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pct.c

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#include        "sadie.h"

/*-Copyright Information------------------------------------------------------*/
/* Copyright (c) 1988 by the University of Arizona Digital Image Analysis Lab */
/*----------------------------------------------------------------------------*/
/*-General Information--------------------------------------------------------*/
/*                                                                            */
/*   This function performs a principal component transform on a multi-band   */
/*   image.                                                                   */
/*                                                                            */
/*----------------------------------------------------------------------------*/
/*-Interface Information------------------------------------------------------*/
void
PCT (IMAGE * in,                /*  I   Pointer to the input image                            */
     short inc,                 /*  I   Line and pixel subsample increment to be used for     */
     /*      calculating the covariance matrix.                    */
     IMAGE ** out               /*  O   Address of a pointer to the output image.             */
     /*      The input image may be overwritten (out = &in).       */
/*----------------------------------------------------------------------------*/
  )
{
  register short i, j, k, l;
  char msg[SLEN];
  double *cov = 0, *cor = 0, *eig = 0, sum, pinc, psum;

  if (TIMES)
    TIMING (T_PCT);
  if (NAMES)
    {
      MESSAGE ('I', "");
      MESSAGE ('I', "PCT");
      MESSAGE ('I', "");
      sprintf (msg, " Input image:                         %s", in->text);
      MESSAGE ('I', msg);
      sprintf (msg, " Line and pixel subsample increment:  %d", inc);
      MESSAGE ('I', msg);
      MESSAGE ('I', " ...............");
    }

  /* check input */
  if (!CHECKIMG (in))
    {
      MESSAGE ('E', " Can't identify image.");
      goto the_end;
    }
  else if (in->nbnd == 1)
    {
      MESSAGE ('E', " Image must be multi-band.");
      goto the_end;
    }
  else if (inc <= 0)
    {
      MESSAGE ('E', " Subsample increment must be greater than zero.");
      goto the_end;
    }

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

  /* allocate space for cov, cor, and eig */
  if (!(cov = (double *) malloc (in->nbnd * in->nbnd * sizeof (double))))
    {
      MESSAGE ('E', " Memory request failed.");
      goto the_end;
    }
  if (!(cor = (double *) malloc (in->nbnd * in->nbnd * sizeof (double))))
    {
      MESSAGE ('E', " Memory request failed.");
      goto the_end;
    }
  if (!(eig = (double *) malloc (in->nbnd * in->nbnd * sizeof (double))))
    {
      MESSAGE ('E', " Memory request failed.");
      goto the_end;
    }

  /* initialize progress indicator */
  if (LINES && !PROGRESS (psum = 0.0))
    goto the_end;
  pinc = 1.0 / (double) in->nbnd / (double) in->nlin;

  /* compute covariance matrix of the input image and its eigenvectors */
  COVAR (in, inc, cov, cor);
  if (ABORT)
    goto the_end;
  EIGEN (cov, in->nbnd, eig);
  if (ABORT)
    goto the_end;

  /* perform principal component transform */
  for (i = 0; i < in->nbnd; i++)
    {
      for (j = 0; j < in->nlin; j++)
        {
          for (k = 0; k < in->npix; k++)
            {
              for (sum = 0.0, l = 0; l < in->nbnd; l++)
                {
                  sum += (double) in->data[l][j][k] * eig[l * in->nbnd + i];
                }
              (*out)->data[i][j][k] = (PIXEL) sum;
            }
          if (LINES && !PROGRESS (psum += pinc))
            goto the_end;
        }
    }

the_end:
  if (cov)
    free (cov);
  if (cor)
    free (cor);
  if (eig)
    free (eig);
  if (TIMES)
    TIMING (T_EXIT);
}

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