diff options
| -rwxr-xr-x | astro/fits/fitsimage.py | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/astro/fits/fitsimage.py b/astro/fits/fitsimage.py index 566cb53..22f066c 100755 --- a/astro/fits/fitsimage.py +++ b/astro/fits/fitsimage.py @@ -13,6 +13,7 @@ import argparse import numpy as np from astropy.io import fits +from scipy import ndimage class FITSImage: @@ -100,6 +101,10 @@ class FITSImage: # Unit: [arcsec] oldvalue = self.pixelsize self._pixelsize = value + # Update header + self.header["PixSize"] = value # [arcsec] + self.header["CDELT1"] *= value / oldvalue + self.header["CDELT2"] *= value / oldvalue @property def fov(self): @@ -113,6 +118,35 @@ class FITSImage: else: return None + def zoom(self, newsize, order=1): + """ + Zoom the image to the specified ``newsize``, meanwhile the header + information will be updated accordingly to preserve the FoV coverage. + + NOTE + ---- + The image aspect ratio cannot be changed. + + Parameters + ---------- + newsize : (Nx, Ny) or N + The size of the zoomed image. + order : int, optional + The interpolation order, default: 1 + """ + try: + Nx2, Ny2 = newsize + except TypeError: + Nx2 = Ny2 = newsize + zoom = ((Ny2+0.1)/self.Ny, (Nx2+0.1)/self.Nx) + if abs(zoom[0] - zoom[1]) > 1e-3: + raise RuntimeError("image aspect ratio cannot be changed") + + pixelsize_old = self.pixelsize + self.image = ndimage.zoom(self.image, zoom=zoom, order=order) + self.pixelsize = pixelsize_old / zoom[0] + return self.image + def write(self, outfile, clobber=False): self.header.add_history(" ".join(sys.argv)) hdu = fits.PrimaryHDU(data=self.data, header=self.header) @@ -127,6 +161,7 @@ def cmd_info(args): Sub-command: "info", show FITS image information """ fimage = FITSImage(args.infile) + print("Image data shape: {0}".format(fimage.shape)) print("Image size: %dx%d" % (fimage.Nx, fimage.Ny)) print("Data unit: [%s]" % fimage.bunit) pixelsize = fimage.pixelsize @@ -213,6 +248,29 @@ def cmd_mul(args): print("Saved FITS image to: %s" % args.outfile) +def cmd_zoom(args): + """ + Sub-command: "zoom", zoom the image to a new size with FoV coverage + preserved. + """ + fimage = FITSImage(args.infile) + print("Image size: %dx%d" % (fimage.Nx, fimage.Ny)) + pixelsize = fimage.pixelsize + if pixelsize is None: + raise RuntimeError("--pixelsize required") + else: + print("Pixel size: %.1f [arcsec]" % pixelsize) + print("Field of view: (%.2f, %.2f) [deg]" % fimage.fov) + + print("Zooming image ...") + print("Interpolation order: %d" % args.order) + print("Zoomed image size: %dx%d" % (args.size, args.size)) + fimage.zoom(newsize=args.size, order=args.order) + print("Zoomed image pixel size: %.1f [arcsec]" % pixelsize) + fimage.write(args.outfile, clobber=args.clobber) + print("Saved zoomed FITS image to: %s" % args.outfile) + + def main(): parser = argparse.ArgumentParser( description="FITS image manipulation tool") @@ -285,6 +343,26 @@ def main(): help="FITS image(s) to be multiplied by") parser_mul.set_defaults(func=cmd_mul) + # sub-command: "zoom" + parser_zoom = subparsers.add_parser( + "zoom", aliases=["rescale"], + help="zoom the image to a new size with FoV coverage preserved") + parser_zoom.add_argument("-C", "--clobber", dest="clobber", + action="store_true", + help="overwrite existing output file") + parser_zoom.add_argument("--order", type=int, default=1, + help="zoom interpolation order (default: 1)") + parser_zoom.add_argument("-s", "--size", type=int, required=True, + help="zoomed image size (number of pixels)") + parser_zoom.add_argument("-p", "--pixelsize", type=float, + help="input FITS image pixel size [arcsec] " + + "(default: try to obtain from FITS header)") + parser_zoom.add_argument("-i", "--infile", dest="infile", required=True, + help="input FITS image") + parser_zoom.add_argument("-o", "--outfile", dest="outfile", required=True, + help="output zoomed FITS image") + parser_zoom.set_defaults(func=cmd_zoom) + args = parser.parse_args() args.func(args) |