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Diffstat (limited to 'astro/fits/rescale_image.py')
| -rwxr-xr-x | astro/fits/rescale_image.py | 197 |
1 files changed, 0 insertions, 197 deletions
diff --git a/astro/fits/rescale_image.py b/astro/fits/rescale_image.py deleted file mode 100755 index d0ae218..0000000 --- a/astro/fits/rescale_image.py +++ /dev/null @@ -1,197 +0,0 @@ -#!/usr/bin/env python3 -# -# Copyright (c) 2017 Aaron LI <aly@aaronly.me> -# MIT license -# - -""" -Rescale the FITS image to increase/decrease the pixel resolution -by interpolation, meanwhile keep the image FoV and update FITS WCS. - -For example, we may simulate the galaxy clusters (and point sources) -foreground component with a (much) higher resolution (smaller pixels) -compared to other foreground components (e.g., Galactic synchrotron) -and EoR signal. After simulating the observed images using OSKAR and -WSClean, the output images may in different sizes/resolution, which -may cause some troubles in subsequent usage, e.g., power spectrum -calculation. -""" - -import sys -import argparse -from datetime import datetime, timezone - -import numpy as np -from astropy.io import fits -from astropy.wcs import WCS -from scipy import ndimage - - -class FITSImage: - def __init__(self, filename, pixelsize=None): - self.filename = filename - self.header, self.image = self.open_image(filename) - if pixelsize is not None: - self.pixelsize = pixelsize - print("Loaded FITS image from file: %s" % filename) - print("FITS image size: %dx%d" % (self.Nx, self.Ny)) - print("Pixel size: %.1f [arcsec]" % self.pixelsize) - print("FoV: %.2fx%.2f [deg^2]" % self.fov) - - def rescale(self, shape, order=1): - print("Rescaling FITS image ...") - try: - Ny2, Nx2 = shape - except TypeError: - Ny2 = Nx2 = shape - print("Scale output size: %dx%d" % (Nx2, Ny2)) - print("Scale interpolation order: %d" % order) - zoom = ((Ny2+0.1)/self.Ny, (Nx2+0.1)/self.Nx) - pixelsize_old = self.pixelsize - self.image = ndimage.zoom(self.image, zoom=zoom, order=order) - self.pixelsize = pixelsize_old / zoom[0] - print("Scaled pixel size: %.1f [arcsec]" % self.pixelsize) - - def crop(self, size): - print("Cropping FITS image ...") - try: - xsize, ysize = size # [deg] - except TypeError: - xsize = ysize = size - Nx2 = round(xsize * 3600 / self.pixelsize) - Ny2 = round(ysize * 3600 / self.pixelsize) - if Nx2 > self.Nx or Ny2 > self.Ny: - raise ValueError("Crop region too large!") - - print("Central crop box size: %.2fx%.2f [deg^2]" % (xsize, ysize)) - print("Cropped image size: %dx%d" % (Nx2, Ny2)) - xi0 = int((self.Nx-Nx2) / 2) - yi0 = int((self.Ny-Ny2) / 2) - self.image = self.image[yi0:(yi0+Ny2), xi0:(xi0+Nx2)] - - def write(self, outfile, clobber=False): - header = self.header.copy(strip=True) - header.extend(self.wcs.to_header(), update=True) - header["DATE"] = (datetime.now(timezone.utc).astimezone().isoformat(), - "File creation date") - header.add_history(" ".join(sys.argv)) - hdu = fits.PrimaryHDU(data=self.image, header=header) - try: - hdu.writeto(outfile, overwrite=clobber) - except TypeError: - hdu.writeto(outfile, clobber=clobber) - print("Wrote FITS image to file: %s" % outfile) - - @property - def fov(self): - # Unit: [deg] - return (self.Nx*self.pixelsize/3600, self.Ny*self.pixelsize/3600) - - @property - def pixelsize(self): - # Unit: [arcsec] - if hasattr(self, "_pixelsize"): - return self._pixelsize - - try: - return self.header["PixSize"] # [arcsec] - except KeyError: - try: - return abs(self.header["CDELT1"]) * 3600 # [deg] -> [arcsec] - except KeyError: - raise ValueError("Cannot obtain pixel size from header; " + - "please manually provide --pixelsize") - - @pixelsize.setter - def pixelsize(self, value): - # Unit: [arcsec] - self._pixelsize = value - - @property - def Nx(self): - return self.image.shape[1] - - @property - def Ny(self): - return self.image.shape[0] - - @property - def wcs(self): - hdr = self.header - w = WCS(naxis=2) - w.wcs.equinox = hdr.get("EQUINOX", 2000.0) - w.wcs.ctype = [hdr.get("CTYPE1", "RA---SIN"), - hdr.get("CTYPE2", "DEC--SIN")] - w.wcs.crval = np.array([hdr.get("CRVAL1", 0.0), - hdr.get("CRVAL2", 0.0)]) - w.wcs.crpix = np.array([self.Ny/2+1, self.Nx/2+1]) - w.wcs.cdelt = np.array([-self.pixelsize/3600, self.pixelsize/3600]) - w.wcs.cunit = [hdr.get("CUNIT1", "deg"), hdr.get("CUNIT2", "deg")] - return w - - @staticmethod - def open_image(infile): - """ - Open the slice image and return its header and 2D image data. - - NOTE - ---- - The input slice image may have following dimensions: - * NAXIS=2: [Y, X] - * NAXIS=3: [FREQ=1, Y, X] - * NAXIS=4: [STOKES=1, FREQ=1, Y, X] - - NOTE - ---- - Only open slice image that has only ONE frequency and ONE Stokes - parameter. - - Returns - ------- - header : `~astropy.io.fits.Header` - image : 2D `~numpy.ndarray` - The 2D [Y, X] image part of the slice image. - """ - with fits.open(infile) as f: - header = f[0].header - data = f[0].data - if data.ndim == 2: - # NAXIS=2: [Y, X] - image = data - elif data.ndim == 3 and data.shape[0] == 1: - # NAXIS=3: [FREQ=1, Y, X] - image = data[0, :, :] - elif data.ndim == 4 and data.shape[0] == 1 and data.shape[1] == 1: - # NAXIS=4: [STOKES=1, FREQ=1, Y, X] - image = data[0, 0, :, :] - else: - raise ValueError("Slice '{0}' has invalid dimensions: {1}".format( - infile, data.shape)) - return (header, image) - - -def main(): - parser = argparse.ArgumentParser( - description="Rescale a FITS image to the desired size/resolution") - parser.add_argument("-C", "--clobber", action="store_true", - help="overwrite existing output file") - parser.add_argument("--order", type=int, default=1, - help="scale interpolation order (default: 1)") - parser.add_argument("-s", "--size", type=int, required=True, - help="output image size (number of pixels)") - parser.add_argument("-p", "--pixelsize", type=float, - help="input FITS image pixel size [arcsec] " + - "(default: try to obtain from FITS header)") - parser.add_argument("-i", "--infile", required=True, - help="input FITS image") - parser.add_argument("-o", "--outfile", required=True, - help="output FITS image") - args = parser.parse_args() - - fitsimage = FITSImage(args.infile, pixelsize=args.pixelsize) - fitsimage.rescale(shape=args.size, order=args.order) - fitsimage.write(args.outfile, clobber=args.clobber) - - -if __name__ == "__main__": - main() |