (in->gmax - in->gmin) / (double) nlev;
  for (i = 0; i < in->nbnd; i++)
    {
      for (j = 0; j < in->nlin; j++)
        {
          for (k = 0; k < in->npix; k++)
            {
              class = (double) (in->data[i][j][k] - in->gmin) / delta;
              (*out)->data[i][j][k] =
                (PIXEL) (fabs (class - (double) rnd (class)) >
                         width ? SMAX : SMIN);
            }
        }
    }
  (*out)->gmin = (PIXEL) SMIN;
  (*out)->gmax = (PIXEL) SMAX;

the_end:
  if (TIMES)
    TIMING (T_EXIT);
}

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