static filt_init()
{
/* count the filters to set nfilt */
for (nfilt=0; nfilt<NFILTMAX && filt[nfilt].name; nfilt++);
/* better way?? */
mitchell_init(1./3., 1./3., (char *)&md);
kaiser_init(6.5, 0., (char *)&kd);
}
/*!
* Selects which filter to use in image reduction with [type] and sets the scaling factor
* with [zoom], a value that must be less than 1. The type can be 0 for a box
* (equivalent to binning), 1 for a Blackman window, 2 for a triangle filter, 3 for a
* Mitchell filter, or 4 or 5 for Lanczos 2 or Lanczos 3. The total
* width of the filter in the source image is returned in [outWidth]. Returns 1 for
* a filter type out of range or 2 for a zoom out of range.
*/
int selectZoomFilter(int type, double zoom, int *outWidth)
{
sFilt_func = NULL;
if (type < 0 || type >= NUM_FILT)
return 1;
if (zoom >= 1. || zoom <= 0.)
return 2;
sFilt_func = filters[type].func;
sXscale = sYscale = 1. / zoom;
sXsupport = sYsupport = filters[type].supp * sXscale;
sXwidth = sYwidth = (int)ceil(2. * sXsupport);
*outWidth = sXwidth;
if (type == 3)
mitchell_init(1./3., 1./3.);
return 0;
}
