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chirp.c

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#include        "sadie.h"

/*-Copyright Information------------------------------------------------------*/
/* Copyright (c) 1993 by the University of Arizona Digital Image Analysis Lab */
/*----------------------------------------------------------------------------*/
/*-General Information--------------------------------------------------------*/
/*                                                                            */
/*   This function creates a chirp test pattern.                              */
/*                                                                            */
/*----------------------------------------------------------------------------*/
/*-Interface Information------------------------------------------------------*/
void
CHIRP (short nlin,              /*  I   Number of lines in the output image.                  */
       short npix,              /*  I   Number of pixels/line in the output image.            */
       double period,           /*  I   Period of the chirp in pixels.                        */
       IMAGE ** out             /*  O   Address of a pointer to the output image.             */
/*----------------------------------------------------------------------------*/
  )
{
  register short j, k;
  char msg[SLEN];
  double x, y;

  if (TIMES)
    TIMING (T_CHIRP);
  if (NAMES)
    {
      MESSAGE ('I', "");
      MESSAGE ('I', "CHIRP");
      MESSAGE ('I', "");
      sprintf (msg, " Image size: lines:           %d", nlin);
      MESSAGE ('I', msg);
      sprintf (msg, "             pixels:          %d", npix);
      MESSAGE ('I', msg);
      sprintf (msg, " Period:                    %12.4e", period);
      MESSAGE ('I', msg);
      MESSAGE ('I', " ...............");
    }

  /* create image of appropriate size */
  if (!CHECKIMG (*out))
    GETMEM (1, nlin, npix, out);

  /* create chirp test pattern */
  period = PI / period;
  for (j = 0; j < nlin; j++)
    {
      y = (double) (j - nlin / 2) * (j - nlin / 2);
      for (k = 0; k < npix; k++)
        {
          x = sqrt ((double) (k - npix / 2) * (double) (k - npix / 2) + y);
          (*out)->data[0][j][k] = (PIXEL) cos (x * x * period);
        }
    }

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

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