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rmsdiff.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 root-mean-squared difference between          */
/*   two images.                                                              */
/*                                                                            */
/*----------------------------------------------------------------------------*/
/*-Interface Information------------------------------------------------------*/
void
RMSDIFF (IMAGE * in1,           /*  I   Pointer to the first input image.                     */
         IMAGE * in2,           /*  I   Pointer to the second input image.                    */
         double *diff           /*  O   Address of a variable to hold the rms-difference.     */
/*----------------------------------------------------------------------------*/
  )
{
  register short i, j, k;
  char msg[SLEN];

  if (TIMES)
    TIMING (T_RMSDIFF);
  if (NAMES)
    {
      MESSAGE ('I', "");
      MESSAGE ('I', "RMSDIFF");
      MESSAGE ('I', "");
      sprintf (msg, " First input image:    %s", in1->text);
      MESSAGE ('I', msg);
      sprintf (msg, " Second input image:   %s", in2->text);
      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 (in1->nbnd != in2->nbnd)
    {
      MESSAGE ('E', " Number of bands must be identical in both images.");
      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;
    }

  /* calculate the root-mean-squared difference */
  for (*diff = 0.0, i = 0; i < in1->nbnd; i++)
    {
      for (j = 0; j < in1->nlin; j++)
        {
          for (k = 0; k < in1->npix; k++)
            {
              *diff +=
                (double) ((in1->data[i][j][k] -
                           in2->data[i][j][k]) * (in1->data[i][j][k] -
                                                  in2->data[i][j][k]));
            }
        }
    }
  *diff =
    sqrt (*diff /
          ((double) in1->nbnd * (double) in1->nlin * (double) in1->npix));

  /* output the resulting difference */
  MESSAGE ('I', "");
  sprintf (msg, " Root-Mean-Squared Difference = %-11.4e", *diff);
  MESSAGE ('I', msg);

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

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