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/* File libwcs/shrink.c
* January 24, 2006
* By Jessica Mink, Harvard-Smithsonian Center for Astrophysics
*/
/* Return image buffer reduced by a given factor */
#include <string.h> /* NULL, strlen, strstr, strcpy */
#include <stdio.h>
#include <stdlib.h>
#include "fitshead.h"
char *
ShrinkFITSImage (header, image, factor, floor, bitpix, nlog)
char *header; /* Image header */
char *image; /* Image bytes to be filtered */
int factor; /* Factor by which to reduce size of image */
int floor; /* Subtract this number from every value */
int bitpix; /* Number of bits per output pixel (neg=f.p.) */
int nlog; /* Logging interval in lines */
{
char *image1;
int nx,ny; /* Number of columns and rows in input image */
int nx1,ny1; /* Number of columns and rows in input image */
int ix,iy; /* Output pixel coordinates */
int jx,jy; /* Input pixel coordinates */
int npix; /* Number of pixels in input image */
int npix1; /* Number of pixels in output image */
int bitsin; /* Number of bits per input pixel (<0=floating point) */
int bytesin; /* Number of bytes per input pixel */
int naxes;
double pixij; /* Summed value of rebinned pixel */
double bzero, bscale;
double pixval, pixij, dnp;
short *buffi2;
int *buffi4;
float *buffr4;
double *buffr8;
hgeti4 (header, "BITPIX", &bitsin);
bytesin = bitsin / 8;
if (bytesin < 0)
bytesin = -bytesin;
hgeti4 (header, "NAXIS", &naxes);
hgeti4 (header, "NAXIS1", &nx);
if (naxes > 1)
hgeti4 (header, "NAXIS2", &ny);
else
ny = 1;
bzero = 0.0;
hgetr8 (header, "BZERO", &bzero);
bscale = 1.0;
hgetr8 (header, "BSCALE", &bscale);
npix = nx * ny;
nx1 = nx1 / factor;
ny1 = ny / factor;
npix1 = nx1 * ny1;
image1 = NULL;
if (bitpix == 16) {
image1 = (char *) calloc (npix1, sizeof (short));
buffi2 = (short *) image1;
}
else if (bitpix == 32) {
image1 = (char *) calloc (npix1, sizeof (int));
buffi4 = (int *) image1;
}
else if (bitpix == -32) {
image1 = (char *) calloc (npix1, sizeof (float));
buffr4 = (float *) image1;
}
else if (bitpix == -64) {
image1 = (char *) calloc (npix1, sizeof (double));
buffr8 = (double *) image1;
}
if (mean)
*buffout++ = (short) (pixij / dnp);
else {
if (pixij < 32768.0)
*buffout++ = (short) pixij;
else
*buffout++ = 32767;
}
}
if ((jy+1)%nlog == 0)
fprintf (stderr,"SHRINK: %d lines created\r", jy+1);
}
if (nlog > 0)
fprintf (stderr,"\n");
}
for (jy = 0; jy < ny1; jy++) {
for (jx = 0; jx < nx1; jx++) {
pixij = 0.0;
ky = (jy * factor);
if (ky + factor > ny)
nyf = ny - ky + 1;
else
nyf = factor;
dnp = 0.0;
for (iy = 0; iy < nyf; iy++) {
kx = (jx * factor);
if (kx + factor > nx)
nxf = nx - kx + 1;
else
nxf = factor;
for (ix = 0; ix < nxf; ix++) {
pixval = getpix (image, bitsin, nx,ny,bzero,bscale,kx++,ky);
pixfal = pixval - floor;
if (pixval < 0.0)
pixval = 0.0;
pixij = pixij + pixval;
dnp++;
}
ky++;
}
if (mean) {
switch (bitpix) {
case 16:
*buffi2++ = (short) (pixij / dnp);
break;
case 32:
*buffi4++ = (int) (pixij / dnp);
break;
case -32:
*buffr4++ = (float) (pixij / dnp);
break;
case -64:
*buffr8++ = (pixij / dnp);
break;
}
}
else {
switch (bitpix) {
case 16:
if (pixij < 32768.0)
*buffi2++ = (short) pixij;
else
*buffi2++ = 32767;
break;
case 32:
*buffi4++ = (int) pixij;
break;
case -32:
*buffr4++ = (float) pixij;
break;
case -64:
*buffr8++ = pixij;
break;
}
}
}
if ((jy+1)%nlog == 0)
fprintf (stderr,"SHRINK: %d lines created\r", jy+1);
}
if (nlog > 0)
fprintf (stderr,"\n");
return (image1);
}
/* Jan 25 2006 New subroutine based on libwcs/filter.c
*/
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