convert.c

数字信号处理实验

void char2double(unsigned char *in, 
		 double *re, double *im,
		 int mat_size)
{
  int i;

  for(i=0;i<mat_size;i++)
    {
      re[i]=(double)in[i];
      im[i]=0.0;
    }
}


void double2char(unsigned char *in, 
		 double *re, double *im,
		 int mat_size)
{
  int i;

  for(i=0;i<mat_size;i++)
    {
      if(re[i]>255.0)
	{
	  in[i]=255;
	}
      else if(re[i]<0.0)
	{
	  in[i]=0;
	}
      else
	{
	  in[i]=(unsigned char)re[i];
	}
    }
}


void power_spectle(double *re, double *im,
		   unsigned char *img,
		   int ms)
{
  int i;
  double *buf, upper,below,ave;

  buf = (double *)malloc(ms * sizeof(double));

  upper =0.0;below=0.0;  ave = 0.0;

  for(i=0;i<ms;i++)
    {
      buf[i] = (re[i] * re[i] + im[i] * im[i]);
      ave += buf[i];

      if(upper<buf[i])
	{
	  upper = buf[i];
	}

      if(below>buf[i])
	{
	  below = buf[i];
	}
    }
  /*
  printf("%f,%f,%f\n",below, upper,ave/ms);*/

  for(i=0;i<ms;i++)
    {

      img[i]=(unsigned char)(buf[i] *256.0 / (3.0 * ave));
    }
  free(buf);
}