---

scatter.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 computes the joint two-dimensional histogram               */
/*   (scattergram) between two bands from either the same or from             */
/*   two different images.  The first input image graylevels are              */
/*   along the ordinate and the second input image graylevels are             */
/*   along the abscissa of the scattergram.                                   */
/*                                                                            */
/*----------------------------------------------------------------------------*/
/*-Interface Information------------------------------------------------------*/
void
SCATTER (IMAGE * in1,           /*  I   Pointer to the first input image.                     */
         IMAGE * in2,           /*  I   Pointer to the second input image.                    */
         short bnd1,            /*  I   Band in the first image.                              */
         short bnd2,            /*  I   Band in the second image.                             */
         short inc,             /*  I   Line and pixel subsample increment.                   */
         short nlev,            /*  I   Histogram resolution (and number of lines and         */
         /*      pixels/line in the output image).                     */
         IMAGE ** out           /*  O   Address of a pointer to the output image.             */
/*----------------------------------------------------------------------------*/
  )
{
  register short i, j, ix, iy;
  char msg[SLEN];
  double width, pinc, psum;
  PIXEL gmin, gmax;

  if (TIMES)
    TIMING (T_SCATTER);
  if (NAMES)
    {
      MESSAGE ('I', "");
      MESSAGE ('I', "SCATTER");
      MESSAGE ('I', "");
      sprintf (msg, " First input image:                    %s - band %d",
               in1->text, bnd1 + 1);
      MESSAGE ('I', msg);
      sprintf (msg, " Second input image:                   %s - band %d",
               in2->text, bnd2 + 1);
      MESSAGE ('I', msg);
      sprintf (msg, " Histogram resolution:                 %d", nlev);
      MESSAGE ('I', msg);
      sprintf (msg, " Line and pixel subsample increment:   %d", inc);
      MESSAGE ('I', msg);
      MESSAGE ('I', " ...............");
    }

  /* check input */
  if (!CHECKIMG (in1))
    {
      MESSAGE ('E', " Can't identify first image.");
      goto the_end;
    }
  else if (!CHECKIMG (in2))
    {
      MESSAGE ('E', " Can't identify second image.");
      goto the_end;
    }
  else if (0 > bnd1 || bnd1 >= in1->nbnd)
    {
      MESSAGE ('E', " Can't identify first band.");
      goto the_end;
    }
  else if (0 > bnd2 || bnd2 >= in2->nbnd)
    {
      MESSAGE ('E', " Can't identify second band.");
      goto the_end;
    }
  else if (in1->nlin != in2->nlin)
    {
      MESSAGE ('E', " Number of lines must be identical in both images.");
      goto the_end;
    }
  else if (in1->npix != in2->npix)
    {
      MESSAGE ('E',
               " Number of pixels/line must be identical in both images.");
      goto the_end;
    }
  else if (inc <= 0)
    {
      MESSAGE ('E', " Subsample increment must be greater than zero.");
      goto the_end;
    }
  else if (nlev <= 0)
    {
      MESSAGE ('E', " Number of histogram bins must be greater than zero.");
      goto the_end;
    }

  /* create image of appropriate size */
  if (!CHECKIMG (*out))
    GETMEM (1, nlev, nlev, out);
  if (!*out)
    goto the_end;

  /* initialize progress indicator */
  if (LINES && !PROGRESS (psum = 0.0))
    goto the_end;
  pinc = 1.0 / (double) (in1->nlin / inc + (in1->nlin % inc ? 1 : 0));

  /* compute min, max, and bandwidth */
  RANGE (in1);
  RANGE (in2);
  gmin = min (in1->gmin, in2->gmin);
  gmax = max (in1->gmax, in2->gmax);
  width = (double) (gmax - gmin) / (double) (nlev - 1);

  /* initialize scattergram */
  for (i = 0; i < nlev; i++)
    {
      for (j = 0; j < nlev; j++)
        {
          (*out)->data[0][i][j] = (PIXEL) 0;
        }
    }

  /* calculate the scattergram */
  for (i = 0; i < in1->nlin; i += inc)
    {
      for (j = 0; j < in1->npix; j += inc)
        {
          ix = (short) ((double) (in1->data[bnd1][i][j] - gmin) / width);
          iy = (short) ((double) (in2->data[bnd2][i][j] - gmin) / width);
          (*out)->data[0][ix][iy] += (PIXEL) 1;
        }
      if (LINES && !PROGRESS (psum += pinc))
        goto the_end;
    }

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

---